Sleepy channel. Anatomy: temporal bone. Temporal bone canals

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(os temporale), steam room. It distinguishes three parts located around the external auditory opening: scaly, pyramid ( rocky part) and drum (Fig. 1, 2).

The organs of hearing and balance are located in the temporal bone; blood vessels and nerves pass through its canals. It is involved in the formation of the temporomandibular joint.

Scaly part(pars squamosa) It is a vertically located plate, connected by its free edge with the lower edge of the parietal bone and with the large wing of the sphenoid bone. Below it is adjacent to the tympanic and petrosal parts and is separated from them tympani-squamous fissure (fissura tympanosquamosa) And stony-scaly fissure (fissura petrosquamosa)[visible only on bones of young subjects].

Outdoor, temporal surface (fades temporalis), the scaly part is smooth, participates in the formation of the temporal fossa. Below it is limited zygomatic process (processus zygomaticus), which is directed anteriorly, connects with the temporal process of the zygomatic bone, forming the zygomatic arch. At the base of the zygomatic process there is a root that forms articular tubercle (tuberculum articulare), and less pronounced retroarticular tubercle (tuberculum retroarticulare), passing into the temporal line. Between the articular and postarticular tubercles a mandibular fossa (fossa mandibularis). It is covered with cartilage and articulates with the condylar process of the lower jaw.

Rice. 1. Temporal bone, right:

a — topography of the temporal bone;

b — external view: 1 — scaly part; 2 - zygomatic process; 3 - articular tubercle; 4 - postarticular tubercle; 5 - mandibular fossa; 6— stony-scaly fissure; 7 — edge of the roof of the tympanic cavity; 8 - petrotympanic fissure; 9 - styloid process; 10 - drum part; 11 - mastoid process; 12— mastoid notch; 13 - external auditory canal; 14— mastoid foramen; 15—supraductal spine; 16 - temporal line; 17 - groove of the middle temporal artery;

c — anterior surface of the pyramid of the temporal bone: 1 — parietal edge; 2 - medullary surface of the scales; 3 - stony-scaly gap; 4 — roof of the tympanic cavity; 5 - arcuate elevation; 6 - groove of the sigmoid sinus; 7 - mastoid foramen; 8 - occipital edge; 9 - groove of the superior petrosal sinus; 10—upper edge of the pyramid; 11 - trigeminal depression; 12—carotid channel; 13 - rocky part; 14 — front surface of the pyramid; 15 — myotubal canal; 16 - wedge-shaped edge; 17 - groove of the lesser petrosal nerve; 18 - groove of the greater petrosal nerve; 19 - cleft canal of the lesser petrosal nerve; 20 - cleft canal of the greater petrosal nerve;

d — view from the inside: 1 — scaly part; 2 - semicircular eminence; 3 - roof of the tympanic cavity; 4 - groove of the sigmoid sinus; 5 - mastoid foramen; 6 - aperture of the vestibular tubule; 7 - styloid process; 8 — aperture of the cochlear tubule; 9 - groove of the inferior petrosal sinus; 10 - internal auditory canal; 11 - groove of the superior sagittal sinus; 12 - zygomatic process;

e - bottom view: 1 - stony-scaly fissure; 2 - petrotympanic fissure; 3 — myotubal canal; 4 - internal aperture of the carotid canal; 5 - top of the pyramid; 6 - lower surface of the pyramid; 7 - groove of the inferior petrosal sinus; 8 - external aperture of the carotid canal; 9 - stony dimple; 10 - condylar tubule; 11 - jugular fossa; 12 - stylomastoid foramen; 13 - groove of the occipital artery; 14 - mastoid notch; 15 - mastoid process; 16 - styloid process; 17 - tympanic-squamosal fissure; 18 - mandibular fossa; 19 - articular tubercle; 20 - zygomatic process

Rice. 2. Cutting the temporal bone through the tympanic cavity:

1 - arcuate elevation; 2 - probe in the elbow of the facial nerve canal; 3 - groove of the greater petrosal nerve; 4 - hemicanal of the tensor muscle eardrum; 5 - half-channel auditory tube; 6 - probe in the carotid canal; 7 - probe in the stylomastoid foramen; 8 - mastoid cells; 9 - mastoid cave

Along the outer surface of the squamous part of the temporal bone runs groove of the middle temporal artery (sulcus a. temporalis mediae).

