Temporal bone. Bones (Anterior surface of the pyramid - Tympanomastoid fissure)

Temporal bone (os temporale) steam room, is part of the base and side wall of the skull between the sphenoid bone in front and the occipital bone behind. It contains the organs of hearing and balance. The temporal bone consists of a pyramid, tympanic and squamous parts.

The pyramid, or rocky part (pars petrosa), has a trihedral shape, located obliquely in a horizontal plane. The top of the pyramid is directed forward and medially, and the base is backward and laterally. At the top of the pyramid is the internal opening of the carotid canal (canalis caroticus). Near and lateral is the musculo-tubal canal (canalis musculotubarius), which is divided by a septum into two semi-canals: the semi-canal of the auditory tube (semicanalis tubae auditivae) and the semi-canal of the muscle that strains the eardrum (semicanalis musculi tensoris tympani).

The pyramid has three surfaces: anterior, posterior, and inferior. Front surface the pyramid faces up and forward. Near the apex on this surface there is a small trigeminal impression (impressio trigemini). Lateral to this impression, two holes are visible. The larger of them is called the cleft (hole) of the canal of the large stony nerve (hiatus canalis nervi petrosi majoris), from which a narrow groove of the same name extends forward and medially. Anteriorly and laterally, there is a cleft of the small stony nerve (hiatus canalis nervi petrosi minoris), passing into the groove of this nerve. On the front surface of the pyramid there is a flattened area - the roof of the tympanic cavity (tegmen thympani), which is its upper wall. Along the upper edge of the pyramid is a furrow of the superior stony sinus (sulcus sinus petrosi superioris).

The back surface of the pyramid facing backwards and medially. In the middle of this surface is the internal auditory opening (porus acusticus internus). It leads to the inner ear canal(medtus acusticus internus). Lateral and slightly above this hole is the subarc fossa (fossa subarcuata), below and lateral to which there is a little noticeable external aperture (hole) of the vestibule water supply (apertura externa aqueductus vestibuli). A furrow of the lower stony sinus (sulcus sinus petrosi inferioris) runs along the posterior edge of the pyramid. At the lateral end of this groove, next to the jugular fossa, there is a recess, at the bottom of which the external aperture of the cochlear tubule (apertura externa canaliculi cochleae) opens.

Bottom surface of the pyramid has a complex terrain. Near the base of the pyramid is a deep jugular fossa (fossa jugularis). Anterior to it is a rounded external opening of the carotid canal, inside which, in its wall, there are 2-3 openings of the carotid canaliculus connecting the carotid canal with the tympanic cavity. On the comb between the jugular fossa and the external opening of the carotid canal is a small lobe (fossula petrosa). Lateral to the jugular fossa, a thin and long styloid process (processus styloideus) is directed downward. Behind the process is the stylomastoid foramen (foramen stylomastoideum), and behind this foramen is directed down a wide, easily palpable through the skin mastoid process (processus mastoideus).

In the thickness of the mastoid process there are cells filled with air. The largest cell, the mastoid cave (Antrum mastoideum), communicates with the tympanic cavity. Medially, the mastoid process is bounded by a deep mastoid notch (incisure mastoidea). Medial to this notch is the sulcus of the occipital artery (sulcus arteriae occipitalis). At the base of the mastoid process sometimes there is a mastoid opening (foramen mastoideum).

The tympanic part (pars tympanica) is formed by a curved narrow bone plate, which in front, below and behind limits the external auditory opening (porus acusticus externus), leading to the external auditory canal (meatus acusticus externus). Between the tympanic part and the mastoid process is a narrow tympanic-mastoid fissure (fissure tympanomastoidea). Anterior to the external auditory opening is the tympanic fissure (fissure tympanosquamosa). A narrow bone plate protrudes from the inside - the edge of the roof of the tympanic cavity. As a result, the tympanic-squamous fissure is divided into a stony-squamous fissure lying anteriorly (fissura petrosquamosa) and a stony-tympanic fissure (fissura petrotympanica, glazer's fissure), through which a branch emerges from the tympanic cavity facial nerve- drum string

The squamous part (pars squamosa) is a plate convex outwards, having a beveled free upper edge for connection with the parietal bone and the greater wing of the sphenoid bone. The outer temporal surface of the scale is smooth. On the inner cerebral surface of the scales there are cerebral eminences, finger-like impressions and arterial grooves. From the scales, above and anterior to the external auditory canal, the zygomatic process (processus zygomaticus) begins. Connecting with the temporal process of the zygomatic bone, it forms the zygomatic arch. Behind the zygomatic process, at its base, is the mandibular fossa (fossa mandibularis) for articulation with the condylar process of the lower jaw to form the temporomandibular joint.

Canals of the temporal bone. Several channels of the temporal bone pass through the pyramid for cranial nerves and blood vessels.

The carotid canalis cardticus) begins on the lower surface of the pyramid with an external carotid opening, goes up, bends almost at a right angle, then goes medially and forward. The channel ends with an internal carotid foramen at the top of the pyramid of the temporal bone. Through this canal, the internal cavity passes into the cranial cavity. carotid artery and carotid plexus nerves.

Carotid-tympanic tubules (canaliculi caroticotympanic!), 2-3 in number, depart from the carotid canal and go into the tympanic cavity. These tubules contain arteries and nerves of the same name.

