Human anatomy, anatomy, anatomy in pictures, anatomy online, anatomy free, osteology. Temporal bone canals
Normal human anatomy: lecture notes by M. V. Yakovlev
11. TEMPORAL BONE
11. TEMPORAL BONE
Temporal bone (os temporale) is a container for the organs of balance and hearing. The temporal bone, connecting with the zygomatic bone, forms the zygomatic arch (arcus zygomaticus). The temporal bone consists of three parts: squamosal, tympanic and petrous.
Scaly part(pars squamosa) of the temporal bone has an outer smooth temporal surface (facies temporalis), on which runs the groove of the middle temporal artery (sulcus arteriae temporalis mediae). From this part (just above the external auditory canal) the zygomatic process (processus zygomaticus) begins, at the base of which there is the mandibular fossa (fossa mandibularis). In front, this fossa is limited by the articular tubercle (tuberculum articulare). On the inner cerebral surface (facies cerebralis) there are finger-like impressions and arterial grooves.
Drum part(pars tympanica) of the temporal bone is fused at its edges with the mastoid process and the scaly part, limiting the external auditory opening (porus acusticus externus) on three sides, the continuation of which is the external auditory canal (meatus acusticus externus). At the back, at the site of fusion of the tympanic part with the mastoid process, a tympanomastoid fissure (fissura tympanomastoidea) is formed. In front of the auditory opening there is a tympanic-squamous fissure (fissura tympanosquamosa), which is divided by the edge of the roof of the tympanic cavity into a stony-squamous fissure (fissura petrosquamosa) and a stony-tympanic fissure (fissura petrotympanica).
Rocky part, or pyramid(pars petrosa), the temporal bone has the shape of a triangular pyramid. The pyramid is distinguished by the apex (apex partis petrosae), anterior, posterior and lower surfaces, upper and posterior edges and the mastoid process.
Canals of the temporal bone.
The anterior surface of the temporal bone on the lateral side passes into the medullary surface of the squamosal bone, from which it is separated by the petrosquamosal fissure (fissura petrosquamosa). Next to the stony-scaly fissure lies the opening of the muscular-tubal canal (canalis musculotubaris), which is divided by a septum into two semi-canals. One of them is the hemicanal of the auditory tube, and the other is the tensor tympani muscle.
In the middle of the anterior surface of the temporal bone there is an arcuate eminence (eminencia arcuata), between it and the petrosquamosal fissure there is the roof of the tympanic cavity (tegmen tympani). Near the apex of the anterior surface there is a trigeminal depression, lateral to which is the opening of the canal of the greater petrosal nerve (hiatus canalis nervi petrosi majoris), from which the groove of the same name begins. Lateral to this canal is the opening of the canal of the lesser petrosal nerve, from which the groove of the same name extends.
In the middle of the posterior surface of the pyramid of the temporal bone is the internal auditory opening (porus acusticus internus), which passes into the internal auditory canal. Lateral to this opening lies the subarcuate fossa (fossa subarcuata), below and lateral to which there is an external opening of the vestibular aqueduct (apertura externa aqueductus vestibuli).
The lower surface of the pyramid of the temporal bone has at its base a jugular fossa (fossa jugularis), on the anterior wall of which there is a groove ending in a mastoid foramen (foramen mastoideus). The posterior wall of the jugular fossa is represented by the notch of the same name. This notch and the notch of the occipital bone form the jugular foramen (foramen jugulare). In front of the jugular fossa, the carotid canal (canalis caroticus) begins, in the wall of which there are small pits that continue into the carotid-tympanic canaliculi. On the ridge separating the jugular fossa and the external opening of the carotid canal, there is a stony dimple (fossula petrosa), at the bottom of which the lower opening of the tympanic tubule opens. Lateral to the jugular fossa begins the styloid process (processus styloideus), posterior to which there is a stylomastoid foramen (foramen stylomastoideum).
The upper edge of the pyramid of the temporal bone separates the anterior surface from the posterior, and a groove of the superior petrosal sinus (sulcus sinus petrosi superioris) runs along its surface.
The posterior edge of the pyramid of the temporal bone separates the posterior and inferior surfaces; along it runs the groove of the inferior petrosal sinus (sulcus sinus petrosi inferioris).
The mastoid process (processus mastoideus) of the temporal bone is separated from the top from the scaly part by the parietal notch (incisura parietalis), and from below the process is limited by the mastoid notch (incisura mastoidea). Medial to the latter is the groove of the occipital artery (sulcus arteriae occipitalis). On the inner surface of the process there is a wide groove of the sigmoid sinus (sulcus sinus sigmoidei). The internal structure of the process is represented by cells, the largest of which is called the mastoid cave (antrum mastoideum).
Numerous canals and tubules pass through the temporal bone:
1) mastoid tubule (canaliculus mastoideus);
2) tympanic tubule (canaliculus tympanicus);
3) canaliculus chordae tympani;
4) carotid-tympanic tubules (canaliculus caroticotympanici);
5) carotid canal (canalis caroticus);
6) facial canal (canalis facialis);
7) muscular-tubal canal (canalis musculotubarius).
author M. V. Yakovlev From the book Normal Human Anatomy: Lecture Notes author M. V. Yakovlev From the book Normal Human Anatomy: Lecture Notes author M. V. Yakovlev by Stephen Juan From the book Oddities of our body. Entertaining anatomy by Stephen Juan From the book Oddities of our body. Entertaining anatomy by Stephen Juan From the book Dementia: a guide for doctors by N. N. Yakhno From the book Nature Healing Newsletters. Volume 1 author John Raymond Christopher From the book Homeopathic Handbook author Sergei Alexandrovich Nikitin From the book Maintenance of the active man's body author Tatiana Bateneva author Viktor Fedorovich Yakovlev From the book Emergency care for injuries, pain shocks and inflammation. Experience in emergency situations author Viktor Fedorovich Yakovlev From the book Emergency care for injuries, pain shocks and inflammation. Experience in emergency situations author Viktor Fedorovich Yakovlev From the book Emergency care for injuries, pain shocks and inflammation. Experience in emergency situations author Viktor Fedorovich Yakovlev From the book Handbook of Sensible Parents. Part two. Urgent Care. author Evgeny Olegovich Komarovsky From the book Great Protective Book of Health author Natalya Ivanovna StepanovaTemporal bone, os temporale, the paired bone has a complex structure, as it performs all 3 functions of the skeleton and not only forms part of the side wall and base of the skull, but also contains the organs of hearing and gravity. It is the product of the fusion of several bones (mixed bone), which independently exist in some animals, and therefore consists of three parts:
1) scaly part, pars squamosa;
2) the drum part, pars tympanica and
3) rocky part, pars petrosa.
