Surfaces of the temporal pyramid. Bones (Anterior surface of the pyramid – Tympanomastoid fissure). Questions to reinforce learned material
scaly part, pars squamosa, has the shape of a plate and is located almost in the sagittal direction. Outer temporal surface facies temporalis, The scaly part is slightly rough and slightly convex. In the posterior section, the groove of the middle temporal artery runs in the vertical direction, sulcus arteriae temporalis mediae
In the posteroinferior part of the scaly part there is an arcuate line, which continues into the lower temporal line, linea temporalis inferior, parietal bone.
rice. 49. Skull, cranium; right view (semi-schematic).From the scaly part, above and slightly anterior to the external auditory opening, the zygomatic process extends horizontally, processus zygomaticus. It is like a continuation of the supramastoid crest, crista supramastoidea, located horizontally along the lower edge of the outer surface of the scaly part (see Fig.). Beginning with a wide root, the zygomatic process then narrows. It has an inner and outer surface and two edges - a longer upper one and a shorter lower one. The anterior end of the zygomatic process is serrated. Zygomatic process of the temporal bone and temporal process, processus temporalis, the zygomatic bones are connected using the temporomygomatic suture, sutura temporozygomatica, forming the zygomatic arch, arcus zygomaticus.
On the lower surface of the root of the zygomatic process there is a transverse oval-shaped mandibular fossa, fossa mandibularis. The anterior half of the fossa, up to the petrosquamosal fissure, is the articular surface, facies articularis, temporomandibular joint. Anteriorly, the mandibular fossa is limited by the articular tubercle, tuberculum articulare, (see fig. , ).
rice. 51. Skull (x-ray, lateral projection). 1 - parietal bone; 2 - sella turcica; 3 - back of the saddle; 4 - slope; 5 - occipital bone; 6 - temporal bone (stony part); 7 - II cervical vertebra; 8 - transverse process; 9 - ossicular process; 10 - condylar process of the lower jaw; 11 - lower jaw; 12 - incisors of the lower jaw; 13 - incisors of the upper jaw; 14 - upper jaw; 15 - maxillary sinus; 16 - anterior nasal spine; 17 - coronoid process of the lower jaw; 18 - infraorbital margin; 19 - eye socket; 20 - sphenoid sinus; 21 - anterior inclined process; 22 - nasal bone; 23 - frontal sinus; 24 - frontal bone. 
rice. 50. Skull (x-ray, posteroanterior projection). 1 - parietal bone; 2 - frontal bone; 3 - temporal bone (stony part); 4 - zygomatic bone; 5 - condylar process of the lower jaw; 6 - coronoid process of the lower jaw; 7 - maxillary sinus: 8 - upper jaw; 9 - tooth (upper lateral incisor); 10 - lower jaw; 11 - inferior nasal concha; 12 - bony nasal septum; 13 - middle turbinate; 14 - temporal bone; 15 - eye socket; 16 - frontal sinus; 17 - septum of the frontal sinuses. The outer surface of the scaly part is involved in the formation of the temporal fossa, fossa temporalis, (the bundles of the temporal muscle begin here, m. temporalis).
Inner brain surface facies cerebralis, slightly concave. It has finger-like indentations, impressiones digitatae, as well as the arterial groove, sulcus arteriosus, (it contains the middle meningeal artery, a. meningea media).
The squamous part of the temporal bone has two free edges - the sphenoid and the parietal.
Anteroinferior wedge-shaped edge, margo sphenoidalis, wide, serrated, connects with the scaly edge of the large wing of the sphenoid bone and forms a sphenoid-squamous suture, sutura sphenosquamosa. Superior posterior parietal edge, margo parietalis, pointed, longer than the previous one, connected to the scaly edge of the parietal bone.
Pyramid of temporal bone
Pyramid, rocky part - pars petrosa, the temporal bone consists of posterolateral and anteromedial sections.
The posterolateral portion of the petrous part of the temporal bone is the mastoid process, processus mastoideus, which is located posterior to the external auditory opening. It distinguishes between outer and inner surfaces. The outer surface is convex, rough and is the site of muscle attachment. Inferiorly, the mastoid process passes into a cone-shaped protrusion, which can be easily felt through the skin,
On the inner side, the process is limited by the deep mastoid notch, incisura mastoidea, (the posterior belly of the digastric muscle originates from it, venter posterior m. digastrici). Parallel to the notch and somewhat posteriorly is the groove of the occipital artery, sulcus arteriae occipitalis, (trace of the junction of the artery of the same name).
On the inner, cerebral, surface of the mastoid process there is a wide S-shaped groove of the sigmoid sinus, sulcus sinus sigmoidei, passing at the top into the groove of the same name of the parietal bone and further into the groove of the transverse sinus of the occipital bone (it contains the venous sinus, sinus transversa). Downwards, the groove of the sigmoid sinus continues as the groove of the same name of the occipital bone.
The posterior border of the mastoid process is the jagged occipital margin, margo occipitalis, which, connecting with the mastoid edge of the occipital bone, forms the occipital-mastoid suture, sutura occipitomastoidea. In the middle of the length of the suture or in the occipital edge there is a mastoid foramen, foramen mastoideum, (sometimes there are several of them), which is the location of the mastoid veins, vv. emissariae mastoidea connecting the saphenous veins of the head with the sigmoid venous sinus, as well as the mastoid branch of the occipital artery, ramus mastoideus a. occipitalis.
From above, the mastoid process is limited by the parietal edge, which, at the border with the same edge of the squamous part of the temporal bone, forms the parietal notch, incisura parietalis; the mastoid angle of the parietal bone enters it, forming the parietal-mastoid suture, sutura parietomastoidea.
At the point of transition of the outer surface of the mastoid process into the outer surface of the squamous part, one can notice the remains of the squamous-mastoid suture, sutura squamosomastoidea, which is well expressed on the skull of children.
On the cut of the mastoid process, the bony air cavities located inside it are visible - mastoid cells, cellulae mastoideae, (rice. ). These cells are separated from one another by the bony mastoid walls (paries mastoideus). The permanent cavity is the mastoid cave, antrum mastoideum, in the central part of the process; mastoid cells open into it, it connects with the tympanic cavity, cavitas tympanica. The mastoid cells and mastoid cave are lined with mucous membrane.
The anteromedial part of the petrous part lies medial to the squamosal part and the mastoid process. It has the shape of a triangular pyramid, the long axis of which is directed from the outside and from behind to the front and medially. The base of the stony part is directed outward and posteriorly; top of the pyramid apex partis petrosae, directed inward and anteriorly.
In the stony part there are three surfaces: anterior, posterior and lower, and three edges: upper, posterior and anterior.
The front surface of the pyramid facies anterior partis petrosae, (see Fig.) smooth and wide, facing the cranial cavity, directed obliquely from top to bottom and forward and passes into the cerebral surface of the scaly part. It is sometimes separated from the latter by a stony-scaly gap, fissura petrosquamosa. Almost in the middle of the front surface there is an arched elevation, eminentia arcuata, which is formed by the anterior semicircular canal of the labyrinth underlying it. Between the elevation and the stony-scaly fissure there is a small platform - the roof of the tympanic cavity, tegmen tympani, under which is the tympanic cavity, cavum tympani. On the anterior surface, near the apex of the petrous part, there is a small trigeminal depression, impressio trigemini, (place of contact of the trigeminal ganglion, ganglion trigeminale).