Internal, cerebral surface (fades cerebralis) has cerebral eminences, gyral depressions (finger-shaped); vascular grooves run along it meninges.

Human anatomy S.S. Mikhailov, A.V. Chukbar, A.G. Tsybulkin

, vestibulocochlear and facial nerves, trigeminal ganglion, branches of the vagus and glossopharyngeal nerves.

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    ✪ Skull #3: Temporal bone; temporal bone canals

    ✪ Temporal bone (Os Temporale)

    ✪ Temporal bone, its parts, purpose of holes, canals, cracks

    ✪ Temporal bone

    ✪ Anatomy of the temporal bone. Part 1

    Subtitles

    Anatomy

    On the surface of the brain, traces of the brain are visible in the form of impressions (impressiones digitatae). The zygomatic process (processus zygomaticus) departs from it, which is directed forward to connect with the zygomatic bone. In the lower part there is an articular fossa for articulation with the lower jaw (fossa mandibularis).

    The tympanic part (pars tympanica) is fused with the mastoid process (processus mastoideus) and the scaly part (pars squamosa), is a thin plate that bounds the external auditory opening (porus acusticus externus) and the external auditory canal (meatus acusticus externus) in front, behind and below. .

    The stony part (pars petrosa) has the shape of a three-sided pyramid, the apex of which faces anteriorly and medially, and the base, which passes into the mastoid process (processus mastoideus), faces posteriorly and laterally.

    There are three surfaces: anterior, posterior and lower, as well as three edges: anterior, posterior and upper.

    The anterior surface (facies anterior) is part of the bottom of the middle cranial fossa; posterior (facies posterior) faces backward and medially, forms part of the anterior wall of the posterior cranial fossa; the lower one (facies inferior) faces down and is visible only on the outer surface of the base of the skull.

    The external relief of the pyramid is due to its structure as a container for the middle and inner ear, as well as for the passage of blood vessels and nerves.

    A thin pointed styloid process (processus styloideus) extends from the lower surface of the pyramid, serving as a site of muscle attachment. The relief of the outer surface of the pyramid is the site of muscle attachment; downward it extends into the mastoid process, to which the sternocleidomastoid muscle is attached.

    On the mastoid process (on its anterior smooth surface) of the temporal bone there is a triangle Spike, which is the place operational access to the cells of the mastoid process. On the X-ray of the temporal bones, the so-called sinodural angle (Citelli angle) is distinguished. Inside, the mastoid process contains cells (cellulae mastoideae), which are air cavities communicating with the tympanic cavity (middle ear) through the mastoid cave (antrum mastoideum).

    The temporal bone is connected to the occipital, parietal and sphenoid bones. Participates in the formation of the jugular foramen.