During the 1st year of life, they merge into a single bone, closing external auditory canal, meatus acusticus externus, in such a way that the scaly part lies above it, the stony part medially from it, and the tympanic part behind, below and in front. Traces of the fusion of individual parts of the temporal bone remain for life in the form of intermediate sutures and fissures, namely: at the border of pars squamosa and pars petrosa, on the anterior superior surface of the latter - fissura petrosquamos a; in the depths of the mandibular fossa - fissura tympanosquamosa, which is divided by a process of the petrous part into fissura petrosquamosa and fissura petrotympanica(the chorda tympani nerve exits through it).
Scaly part, pars squamosa, participates in the formation of the lateral walls of the skull. It belongs to the integumentary bones, i.e. it ossifies on the basis of connective tissue and has a relatively simple structure in the form of a vertically standing plate with a rounded edge overlapping the corresponding edge of the parietal bone, margo squamosa, in the form of fish scales, which is where its name comes from.
On its brain surface, facies cerebralis, traces of the brain are visible, finger impressions, impressiones digitatae, and ascending upward groove from a. meningea media. The outer surface of the scales is smooth, participates in the formation of the temporal fossa (the anatomy of which is discussed) and is therefore called facies temporalis.
Moves away from her zygomatic process, processus zygomaticus, which goes forward to connect with the zygomatic bone. At its origin, the zygomatic process has two roots: anterior and posterior, between which there is a fossa for articulation with the lower jaw, fossa mandibularis.
On the lower surface of the anterior root is placed articular tubercle, tuberculum articulare, preventing the head of the lower jaw from dislocating forward when the mouth opens significantly.
Drum part, pars tympanica, the temporal bone forms the anterior, lower and part of the posterior edge of the external auditory canal, ossifies endesmally and, like all integumentary bones, has the appearance of a plate, only sharply curved.
External auditory canal, meatus acusticus externus, is a short canal directed inward and somewhat forward and leading into the tympanic cavity. Its upper edge external opening, porus acusticus externus, and part of the posterior edge is formed by the scales of the temporal bone, and along the remaining length by the tympanic part.
In a newborn, the external auditory canal is not yet formed, since the tympanic part is an incomplete ring (annulus tympanicus), covered by the eardrum. Due to such a close position of the eardrum outwards, diseases of the tympanic cavity are more often observed in newborns and young children.
The petrous part, pars petrosa, is so named for the strength of its bone substance, due to the fact that this part of the bone is involved in the base of the skull, and is the bony seat of the organs of hearing and gravity, which have a very thin structure and require strong protection from damage. It develops on the basis of cartilage. The second name of this part is the pyramid, given by its shape as a triangular pyramid, the base of which faces outward, and the apex faces forward and inward towards the sphenoid bone.
The pyramid has three surfaces: front, back and bottom. The anterior surface is part of the bottom of the middle cranial fossa; the posterior surface faces posteriorly and medially and forms part of the anterior wall of the posterior cranial fossa; the lower surface faces down and is visible only on the outer surface of the base of the skull. The external relief of the pyramid is complex and is determined by its structure as a container for the middle (tympanic cavity) and inner ear (bone labyrinth, consisting of the cochlea and semicircular canals), as well as the passage of nerves and blood vessels.
On the front surface of the pyramid, near its apex, a small depression is noticeable, impressio trigemini, from the trigeminal nerve ganglion (n. trigemini,). Outwards pass from him two thin grooves, medial - sulcus n. petrosi majoris, and lateral - sulcus n. petrosi minoris. They lead to two foramina of the same name: the medial one, hiatus candlis n. petrosi majoris, and lateral, hiatus canalis n. petrosi minoris. Outside of these holes, an arched elevation is noticeable, eminentia arcuata, formed due to the protrusion of a rapidly developing labyrinth, in particular the superior semicircular canal.
The surface of the bone between eminentia arcuata and squama temporalis forms the roof of the tympanic cavity, tegmen tympani.
Approximately in the middle of the back surface of the pyramid is internal auditory opening, porus acusticus internus, which leads to internal auditory canal, meatus acusticus internus, where the facial and auditory nerves pass, as well as the artery and veins of the labyrinth.
From the lower surface of the pyramid, facing the base of the skull, a thin pointed styloid process, processus styloideus, serving as a site of muscle attachment "anatomical bouquet"(mm. styloglossus, stylohyoideus, stylopharyngeus), as well as ligaments - ligg. stylohyoideum and stylomandibular. The styloid process represents a part of the temporal bone of branchial origin. Together with lig. stylohyoideum it is a remnant of the hyoid arch.
Between the styloid and mastoid processes is stylomastoid foramen, foramen stylomastoideum, through which n comes out. facialis and a small artery enters. Medial to the styloid process there is a deep jugular fossa, fossa jugularis. Anterior to the fossa jugularis, separated from it by a sharp ridge, is the external opening of the carotid canal, foramen caroticum externum.