The musculoskeletal canal (canalis musculotubarius) begins at the top of the pyramid of the temporal bone, goes back and laterally and opens into the tympanic cavity. A horizontal partition divides it into two parts. Above is the semi-canal of the muscle that strains the eardrum (semicanalis musculi tensoris tympani), containing the muscle of the same name. Below is the semicanal of the auditory tube (semicanalis tubae auditivae).

The facial canal (canalis facialis) begins in the internal auditory meatus. It goes first across in relation to the long axis of the pyramid to the level of the cleft of the canal of the large stony nerve. Having reached the cleft, the canal forms a knee, then goes at a right angle back and laterally. After passing along the medial wall of the tympanic cavity, the canal turns vertically downwards and ends with the stylomastoid foramen. The facial nerve passes through this canal.

The tubule of the drum string (canaliculus chordae tympani) goes from the wall of the facial canal in its final section and opens into the tympanic cavity. A nerve passes through this canal - a drum string.

The tympanic tubule (canaliculus tympanicus) begins at the bottom of the stony pit, goes up, pierces the wall of the tympanic cavity. Next, the tubule passes through it medial wall and ends in the area of ​​the cleft canal of the small stony nerve. The tympanic nerve passes through this tubule.

The mastoid tubule (canaliculus mastoideus) begins in the jugular fossa and ends in the tympanic mastoid fissure. The ear branch passes through this tubule. vagus nerve.

Temporal bone contains the organ of hearing and balance, serves as a support for the base of the skull and the masticatory apparatus. It consists of five parts - scaly, mastoid (mastoid). tympanic (tympanal), stony part and styloid complex. The basis of the temporal bone is a pyramid, which has an apex directed towards the sphenoid bone, three faces and a base facing the mastoid process.

Upper inner face of the pyramid supports the middle cranial fossa. The cranial fossa itself is bounded in front by the small wings of the main bone, in the back by the pyramid and partially by the back of the Turkish saddle. The main elements of the middle cranial fossa are the temporal lobes of the brain, the pituitary gland and the cavernous plexus.

Through row of holes is carried out connection between the middle cranial fossa, the pyramid and the cellular spaces of the face and neck. One of these openings is the optic nerve canal, where optic nerve and ophthalmic artery. Further, this is the superior orbital fissure, here follow the oculomotor, trochlear and abducens nerves, as well as ophthalmic branch trigeminal nerve and ocular veins. The maxillary branch of the trigeminal nerve passes through the round hole, through the hole the middle cranial fossa is connected with the pterygopalatine fossa. The canal of the internal carotid artery and the sympathetic carotid plexus are located in the carotid foramen. Through this hole, a connection is made with the cellular space of the neck.

in the oval hole the mandibular branch of the trigeminal nerve passes through the opening, communication with the interpterygoid space is possible. Through the spinous opening, where the middle sheath (meningeal) artery follows, a connection is made with the temporal pterygoid space.

To upper inner face of the pyramid large nerves are related: oculomotor, trochlear, trigeminal and efferent. On the upper part of the inner face of the pyramid, two anatomical elevations can be found. One elevation is formed by the gasser node (trigeminal ganglion), the other is formed by the superior semicircular canal. Two slits run along the upper face of the pyramid; stony nerves are located in them.

Rear inner face of the pyramid creates support for the posterior cranial fossa. The posterior cranial fossa is formed in front by the pyramid of the temporal bone, in the back by the cruciform eminence of the occipital bone. The main structures of the posterior cranial fossa are the cerebellum, the pons, and medulla.
Connection of the posterior cranial fossa with pyramid, as well as with the tissue of the face and neck can be carried out through a series of holes.

Through foramen magnum(in it pass: the medulla oblongata, accessory nerve, vertebral artery and spinal nerve) there is a message with the spinal canal.

Through the jugular, opening (through it follow: the internal jugular vein, the posterior meningeal artery, the glossopharyngeal, vagus and accessory nerves) anatomical contacts with the tissue of the neck are possible.

Through the hypoglossal canal communication occurs with the tissue of the submandibular fossa. Through the emissaries of the mastoid veins, the posterior cranial fossa communicates with the veins of the diploe, the veins of the integument of the skull, and with the sigmoid sinus.

To the back of the pyramid large cranial nerves are related: a branch of the trigeminal nerve, facial nerve, vestibulocochlear nerve, glossopharyngeal, vagus. accessory, hypoglossal and intermediate nerves. Three sinuses pass along the inner surface of the back face of the pyramid. The upper stony sinus runs along the upper edge of the rear inner face of the pyramid, and the lower stony sinus runs along the lower surface of the pyramid. They carry venous blood to the sigmoid sinus.

On the inner surface of the mastoid process is a deep groove of the sigmoid sinus. The sigmoid sinus itself is located between the mastoid process and the cerebellum.

transverse sinus flows into the superior knee of the sigmoid sinus. The lower knee of the sigmoid sinus turns anteriorly and inward and passes into the bulb of the internal jugular vein, located under the bottom of the tympanic cavity. The sigmoid sinus sends its blood to the internal jugular vein.

On the posterior inner face of the pyramid three main holes can be seen. This is the opening of the internal auditory meatus (porus acusticus internus) with a diameter of 4-5 mm, behind it at a distance of 5-6 mm horizontally there is an opening of the outer aperture of the water supply of the vestibule. Downward from the opening of the internal auditory meatus at a distance of 5-6 mm on the lower face of the pyramid, the outer aperture of the cochlear tubule (the aperture of the cochlear aqueduct) opens.