    Temporal bone canals

    • sleepy channel, canalis caroticus, in which the internal carotid artery lies. It begins on the lower surface of the pyramid, with the external carotid foramen (foramen caroticum externum), directed vertically upward, bending at a right angle, directed forward and medially. The canal opens into the cranial cavity through the internal carotid foramen (foramen caroticum internum).
    • drum string channel, canaliculus chordae tympani, starts from the canal of the facial nerve, slightly above the stylomastoid foramen (foramen stylomastoideum), goes forward and opens into the tympanic cavity. A branch of the facial nerve, the chorda tympani, passes through this canaliculus, which then exits the tympanic cavity through the petrotympanic fissure (fissura petrotympanica).
    • facial canal, canalis facialis, in which the facial nerve passes, it begins at the bottom of the internal ear canal, then goes horizontally from back to front. Having reached the level of the cleft of the canal of the greater petrosal nerve, the canal goes back and laterally, at a right angle, forming a bend, or knee facial canal. Next, the channel is directed back, following horizontally along the axis of the pyramid. Then it turns vertically downwards, bending around the tympanic cavity, and on the lower surface of the pyramid it ends with a stylomastoid opening.
    • myotubal canal, canalis musculotubaris, has a common wall with the carotid canal. Begins in the angle formed by the anterior edge of the pyramid and the scales of the temporal bone, runs posteriorly and laterally, parallel leading edge pyramids. The muscular-tubal canal is divided into two half-canals by a longitudinal horizontal septum. The upper hemicanal is occupied by the tensor tympani muscle, and the lower is the bony part of the auditory tube. Both canals open into the tympanic cavity on its anterior wall.
    • mastoid tubule, canaliculus mastoideus, originates at the bottom of the jugular fossa and ends in the tympanomastoid fissure. A branch of the vagus nerve passes through this canaliculus.
    • tympanic canaliculus, canaliculus tympanicus, arises in the stony fossa (fossula petrosa) with an opening through which a branch of the glossopharyngeal nerve, the tympanic nerve, enters. After passing through the tympanic cavity, this nerve, called the lesser petrosal nerve, exits through the cleft of the same name on the anterior surface of the pyramid.
    • carotid tympanic tubules, canaliculi caroticotympanici, pass in the wall of the canal of the internal carotid artery near its external opening and open into the tympanic cavity. They serve for the passage of the vessels and nerves of the same name.
    • vestibule water supply, aqueductus vestibuli, a canal in the pyramid of the temporal bone connecting the vestibule of the bony labyrinth (the expanded part of the bony labyrinth between the cochlea inner ear and bony semicircular canals) with the cranial cavity (posterior cranial fossa). It opens with a gap on the posterior surface of the pyramid of the temporal bone, behind the opening of the internal auditory canal. The canal contains the vein of the aqueduct of the vestibule and the ductus endolymphaticus, which ends in the blind sac (saccus endolymphaticus), on the posterior surface of the pyramid of the temporal bone, between the opening of the internal auditory canal and the sigmoid sinus.
    • snail plumbing, aqueductus cochleae, about 10 mm long, connects the vestibule of the inner ear and the posterior surface of the pyramid of the temporal bone, opening at its lower edge, below the opening of the internal auditory canal. Its internal opening is located at the beginning of the staircase of the drum of the bony cochlea. The vein of the cochlear canaliculus passes through the canal.

It is impossible to say for sure which bones present in the human body are more important than others. All of them are an integral part of the musculoskeletal system, and damage to one of them can lead to unpredictable consequences. The temporal bone of the skull is no exception and has its own characteristics.

The role and features of the temporal bone

First of all, it should be noted that the temporal bone of the skull is a pair. Both parts are located in the center of the skull on both sides. The occipital, parietal, and sphenoid bones are located around them. These sections perform protective function. The organs of hearing and balance are attached to them. In addition, they serve as a support for the lower cheekbone, forming the base and lateral part of the skull. Together with the cheekbones, this element forms a movable joint.

The temporal part of the skull has the following purpose.

  1. The main function of the paired element is to protect the brain from direct physical influences.
  2. The supporting function, thanks to which the brain is fixed on both sides, is of no small importance.
  3. The muscles of the head are attached to this bone.
  4. It is a conductor for various vessels, having many channels.

The right and left parts have an identical anatomical structure.

Anatomy

The outer side of the temporal lobe contains the ear canal, around which three sections are localized.

  • scaly – located above the temple;
  • the stony part of the temporal bone, located on the back side closer to the center, it is also called the pyramid;
  • the tympanic section, which is localized at the bottom of the anterior part.

The pyramid has three planes, which is why it got its name.

Squamous department

This area looks like a kind of plate. Its outer side is somewhat convex and has roughness. From the back, vertically, the groove for the temporal artery is localized. There is a curved line below, and closer to the frontal part, the bone has a horizontal extension - a process of the lower jaw, visually representing an extension of the comb protrusion, passing along the lower edge of the outer side. Its base is presented in the form of a pot-bellied root, and towards the end it tapers.

The process also has a back, outer side and edges, one of which is longer than the other. The base of the element has small teeth.

The processes of the temporal lobe at its base have an articulation resembling a suture. This creates the zygomatic arch, under which the mandibular recess is localized. It has an egg-shaped shape, stretched across. In front of the depression there is a tuberous body. The outer side of the scaly plate forms a depression where muscle tissue is attached. From the inside, finger-shaped grooves and a vascular canal are observed.

As we have already found out, the scaly area has 2 edges: wedge-shaped and parietal. The first wide edge has teeth, it joins in the area of ​​the sphenoid bone. The upper dorsal parietal edge is slightly longer than the first. It has a pointed shape and converges in the parietal lobe.