The pyramid has three edges: anterior, posterior and upper. The short anterior margin forms an acute angle with the scales. In this corner it is noticeable opening of the myotubal canal, candlis musculo tubarius leading into the tympanic cavity. This channel is divided by a partition into two sections: upper and lower. Upper, smaller, semicanal, semicanalis m. tensoris tympani, contains this muscle, and the lower one, larger, semicandlis tubae auditivae, is the bony part of the auditory tube, which serves to conduct air from the pharynx into the tympanic cavity.
Along the upper edge of the pyramid, separating the anterior and posterior surfaces, there is a clearly visible groove, sulcus sinus petrosi superiors, a trace of the venous sinus of the same name.
Posterior edge of the pyramid anterior to the fossa jugularis connects with the basilar part of the occipital bone and forms together with this bone sulcus sinus petrosi inferioris- trace of the inferior petrosal venous sinus.
The outer surface of the base of the pyramid serves as a place for muscle attachment, which determines its external relief (process, notches, roughness). Downwards it extends into mastoid process, processus mastoideus. The sternocleidomastoid muscle is attached to it, which maintains the head in the balance necessary for an upright position of the body. Therefore, the mastoid process is absent in quadrupeds and even apes and develops only in humans in connection with their upright posture.
On the medial side of the mastoid process there is a deep mastoid notch, incisura mastoidea, - place of attachment of m. digastricus; even more inward - a small furrow, sulcus a. occipitalis, - trace of the artery of the same name.
On the outer surface of the base of the mastoid process, a smooth triangle is distinguished, which is a place for rapid access to the cells of the mastoid process when they are filled with pus.
Inside the mastoid process contains these cells cellulae mastoideae, which are air cavities separated by bone bars that receive air from the tympanic cavity, with which they communicate through antrum mastoideum. On the cerebral surface of the base of the pyramid there is deep groove, sulcus sinus sigmoidei, where the venous sinus of the same name lies.
Canals of the temporal bone. The largest channel is canalis caroticus, through which the internal carotid artery passes. Beginning with its external opening on the lower surface of the pyramid, it rises upward, then bends at a right angle and opens with its internal opening at the apex of the pyramid medial to the canalis musculotubarius.
Facial canal, canalis facialis, begins in the depths porus acusticus internus, from where the canal first runs forward and laterally to the fissures (hiatus) on the anterior surface of the pyramid; at these holes, the canal, remaining horizontal, turns at a right angle laterally and backward, forming a bend - knee, geniculum canalis facialis, and then down and ends through the foramen stylomastoideum, located on the lower surface of the pyramid of the temporal bone, canalis muculotubarius.
Video No. 1: normal anatomy of the temporal bone of the skull
Other video lessons on this topic are:Video No. 2: normal anatomy of the temporal bone canals
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).
The scales (squama) have 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, there is a mandibular fossa (fossa mandibularis), in front of which there is an articular tubercle (tuberculum articulare). On the cerebral surface of the scales there are imprints from the middle meningeal artery (a. meningea media) and the convolutions of the temporal lobe of the brain.
51. Right temporal bone.
A - view from the inside: 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 semiring and 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 edges.
On the front surface of the stony part, when connecting it to the scales, there is a platform - the roof of the tympanic cavity (tegmen tympani). In front, this area is limited by a fissure (fissura petrosquamosa), and laterally by an arcuate elevation (eminentia arcuata). Below it are the anterior and posterior semicircular canals of the inner ear. From the eminentia arcuata, closer to the apex of the pyramid, there are two openings representing the exit points of the greater and lesser petrosal nerves (hiatus canalis n. petrosi majoris et minoris), opening into the grooves of the same name, which are oriented towards the apex of the pyramid.
On the posterior surface of the petrous part there is an internal auditory opening (porus acusticus internus), where the facial and vestibulocochlear nerves pass. At the base of the stony part there is a deep sigmoid groove (sulcus sigmoideus), into which the opening of the mastoid venous outlet opens. Lateral to the internal auditory canal 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 groove (siilcus sinus petrosi superioris), which reaches the sigmoid groove behind and the apex of the pyramid in front.
On the lower surface of the base of the stony part there is a styloid process (processus styloideus); behind it, the stylomastoid foramen (for. stylomastoideum) opens, representing the opening of the facial nerve canal. Medial to the styloid process the jugular fossa (fossa jugularis) is visible, the posterior edge of which has a notch of the same name. The anterior edge of the jugular fossa borders the external opening of the carotid canal (for. caroticum externum). In the anterior edge there is a small stony fossa (fossula petrosa), at the bottom of which the tympanic canal (canaliculus tympanicus) begins. In adults, behind the stylomastoid foramen and the external auditory canal is the mastoid process (processus mastoideus). In its thickness there are cells lined with mucous membrane and communicating with the tympanic cavity. Medial to the mastoid process are the mastoid fissure and the occipital groove. The latter contains the occipital artery. In the middle of the posterior edge of the pyramid there is an external opening of the cochlea's aqueduct (apertura externa canaliculi cochleae).
Temporal bone canals. The carotid canal (canalis caroticus) begins on the lower surface of the pyramid with the 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 opening (for. caroticum internum).
The facial canal (canalis facialis) begins in the internal auditory canal, then crosses transversely the pyramid and at the cleft of the greater petrosal 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 labyrinthine wall of the inner ear. At the posterior wall of the tympanic cavity, the canal turns 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 anterior edge of the apex of the pyramid and the scales. It consists of two sections: the semicanal of the auditory tube (semicanalis tubae auditivae) and the semicanal of the tensor tympani muscle (semicanalis m. tensoris tympani).
The tympanic canaliculus (canaliculus tympanicus) is very narrow; begins in the fossula petrosa and opens on the anterior surface of the petrous part of the pyramid with the cleft of the canal of the lesser petrosal nerve (hiatus canalis n. petrosi minoris).
The canaliculus chordae tympani extends from the facial canal before it exits the petrous part. It opens into the petrotympanic fissure of the mandibular fossa.