Lateral to the depression is the cleft of the greater petrosal nerve canal, , from which the narrow groove of the greater petrosal nerve extends medially, sulcus n. petrosi majoris. Anterior and somewhat lateral to this opening there is a small cleft of the canal of the lesser petrosal nerve, hiatus canalis n. petrosi minoris, from which the groove of the lesser petrosal nerve is directed, sulcus n. petrosi minoris.
Back surface of the pyramid facies posterior partis petrosae, (see Fig.) just like the anterior one, it faces the cranial cavity, but is directed upward and posteriorly, where it passes into the mastoid process. Almost in the middle of it there is a round internal auditory opening, porus acusticus internus, which leads to the internal auditory canal, meatus acusticus internus (facial, intermediate, vestibulocochlear nerves pass through it, nn. facialis, intermedius, vestibulocochlearis, as well as the artery and vein of the labyrinth, a. et v. labirinthi). Slightly above and lateral to the internal auditory opening there is a well-defined subarcicular fossa of small depth in newborns, fossa subarcuata, (it includes a process of the dura mater of the brain). Even more lateral lies the slit-like external aperture of the vestibule aqueduct, apertura externa aqueductus vestibuli, opening into the aqueduct of the vestibule, aqueductus vestibuli. The endolymphatic duct emerges from the cavity of the inner ear through the aperture.
The bottom surface of the pyramid facies inferior partis petrosae, (see Fig.), rough and uneven, forms part of the lower surface of the base of the skull. On it there is a round or oval jugular fossa, fossa jugularis, (place of contact of the superior bulb of the internal jugular vein).
A small groove is noticeable at the bottom of the fossa (the auricular branch of the vagus nerve passes through it). The groove leads into the opening of the mastoid tubule, canaliculus mastoideus which opens in the tympanomastoid fissure, fissura tympanomastoidea.
The posterior edge of the jugular fossa is limited by the jugular notch, incisura jugularis, which is a small intrajugular process, processus intrajugularis, divides into two parts - anteromedial and posterolateral. Anterior to the jugular fossa lies a rounded opening; it leads to the sleepy canal, canalis caroticus, opening at the top of the rocky part.
Between the anterior circumference of the jugular fossa and the external opening of the carotid canal there is a small stony dimple, fossula petrosa, (place of contact of the inferior ganglion of the glossopharyngeal nerve). In the depths of the dimple there is a hole - a passage into the tympanic canaliculus, canaliculus tympanies, (the tympanic nerve and the inferior tympanic artery pass through it). The tympanic canaliculus leads to the middle ear, auris media, or tympanic cavity, cavum lympani), cavitas tympanis).
Laterally from the jugular fossa, the styloid process, directed downwards and somewhat anteriorly, protrudes, processus styloideus, from which muscles and ligaments begin. In front of the outside of the base of the process, the bony protrusion of the tympanic part descends - the sheath of the styloid process, vagina processus styloidei. Behind the base of the process there is a stylomastoid foramen, foramen stytomastoideum, which is the outlet of the facial canal, canalis facialis.
The top edge of the pyramid marge superior partis petrosae, (see Fig. , ), separates its front surface from the back. A groove of the superior petrosal sinus runs along the edge, sulcus sinus petrosi superioris, - an imprint of the superior petrosal venous sinus lying here and the attachment of the tentorium cerebellum - part of the dura mater of the brain. This groove passes posteriorly into the groove of the sigmoid sinus of the mastoid process of the temporal bone.
Rear edge of the pyramid margo posterior partis petrosae, (see Fig.), separates its back surface from the bottom. Along it, on the brain surface, runs the groove of the inferior petrosal sinus, sulcus sinus petrosi inferioris, (see Fig.) (trace of the contact of the inferior stony venous sinus). Almost in the middle of the posterior edge, near the jugular notch, there is a triangular funnel-shaped depression in which the external aperture of the cochlear tubule lies, apertura externa canaliculi cochleae, the cochlear tubule ends in it, canaliculus cochleae.
rice. 117. Inner base of the skull, basis cranii interna; top view (semi-schematic). 1 - anterior cranial fossa, fossa cranii anterior; 2 - middle cranial fossa, fossa cranii media; 3 - posterior cranial fossa, fossa cranii posterior.
The anterior edge of the petrous part, located on the lateral side of its anterior surface, is shorter than the upper and posterior ones; it is separated from the scaly part of the temporal bone by a stony-squamosal fissure, fissura petrosquamosa. On it, lateral to the internal opening of the carotid canal, there is an opening of the muscular-tubal canal leading to the tympanic cavity.
Canals and cavities of the petrous part of the temporal bone:- Sleepy channel, canalis caroticus, (see Fig. -), begins in the middle sections of the lower surface of the stony part with an external opening. Initially, the canal is directed upward, located here in front of the middle ear cavity, then, bending, it follows anteriorly and medially and opens at the apex of the pyramid with an internal opening (the internal carotid artery, accompanying veins and a plexus of sympathetic nerve fibers pass through the carotid canal).
- Carotid-tympanic tubules, canaliculi caroticotympanici, are two small tubules that branch from the carotid canal and lead into the tympanic cavity (the carotid-tympanic nerves pass through them).
- Facial canal, canalis facialis, (see Fig. , , ), begins at the bottom of the internal auditory canal, meatus acusticus internus, (in the field of the facial nerve, area n. facialis). The canal runs horizontally and almost at right angles to the axis of the petrous part, and is directed to its anterior surface, to the cleft of the canal of the greater petrosal nerve, hiatus canalis n. petrosi majoris. Here, turning at a right angle, it forms the elbow of the facial canal, geniculum canalis facialis, and passes to the posterior section of the medial wall of the tympanic cavity (accordingly, on this wall of the tympanic cavity there is a protrusion of the facial canal, prominentia canalis facialis). Next, the canal, heading posteriorly, follows along the axis of the stony part to the pyramidal eminence, eminentia pyramidalis; from here it goes vertically downwards and opens with a stylomastoid foramen, foramen stylomastoideum, (the facial and intermediate nerves, arteries and veins pass through the canal).
- Drum string channel, canaliculus chordae tympani, begins on the outer wall of the facial canal, a few millimeters above the stylomastoid foramen. Heading forward and upward, the canaliculus enters the tympanic cavity and opens on its posterior wall (a branch of the intermediate nerve passes through the canaliculus - the chorda tympani, chorda tympani, which, having entered the tympanic cavity through the canaliculus, exits it through the petrotympanic fissure, fissura petrotympanica).
- tympanic canaliculus, canaliculus tympanicus, begins on the lower surface of the stony part, in the depths of the stony dimple. Then it goes to the lower wall of the tympanic cavity and, perforating it, enters the tympanic cavity, passes along its medial wall and is located in the promontory groove, sulcus promontorii. Then it follows to the upper wall of the tympanic cavity, where it opens with the cleft of the canal of the lesser petrosal nerve (hiatus canalis n. petrosi minoris).