The anatomy of the temporal bone has a complex bone structure. Its pyramidal part consists of two sections: the frontal median and the dorsal lateral, represented by the mastoid bone, located behind the ear canal. It has a double-sided rough convex plane. Muscles are attached to it, and downwards the process smoothly forms into a cone-shaped protrusion. It can be felt when pressed through the epidermis.

The internal fragment has a deep opening. Parallel to it, next to the back part, there is a groove of the occipital blood vessels. The back side of the process ends in notches, and at the junction a suture is formed, in the center of which a mastoid opening is localized. Sometimes there may be several of them. Connecting veins pass at the same place. At the top, this process ends with the parietal edge. At the junction of the pyramidal and scaly areas, a recess is formed into which the corner of the parietal bone enters, thereby forming a suture.

Pyramid planes

The anatomy of the pyramid of the temporal bone has three planes. One of them is directed inward at an angle, gradually moving to the surface of the scaly section. In the middle of the frontal part there is a horseshoe-shaped eminence, which is formed by the anterior groove of the oval-shaped ear canal located below. Between this passage and the tubercle the plane of the tympanic region is localized.

The rear plane is located similarly to the front, only facing the rear upper area. Its continuation is the mastoid process, and the ear opening is localized in the center of the plane.

The anatomy of the inferior plane is different from the other two and has an uneven rough surface. It is a fragment of the lower base of the skull. There is also an egg-shaped jugular recess located here. At the bottom of this fossa there is a small canal leading to the mastoid process. Its back part is limited by a notch divided by a process into two halves.

Edges of rocky area

At the top of the pyramid there is a canal, which is intended for the transverse sinus and fixation of the dura mater. The dorsal edge is located between the posterior and inferior planes of the petrous part. The pyramidal sinus canal runs along the upper plane along the posterior edge. Almost in the very center, near the jugular notch, a small depression in the shape of a triangle is localized.

The anterior edge of the pyramid is somewhat shorter in length than the rear or upper one. Between it and the scaly fragment there is a small gap, as well as a hole that opens into the cranial cavity.

Pyramid channels

Inside the walls of the skull are the canals of the temporal bone. The sleepy one extends from the outer opening of the lower plane of the pyramid. It shoots upward and then levels out in the middle and exits through a hole at its top. The atlas of the carotid tympanic tubules is presented as its branches leading inward. At the bottom of the ear canal there is an entrance to the facial canal, which runs horizontally at a right angle to the axis of the pyramid. Then it rushes to the frontal plane, where, turning sharply, it forms a kind of knee. After this, he moves to the middle of the back wall, heading back, running parallel to the axis of the pyramid to its top. Next, the canal goes vertically downward, rushing to the stylomastoid foramen.

String channel

This canal originates slightly below the exit of the facial foramen, rushing to the top of the frontal wall of the tympanic plane, and ends on the back wall. The string is the branch of the median nerve passing along this path, which is exited through the fissure of the petrotympanic joint.

Muscular auditory canal

This outlet is a kind of continuation of the upper frontal side of the tympanic cavity. Its exit is localized next to the notch, between the pyramid and the scaly plate. It runs from the lateral part to the horizontal axis of the carotid tubule. In addition, it has an internal horizontal wall that divides it into two halves. Upper cavity occupy the muscles responsible for the membrane, and the lower part is represented as a tubal auditory meatus to the main ear opening.

The path starts from the bottom plane of the pyramid at the bottom of the pyramidal recess. It is directed towards the lower cavity, and then passes through the middle of the wall, bypassing the groove of the promontory. After this, it rushes to the upper platform, and then exits outside in the cleft of the canal, where the nerve branch stretches.

Tympanum

The tympanic section is endowed smallest area unlike other areas of the temporal lobe. It is a bent ring-shaped plate. This part of the temporal plate forms the external auditory opening with three sides, which speaks about its shape. In addition, the boundary gap is localized here - the articulation of the tympanic section with the pyramid, dividing it with the jaw recess. The outer part is expressed by a scaly plane and separates the ear canal. Near the back side of the upper outer part there is a process, under which there is a supra-ductal depression.

Damage

The temporal region may be subjected to various injuries, but the most dangerous of them is a fracture. Bone damage can be transverse or longitudinal. Such injuries have one feature - the absence of displacement of the debris. This suggests that the width of the crack is insignificant, and bone fusion occurs quickly, which cannot be said about damage to scaly surfaces.