Ossification. The temporal bone of a newborn consists of three independent parts, which are described above. The external auditory canal is relatively short and wide. The tympanic cavity is filled with loose connective tissue, which resolves within the first 3 months after birth.
The tympanic part is presented in the form of an incomplete ring located under the scales lateral to the pyramid. The eardrum is stretched in the lumen of the ring. The process of ossification occurs in connective tissue (primary bone), bypassing the cartilaginous stage. By the age of 6 years, the external auditory canal develops from the semiring, scales and mastoid process. 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, the mastoid process is formed, which is pneumatized in three stages: up to 1 year, a tympanic invagination is formed, up to 3 years, cells are formed, and up to 6 years, pneumatization of the process is completely completed. In the cartilaginous base of the pyramid, 5 bone nuclei appear in the fifth month of intrauterine development, which merge at the time of birth.
| Temporal bone, (os temporale). Outside surface. Right view. 1-squamous part (scales) of the temporal bone; |
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Temporal bone(os temporale). Inner surface. 1-squamosal part of the temporal bone; |
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Temporal bone(os temporale). A cut through the tympanic cavity along the long axis of the pyramid (right bone). 1-temporal bone scales |
The temporal bone, os temporale, paired, is very complex in structure, since its thickness contains the organs of hearing and balance, and, in addition, the bone is penetrated by a number of canals through which vessels and nerves pass. The temporal bone is located in the lateral sections of the skull between the occipital, parietal and sphenoid bones, complementing one part with the cranial vault and the other with the base of the skull. The temporal bone is connected to the facial skull: through a joint - with the lower jaw, and a suture - with the zygomatic bone.
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The temporal bone consists of several fused parts. When examining the temporal bone from the outer, temporal surface, at its lower edge, there is a large opening, which is called the external auditory foramen, porus acusticus externus. The hole is surrounded by four components of the temporal bone: above and in front - a flat scale of the temporal bone with a pointed edge, squama temporalis, in front and below - a small, groove-shaped plate - the tympanic part, pars tympanica, behind - a powerful bony protrusion - the mastoid part , pars mastoidea, from the inside - in the form of a pyramid, tapering in the direction from the mastoid part obliquely inward and anteriorly - the stony part or pyramid, pars petrosa s. pyramids. The scales of the temporal bone, squama temporalis, have the shape of a semicircular bone plate, facing with its smooth temporal surface, fades temporalis, outward and with its internal, cerebral surface, fades cerebralis, into the cranial cavity. The semicircular edge delimiting the scales is not the same everywhere; the anterior and posterior portions of the edge are more jagged and less pointed on the inside than the upper portion. The anterior edge connects with the scaly edge of the large wing of the main bone and is called the main edge, margo sphenoidalis; the upper posterior edge, connecting with the scaly edge of the parietal bone, is called the parietal edge, margo parietalis. The posterior-inferior part of the scales passes into the mastoid part.
In children, at the junction of these parts, there is a squamous-mastoid suture, sutura squamomastoidea, directed obliquely from top to bottom and anteriorly. Remnants of this suture are sometimes preserved in adults. Somewhat higher and along it there is a temporal line, the anterior end of which approaches the root of the zygomatic process of the temporal bone, processus zygomaticus ossis temporalis. The zygomatic process arises from two roots: posterior and anterior. It runs horizontally, first outward, and then at an angle anteriorly, and ends with a serrated end. Lastly, it connects with the temporal process of the zygomatic bone, forming with it the zygomatic arch, arcus zygomaticus. Below the zygomatic process and in front of the external auditory opening, the articular fossa of the lower jaw, fossa mandibularis, is located. In the anterior sections, the fossa is limited by a clearly visible articular tubercle, tuberculum articulare; in the rear - smaller in size, behind - the articular process, processus retroarticularis. The anterior part of the fossa and the articular tubercle are covered with cartilage. In the posterior part of the outer surface, fades temporalis, the scales of the temporal bone bear the groove of the middle temporal artery, sulcus arteriae temporalis mediae. This furrow rises upward and branches in the upper segment of the scales.
Brain surface, fades cerebralis, the bone is somewhat concave, has a well-defined, deep arterial groove in the anterior section, sulcus arteriosus (meningeus) (place of contact of the meningeal artery of the brain), traces of depression of the convolutions of the brain - finger impressions, impressiones digitatae, and between the latter projections - cerebral eminences , juga cerebralia. Stony part or pyramid, parspetrosa s. pyramidis, has the appearance of a three-sided pyramid, located in a supine position, so that its base, basis pyramidis, is directed outward and connects with the mastoid and squamosal parts of the temporal bone. At the site where the base of the pyramid meets the scaly part, in childhood there is a gap, flssura petrosquamosa, over the years it is filled with bone tissue, and thus the boundary between these two parts disappears.
The top of the pyramid has an uneven edge. It is directed forward and inward, towards the lateral surface of the bodies of the sphenoid and occipital bones. The gap remaining between them on the whole skull is called torn hole, foramen lacerum (Fig. 124), filled with fibrous cartilage, fibrocartilago basilaris. In the area of the apex, a large internal opening of the carotid artery canal, foramen caroticum intemum, opens. The upper corner of the pyramid, angulus superior pyramidis, protrudes freely into the cranial cavity at the border of the anterior and posterior surfaces of the pyramid, fades anterior and fades posterior pyramidis. The upper stony groove, sulcus petrosus superior, runs along the upper corner of the pyramid, a trace of the venous sinus located here. The anterior corner of the pyramid, angulus anterior pyramidis, is located on the border of the anterior and lower surfaces of the pyramid, facies anterior and facies inferior pyramidis. The internal segment of the anterior angle connects to the edge of the large wing of the main bone with the help of cartilage, forming the main-stony synchondrosis, synchondrosis sphenopetrosa. The outer segment of the anterior angle connects with the scales of the temporal bone, forming a stony-squamous fissure, fissura petrosquamosa.