- Musculo-tubal canal, canalis muculotubarius, (see Fig. , , ), is a continuation of the anterosuperior part of the tympanic cavity. The external opening of the canal is located at the notch between the petrous and squamosal parts of the temporal bone, at the anterior end of the petrosquamosal fissure. The canal is located lateral and slightly posterior to the horizontal part of the carotid canal, almost along the longitudinal axis of the petrous part. Horizontally located septum of the muscular-tubal canal, septum canalis musculotubarii, divides the canal into an upper, smaller hemicap of the tensor tympani muscle, semicanals m. tensoris tympani, and the lower larger palucanal of the auditory tube, semicanals lubae auditivae, (in the first lies the muscle that strains the tympanic membrane, the second connects the tympanic cavity with the pharyngeal cavity.
- mastoid tubule, canaliculus mastoideus, (see Fig.), begins in the depths of the jugular fossa, runs across the lower part of the facial canal and opens in the tympanomastoid fissure (the auricular branch of the vagus nerve passes through the canaliculus).
- tympanic cavity, cavum tympani, (see figure , , ). - an elongated, laterally compressed cavity lined with mucous membrane. Inside the cavity lie three auditory ossicles: the malleus, malleus, anvil, incus, and stapes (stapes), which, articulated with each other, form a chain of auditory ossicles (more about the structure of these canals, the tympanic cavity, auditory ossicles and the labyrinth.
Tympanic part of the temporal bone
drum part, pars tympanlca, (see Fig.), is the smallest section of the temporal bone. It is a slightly curved ring-shaped plate and forms the anterior, lower walls and part of the posterior wall of the external auditory canal, meatus acusticus extenus. Here you can see the border tympanic-squamous fissure, fissura tympanosquamosa (see Fig. ,), which, together with the stony-squamous fissure, separates the tympanic part from the mandibular fossa of the scaly part. The outer edge of the tympanic part, closed on top by the scales of the temporal bone, limits the external auditory opening, porus acusticus externus. At the posterosuperior outer edge of this opening there is a supraductal spine, spina suprameatica. Below it is the supraductal fossa, foveola suprameatica. On the border of the larger, internal, and smaller, external, parts of the external auditory canal there is a tympanic groove, sulcus tympanicus, (place of attachment of the eardrum). At the top it is limited by two curved projections: in front - the greater tympanic spine, spina tympanica major, and behind is the small tympanic spine, spina tympanica minor. Between these projections there is a tympanic notch (incisura tympanica) opening into the supratympanic recess, recessus epitympanicus.
The lower process of the roof of the tympanic cavity is wedged between the medial part of the tympanic part and the squamosal part of the temporal bone. In front of this process there is a stony-scaly fissure, fissura petrosquamosa, and behind - the petrotympanic fissure, fissura petrotympanica, (from the latter the nerve emerges - the chorda tympani and small vessels). Both grooves continue outward into the tympani-squamosal fissure, fissura tympanosquamosa.
The lateral section of the tympanic part passes into the stony ridge, the elongated part of which forms the sheath of the styloid process, vagina processus styloidei. In a newborn, the external auditory canal is still absent and the tympanic part is represented by the tympanic ring, anulus tympanicus (see Fig.), which then grows, forming a significant part of the external auditory canal.
On the inner surface of the greater tympanic spine, the spinous crest is clearly visible, at the ends of which there are anterior and posterior tympanic processes, and the malleus groove runs along it.
Os temporale - steam room, complex in shape and structure. It participates in the formation of the base of the skull and complements the lateral walls of the roof of the skull. The organs of hearing and balance are located in the temporal bone; nerves and blood vessels pass through its canals. On its outer surface there is the external auditory opening, porus acusticus extemus, around which there are three parts of the temporal bone: the squamous bone, pars squamosa; stony, pars petrosa and drum, pars tympanica.
The scales and tympanic part develop on the basis of connective tissue, and the stony part develops on the basis of cartilage.
Scaly part, pars squamosa, has the shape of a thin plate located in the sagittal plane. A squamoid suture connects its free edge with the lower edge of the parietal bone and the greater wing. The lower part of the scales is adjacent to the stony and tympanic part and is delimited from it by a stony-scaly fissure, fissura petrosquamosa, and from the tympanic part by a tympanic-squamous fissure, fissura thympanosquamosa. In the posterior part of the scales there is a groove of the middle temporal artery, sul. A. temporalis mediae. In the posterior-inferior section, the temporal line is distinguished. Above the scales and slightly forward, the zygomatic process, processus zygomaticus, extends, which originates with a wide root and then tapers. It fuses with the process of the zygomatic bone and forms the zygomatic arch, arcus zygomaticus. On the lower surface of the root there is an articular mandibular fossa, fossa mandibularis. In front, the articular fossa is limited by the articular tubercle, tuberculum articulare, and behind by the extraglobal tubercle, tuberculum retroarticulare. The inner medullary surface of the squama contains finger-like indentations, cerebral protrusions and grooves from the middle meningeal artery, a. meningea media, in case of damage to the scales, aneurysms of this artery may occur; this should be taken into account in clinical (neurosurgical) practice.
Rocky part, pars petrosa, has the shape of a triangular pyramid, the top of which is directed inward and forward, and the base is directed back and sideways. In the stony part, the following surfaces are distinguished: anterior, fades anterior partis petrosae, posterior, fades posterior partis petrosae, and lower, fades inferior partis petrosae, as well as the upper, posterior and anterior corner.
The front surface of the pyramid faces the cranial cavity. Almost in the middle of the anterior surface there is an arcuate elevation, eminentia arcuata, which coincides with the anterior semicircular canal of the labyrinth.
The roof of the tympanic cavity is adjacent to the elevation. On the anterior surface of the pyramid, at its apex, there is a trigeminal squeeze, impressio trigeminalis, for the trigeminal ganglion. To the side of it is the formation of the canal of the greater petrosal nerve, hiatus canalis n. petrosi majoris, from which the medial groove of the greater petrosal nerve, sul. n. petrosi majoris. Slightly in front and to the side is the upper course of the lesser petrosal nerve, hiatus canalis n. petrosi minoris, from which the groove of the lesser petrosal nerve, sul. n. petrosi minoris. The nerves of the same name exit through these holes.
On the posterior surface of the stony part, almost in the middle, there is an internal auditory opening, porus acusticus internus, leading to the internal auditory canal, meatus acusticus internus. At the upper edge of the stony part, in the area between the internal auditory opening and the external opening of the aqueduct of the vestibule, there is a subarc fossa, fossa subarcuata. And at the lower edge there is the opening of the cochlea's aqueduct, apertura externa agueductus cochleae. Above and to the side of this opening is the external opening of the vestibular aqueduct, apertura externa agueductus vestibuli, through which the endolymphatic duct, ductus endolymphaticus, passes.
On the lower surface of the stony part there is an oval-shaped jugular fossa, fossa jugularis, at the bottom of which there is a groove leading to the opening of the mastoid canaliculus. The posterior edge of the jugular fossa is limited by the jugular notch, incisura jugularis. Anterior to the jugular fossa is the external opening of the carotid canal, apertura externa canalis carotid, which leads into the carotid canal, canalis caroticus, which opens at the apex of the petrous part with an internal opening, apertura interna canalis carotid. At the external opening on the posterior wall of the carotid artery canal there are openings of the carotid-tympanic tubules, canaliculi caroticotympanici, opening into the tympanic cavity through which vessels and nerves pass. Between the jugular fossa and the external opening of the carotid canal there is a stony dimple, fossula petrosa, in the depth of which is the lower opening of the tympanic tubule, apertura inferior canaliculi tympanici (BNA). On the side of the jugular fossa there is a downward styloid process, processus styloideus, which is the site of attachment of the “anatomical bouquet” (mm. styloglossus, stylohyoideus, stylophmyngeus) and the ligament ligg. stylohyoideum et stylomandibular. Behind the root of the process there is a stylomastoid opening, foramen stylomastoideus. In front and outside the styloid process there is a bony protrusion of the tympanic part - the vagina of the styloid process, vagina processus styloidei.