	Temporal bone, (os temporale). Outside surface. Right view. 1-squamous part (scales) of the temporal bone; 2-zygomatic process; 3-articular tubercle; 4-mandibular fossa 5-stony-scaly gap; 6-stony-tympanic (glaser) fissure; 7-styloid process; 8-drum part of the temporal bone; 9-external auditory opening; 10-mastoid process; 11-mastoid notch; 12-tympanic mastoid fissure; 13-nadal spine (above ear canal); 14-mastoid opening; 15 parietal notch; 16-temporal line.
	Temporal bone(os temporale). Inner surface. 1-squamous part of the temporal bone; 2-arched elevation; 3 parietal notch; 4-roof of the drum cavity; 5-groove of the superior stony sinus; 6-boroed of the sigmoid sinus; 7-mastoid opening; 8-occipital margin; 9-external opening (aperture) of the water supply of the vestibule; 10-subarc fossa .; 11-sheath of the styloid process; 12-styloid process; 13-outer opening (aperture) of the cochlear tubule; 14-internal auditory opening; 15-furrow of the lower stony sinus; 16-posterior surface of the pyramid of the temporal bone; 17-top of the pyramid; 18-zygomatic process; 19-arterial grooves.
	Temporal bone(os temporale). Saw through the tympanic cavity along the long axis of the pyramid ( right bone). 1-scales of the temporal bone 2-mastoid cave; 3-protrusion of the lateral semicircular canal; 4-protrusion of the canal of the facial nerve; 5-window vestibule; 6-probe in the canal of the facial nerve; 7-cleft canal of the large stony nerve; 8-cleft canal of the small stony nerve; 9-groove of the large stony nerve; 10-groove of the small stony nerve; 11-half-channel of the muscle stretching the tympanic membrane; 12-semi-canal of the auditory tube; 13-internal opening of the carotid canal; 14-external opening of the carotid canal; 15th cape; 16-drum cavity; 17-pyramidal elevation; 18-awl-mastoid opening; 19 mastoid cells.

The temporal bone consists of several fused parts. When considering the temporal bone from the side of the outer, temporal surface, at its lower edge, there is a large opening, which is called the external auditory opening, porus acusticus externus. The hole is surrounded by four components of the temporal bone: from above and in front - a flat, with a pointed edge of the scales of the temporal bone, squama temporalis, in front and below - a small, in the form of a gutter, plate - the tympanic part, pars tympanica, behind - a powerful bone 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. pyramis. The scales of the temporal bone, squama temporalis, has the shape of a semicircular bone plate, facing its smooth temporal surface, fades temporalis, outwards and the inner, cerebral surface, fades cerebralis, into the cranial cavity. The semicircular shape of the edge limiting the scales is not the same everywhere; the anterior and posterior sections of the edge are more serrated and less pointed on the inside than the upper section. The front edge is connected to the scaly edge of the large wing of the sphenoid 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-lower part of the scale passes into the mastoid part.

In children, at the junction of these parts, there is a scaly-mastoid suture, sutura squamomastoidea, obliquely directed from top to bottom and anteriorly. The remnants of this suture are sometimes preserved in adults. A little higher and along it is the 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 departs with two roots: posterior and anterior. It runs horizontally, first outward, and then at an angle anteriorly, and ends with a jagged end. Lastly, it connects to 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 canal, is the articular fossa of the lower jaw, fossa mandibularis. In the anterior sections, the fossa is limited by a well-marked articular tubercle, tuberculum articulare; in the posterior - smaller, 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 out in the upper segment of the scale.

cerebral surface, fades cerebralis, the bones are somewhat concave, has in anterior section a well-defined, deep arterial sulcus, sulcus arteriosus (meningeus) (the place of attachment of the meningeal artery of the brain), traces of depression of the convolutions of the brain - digital impressions, impressiones digitatae, and between the latter protrusions - cerebral elevations, juga cerebralia. Stony part or pyramid, parspetrosa s. pyramis, has the appearance of a three-sided pyramid, located in a supine position, so that its base, basis pyramidis, is directed outward and connects to the mastoid and squamous parts of the temporal bone. At the place where the base of the pyramid fits to the squamous part in childhood, there is a gap, flssura petrosquamosa, over the years it is filled with bone tissue, and thus the border 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 region of the apex, a large internal opening of the canal of the carotid artery, 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 furrow, sulcus petrosus superior, runs along the upper corner of the pyramid, a trace of the venous sinus of the same name that lies here. With an internal segment, the anterior angle is connected to the edge of the large wing of the sphenoid bone with the help of cartilage, forming the main stony synchondrosis, synchondrosis sphenopetrosa. The outer segment connects the anterior angle with the scales of the temporal bone, forming a stony-scaly fissure, fissura petrosquamosa.

Near the medial end of the stony-squamous fissure, in the corner where the front corner of the pyramid converges with the anterior edge of the scale, one can see orifice of the musculoskeletal canal, canalis musculotubarius. The latter, located obliquely outward and backward, is divided by a horizontally standing thin bone plate - the septum of the musculo-tubal canal, septum canalis musculotubarii, into two parts: the upper one is the semi-canal of the muscle that strains the eardrum, semicanalis musculi tensoris tympani, and the lower one is the semi-canal of the auditory (Eustachian ) pipes, semicanalis tubae auditivae Eustachii. Both semi-canals lead to the middle ear cavity. The back corner of the pyramid, angulus posterior pyramidis, is located on the border of its back and lower surfaces, facies posterior et facies inferior pyramidis. It is adjacent to the lateral margins of the partes basilaris and lateralis ossis occipitalis. The inner part of the posterior angle adjoins the pars basilaris ossis occipitalis, and a petrooccipital fissure, fissura petrooccipitalis, is formed here, made by cartilage connecting both bones - synchondrosis petrooccipitalis. On the cerebral surface of this part of the posterior angle passes the lower stony furrow, sulcus petrosus inferior. The latter, connecting with the sulcus of the same name on the adjacent part of the occipital bone, is the site of the temporal sinus (sinus petrosus inferior).