Examination of the temporal bones

At the slightest suspicion of damage to the temporal bones, specialists use computed tomography, allowing us to identify various types of violations in great detail. A special feature of this technique is the layer-by-layer diagnosis of bone.

For the final diagnosis, several images are taken, and the indications for examination are the following factors.

  • Unilateral or bilateral injuries.
  • Otitis of uncertain form or nature.
  • Violation auditory characteristics, deterioration of coordination, as well as other dysfunctions of nearby organs.
  • For tumor symptoms of both internal and external nature.
  • Disorders brain activity associated with damage to the temporal lobe.
  • Otosclerosis.
  • Mastoiditis.
  • Discharge from the ears.

Contraindications for the study

Methods computer diagnostics are considered very popular, as they allow you to get detailed clinical picture with the slightest detail for any bone injuries. This technique carried out using ionized rays and a special substance introduced into the body. Therefore, in some cases its use may be hazardous to health. Tomography is not recommended for use under the following circumstances.

  • Women during pregnancy. Irradiation has a negative effect on the fetus, which in the future can cause irreversible pathological disorders.
  • Excess weight. This diagnostic method was not originally intended for obese people.
  • Individual intolerance to the administered drug. The contrast agent may cause allergic reactions.
  • At renal failure the substance does not leave the body and can have negative effects.

Listed here are the most common factors that contradict the use of CT, however, there are other contraindications, but they are extremely rare.

The temporal bone, os temporale, is a paired bone, complex in shape and structure, which participates in the formation of the base of the skull, being placed between the occipital and sphenoid bones, and also complements the lateral walls of the cranial roof. There are three parts located around the external auditory opening: scaly, tympanic and stony.
The scaly part, pars squamosa, is a vertically located bone plate. With a free, uneven, obliquely cut edge, it is connected through a scaly suture to the lower edge of the parietal bone and to the greater wing of the sphenoid bone. Below, the scaly part is adjacent to the petrous and tympanic parts and is separated from it by a petrosquamous fissure, fissura petrosquamosa (visible only on the bones of young subjects), and from the tympanic part by a tympanic-squamous fissure, fissura tympanosquamosa.
The outer temporal surface, facies temporalis, the scaly part is smooth, participates in the formation of the temporal fossa. Near the lower edge, the zygomatic process, processus zygomaticus, departs from it, directed anteriorly, where it connects with the temporal process of the zygomatic bone and forms the zygomatic arch, arcus zygomaticus. The zygomatic process extends with two roots, between which the mandibular fossa, fossa mandibularis, is formed. It is covered with cartilage and articulates with the articular process of the lower jaw. The anterior root of the zygomatic process, thickening anterior to the mandibular fossa, forms the articular tubercle, tuberculum articulare. On the posterior root of the zygomatic process there is a similar retroarticular tubercle, tuberculum retroarticulare, less pronounced. Posteriorly it passes into the temporal line, linea temporalis.
The inner cerebral surface, facies cerebralis, of the scaly part is equipped with cerebral elevations, digital impressions, as well as grooves for the vessels of the meninges.

Figure: Temporal bone, right, external view.
1 - zygomatic process; 2 - articular tubercle; 3 - mandibular fossa; 4 - petrotympanic fissure; 5 - styloid process; 6 - drum part; 7 - external auditory opening; 8 - edge of the drum part; 9 - mastoid process; 10 - mastoid foramen; 11 - temporal line; 12 - scaly part.