The upper edge of the stony part separates its anterior surface from the posterior one. Along this edge runs the upper stony groove, sul. sinus petrosi superioris. The posterior edge of the petrous portion separates the posterior surface from the inferior surface. Along this edge runs the lower stony groove, sul. sinus petrosi inferioris. The anterior edge of the stony part separates its anterior surface from the lower one. On it, on the side of the internal opening of the carotid canal, there is an opening of the muscular-tubal canal, canalis musculotubarius, which connects the tympanic cavity with the nasal part of the pharynx.
Below, the base of the stony part is elongated into the mastoid process, processus mastoideus, the outer surface on it is rough from the muscle attached to it. At the opening of the mastoid process, cells, cellulae mastoidei, are visible, lined with mucous membrane. The largest cell, called the mastoid cave, antrum mastoideum, communicates with the cavity of the middle ear. In the case of inflammation of the middle ear (otitis), the infection can penetrate into the cells and lead to purulent inflammation (mastoiditis), the treatment of which requires surgery.
Externally, two grooves run from the mastoid process: the medial one - for the occipital artery, sul. a. occipitalis, and slightly to the side - the mastoid notch, incisura mastoidea. The mastoid process is separated from the tympanic part by the tympanomastoid fissure, fissura tympanomastoidea, which is the site of passage of the auricular branch of the vagus nerve.
In the area between the occipital bone and the mastoid process there is a mastoid foramen, the foramen mastoideum is the widest. Basically, the mastoid foramen is located in the occipital-mastoid suture (C. Libersa, 1934). On the outer surface of the mastoid process, the mastoid triangle (Shipo) is conventionally distinguished, which is the site of trephination (anthrotomy) for inflammatory conditions of the middle ear (cells and cave). On the inner surface of the mastoid process there is a groove of the sigmoid sinus, sul. sinus sigmoidei. Along with the S-shaped form, there are hook-shaped, crescent-shaped, straight and arched forms (G.D. Burdei, 1951, 1955). In the middle section of the groove of the sigmoid sinus, the mastoid opening, foramen mastoideum, opens, through which the mastoid emissary vein passes, connecting the sigmoid sinus with the suboccipital venous plexus.
Drum part, pars tympanica, located around the external auditory canal, meatus acusticus extemus. It limits below and behind the external auditory opening, porus acusticus extemus, and the tympanic cavity, cavitas tympanica, and with its free edge it fuses with the scales and the mastoid process.
It is separated from the scales by a tympanic-squamous fissure, fissura tympanosquamosa, into which a process of the roof of the tympanic cavity is inserted. It divides it into two fissures: the stony-squamous, fissura petrosquamosa, and the stony-tympanic, fissura petrotympanica (Glaseri), through which a branch of the intermediate nerve emerges from the tympanic cavity - the chorda tympani. Above the external auditory opening is the suprachnoid spine, spina suprameatica. The cartilaginous part of the auditory canal is attached to the free rough edge of the tympanic part, which limits the external auditory opening.
Ossification. A baby's temporal bone is made up of three parts. The first ossification points appear in the scales at 8 weeks of intrauterine development, and at 3 months - in the tympanic part. At the 5th month, five points of ossification appear in the cartilaginous base of the petrous part. In a newborn, parts of the temporal bone are separated by gaps filled with connective tissue, which grow together during the first year of life.
Canals and cavities of the temporal bone
There are seven canals of the temporal bone: 1. Facial nerve canal, canalis n. facialis;2. Musculo-tubal canal, canalis musculotubarius;
3. Carotid canal, canalis caroticus
4. Carotid-tympanic tubules, canaliculi caroticotympanic;
5. Canaliculus chorde tympanv,
6. Tympanic tubule, canaliculus tympanicus;
7. Mastoid tubule, canaliculus mastoideus.
Facial nerve canal, canalis n. facialis - originates at the bottom of the auditory canal, goes at a right angle to the axis of the petrous part and goes to the formation of the large petrosal nerve, hiatus canalis n. petrosi majoris, where it turns and forms the elbow of the facial canal, geniculum canalis facialis. The ganglion of the geniculate facial nerve is located here, from which the greater petrosal nerve arises. After which it passes along the posterior wall of the tympanic cavity, forming protrusions of the facial canal, prominentia canalis facialis, then the canal goes vertically downwards, where it opens with a stylomastoid opening, foramen stylomastoideus. The canal contains the facial and intermediate nerves (VII pair), the superficial petrosal branch from the middle meningeal artery and the stylomastoid artery and vein.
Musculo-tubal canal, canalis musculotubarius - originates in the notch between the petrous and squamosal parts of the temporal bone and runs along the axis of the petrous part. The bony septum divides it into two semi-canals: the upper - the semi-canal of the muscle that stretches the tympanic membrane, semicanalis musculi tensoris tympani, and the lower - the semi-canal of the auditory tube, semicanalis tube auditoriae (LNA). The upper one contains a muscle that stretches the eardrum, the lower one connects the tympanic cavity with the pharyngeal cavity.
Sleepy channel, canalis caroticus - originates on the lower surface of the stony part with the external carotid foramen, apertura externa canalis carotici. The canal goes upward, passes in front of the tympanic cavity, forming a bend, and then goes forward and medially, opening with the internal carotid foramen, apertura interna canalis carotid, at the apex of the petrous part. The canal contains the internal carotid artery, the veins that accompany it, and a nice nerve plexus.
Carotid tympanic tubules, canaliculi caroticotympanici - small tubules that branch from the carotid canal and lead into the tympanic cavity. The carotid-tympanic nerves pass through here.
Drum String Canadian, canaliculus chorde tympani - originates on the wall of the facial canal above the stylomastoid foramen, goes forward and upward, enters the tympanic cavity and opens on its posterior wall. A branch of the intermediate nerve passes through the canal - the chorda tympani, which exits the tympanic cavity through the petrotympanic fissure.
Tympanic canaliculus, canaliculus tympanicus - originates in the petrosal fossa, fossula petrosa, then through the lower wall enters the tympanic cavity, passes along its medial wall, and rises upward, where it opens with the gap of the lesser petrosal nerve, hiatus canalis n. petrosi minoris. The tympanic nerve passes through the canal, which, at the exit from the tympanic cavity, is called the lesser petrosal nerve (branch of the IX pair).
Mastoid tubule, canaliculus mastoideus - originates in the depths of the jugular fossa, crosses the facial canal in its lower part and opens in the tympanomastoid fissure. The auricular branch of the vagus nerve passes through the canal.