Near the medial end of the petrosquamous fissure, in the corner where the anterior corner of the pyramid meets the anterior edge of the squamosal, one can see opening of the myotubal canal, canalis musculotubarius. The latter, located obliquely outward and backward, is divided by a horizontally standing thin bone plate - the septum of the muscular-tubal canal, septum canalis musculotubarii, into two parts: the upper - the semicanal of the tensor tympani muscle, semicanalis musculi tensoris tympani, and the lower - the auditory semicanal (Eustachian ) pipes, semicanalis tubae auditivae Eustachii. Both hemicanals lead to the middle ear cavity. The posterior corner of the pyramid, angulus posterior pyramidis, is located on the border of its posterior and lower surfaces, facies posterior et facies inferior pyramidis. It is adjacent to the lateral edges of the partes basilaris and lateralis ossis occipitalis. The inner part of the posterior angle is adjacent to the pars basilaris ossis occipitalis, and here a stony-occipital fissure, fissura petrooccipitalis, is formed, made of cartilage connecting both bones - synchondrosis petrooccipitalis. On the cerebral surface of this part of the posterior angle runs the lower stony groove, sulcus petrosus inferior. The latter, connecting with the groove of the same name on the adjacent part of the occipital bone, is the location of the temporal sinus (sinus petrosus inferior).
At the outer end of the groove, at the posterior corner of the pyramid, there is a small depression, at the bottom of which a small external opening of the cochlear canal, apertura externa canaliculi cochleae, opens. (V. canaliculi cochleae and ductus perilymphaticus, coming from the cavity of the inner ear, pass here). The lateral part of the posterior corner of the pyramid is adjacent to the pars lateralis ossis occipitalis. There is a small jugular notch, incisura jugularis, which corresponds to the notch of the same name on the occipital bone and together with it forms the jugular foramen, foramen jugulare, on the entire skull.
At the indicated three corners of the pyramid, its three surfaces converge: front, back and bottom. The first two are facing the cranial cavity, the latter is directed towards the outer surface of the base of the skull. The anterior surface of the pyramid, fades anterior pyramidis, is uneven and is located obliquely anteriorly. Outside, it borders with scales, forming a stony-scaly fissure, fissura petrosquamosa; from the inside, it borders on the body of the main bone, without reaching it and here, with the uneven edge of its apex, forms the ragged hole described above, foramen lacerum. The anterior-inferior and postero-superior boundaries are the corresponding corners or edges of the pyramid. On the anterior surface of the pyramid, near the apex, there is a depression of the trigeminal nerve, impressio nervi trigemini, an imprint of the adjacent Gasserian ganglion of the trigeminal nerve (ganglion Gasseri).
A semicircular eminence, eminentia arcuata, protrudes slightly to the side from the middle of the front surface of the pyramid, the relief of the superior semicircular canal. The area of the anterior surface located between the elevation and the stony-scaly fissure (fissura etrosquamosa) is the roof of the tympanic cavity, legmen tympani; which is a thin layer that forms the upper wall of the middle ear cavity. Tegmen tympani with its anterior edge enters the gap between the pars tympanica behind and the pars squamosa in front, forming a noticeable ridge in the area of the fossa mandibularis, called processus inferior tegmenis tympani (s. crista tegmcntalis) (see more about this in the description of pars tympanica).
Two openings are visible slightly inward and downward from the eminentia arcuata. One of them is located more medially and is the opening of the facial nerve canal, hiatus canalis facialis. A branch of the facial nerve emerges through this hole - the large stony nerve, nervus petrosus superficialis major, which lies in the corresponding groove - sulcus nervi petrosi superficialis majoris, running longitudinally inward and anterior to the hiatus canalis facialis.
The other opening is located lateral and is the superior opening of the tympanic tubule, apertura superior canaliculi tympanici. Through this hole, the small stony nerve emerges - nervus petrosus superficialis minor, which lies in the groove of the same name - sulcus nervi petrosi superficialis minoris. This groove, heading inward and anterior to the pyramid, runs parallel and outward from the sulcus nervi petrosi superficialis majoris. The posterior surface of the pyramid, fades anterior pyramidis, is located more vertically than the anterior one, however, having some slope posteriorly and downward. Inward from the upper corner, closer to the middle of the posterior surface, there is a rather wide internal auditory opening, porus acusticus internus. It opens into a channel going inside the rocky part. This channel is called internal auditory canal, meatus acusticus interims. (For its further progress inside the rocky part, see “Ear.”)
Outside and posterior to the porus acusticus internus, a small slit-shaped opening is visible, called external opening of the aqueduct-vestibule, apertura externa aquaeductus vestibuli, which is the exit point of the internal lymphatic duct, ductus endolymphaticus, from the cavity of the inner ear. Slightly above the water supply hole, at the upper corner of the pyramid, is located subsemicircular fossa, fossa subarcuata, clearly visible in young people. The lower surface of the pyramid, fades inferior pyramidis, is directed downward and faces the outer surface of the base of the skull; outside and somewhat in front, this surface is in contact with the tympanic part of the temporal bone. It has a large number of holes, recesses and protrusions.
The central place on the lower surface of the pyramid is occupied by a large round hole, which is the entrance to the carotid artery canal, the external opening of the carotid canal, foramen caroticum externum. (Through this opening the internal carotid artery and the nerve plexus enter.) Posterior and outward from the foramen caroticum externum, separated from it by a ridge, there is a wide jugular fossa, fossa jugularis, reaching the posterior edge of the lower surface of the petrous part, where there is a jugular notch, incisura jugularis. It houses the bulb of the jugular vein. At the bottom of the jugular fossa, closer to its anterior edge, there is a groove of the mastoid tubule, sulcus canaliculi mastoidei, ending with the opening of the mastoid tubule, canaliculus mastoideus.