The tympanic part, pars tympanica, is centered around the external auditory canal, meatus acusticus externus. In newborns, it is expressed in the form of a ring, anulus tympanicus, open upward and surrounding the external auditory canal. Subsequently, it grows and merges with neighboring parts. In adults, the tympanic part limits below and behind the external auditory opening, porus acusticus externus, and the tympanic cavity, cavum tympani, merging with the free edge with the scales and the mastoid part. It is separated from the scales by a tympanic-squamous fissure, into which a process of the tympanic roof enters from the front surface of the pyramid, due to which the said fissure is divided into two parallel fissures: the stony-squamous one, fissura petrosquamosa, and the stony-tympanic one, fissura petrotympanica, through which from the tympanic a branch of the facial nerve passes through the cavity - the chorda tympani. The cartilaginous part of the auditory canal is attached to the free rough and curved edge of the tympanic part, limiting the external auditory opening.
Above the external auditory opening rises the supra-ductal spine, spina supra meatum.
The petrous part, pars petrosa, or pyramid, is shaped like a three-sided pyramid, the base of which faces posteriorly and laterally, the apex facing anteriorly and medially. There are three surfaces on the pyramid, of which the anterior, facies anterior, and posterior, facies posterior, face the cranial cavity, and the lower, facies inferior, is part of the outer surface of the base of the skull. The surfaces are separated by three edges: top, back and front. The base of the pyramid is fused with the scaly part. A small portion of the base of the pyramid, facing outward, remains uncovered and contains the external auditory opening. The pyramid of the temporal bone contains most elements of the hearing organs: the bony part of the external auditory canal, the middle and inner ear.
On the anterior surface of the pyramid there is an arcuate eminence, eminentia arcuata, corresponding to the anterior semicircular canal of the labyrinth of the inner ear. In front of this elevation there are two thin grooves: the greater and lesser petrosal nerves, sulcin. retrosi majoris et n. petrosi minoris, ending in front with clefts of the same name, hiatus canalis n. petrosi majoris et hiatus canalis n. petrosi minoris. Nerves exit through these holes. The lateral part of this surface of the bone, lying between the arcuate eminence and the squamous-stony fissure, constitutes the upper wall of the tympanic cavity and is therefore called the tympanic roof, tegmen tympani. Near the apex of the pyramid there is a trigeminal impression, impressio trigemini. Along the upper edge of the pyramid there is a groove of the superior petrosal sinus, sulcus sinus petrosi superioris. On the posterior surface of the pyramid there is an internal auditory opening, porus acusticus internus, leading to the internal auditory canal, meatus acusticus internus. Posterior to the internal auditory opening is the external opening of the aqueduct of the vestibule, apertura externa aqueductus vestibuli, through which the ductus endolymphaticus passes. At the upper edge of the pyramid, between the internal auditory opening and the external opening of the aqueduct of the vestibule, there is a subarc fossa, fossa subarcuata, which in children reaches large sizes, and in adults it decreases significantly. At the lower edge at the level of porus acusticus internus there is an opening of the cochlear canaliculus, apertura externa canaliculi cochleae. Along the posterior edge of the pyramid there is a groove of the inferior petrosal sinus, sulcus sinus petrosi inferioris. The bottom surface of the pyramid is uneven. From it the styloid process, the processus styloideus, is the place of muscle attachment and goes down and forward. The process reaches its full development in older people. It is composed of several segments that ossify separately and merge with each other quite late. Between the styloid and mastoid processes, under the external auditory foramen, there is a stylomastoid foramen, foramen stylomastoideum, which serves as the exit point for the facial nerve. Anterior and medial to the styloid process is the jugular fossa, fossa jugularis. At the bottom of this fossa, the opening of the mastoid tubule, canaliculus mastoideus, is visible. Anterior to the jugular fossa is the external opening of the canal carotid artery, foramen caroticum externum, leading into the canal of the carotid artery, canalis caroticus, which opens at the apex of the pyramid with an internal outlet, foramen caroticum internum. On back wall of the carotid artery canal, near the external opening, there are several small openings of the carotid-tympanic tubules, canaliculi caroticotympanici, opening into the tympanic cavity and conducting vessels and nerves. In the ridge between the external opening of the carotid canal and the jugular fossa, a stony fossa, fossula petrosa, is identified, at the bottom of which the tympanic canaliculus for the nerve of the same name begins. Laterally from the foramen caroticum internum, in the depth of the angle formed by the scales and the anterior edge of the pyramid, the entrance opening of the muscular-tubal canal, canalis musculotubarius, is determined, divided by an incomplete bone septum into two semi-canals: for the tensor tympani muscle, semicanalis m. tensoris tympani, auditory tube, semicanalis tubae auditivae.