At the outer end of the furrow, 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 pass here, coming from the cavity inner ear). The lateral part of the posterior corner of the pyramid is adjacent to the pars lateralis ossis occipitalis. There is a small jugular notch, incisurajugularis, which corresponds to the same notch on the occipital bone and together with it forms the jugular foramen, foramen jugulare, on the whole skull.

At these three corners of the pyramid, three of its surfaces converge: front, back and bottom. The first two face 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, inclined anteriorly. Outside, it borders on scales, forming a stony-scaly gap, fissura petrosquamosa; from the inside, it borders on the body of the main bone, not reaching it and forming here the ragged hole described above, foramen lacerum, with the uneven edge of its top. The anterior-inferior and posterior-superior boundaries are the corresponding corners or edges of the pyramid. On the anterior surface of the pyramid, near the apex, there is an impression of the trigeminal nerve, impressio nervi trigemini, - the imprint of the gasser ganglion of the trigeminal nerve (ganglion Gasseri) adjacent here.

Slightly away from the middle of the front surface of the pyramid, a semicircular elevation, eminentia arcuata, protrudes - the relief of the upper 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 plate that forms the upper wall of the middle ear cavity. Tegmen tympani, with its front edge, enters the gap between pars tympanica behind and pars squamosa in front, forming a ridge visible in the fossa mandibularis region, called processus inferior tegmenis tympani (s. crista tegmcntalis) (see more about this when describing pars tympanica).

Slightly inwards and downwards from eminentia arcuata, two holes are visible. One of them is located more medially and is the opening of the facial nerve canal, hiatus canalis facialis. Through this opening, a branch of the facial nerve emerges - a 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 opening, a 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 anteriorly from the pyramid, runs parallel and outward from the sulcus nervi petrosi superficialis majoris. Inside 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. (See "The Ear" for its further move inside the rocky part.)

Outside and behind the porus acusticus internus, a small slit-like opening is visible, called external opening of the water supply-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 opening of the water supply, 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. She carries 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 canal, the external opening of the carotid canal, foramen caroticum externum. (The internal carotid artery and the nerve plexus enter through this opening.) Behind and outward from the foramen caroticum externum, separated from it by a crest, there is a wide jugular fossa, fossa jugularis, reaching the posterior edge of the lower surface of the stony part, where there is a jugular notch, incisura jugularis. It contains the bulb of the jugular vein. At the bottom of the jugular fossa, closer to its anterior edge, is the groove of the mastoid tubule, sulcus canaliculi mastoidei, ending in the opening of the mastoid tubule, canaliculus mastoideus.

On the scallop separating the fossa jugularis from the foramen caroticum externum, there is a barely noticeable stony dimple, fossula petrosa, leading to the lower opening of the tympanic tubule, apertura inferior canaliculi tympanici. (A. tympanica inferior and n. tympanicus pass here - from the stony node.) At the very base of the pyramid, on the outer part of the lower surface, the styloid process protrudes downward and anteriorly, processus styloideus, which is semi-circled in front by a bony vagina, 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, is the stylomastoid opening, foramen stylomastoideum, the exit point of the facial nerve and blood vessels. In the pyramid of the temporal bone there are a number of channels through which the vessels and nerves pass, and the organ of hearing and the organ of balance of the body are laid , so 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 canal, porus acusticus externus, and its continuation into the external auditory canal, meatus acusticus externus, are the bony parts of the outer ear;
b). tire of the tympanic cavity, tegmen tympani, is the upper wall of the middle ear cavity, where the canalis musculo-tubarius opens, lying on the outer edge of the anterior corner of the pyramid;
in). 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 holes on the back 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 an opening in the bottom of the internal auditory meatus, in the region of its upper deepening - area facialis (see "Ear"), and continues the direction of the internal auditory meatus 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 a hole - hiatus canalis facialis; the canal itself, turning outward and backward, forms at the place of rotation the knee of the auditory nerve canal, geniculum canalis facialis.

After the formation of the knee, the canal follows backwards and somewhat downwards and, having reached the posterior section of the inner wall, cavum tympani, passes into the vertical part. Then it goes down and opens behind the base of the styloid and anterior to the mastoid processes - the stylomastoid opening, foramen stylomastoideum. The upper end of the vertical part of the canal forms a protrusion of the facial nerve canal, prominentia canalis facialis, located in the posterior part of the medial wall of the inner ear. A little lower, the canal of the facial nerve gives a branch of the Canadian drum string, canaliculus chordae tympani, through which the nerve passes - the drum string, chorda tympani, and which ends in fissura petrotympanica (Glaseri).

3. drum tubule, 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 stony fossa, fossula petrosa (from the side of the lower surface of the stony part), and, heading arcuately backwards, upwards and then forward, opens with the upper opening of the tympanic tubule, apertura superior canaliculi tympanici (on the anterior surface of the stony part) . Canaliculus tympanicus communicates with canalis nervi facialis Falloppii in the region of his knee.4. The carotid canal, canalis caroticus, is short, wide and curved. Through it pass the internal carotid artery and its venous and nervous plexuses. The channel begins with a hole located on the lower surface of the pyramid - foramen caroticum externum.