On the ridge separating the fossa jugularis from the foramen caroticum externum, there is a barely noticeable stony dimple, fossula petrosa, leading into the lower opening of the tympanic tubule, apertura inferior canaliculi tympanici. (A. tympanica inferior and n. tympanicus pass here from the petrosal ganglion.) At the very base of the pyramid, on the outer part of the lower surface, the styloid process, processus styloideus, protrudes downwards and anteriorly, which is semi-surrounded in front by a bone sheath, vagina processus styloidei, formed by the tympanic part of the temporal bone.
Near the styloid process, on the border with the mastoid process, processus mastoideus, there is a stylomastoid foramen, foramen stylomastoideum, the exit point of the facial nerve and vessels. In the pyramid of the temporal bone there are a number of canals through which vessels and nerves pass, and the organ of hearing and the organ of balance of the body are located , which is why the pyramid has such a complex structure. All these formations are visible on special preparations of cuts of the temporal bone carried out in various directions.
1.Formations related to the structure of the organs of hearing and balance:
A). external auditory opening, porus acusticus externus, and its continuation into the external auditory canal, meatus acusticus externus, are the bony parts of the external ear;
b). tympanum tire, tegmen tympani, is the upper wall of the middle ear cavity, into which the canalis musculo-tubarius opens, lying on the outer edge of the anterior corner of the pyramid;
V). inner ear cavity(labyrinth) is indicated on the anterior surface of the pyramid by a semicircular eminence, eminentia arcuata, where the superior semicircular canal fits, and on the posterior surface by a fossa, fossa subarcuata.
Small openings on the posterior surface of the pyramid, apertura externa canaliculi cochleae and apertura externa aquaeductus vestibuli, lead to the inner ear; they contain vessels and lymphatic ducts through the porus acusticus internus passing the auditory and facial nerves.
2. Facial nerve canal(fallopian canal), canalis facialis (Falloppii), inside the petrous part of the temporal bone. It begins with the opening of the bottom of the internal auditory canal, in the area of its upper recess - area facialis (see "Ear"), and continues the direction of the internal auditory canal forward and outward under the anterior surface of the stony part. Here, to the front surface of the pyramid, a branch departs from it, ending with an opening - hiatus canalis facialis; the canal itself, turning outward and backward, forms at the point of rotation the knee of the auditory nerve canal, geniculum canalis facialis.
After the formation of the knee, the canal follows posteriorly and somewhat downward and, reaching the posterior part of the inner wall, cavum tympani, passes into the vertical part. Then it goes down and opens behind the base of the styloid and in front of the mastoid processes - the stylomastoid foramen, foramen stylomastoideum. The upper end of the vertical part of the canal forms the protrusion of the facial nerve canal, prominentia canalis facialis, located in the posterior part of the medial wall of the inner ear. Somewhat lower, the canal of the facial nerve gives off a branch of the canaliculus chordae tympani, through which the chorda tympani nerve passes, and which ends in the fissura petrotympanica (Glaseri).
3. Tympanic canaliculus, canaliculus tympanicus, passes a branch of the glossopharyngeal nerve. The tubule begins with the lower opening of the tympanic tubule at the bottom of the petrosal fossa, fossula petrosa (from the lower surface of the petrous part), and, moving in an arcuate manner backward, upward and then forward, opens with the upper opening of the tympanic tubule, apertura superior canaliculi tympanici (on the anterior surface of the petrous part) . Canaliculus tympanicus communicates with the canalis nervi facialis Falloppii in the area of its knee.4. The canal of the carotid artery, canalis caroticus, is short, wide and curved. The internal carotid artery and its venous and nerve plexuses pass through it. The canal begins with a hole located on the lower surface of the pyramid - foramen caroticum externum.
Next, the canal rises upward, then forms an almost right-angle bend and, going horizontally anteriorly and internally, opens with the internal opening of the carotid canal, foramen caroticum internum. Near the external opening, in the wall of the carotid artery canal, small openings of the carotid tubules, canaliculi curaticotympanici, open. These tubules are short, go to the anterior wall of the cavum tympani, bypassing the wall of the carotid canal from above. Opening in the anterior wall of the cavum tympani, they pass branches of the internal carotid artery and the superior and inferior carotid tympanic nerves.
mastoid part, pars mastoidea, located posterior to the external auditory canal. From the outside it smoothly turns into scales, and from the inside into the rocky part. The mastoid part faces downwards with a free convex surface, posteriorly and outwards with a rough surface. The posterior inferior, occipital edge, margo occipitalis, connects with the mastoid edge of the occipital bone, forming the occipital-mastoid suture, sutura occipitomastoidea.
Top edge, together with the posterior portion of the parietal edge of the scales, forms the parietal notch, incisura parietalis. This notch is made by the mastoid angle of the parietal bone, angulus mastoideus, which connects to the mastoid part using the mastoid-parietal suture, suturaparietomastoidea. In front, in the upper section, the mastoid part passes into the scales, in the lower part it borders on the tympanic part, forming with it the tympanomastoid fissure, fissura tympanomastoidea. In the anterior section, which makes up the upper-posterior part of the edge of the external auditory opening, there is a small protrusion - the supra-entrance spine, spina suprameatum, and near it posteriorly - the mastoid fossa, fossa mastoidea.
The rough anterior-lower section of the outer surface ends in a blunt and powerful mastoid process, processus mastoideus, which is directed obliquely anteriorly and downward and can be easily felt through the skin; in adults it varies, the degree of its development in children of the first years of life is poorly expressed (Fig. 83 ). In the postero-inferior section of the outer surface of the process there is a mastoid foramen, foramen mastoideum, belonging to the group of graduate foramina, emissaria Santorini; it penetrates the entire thickness of the bone and opens on the inner surface of the mastoid process. This hole is variable in size and position: sometimes there is only one and is located in the area of the sutura squamomastoidea, sometimes there are several.