Figure: Right temporal bone, internal and posterior view.
1 - arcuate elevation; 2 - parietal edge; 3 - roof of the tympanic cavity; 4 - groove of the superior petrosal sinus; 5 - groove of the sigmoid sinus; 6 - mastoid foramen; 7 - occipital edge; 8 - styloid process; 9 - groove of the inferior petrosal sinus; 10 - top of the pyramid; 11 - rocky part, or pyramid; 12 - zygomatic process; 13 - wedge-shaped edge; 14 - arterial groove; 15 - rear surface of the pyramid; 16 - internal auditory opening.

The base of the pyramid is extended downward into the mastoid process, processus mastoideus, the outer surface of which is rough due to the attachment of the sternocleidomastoid muscle to it. Inside the mastoid process there are cells, cellulae mastoidei, various shapes and sizes lined with mucous membrane. The largest cell is the mastoid cave, antrum mastoideum, which communicates with the cavity of the middle ear. Inward from the apex of the mastoid process there are two parallel grooves. The groove of the occipital artery, sulcus a, runs medially. occipitalis, and laterally - the mastoid notch, incisura mastoidea, which is the origin of the digastric muscle. The mastoid process is separated from the tympanic part by the tympanomastoid fissure, fissura tympanomastoidea, through which the auricular branch of the vagus nerve passes. In the seam between the mastoid part and occipital bone there is a mastoid foramen, foramen mastoideum. On the outer surface of the mastoid process, a practically important area is distinguished - the mastoid triangle, which is limited in front by a line drawn from the spina supra meatum (see the chapter “Temporal bone”) to the apex of the mastoid process, behind - by the line of attachment of the sternocleidomastoid muscle and above - a line that is a continuation of the lower edge of the zygomatic process. The triangle serves as a trepanation site for inflammatory processes middle ear.
On inner surface The mastoid process has an S-shaped curved groove of the sigmoid sinus, sulcus sinus sigmoidei. Approximately halfway along its length, the mastoid opening opens.
Canals of the temporal bone. 1. The canal of the facial nerve, canalis facialis, begins at the bottom of the internal auditory canal and goes forward and laterally to the level of the clefts of the petrosal nerve canals. From here, at a right angle, it goes laterally and backwards, forming a bend - the geniculum canalis facialis, changes direction from horizontal to vertical and ends with the stylomastoid foramen.
2. Canal of the carotid artery, canalis caroticus (described in the text).
3. Musculotubal canal, canalis musculotubarius.
4. The canaliculus chordae tympani, starts from the facial canal slightly above the stylomastoid foramen and ends in the area of ​​fissura petrotympanica. A branch of the facial nerve passes through it - the chorda tympani.
5. The mastoid tubule, canaliculus mastoideus, originates at the bottom of the jugular fossa and ends in the tympanomastoid fissure. A branch of the vagus nerve passes through this canaliculus.
6. The tympanic canaliculus, canaliculus tympanicus, arises in the fossula petrosa with the opening apertura inferior canaliculi tympanici, through which the branch of the glossopharyngeal nerve enters, n. tympanicus. After passing through the tympanic cavity, this nerve called n. petrosus superficialis minor exits through the upper opening of the canal, located on the front surface of the pyramid.


Figure: Right temporal bone, ventral view.
1 - articular tubercle; 2 - mandibular fossa; 3 - petrotympanic fissure; 4 - drum part; 5 - mastoid process; 6 - mastoid notch; 7 - muscular-tubal canal; 8 - internal carotid foramen; 9 - external carotid foramen; 10 - jugular fossa; 11 - stylomastoid foramen; 12 - groove of the occipital artery.

7. Carotid-tympanic tubules, canaliculi caroticotympanici, pass in the wall of the carotid artery canal near its external opening and open into the tympanic cavity. They serve for the passage of blood vessels and nerves.
Ossification. The temporal bone has 6 ossification points. At the end of the 1st month intrauterine development ossification points appear in the scales, in the 3rd month - in the tympanic part. At the 5th month, several points of ossification appear in the cartilaginous anlage of the pyramid. By the time of birth, the temporal bone consists of three parts: the squamous with the rudiment of the zygomatic process, the petrous with the rudiment of the mastoid part and the tympanic, which are basically already connected, but in the newborn there are still gaps between them, filled connective tissue. The styloid process develops from two centers. The superior centrum appears before birth and fuses with the petrosal portion during the 1st year of life. Lower center appears after birth and merges with the upper one only after the onset of puberty. During the 1st year of life, the three parts of the bone fuse together.

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