Further, the canal rises upward, then forms a bend almost at a right angle and, heading horizontally anteriorly and inside, opens with the internal opening of the carotid canal, foramen caroticum internum. 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 the 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. Outside, it smoothly turns into scales, and from the inside - into the stony part. From top to bottom, the mastoid part faces a free convex, posteriorly and outwards - a rough surface. The posterior, occipital margin, margo occipitalis, connects to the mastoid margin 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 performed by the mastoid angle of the parietal bone, angulus mastoideus, which is connected to the mastoid part with the help of 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 tympanic-mastoid 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-inlet spine, spina suprameatum, and near it posteriorly - the mastoid fossa, fossa mastoidea.

The rough anterior-inferior section of the outer surface ends with a blunt and powerful mastoid process, processus mastoideus, which is directed obliquely anteriorly and downward and is well palpable through the skin, in adults it varies, the degree of its development in children of the first years of life is weakly expressed (Fig. 83 ). In the posterior-lower section of the outer surface of the process there is a mastoid opening, foramen mastoideum, belonging to the group of graduates' openings, emissaria Santorini; it penetrates through the entire thickness of the bone and opens on the inner surface of the mastoid process. This hole is not constant in size and position: sometimes it is one and is located in the region of the sutura squamomastoidea, sometimes there are several.

From the outside and from below, the mastoid process bears a deep mastoid notch, incisura mastoidea, the place where the digastric muscle (m. digastricus) begins. 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 place of occurrence of the venous sinus of the same name - sinus sigmoideus. Very often, the inlet of the foramen mastoideum mentioned above opens into the same furrow. 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 a mucous membrane. The cells are filled with air penetrating here from the cavity of the middle ear. In the anterior upper 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 from individual to individual. The tympanic part, pars tympanica, is laid during the period of embryonic development in the form of a horseshoe-shaped half ring - the tympanic ring, annuhis tympanicus, which forms the lower periphery of the external auditory canal. The ends of the semicircle: the anterior, greater tympanic spine, spina tympanica major, and the posterior, lesser tympanic spine, spina tympanica minor, limit a gap called the tympanic notch, incisura tympanica (Rivini), over which (above both spines) hangs the lower edge of the scaly part of the temporal bones, thus closing the semicircle from above. Along the circumference of the inner surface of the ring, there is a tympanic groove, sulcus tympanicus, which is the site of attachment eardrum.

On the inner surface of the spina tympanica major there is an oblique spinous scallop, crista spinarum, the sharp ends of which are called: the anterior - processus tympanicus anterior, and the posterior - processus tympanicus posterior. A groove runs along the ridge and below it - sulcus mallei. Due to the growth of bone substance from the side of the outer surface of the semicircle, the latter takes the form of a trough-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 outer auditory canal, meatus acusticus externus. With the lengthening of the bony groove of the tympanic part, the external auditory meatus also lengthens with age: thus, the tympanic membrane, which lies more superficially in children, due to this goes into depth.

The upper anterior edge of the tympanic part is separated from the scaly part for a long distance by the front 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 pars tympanica behind, a stony-tympanic fissure is formed, fissura petrotympanica (Glaseri), through which small vessels and a nerve pass - a drum string, 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 posterior lower edge of the tympanic part borders on the mastoid part of the temporal bone, forming at the point of contact a tympanic-mastoid fissure, fissura tympanomastoidea, in the depth of which the exit opening of the mastoid tubule, canaliculus mastoideus, begins in fossa jugularis. The edge is pointed and stretched downwards in the form of a ridge, crista peirosa, part of which is the most developed at the base of the processus styloideus, is called the styloid sheath, 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 are fissura petrotympanica (Glaseri) and fissura petrosquamosa. This fossa is divided by the glazing 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; back - located outside the joint and is called out- or extracapsular part, pars extracapsularis (see "Mandibular joint").

The temporal bone (os temporale) is paired, it contains the organs of hearing and balance. Nerves and blood vessels pass through its channels. The bone consists of three parts (Fig. 51).

Scales (squama) has the shape of an oval thin plate, located vertically, almost in the sagittal plane. The zygomatic process (processus zygomaticus) begins from the temporal surface of the scales. At the beginning of this process on the lower surface of the scales is the mandibular fossa (fossa mandibularis), in front of which is the articular tubercle (tuberculum articulare). On the cerebral surface of the scales there are imprints from the middle meningeal artery (a. meningea media) and convolutions of the temporal lobe of the brain.

51. Temporal bone right.
A - inside view: 1 - eminentia arcuata; 2 - tegmen tympani; 3 - pars petrosa; 4 - sulcus sinus sigmoidei; 5 - apertura externa canaliculi cochleae; 6 - processus styloideus; 7 - apertura externa aqueductus vestibuli; 8 - porus acusticus internus; 9 - sulcus sinus petrosi superioris; 10 - processus zygomaticus.
B - bottom view: 1 - processus zygomaticus; 2 - fissura petrosquamosa; 3 - canalis musculotubarius; 4 - for. caroticum externtum; 5 - fossula petrosa; B - apertura externa canaliculi cochleae; 7 - fossa jugularis; 8 - sulcus arteriae occipitalis; 9 - incisura mastoidea; 10 - processus mastoideus; 11 - for. stylomastoideum; 12 - meatus acusticus externus; 13 - fossa mandibularis; 14 - tuberculum articulare.