On the outer side and below, the mastoid process bears a deep mastoid notch, incisura mastoidea, the origin of the digastric muscle (m. digastricus). The groove of the occipital artery, sulcus arteriaeoccipitalis, runs medially and parallel to the notch. On the inner, cerebral, surface of the mastoid part there is an S-shaped groove, sulcus sigmoideus, - the location of the venous sinus of the same name - sinus sigmoideus. Very often, the entrance opening of the above-mentioned foramen mastoideum opens into the same groove. Processus mastoideus belongs to the group of pneumatic bones. As can be seen from the drawings depicting the cut of the mastoid process, it has a large number of interconnected cells, cellulae mastoideae, lined with mucous membrane. The cells are filled with air penetrating here from the middle ear cavity. In the anterior-superior corner, inside the mastoid process, there is a large cell called the cave of the tympanic cavity, antrum tympanicum, communicating, on the one hand, with the cavity of the middle ear, and on the other, with the cells of the mastoid process.
The number and size of cells may vary between individuals. The tympanic part, pars tympanica, is formed during embryonic development in the form of a horseshoe-shaped semi-ring - the tympanic ring, annuhis tympanicus, forming the lower periphery of the external auditory canal. The ends of the semiring: the anterior, greater tympanic spine, spina tympanica major, and the posterior, lesser tympanic spine, spina tympanica minor, limit the gap called the tympanic notch, incisura tympanica (Rivini), over which (over both spines) hangs the lower edge of the scaly part of the temporal bones, thus closing the semi-ring at the top. Along the circumference of the inner surface of the ring runs the tympanic groove, sulcus tympanicus, which is the attachment site of the eardrum.
On the inner surface of the spina tympanica major there is an obliquely running spinous ridge, crista spinarum, the sharp ends of which are called: the anterior one - processus tympanicus anterior, and the posterior one - processus tympanicus posterior. Along the ridge and below it runs a groove - sulcus mallei. Due to the growth of bone substance from the outer surface of the semiring, the latter takes the form of a groove-shaped plate, which on the temporal bone of an adult forms the anterior, lower and part of the posterior wall of the external auditory opening, porus acusticus externus, and the external ear canal, meatus acusticus externus. As the bony groove of the tympanic part lengthens with age, the external auditory canal also lengthens: thus, the eardrum, which lies more superficially in children, due to this goes deeper.
The upper anterior edge of the tympanic part is separated over a large area from the scaly part by the anterior edge of the stony part wedged between them - the lower process of the roof of the tympanic cavity, processus inferior tegmenis tympani (s. crista tegmentalis). Between this process in front and the pars tympanica behind, a petrotympanic fissure is formed, fissura petrotympanica (Glaseri), through which small vessels and a nerve pass - the chorda tympani. Between the process at the back and the pars squamosa at the front, another gap is formed - stony-scaly, fissura petrosquamosa, made of connective tissue.
The posteroinferior edge of the tympanic part borders on the mastoid part of the temporal bone, forming at the point of contact the tympanomastoid fissure, fissura tympanomastoidea, in the depth of which the exit opening of the mastoid canaliculus, canaliculus mastoideus, begins in the fossa jugularis. The edge is pointed and extended downwards in the shape of a ridge, crista peirosa, the part of which at the base of the processus styloideus is the most developed, is called the vagina of the styloid process, vagina processus styloidei. The lower surface of the tympanic part and the fossa at the root of the zygomatic process of the squamous part form the articular fossa of the lower jaw, fossa mandibularis, at the bottom of which there are fissura petrotympanica (Glaseri) and fissura petrosquamosa. This fossa is divided by the glazer fissure into two parts - anterior and posterior.
The anterior part, lined with articular cartilage, faces the cavity of the mandibular joint, it is called inside- or intracapsular part, pars intracapsularis; posterior - located outside the joint and is called out- or extracapsular part, pars extracapsularis (see "Mandibular joint").
TEMPORAL BONE
Temporal bone, os tempordle, a paired bone, has a complex structure, as it performs all 3 functions of the skeleton and not only forms part of the side wall and base of the skull, but also contains the organs of hearing and balance. It is the product of the fusion of several bones (mixed bone), which exist independently in some animals, and therefore consists of three parts: 1) the scaly part, pars squamosa (in animals - os squamosum); 2) the tympanic part, pars tympanica (in animals - tympanicum), and 3) the stony part, pars petrosa (in animals - petrosum).
During the 1st year of life, they merge into a single bone, closing the external auditory canal, meatus acusticus externus, in such a way that the scaly part lies above it, the stony part medially from it, and the tympanic part behind, below and in front. Traces of the fusion of individual parts of the temporal bone remain for life in the form of intermediate sutures and fissures, namely: at the border of pars squamosa and pars petrosa, on the anterior superior surface of the latter - fissura petrosquamosa, in the depths of the jaw fossa - fissura tympanosquamosa, which is divided by the process of the petrous part on fissura petrosquamosa and fissura petrotympanica (the chorda tympani nerve exits through it).
The scaly part, pars squamosa, is involved in the formation of the lateral walls of the skull. It belongs to the integumentary bones, i.e. it ossifies on the basis of connective tissue and has a relatively simple structure in the form of a vertical plate with a rounded edge overlapping the corresponding edge of the parietal bone, margo squamosa, in the form of fish scales, which is where its name comes from.
On its cerebral surface, facies cerebralis, traces of the brain, finger impressions, impressiones digitatae, and an upward groove from a. meningea media. The outer surface of the scales is smooth, participates in the formation of the temporal fossa and is therefore called facies temporalis. The zygomatic process, processus zygomaticus, departs from it, which goes forward to connect with the zygomatic bone. At its origin, the zygomatic process has two roots: anterior and posterior, between which there is a fossa for articulation with the lower jaw, fossa mandibularis. An articular tubercle, tuberculum articulare, is placed on the lower surface of the anterior root, which prevents the head of the mandible from dislocating forward when the mouth opens significantly.
The tympanic part, pars tympanica, of the temporal bone forms the anterior, lower and part of the posterior edge of the external auditory canal, ossifies endesmally and, like all integumentary bones, has the appearance of a plate, only sharply curved.