Tympanic cavity, cavitas tympania, discussed in the “Sense Organs” section.
| Temporal bone, (os temporale). Outside surface. Right view. 1-squamous part (scales) of the temporal bone; |
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Temporal bone(os temporale). Inner surface. 1-squamosal part of the temporal bone; |
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Temporal bone(os temporale). A cut through the tympanic cavity along the long axis of the pyramid (right bone). 1-temporal bone scales |
The temporal bone, os temporale, paired, is very complex in structure, since its thickness contains the organs of hearing and balance, and, in addition, the bone is penetrated by a number of canals through which vessels and nerves pass. The temporal bone is located in the lateral sections of the skull between the occipital, parietal and sphenoid bones, complementing one part with the cranial vault and the other with the base of the skull. The temporal bone is connected to the facial skull: through a joint - with the lower jaw, and a suture - with the zygomatic bone.
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The temporal bone consists of several fused parts. When examining the temporal bone from the outer, temporal surface, at its lower edge, there is a large opening, which is called the external auditory foramen, porus acusticus externus. The hole is surrounded by four components of the temporal bone: above and in front - a flat scale of the temporal bone with a pointed edge, squama temporalis, in front and below - a small, groove-shaped plate - the tympanic part, pars tympanica, behind - a powerful bony protrusion - the mastoid part , pars mastoidea, from the inside - in the form of a pyramid, tapering in the direction from the mastoid part obliquely inward and anteriorly - the stony part or pyramid, pars petrosa s. pyramids. The scales of the temporal bone, squama temporalis, have the shape of a semicircular bone plate, facing with its smooth temporal surface, fades temporalis, outward and with its internal, cerebral surface, fades cerebralis, into the cranial cavity. The semicircular edge delimiting the scales is not the same everywhere; the anterior and posterior portions of the edge are more jagged and less pointed on the inside than the upper portion. The anterior edge connects with the scaly edge of the large wing of the main bone and is called the main edge, margo sphenoidalis; the upper posterior edge, connecting with the scaly edge of the parietal bone, is called the parietal edge, margo parietalis. The posterior-inferior part of the scales passes into the mastoid part.
In children, at the junction of these parts, there is a squamous-mastoid suture, sutura squamomastoidea, directed obliquely from top to bottom and anteriorly. Remnants of this suture are sometimes preserved in adults. Somewhat higher and along it there is a temporal line, the anterior end of which approaches the root of the zygomatic process of the temporal bone, processus zygomaticus ossis temporalis. The zygomatic process arises from two roots: posterior and anterior. It runs horizontally, first outward, and then at an angle anteriorly, and ends with a serrated end. Lastly, it connects with the temporal process of the zygomatic bone, forming with it the zygomatic arch, arcus zygomaticus. Below the zygomatic process and in front of the external auditory opening, the articular fossa of the lower jaw, fossa mandibularis, is located. In the anterior sections, the fossa is limited by a clearly visible articular tubercle, tuberculum articulare; in the rear - smaller in size, behind - the articular process, processus retroarticularis. The anterior part of the fossa and the articular tubercle are covered with cartilage. In the posterior part of the outer surface, fades temporalis, the scales of the temporal bone bear the groove of the middle temporal artery, sulcus arteriae temporalis mediae. This furrow rises upward and branches in the upper segment of the scales.
Brain surface, fades cerebralis, the bone is somewhat concave, has a well-defined, deep arterial groove in the anterior section, sulcus arteriosus (meningeus) (place of contact of the meningeal artery of the brain), traces of depression of the convolutions of the brain - finger impressions, impressiones digitatae, and between the latter projections - cerebral eminences , juga cerebralia. Stony part or pyramid, parspetrosa s. pyramidis, has the appearance of a three-sided pyramid, located in a supine position, so that its base, basis pyramidis, is directed outward and connects with the mastoid and squamosal parts of the temporal bone. At the site where the base of the pyramid meets the scaly part, in childhood there is a gap, flssura petrosquamosa, over the years it is filled with bone tissue, and thus the boundary between these two parts disappears.
The top of the pyramid has an uneven edge. It is directed forward and inward, towards the lateral surface of the bodies of the sphenoid and occipital bones. The gap remaining between them on the whole skull is called torn hole, foramen lacerum (Fig. 124), filled with fibrous cartilage, fibrocartilago basilaris. In the area of the apex, a large internal opening of the carotid artery canal, foramen caroticum intemum, opens. The upper corner of the pyramid, angulus superior pyramidis, protrudes freely into the cranial cavity at the border of the anterior and posterior surfaces of the pyramid, fades anterior and fades posterior pyramidis. The upper stony groove, sulcus petrosus superior, runs along the upper corner of the pyramid, a trace of the venous sinus located here. The anterior corner of the pyramid, angulus anterior pyramidis, is located on the border of the anterior and lower surfaces of the pyramid, facies anterior and facies inferior pyramidis. The internal segment of the anterior angle connects to the edge of the large wing of the main bone with the help of cartilage, forming the main-stony synchondrosis, synchondrosis sphenopetrosa. The outer segment of the anterior angle connects with the scales of the temporal bone, forming a stony-squamous fissure, fissura petrosquamosa.
Near the medial end of the petrosquamous fissure, in the corner where the anterior corner of the pyramid meets the anterior edge of the squamosal, one can see opening of the myotubal canal, canalis musculotubarius. The latter, located obliquely outward and backward, is divided by a horizontally standing thin bone plate - the septum of the muscular-tubal canal, septum canalis musculotubarii, into two parts: the upper - the semicanal of the tensor tympani muscle, semicanalis musculi tensoris tympani, and the lower - the auditory semicanal (Eustachian ) pipes, semicanalis tubae auditivae Eustachii. Both hemicanals lead to the middle ear cavity. The posterior corner of the pyramid, angulus posterior pyramidis, is located on the border of its posterior and lower surfaces, facies posterior et facies inferior pyramidis. It is adjacent to the lateral edges of the partes basilaris and lateralis ossis occipitalis. The inner part of the posterior angle is adjacent to the pars basilaris ossis occipitalis, and here a stony-occipital fissure, fissura petrooccipitalis, is formed, made of cartilage connecting both bones - synchondrosis petrooccipitalis. On the cerebral surface of this part of the posterior angle runs the lower stony groove, sulcus petrosus inferior. The latter, connecting with the groove of the same name on the adjacent part of the occipital bone, is the location of the temporal sinus (sinus petrosus inferior).
At the outer end of the groove, at the posterior corner of the pyramid, there is a small depression, at the bottom of which a small external opening of the cochlear canal, apertura externa canaliculi cochleae, opens. (V. canaliculi cochleae and ductus perilymphaticus, coming from the cavity of the inner ear, pass here). The lateral part of the posterior corner of the pyramid is adjacent to the pars lateralis ossis occipitalis. There is a small jugular notch, incisura jugularis, which corresponds to the notch of the same name on the occipital bone and together with it forms the jugular foramen, foramen jugulare, on the entire skull.
At the indicated three corners of the pyramid, its three surfaces converge: front, back and bottom. The first two are facing the cranial cavity, the latter is directed towards the outer surface of the base of the skull. The anterior surface of the pyramid, fades anterior pyramidis, is uneven and is located obliquely anteriorly. Outside, it borders with scales, forming a stony-scaly fissure, fissura petrosquamosa; from the inside, it borders on the body of the main bone, without reaching it and here, with the uneven edge of its apex, forms the ragged hole described above, foramen lacerum. The anterior-inferior and postero-superior boundaries are the corresponding corners or edges of the pyramid. On the anterior surface of the pyramid, near the apex, there is a depression of the trigeminal nerve, impressio nervi trigemini, an imprint of the adjacent Gasserian ganglion of the trigeminal nerve (ganglion Gasseri).