The tympanic part (pars tympanica) has the shape of a semicircle, takes part in the construction of the anterior, lower and posterior walls of the external auditory canal (meatus acusticus externus), the upper wall of which is limited by scales.

The stony part (pyramid) (pars petrosa) is triangular in shape, facing medially and anteriorly, has anterior, posterior and inferior surfaces, anterior, superior and posterior margins.

On the front surface of the stony part, when it is connected to the scales, there is a platform - the roof of the tympanic cavity (tegmen tympani). Ahead, this platform is limited by a gap (fissura petrosquamosa), laterally - an arcuate elevation (eminentia arcuata). Below it are the anterior and posterior semicircular canals of the inner ear. From eminentia arcuata, closer to the top of the pyramid, there are two openings representing the exit points of the large and small stony nerves (hiatus canalis n. petrosi majoris et minoris), opening into the same furrows, which are oriented towards the top of the pyramid.

On the back surface of the stony part there is an internal auditory opening (porus acusticus internus), where the facial and vestibulocochlear nerves pass. At the base of the stony part is a deep sigmoid groove (sulcus sigmoideus), where the opening of the mastoid venous outlet opens. Lateral to the internal auditory meatus there is a slit-like opening of the aqueduct of the vestibule of the inner ear (apertura externa aqueductus vestibuli). On the upper edge, between the anterior and posterior surfaces of the stony part, there is a sulcus (siilcus sinus petrosi superioris), which reaches the sigmoid sulcus in the back, and the top of the pyramid in the front.

On the lower surface of the base of the stony part there is a styloid process (processus styloideus); behind it opens the stylomastoid opening (for. stylomastoideum), representing the opening of the canal of the facial nerve. Medial to the styloid process, the jugular fossa (fossa jugularis) is visible, in which the posterior edge has the same notch. The front edge of the jugular fossa borders on the external opening of the carotid canal (for. caroticum externum). In the anterior margin there is a small stony fossa (fossula petrosa), at the bottom of which the tympanic canal (canaliculus tympanicus) begins. In adults, behind the stylomastoid opening and the external auditory canal is the mastoid process (processus mastoideus). In its thickness there are cells lined with a mucous membrane and communicating with the tympanic cavity. The mastoid fissure and the occipital sulcus pass medially to the mastoid process. In the latter is the occipital artery. In the middle of the posterior edge of the pyramid there is an external opening of the cochlea's water supply (apertura externa canaliculi cochleae).

Canals of the temporal bone. The carotid canal (canalis caroticus) begins on the lower surface of the pyramid with an external opening of the same name. The channel in the thickness of the pyramid turns at an angle of 90 ° and goes to the top of the pyramid, where it ends with an internal hole (for. caroticum internum).

The facial canal (canalis facialis) begins in the internal auditory meatus, then crosses the pyramid transversely and at the cleft of the large stony nerve (hiatus canalis n. petrosi majoris) turns at a right angle to the side - the knee of the facial canal (geniculum canalis facialis), then goes laterally , located at the junction of the roof of the tympanic cavity with the labyrinth wall of the inner ear. At the posterior wall of the tympanic cavity, the canal makes a turn and goes down, ending on the lower surface of the pyramid of the temporal bone with a stylomastoid foramen.

The muscular-tubal canal (canalis musculotubarius) is limited by the front edge of the top of the pyramid and scales. It consists of two sections: the semicanal of the auditory tube (semicanalis tubae auditivae) and the semicanal of the muscle stretching the eardrum (semicanalis m. tensoris tympani).

The tympanic tubule (canaliculus tympanicus) is very narrow; begins in fossula petrosa and opens on the front surface of the stony part of the pyramid with a cleft canal of the small stony nerve (hiatus canalis n. petrosi minoris).

The tubule of the drum string (canaliculus chordae tympani) departs from the facial canal before it leaves the stony part. It opens into the stony-tympanic fissure of the mandibular fossa.

Ossification. The temporal bone of a newborn consists of three independent parts, which are described above. The external auditory meatus is relatively short and wide. The tympanic cavity is filled with loose connective tissue, which resolves during the first 3 months after birth.

The tympanic part is represented as an incomplete ring located under the scales laterally from the pyramid. The tympanic membrane is stretched in the lumen of the ring. The ossification process occurs in the connective tissue (primary bone), bypassing the cartilaginous stage. From the semi-ring, scales and mastoid process, by the age of 6, the external auditory meatus develops. At the 8th week of intrauterine development, three ossification points appear in the fibrous connective tissue of the scales. From the back of the scales and the lateral part of the pyramid, under the action of the sternocleidomastoid muscle, a mastoid process is formed, which is pneumatized in three stages: up to 1 year, a tympanic protrusion is formed, up to 3 years, cells are formed, up to 6 years, pneumatization of the process completely ends. In the cartilaginous base of the pyramid, at the fifth month of intrauterine development, 5 bone nuclei appear, which merge by the time of birth.

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 part of it, the groove of the middle temporal artery passes in the vertical direction, sulcus arteriae temporalis mediae

In the posterior inferior part of the squamous part, an arcuate line passes, which continues into the lower temporal line, linea temporalis inferior, parietal bone.