The external auditory canal, meatus acusticus extern us, is a short canal that goes inward and somewhat forward and leads into the tympanic cavity. The upper edge of its external opening, porus acusticus externus and part of the posterior edge are formed by the scales of the temporal bone, and along the remaining length by the tympanic part.
In a newborn, the external auditory canal is not yet formed, since the tympanic part is an incomplete ring (anulus tympanicus), covered by the eardrum. Due to such a close position of the eardrum outwards, diseases of the tympanic cavity are more often observed in newborns and young children.
An important part of the temporal bone is the petrous part, pars petrosa, so named for the strength of its bone substance, due to the fact that this part of the bone is both involved in the base of the skull and is the bony seat of the organs of hearing and balance, which have a very delicate structure and require strong protection from damage. It develops on the basis of cartilage. The second name of this part is the pyramid, given by its shape as a triangular pyramid, the base of which faces outward, and the apex faces forward and inward towards the sphenoid bone.
The pyramid has three surfaces: front, back and bottom. The anterior surface is part of the bottom of the middle cranial fossa; the posterior surface faces posteriorly and medially and forms part of the anterior wall of the posterior cranial fossa; the lower surface faces down and is visible only on the outer surface of the base of the skull. The external relief of the pyramid is complex and is determined by its structure as a container for the middle (tympanic cavity) and inner ear (bone labyrinth, consisting of the cochlea and semicircular canals), as well as the passage of nerves and blood vessels. On the anterior surface of the pyramid, near its apex, there is a noticeable small depression, impressio trigimini, from the trigeminal ganglion (n. trigeminus). Two thin grooves run outward from it, the medial one is sulcus n. petrosi majoris, and lateral-sulcus n. petrosi minoris. They lead to two foramina of the same name: the medial one, hiatus canalis n. petrosi majoris, and lateral, hiatus canalis n. re trosi minoris. Outside of these openings, an arched elevation is noticeable, etineptia arcuata, formed due to the protrusion of the rapidly developing labyrinth, in particular the superior semicircular canal. The surface of the bone between eminentia arcuata and squama temporalis forms the roof of the tympanic cavity, tegmen tympani.
Approximately in the middle of the posterior surface of the pyramid is the internal auditory opening, porus acusticus internus, which leads into the internal auditory canal, meatus acdsticus internus, where the facial and auditory nerves, as well as the internal auditory artery and veins, pass.
From the lower surface of the pyramid, facing the base of the skull, extends a thin pointed styloid process, processus styloideus, which serves as the attachment point for the muscles of the “anatomical bouquet” (mm. styloglossus, stylohyoideus, stylopharyngeus), as well as ligaments - ligg. stylohyoideum and stylomandibulare. The styloid process represents a part of the temporal bone of branchial origin. Together with lig. stylohyoideum it is a remnant of the second visceral arch, the sublingual (hyoid).
Between the styloid and mastoid processes there is a stylomastoid foramen, foramen stylomastoideum, through which n. facialis and one of the arteries enters. Medial to the styloid process there is a deep jugular fossa, fossa jugularis. Anterior to the fossa jugularis, separated from it by a sharp ridge, is the external opening of the carotid canal, foramen caroticum externum.
The pyramid has three edges: anterior, posterior and upper. The short anterior margin forms an acute angle with the scales. In this corner, the opening of the myotubal canal, canalis musculotubarius, leading into the tympanic cavity is noticeable. This channel is divided by a partition into two sections: upper and lower. The upper, smaller, semicanal, semicanalis tensoris tympani, contains this muscle, and the lower, larger, semicatialis tiibae auditvae, is the bony part of the auditory tube, which serves to conduct air from the pharynx into the tympanic cavity.
Along the upper edge of the pyramid, separating the anterior and posterior surfaces, there runs a clearly visible groove, sulcus sinus petrosi superioris, a trace of the venous sinus of the same name.
The posterior edge of the pyramid anterior to the fossa jugularis connects to the main part of the occipital bone and, together with this bone, forms the siilcus sinus petrosi inferioris - a trace of the inferior petrosal venous sinus.
The outer surface of the base of the pyramid serves as a place for muscle attachment, which determines its external relief (process, notches, roughness). Downwards it extends into the mastoid process, processus mastoideus. The sternocleidomastoid muscle is attached to it, which maintains the head in the balance necessary for an upright position of the body. Therefore, the mastoid process is absent in quadrupeds and even apes and develops only in humans in connection with their upright posture. On the medial side of the mastoid process there is a deep mastoid notch, incisura mastoidea, - the place of attachment of m. digastricus; even more inward - a small groove, sulcus a. occipitalis, - trace of the artery of the same name.
On the outer surface of the base of the mastoid process, a smooth triangle is distinguished, which is a place for rapid access to the cells of the mastoid process when they are filled with pus.
Inside the mastoid process contains these cells or cells, cellulae mastoideae, which are air cavities separated by bone bars, receiving air from the tympanic cavity, with which they communicate through the antrum mastoideum. On the cerebral surface of the base of the pyramid there is a deep groove, sulcus sinus sigmoidei, where the venous sinus of the same name lies.
Canals of the temporal bone. The largest canal is the canalis caroticus, through which the internal carotid artery passes. Beginning with its external opening, foramen caroticum externum, on the lower surface of the pyramid, it rises upward, then bends at a right angle and opens with its internal opening, foramen caroticum internum, at the apex of the pyramid medial to the canalis musculotubarius. The canal of the facial nerve (Fig. 27), canalis facialis, begins in the depths of the porus acusticus internus, from where the canal first goes forward and laterally to the cracks (hiatus) on the anterior surface of the pyramid; at these openings the canal, remaining horizontal, turns at a right angle laterally and backwards, forming a bend - the genu, geniculum canalis facialis, and then goes down and ends through the foramen stylomastoideum, located on the lower surface of the pyramid of the temporal bone.