A semicircular eminence, eminentia arcuata, protrudes slightly to the side from the middle of the front surface of the pyramid, the relief of the superior semicircular canal. The area of the anterior surface located between the elevation and the stony-scaly fissure (fissura etrosquamosa) is the roof of the tympanic cavity, legmen tympani; which is a thin layer that forms the upper wall of the middle ear cavity. Tegmen tympani with its anterior edge enters the gap between the pars tympanica behind and the pars squamosa in front, forming a noticeable ridge in the area of the fossa mandibularis, called processus inferior tegmenis tympani (s. crista tegmcntalis) (see more about this in the description of pars tympanica).
Two openings are visible slightly inward and downward from the eminentia arcuata. One of them is located more medially and is the opening of the facial nerve canal, hiatus canalis facialis. A branch of the facial nerve emerges through this hole - the large stony nerve, nervus petrosus superficialis major, which lies in the corresponding groove - sulcus nervi petrosi superficialis majoris, running longitudinally inward and anterior to the hiatus canalis facialis.
The other opening is located lateral and is the superior opening of the tympanic tubule, apertura superior canaliculi tympanici. Through this hole, the small stony nerve emerges - nervus petrosus superficialis minor, which lies in the groove of the same name - sulcus nervi petrosi superficialis minoris. This groove, heading inward and anterior to the pyramid, runs parallel and outward from the sulcus nervi petrosi superficialis majoris. The posterior surface of the pyramid, fades anterior pyramidis, is located more vertically than the anterior one, however, having some slope posteriorly and downward. Inward from the upper corner, closer to the middle of the posterior surface, there is a rather wide internal auditory opening, porus acusticus internus. It opens into a channel going inside the rocky part. This channel is called internal auditory canal, meatus acusticus interims. (For its further progress inside the rocky part, see “Ear.”)
Outside and posterior to the porus acusticus internus, a small slit-shaped opening is visible, called external opening of the aqueduct-vestibule, apertura externa aquaeductus vestibuli, which is the exit point of the internal lymphatic duct, ductus endolymphaticus, from the cavity of the inner ear. Slightly above the water supply hole, at the upper corner of the pyramid, is located subsemicircular fossa, fossa subarcuata, clearly visible in young people. The lower surface of the pyramid, fades inferior pyramidis, is directed downward and faces the outer surface of the base of the skull; outside and somewhat in front, this surface is in contact with the tympanic part of the temporal bone. It has a large number of holes, recesses and protrusions.
The central place on the lower surface of the pyramid is occupied by a large round hole, which is the entrance to the carotid artery canal, the external opening of the carotid canal, foramen caroticum externum. (Through this opening the internal carotid artery and the nerve plexus enter.) Posterior and outward from the foramen caroticum externum, separated from it by a ridge, there is a wide jugular fossa, fossa jugularis, reaching the posterior edge of the lower surface of the petrous part, where there is a jugular notch, incisura jugularis. It houses the bulb of the jugular vein. At the bottom of the jugular fossa, closer to its anterior edge, there is a groove of the mastoid tubule, sulcus canaliculi mastoidei, ending with the opening of the mastoid tubule, canaliculus mastoideus.
On the ridge separating the fossa jugularis from the foramen caroticum externum, there is a barely noticeable stony dimple, fossula petrosa, leading into the lower opening of the tympanic tubule, apertura inferior canaliculi tympanici. (A. tympanica inferior and n. tympanicus pass here from the petrosal ganglion.) At the very base of the pyramid, on the outer part of the lower surface, the styloid process, processus styloideus, protrudes downwards and anteriorly, which is semi-surrounded in front by a bone sheath, vagina processus styloidei, formed by the tympanic part of the temporal bone.
Near the styloid process, on the border with the mastoid process, processus mastoideus, there is a stylomastoid foramen, foramen stylomastoideum, the exit point of the facial nerve and vessels. In the pyramid of the temporal bone there are a number of canals through which vessels and nerves pass, and the organ of hearing and the organ of balance of the body are located , which is why the pyramid has such a complex structure. All these formations are visible on special preparations of cuts of the temporal bone carried out in various directions.
1.Formations related to the structure of the organs of hearing and balance:
A). external auditory opening, porus acusticus externus, and its continuation into the external auditory canal, meatus acusticus externus, are the bony parts of the external ear;
b). tympanum tire, tegmen tympani, is the upper wall of the middle ear cavity, into which the canalis musculo-tubarius opens, lying on the outer edge of the anterior corner of the pyramid;
V). inner ear cavity(labyrinth) is indicated on the anterior surface of the pyramid by a semicircular eminence, eminentia arcuata, where the superior semicircular canal fits, and on the posterior surface by a fossa, fossa subarcuata.
Small openings on the posterior surface of the pyramid, apertura externa canaliculi cochleae and apertura externa aquaeductus vestibuli, lead to the inner ear; they contain vessels and lymphatic ducts through the porus acusticus internus passing the auditory and facial nerves.
2. Facial nerve canal(fallopian canal), canalis facialis (Falloppii), inside the petrous part of the temporal bone. It begins with the opening of the bottom of the internal auditory canal, in the area of its upper recess - area facialis (see "Ear"), and continues the direction of the internal auditory canal forward and outward under the anterior surface of the stony part. Here, to the front surface of the pyramid, a branch departs from it, ending with an opening - hiatus canalis facialis; the canal itself, turning outward and backward, forms at the point of rotation the knee of the auditory nerve canal, geniculum canalis facialis.
After the formation of the knee, the canal follows posteriorly and somewhat downward and, reaching the posterior part of the inner wall, cavum tympani, passes into the vertical part. Then it goes down and opens behind the base of the styloid and in front of the mastoid processes - the stylomastoid foramen, foramen stylomastoideum. The upper end of the vertical part of the canal forms the protrusion of the facial nerve canal, prominentia canalis facialis, located in the posterior part of the medial wall of the inner ear. Somewhat lower, the canal of the facial nerve gives off a branch of the canaliculus chordae tympani, through which the chorda tympani nerve passes, and which ends in the fissura petrotympanica (Glaseri).
3. Tympanic canaliculus, canaliculus tympanicus, passes a branch of the glossopharyngeal nerve. The tubule begins with the lower opening of the tympanic tubule at the bottom of the petrosal fossa, fossula petrosa (from the lower surface of the petrous part), and, moving in an arcuate manner backward, upward and then forward, opens with the upper opening of the tympanic tubule, apertura superior canaliculi tympanici (on the anterior surface of the petrous part) . Canaliculus tympanicus communicates with the canalis nervi facialis Falloppii in the area of its knee.4. The canal of the carotid artery, canalis caroticus, is short, wide and curved. The internal carotid artery and its venous and nerve plexuses pass through it. The canal begins with a hole located on the lower surface of the pyramid - foramen caroticum externum.