From the scaly part, above and somewhat anterior to the external auditory opening, the zygomatic process extends in the horizontal direction, processus zygomaticus. It is, as it were, 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 broad root, the zygomatic process then narrows. It has an inner and outer surface and two edges - a longer upper and lower, shorter. The anterior end of the zygomatic process is serrated. The zygomatic process of the temporal bone and the temporal process, processus temporalis, the zygomatic bone are connected using the temporo-zygomatic suture, sutura temporozygomatica, forming the zygomatic arch, arcus zygomaticus.

On the lower surface of the root of the zygomatic process is a transversely oval-shaped mandibular fossa, fossa mandibularis. The anterior half of the fossa, up to the stony-squamous fissure, is the articular surface, facies articularis, temporomandibular joint. Anteriorly, the mandibular fossa limits the articular tubercle, tuberculum articulare, (see Fig. , ).

The outer surface of the squamous part is involved in the formation of the temporal fossa, fossa temporalis, (here the bundles of the temporal muscle begin, m. temporalis).

Inner cerebral surface facies cerebralis, slightly concave. It has finger-like indentations, impressiones digitatae, as well as the arterial sulcus, sulcus arteriosus, (it contains the middle meningeal artery, a. meningea media).

The squamous part of the temporal bone has two free edges - sphenoid and parietal.

Antero-inferior wedge-shaped edge, margo sphenoidalis, wide, serrated, connects to the scaly edge of the large wing of the sphenoid bone and forms a wedge-scaly 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 the temporal bone

Pyramid, rocky part - pars petrosa, the temporal bone consists of posterolateral and anteromedial sections.

The posterolateral part 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 the outer and inner surfaces. The outer surface is convex, rough and is the site of muscle attachment. From top to bottom, the mastoid process passes into a cone-shaped protrusion, which is well palpable through the skin,

FROM inside the process is limited by a 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 sulcus of the occipital artery, sulcus arteriae occipitalis, (trace of the adjacent 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 sulcus of the parietal bone of the same name and further into the sulcus of the transverse sinus of the occipital bone (the venous sinus lies in it, sinus transversa). From top to bottom, the sulcus of the sigmoid sinus continues as the sulcus of the occipital bone of the same name.

Behind the border of the mastoid process is a 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 seam or in the occipital margin is the mastoid opening, foramen mastoideum, (sometimes there are several), 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 bounded by the parietal edge, which, on the border with the same edge of the squamous part of the temporal bone, forms a parietal notch, incisura parietalis; it includes the mastoid angle of the parietal bone, forming the parieto-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 bone air-bearing cavities located inside it are visible - mastoid cells, cellulae mastoideae, (rice. ). These cells separate one from the other bone 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 to the tympanic cavity, cavitas tympanica. The mastoid cells and the mastoid cave are lined with a mucous membrane.

The anteromedial part of the petrous part lies medially from the squamous part and the mastoid process. It has the shape of a trihedral pyramid, the long axis of which is directed from the outside and back to front and medially. The base of the stony part is turned outwards and backwards; top of the pyramid apex partis petrosae, directed inward and anteriorly.

In the stony part, three surfaces are distinguished: anterior, posterior and lower, and three edges: upper, posterior and anterior.

The anterior 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 squamous 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 arcuate elevation, eminentia arcuata, which is formed by the anterior semicircular canal of the labyrinth lying under 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 top of the petrous part, there is a small trigeminal depression, impressio trigemini, (place of attachment of the trigeminal node, ganglion trigeminale).

Lateral to the impression is a cleft canal of the large stony nerve, , from which the narrow groove of the large stony nerve extends medially, sulcus n. petrosi majoris. Anterior and somewhat lateral to the specified hole is a small cleft canal of the small stony nerve, hiatus canalis n. petrosi minoris, from which the furrow of the small stony nerve is directed, sulcus n. petrosi minoris.

Back surface of the pyramid facies posterior partis petrosae, (see fig. ) as well as the anterior one, faces the cranial cavity, but goes up and backwards, where it passes into the mastoid process. Almost in the middle of it is a round-shaped internal auditory opening, porus acusticus internus, which leads to the internal auditory canal, meatus acusticus internus (the facial, intermediate, vestibulocochlear nerves pass through it, nn. facialis, intermedius, vestibulocochlearis, as well as the artery and vein of the labyrinth, a. et v. labyrinthi). A little higher and laterally from the internal auditory opening there is a well-defined in newborns, a small depth of the infraarc fossa, fossa subarcuata, (it includes the process of the hard shell of the brain). Even more lateral lies the slit-like outer aperture of the water supply of the vestibule, apertura externa aqueductus vestibuli, opening into the water supply of the vestibule, aqueductus vestibuli. Through the aperture, the endolymphatic duct exits the cavity of the inner ear.

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 is a rounded or oval jugular fossa, fossa jugularis, (place of attachment of the superior bulb of the internal jugular vein).

At the bottom of the fossa, a small groove is noticeable (the ear branch of the vagus nerve passes through it). The sulcus 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 bounded 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 sleep 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 attachment of the lower node of the glossopharyngeal nerve). In the depths of the dimple there is a hole - a passage into the tympanic tubule, canaliculus tympanies, (the tympanic nerve and the lower tympanic artery pass through it). The tympanic tubule leads to the middle ear auris media, or tympanic cavity, cavum lympani), cavitas tympanies).