Next, the canal rises upward, then forms an almost right-angle bend and, going horizontally anteriorly and internally, opens with the internal opening of the carotid canal, foramen caroticum internum. Near the external opening, in the wall of the carotid artery canal, small openings of the carotid tubules, canaliculi curaticotympanici, open. These tubules are short, go to the anterior wall of the cavum tympani, bypassing the wall of the carotid canal from above. Opening in the anterior wall of the cavum tympani, they pass branches of the internal carotid artery and the superior and inferior carotid tympanic nerves.
mastoid part, pars mastoidea, located posterior to the external auditory canal. From the outside it smoothly turns into scales, and from the inside into the rocky part. The mastoid part faces downwards with a free convex surface, posteriorly and outwards with a rough surface. The posterior inferior, occipital edge, margo occipitalis, connects with the mastoid edge of the occipital bone, forming the occipital-mastoid suture, sutura occipitomastoidea.
Top edge, together with the posterior portion of the parietal edge of the scales, forms the parietal notch, incisura parietalis. This notch is made by the mastoid angle of the parietal bone, angulus mastoideus, which connects to the mastoid part using the mastoid-parietal suture, suturaparietomastoidea. In front, in the upper section, the mastoid part passes into the scales, in the lower part it borders on the tympanic part, forming with it the tympanomastoid fissure, fissura tympanomastoidea. In the anterior section, which makes up the upper-posterior part of the edge of the external auditory opening, there is a small protrusion - the supra-entrance spine, spina suprameatum, and near it posteriorly - the mastoid fossa, fossa mastoidea.
The rough anterior-lower section of the outer surface ends in a blunt and powerful mastoid process, processus mastoideus, which is directed obliquely anteriorly and downward and can be easily felt through the skin; in adults it varies, the degree of its development in children of the first years of life is poorly expressed (Fig. 83 ). In the postero-inferior section of the outer surface of the process there is a mastoid foramen, foramen mastoideum, belonging to the group of graduate foramina, emissaria Santorini; it penetrates the entire thickness of the bone and opens on the inner surface of the mastoid process. This hole is variable in size and position: sometimes there is only one and is located in the area of the sutura squamomastoidea, sometimes there are several of them.
On the outer side and below, the mastoid process bears a deep mastoid notch, incisura mastoidea, the origin of the digastric muscle (m. digastricus). The groove of the occipital artery, sulcus arteriaeoccipitalis, runs medially and parallel to the notch. On the inner, cerebral, surface of the mastoid part there is an S-shaped groove, sulcus sigmoideus, - the location of the venous sinus of the same name - sinus sigmoideus. Very often, the entrance opening of the above-mentioned foramen mastoideum opens into the same groove. Processus mastoideus belongs to the group of pneumatic bones. As can be seen from the drawings depicting the cut of the mastoid process, it has a large number of interconnected cells, cellulae mastoideae, lined with mucous membrane. The cells are filled with air penetrating here from the middle ear cavity. In the anterior-superior corner, inside the mastoid process, there is a large cell called the cave of the tympanic cavity, antrum tympanicum, communicating, on the one hand, with the cavity of the middle ear, and on the other, with the cells of the mastoid process.
The number and size of cells may vary between individuals. The tympanic part, pars tympanica, is formed during embryonic development in the form of a horseshoe-shaped semi-ring - the tympanic ring, annuhis tympanicus, forming the lower periphery of the external auditory canal. The ends of the semiring: the anterior, greater tympanic spine, spina tympanica major, and the posterior, lesser tympanic spine, spina tympanica minor, limit the gap called the tympanic notch, incisura tympanica (Rivini), over which (over both spines) hangs the lower edge of the scaly part of the temporal bones, thus closing the semi-ring at the top. Along the circumference of the inner surface of the ring runs the tympanic groove, sulcus tympanicus, which is the attachment site of the eardrum.
On the inner surface of the spina tympanica major there is an obliquely running spinous ridge, crista spinarum, the sharp ends of which are called: the anterior one - processus tympanicus anterior, and the posterior one - processus tympanicus posterior. Along the ridge and below it runs a groove - sulcus mallei. Due to the growth of bone substance from the outer surface of the semiring, the latter takes the form of a groove-shaped plate, which on the temporal bone of an adult forms the anterior, lower and part of the posterior wall of the external auditory opening, porus acusticus externus, and the external ear canal, meatus acusticus externus. As the bony groove of the tympanic part lengthens with age, the external auditory canal also lengthens: thus, the eardrum, which lies more superficially in children, due to this goes deeper.
The upper anterior edge of the tympanic part is separated over a large area from the scaly part by the anterior edge of the stony part wedged between them - the lower process of the roof of the tympanic cavity, processus inferior tegmenis tympani (s. crista tegmentalis). Between this process in front and the pars tympanica behind, a petrotympanic fissure is formed, fissura petrotympanica (Glaseri), through which small vessels and a nerve pass - the chorda tympani. Between the process at the back and the pars squamosa at the front, another gap is formed - stony-scaly, fissura petrosquamosa, made of connective tissue.
The posteroinferior edge of the tympanic part borders on the mastoid part of the temporal bone, forming at the point of contact the tympanomastoid fissure, fissura tympanomastoidea, in the depth of which the exit opening of the mastoid canaliculus, canaliculus mastoideus, begins in the fossa jugularis. The edge is pointed and extended downwards in the shape of a ridge, crista peirosa, the part of which at the base of the processus styloideus is the most developed, is called the vagina of the styloid process, vagina processus styloidei. The lower surface of the tympanic part and the fossa at the root of the zygomatic process of the squamous part form the articular fossa of the lower jaw, fossa mandibularis, at the bottom of which there are fissura petrotympanica (Glaseri) and fissura petrosquamosa. This fossa is divided by the glazer fissure into two parts - anterior and posterior.
The anterior part, lined with articular cartilage, faces the cavity of the mandibular joint, it is called inside- or intracapsular part, pars intracapsularis; posterior - located outside the joint and is called out- or extracapsular part, pars extracapsularis (see "Mandibular joint").
The temporal bone is divided into the pyramid (stony part) with the mastoid process, the tympanic part, and the scaly part.
Pyramid, or the stony part is so called due to the hardness of its bone substance and has the shape of a triangular pyramid. Inside it is the organ of hearing and balance. The pyramid in the skull lies almost in a horizontal plane, its base is turned back and laterally and passes into the mastoid process.
Several channels of the temporal bone pass through the pyramid for cranial nerves and blood vessels.
Sleepy channel
The carotid canal (canalis caroticus) begins on the lower surface of the pyramid with the external carotid foramen, goes upward, bends almost at a right angle, then goes medially and forward. The canal ends with the internal carotid foramen at the top of the pyramid of the temporal bone. The internal carotid artery and the nerves of the carotid plexus pass through this canal into the cranial cavity.
The internal carotid artery, the internal carotid (autonomic) nerve plexus, passes through the carotid canal.
Carotid tympanic tubules
Carotid-tympanic tubules (canaliculi caroticotympanici), numbering 2-3, begin on the wall of the carotid canal (near its external opening) and penetrate into the tympanic cavity.
These tubules contain the carotid-tympanic nerves and arteries.
Musculo-tubal canal
The muscular-tubal canal (canalis musculotubularis) has a common wall with the carotid canal, begins at the apex of the pyramid of the temporal bone, goes backward and laterally and opens into the tympanic cavity.