Laterally from the jugular fossa, the styloid process protrudes downward and somewhat anteriorly, processus styloideus from which muscles and ligaments begin. Ahead to the outside of the base of the process descends the bone protrusion of the tympanic part - the sheath of the styloid process, vagina processus styloidei. Behind the base of the process there is a stylomastoid opening, 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 furrow of the superior stony sinus runs along the edge, sulcus sinus petrosi superioris, - the imprint of the superior stony venous sinus lying here and the attachment of the cerebellar tenon - part of the hard shell of the brain. This sulcus passes posteriorly into the sulcus of the sigmoid sinus of the mastoid process of the temporal bone.

The rear end of the pyramid margo posterior partis petrosae, (see Fig.), separates its back surface from the bottom. Along it, on the cerebral surface, there is a furrow of the inferior stony sinus, sulcus sinus petrosi inferioris, (see Fig. ) (a trace of the fit of the lower 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 outer aperture of the cochlear tubule lies, apertura externa canaliculi cochleae, it ends with a snail tubule, canaliculus cochleae.

The anterior margin 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 squamous part of the temporal bone by a stony-scaly fissure, fissura petrosquamosa. On it, lateral to the internal opening of the carotid canal, there is an opening of the musculo-tubal canal leading to the tympanic cavity.

1. dream channel, canalis caroticus, (see Fig. -), begins in the middle sections of the lower surface of the stony part with an outer opening. At first, the canal goes up, located here in front of the middle ear cavity, then, bending, it follows anteriorly and medially and opens at the top of the pyramid with an internal opening (the internal carotid artery, the accompanying veins and the plexus of sympathetic nerve fibers pass through the carotid canal).
2. carotid tubules, canaliculi caroticotympanici, are two small tubules that branch off from the carotid canal and lead to the tympanic cavity (the carotid-tympanic nerves pass through them).
3. face channel, 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 stony part, goes to its front surface, to the cleft of the canal of the large stony nerve, hiatus canalis n. petrosi majoris. Here, turning at a right angle, it forms the knee of the facial canal, geniculum canalis facialis, and passes to the posterior part of the medial wall of the tympanic cavity (respectively, on this wall of the tympanic cavity there is a protrusion of the facial canal, prominentia canalis facialis). Further, the channel, heading backwards, follows along the axis of the rocky part to the pyramidal elevation, eminentia pyramidalis; from here it goes vertically down and opens with a stylomastoid foramen, foramen stylomastoideum, (the facial and intermediate nerves, arteries and veins pass through the canal).
4. drum string tubule, canaliculus chordae tympani, begins on the outer wall of the facial canal, a few millimeters above the stylomastoid foramen. Heading forward and upward, the tubule enters the tympanic cavity and opens on its back wall (a branch of the intermediate nerve passes through the tubule - the tympanic string, chorda tympani, which, having entered the tympanic cavity through the tubule, leaves it through the stony-tympanic fissure, fissura petrotympanica).
5. drum tubule, 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 groove of the cape, sulcus promontorii. Then it follows to the upper wall of the tympanic cavity, where it opens with a cleft canal of the small stony nerve (hiatus canalis n. petrosi minoris).
6. musculoskeletal canal, canalis musculotubarius, (see Fig. , , ), is a continuation of the anterior upper part of the tympanic cavity. The external opening of the canal is located at the notch between the stony and squamous parts of the temporal bone, at the anterior end of the stony-squamous 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 musculo-tubal canal, septum canalis musculotubarii, divides the canal into the upper smaller half-capal of the muscle that strains the eardrum, semicanals m. tensoris tympani, and the lower greater palucanal of the auditory tube, semicanals lubae auditivae, (in the first lies a muscle that strains the eardrum, the second connects the tympanic cavity with the pharyngeal cavity.
7. mastoid canal, 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 tympanic-mastoid fissure (the ear branch of the vagus nerve passes through the tubule).
8. tympanic cavity, cavum tympani, (see Fig. , , ). - an elongated, laterally compressed cavity lined with a mucous membrane. Inside the cavity lie three auditory ossicles: hammer, malleus, anvil, incus, and stirrup (stapes), which, articulated with each other, form a chain of auditory ossicles (more about the structure of these canals, the tympanic cavity, the auditory ossicles and the labyrinth.

Tympanic part of the temporal bone

drum part, pars tympanlca, (see fig.), - the smallest section of the temporal bone. It is a slightly curved annular plate and forms the anterior, inferior walls and part of the posterior wall of the external auditory canal, meatus acusticus extenus. Here you can also 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 squamous 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 posterior upper outer edge of this hole there is a supra-anal spine, spina suprameatica. Beneath it is the suprapassal fossa, foveola suprameatica. On the border of the larger, inner, and smaller, outer, parts of the external auditory canal, there is a tympanic sulcus, Sulcus tympanicus, (site of attachment of the tympanic membrane). At the top, it is limited by two curved protrusions: in front - a large tympanic spine, spina tympanica major, and behind - a small tympanic spine, spina tympanica minor. Between these protrusions is a tympanic notch (incisura tympanica) that opens into the epitympanic recess, recessus epitympanicus.

Between the medial part of the tympanic part and the squamous part of the temporal bone, the lower process of the roof of the tympanic cavity is wedged. A stony-scaly fissure passes in front of this process, fissura petrosquamosa, and behind - a stony-tympanic fissure, fissura petrotympanica, (a nerve comes out of the latter - a drum string and small vessels). Both furrows continue outwards into the tympanic-squamous fissure, fissura tympanosquamosa.

The lateral part of the tympanic part passes into the stony crest, 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, a spinous crest is clearly distinguishable, at the ends of which there are anterior and posterior tympanic processes, and a furrow of the malleus runs along it.