It consists of two sections: the semicanal of the auditory tube (semicanalis tubae auditivae) and the semicanal of the tensor tympani muscle (semicanalis m. tensoris tympani). The upper hemicanal is occupied by the tensor tympani muscle, and the lower hemicanal is the bony part of the auditory tube. Both half-channels open into the tympanic cavity on its anterior wall.
A horizontal partition divides it into two parts. Above is the hemicanal of the tensor tympani muscle (semicanalis musculi tensoris tympani), containing the muscle of the same name.
Below is the semicanal of the auditory tube (semicanalis tubae auditivae).
The tensor tympani muscle (half-canal of the tensor tympani muscle) and the auditory tube (half-canal of the auditory tube) pass through the muscular-tubal canal.
Facial canal
The canal of the facial nerve (canalis n. facialis) begins at the bottom of the internal auditory canal and goes forward and laterally to the level of the cleft of the canal of the greater petrosal nerve. Here a bend is formed - the knee of the facial canal (geniculum n. facialis). From the genu the canal runs at a right angle laterally and backward along the axis of the pyramid, then changes horizontal direction to vertical and ends at the posterior wall of the tympanic cavity with the stylomastoid foramen.
The facial canal connects the posterior surface of the pyramid of the temporal bone (internal auditory canal) and the stylomastoid foramen (outer base of the skull).
The facial nerve (VII pair of cranial nerves) passes through the facial canal.
Drum string channel
The canaliculus chordae tympani starts from the facial nerve canal slightly above the stylomastoid foramen and ends in the petrotympanic fissure.
A branch of the facial nerve passes through it - the chorda tympani.
Tympanic canaliculus
The tympanic canaliculus (canaliculus tympanicus) is very narrow; begins in the depths of the stony dimple, goes upward, pierces the lower wall of the tympanic cavity and continues on the labyrinthine wall of this cavity on the surface of the promontory in the form of a groove. Then it pierces the septum of the muscular-tubal canal and ends with the cleft of the canal of the lesser petrosal nerve on the anterior surface of the pyramid.
The tympanic canaliculus contains the tympanic nerve, a branch of the 9th pair of cranial nerves.
Mastoid tubule
The mastoid canal (canaliculus mastoideus) originates in the jugular fossa, crosses the facial canal in its lower part and opens into the tympanomastoid fissure. The auricular branch of the vagus nerve passes through this canaliculus.
The auricular branch of the vagus nerve passes through this canaliculus.
Temporal bone(os temporale) is a container for the organs of balance and hearing. The temporal bone, connecting with the zygomatic bone, forms the zygomatic arch (arcus zygomaticus). The temporal bone consists of three parts: squamosal, tympanic and petrous.
Scaly part(pars squamosa) of the temporal bone has an outer smooth temporal surface (facies temporalis), on which runs the groove of the middle temporal artery (sulcus arteriae temporalis mediae). From this part (just above the external auditory canal) the zygomatic process (processus zygomaticus) begins, at the base of which there is the mandibular fossa (fossa mandibularis). In front, this fossa is limited by the articular tubercle (tuberculum articulare). On the inner cerebral surface (facies cerebralis) there are finger-like impressions and arterial grooves.
Drum part(pars tympanica) of the temporal bone is fused at its edges with the mastoid process and the scaly part, limiting the external auditory opening (porus acusticus externus) on three sides, the continuation of which is the external auditory canal (meatus acusticus externus). At the back, at the site of fusion of the tympanic part with the mastoid process, a tympanomastoid fissure (fissura tympanomastoidea) is formed. In front of the auditory opening there is a tympanic-squamous fissure (fissura tympanosquamosa), which is divided by the edge of the roof of the tympanic cavity into a stony-squamous fissure (fissura petrosquamosa) and a stony-tympanic fissure (fissura petrotympanica).
Rocky part, or pyramid(pars petrosa), the temporal bone has the shape of a triangular pyramid. The pyramid is distinguished by the apex (apex partis petrosae), anterior, posterior and lower surfaces, upper and posterior edges and the mastoid process.
Canals of the temporal bone.
The anterior surface of the temporal bone on the lateral side passes into the medullary surface of the squamosal bone, from which it is separated by the petrosquamosal fissure (fissura petrosquamosa). Next to the stony-scaly fissure lies the opening of the muscular-tubal canal (canalis musculotubaris), which is divided by a septum into two semi-canals. One of them is the hemicanal of the auditory tube, and the other is the tensor tympani muscle.
In the middle of the anterior surface of the temporal bone there is an arcuate eminence (eminencia arcuata), between it and the petrosquamosal fissure there is the roof of the tympanic cavity (tegmen tympani). Near the apex of the anterior surface there is a trigeminal depression, lateral to which is the opening of the canal of the greater petrosal nerve (hiatus canalis nervi petrosi majoris), from which the groove of the same name begins. Lateral to this canal is the opening of the canal of the lesser petrosal nerve, from which the groove of the same name extends.
In the middle of the posterior surface of the pyramid of the temporal bone is the internal auditory opening (porus acusticus internus), which passes into the internal auditory canal. Lateral to this opening lies the subarcuate fossa (fossa subarcuata), below and lateral to which there is an external opening of the vestibular aqueduct (apertura externa aqueductus vestibuli).
The lower surface of the pyramid of the temporal bone has at its base a jugular fossa (fossa jugularis), on the anterior wall of which there is a groove ending in a mastoid foramen (foramen mastoideus). The posterior wall of the jugular fossa is represented by the notch of the same name. This notch and the notch of the occipital bone form the jugular foramen (foramen jugulare). In front of the jugular fossa, the carotid canal (canalis caroticus) begins, in the wall of which there are small pits that continue into the carotid-tympanic canaliculi. On the ridge separating the jugular fossa and the external opening of the carotid canal, there is a stony dimple (fossula petrosa), at the bottom of which the lower opening of the tympanic tubule opens. Lateral to the jugular fossa begins the styloid process (processus styloideus), posterior to which there is a stylomastoid foramen (foramen stylomastoideum).
The upper edge of the pyramid of the temporal bone separates the anterior surface from the posterior, and a groove of the superior petrosal sinus (sulcus sinus petrosi superioris) runs along its surface.
The posterior edge of the pyramid of the temporal bone separates the posterior and inferior surfaces; along it runs the groove of the inferior petrosal sinus (sulcus sinus petrosi inferioris).
The mastoid process (processus mastoideus) of the temporal bone is separated from the top from the scaly part by the parietal notch (incisura parietalis), and from below the process is limited by the mastoid notch (incisura mastoidea). Medial to the latter is the groove of the occipital artery (sulcus arteriae occipitalis). On the inner surface of the process there is a wide groove of the sigmoid sinus (sulcus sinus sigmoidei). The internal structure of the process is represented by cells, the largest of which is called the mastoid cave (antrum mastoideum).
Numerous canals and tubules pass through the temporal bone:
1) mastoid tubule (canaliculus mastoideus);
2) tympanic tubule (canaliculus tympanicus);
3) canaliculus chordae tympani;
4) carotid-tympanic tubules (canaliculus caroticotympanici);
5) carotid canal (canalis caroticus);
6) facial canal (canalis facialis);
7) muscular-tubal canal (canalis musculotubarius).