Posterior part of the outer base of the skull. The outer base of the human skull. The outer surface of the base of the skull: openings, canals and their purpose
21. External surface of the base of the skull: openings, canals and their purpose.
Outer base of the skullbasis cranii externa, covered in front by facial bones. The posterior section of the base of the skull, free for inspection, is formed by the outer surfaces of the occipital, temporal and sphenoid bones. Here you can see numerous holes through which arteries, veins, and nerves pass in a living person. Almost in the center of this area there is a large occipital foramen, and on its sides there are occipital condyles. Behind each condyle there is a condylar fossa with a non-permanent opening - the condylar canal. The base of each condyle is penetrated by the hypoglossal canal. The posterior section of the base of the skull ends with the external occipital protrusion with the superior nuchal line extending from it to the right and left. Anterior to the foramen magnum lies the basilar part of the occipital bone with a well-defined pharyngeal tubercle. The basilar part passes into the body of the sphenoid bone. On each side of the occipital bone, on each side, the lower surface of the pyramid of the temporal bone is visible, on which the following important formations are located: the external opening of the carotid canal, the muscular-tubal canal, the jugular fossa and the jugular notch, which with the jugular notch of the occipital bone forms the jugular foramen, the styloid process , mastoid process, and between them the stylomastoid foramen. Adjacent to the pyramid of the temporal bone on the lateral side is the tympanic part of the temporal bone, surrounding the external auditory opening. Posteriorly, the tympanic part is separated from the mastoid process by the tympanomastoid fissure. On the posteromedial side of the mastoid process are the mastoid notch and the groove of the occipital artery.
On a horizontally located section of the squamous part of the temporal bone there is a mandibular fossa, which serves for articulation with the condylar process of the lower jaw. In front of this fossa is the articular tubercle. In the gap between the petrous and scaly parts of the temporal bone on the whole skull, the posterior part of the large wing of the sphenoid bone enters; the foramen spinosum and foramen ovale are clearly visible here. The pyramid of the temporal bone is separated from the occipital bone by the petrooccipital fissure, fissura petrooccipitalis, and from the greater wing of the sphenoid bone - the sphenoid-petrosal fissure, fissura sphenopetrosa. In addition, on the lower surface of the outer base of the skull, a hole with uneven edges is visible - a ragged hole, foramen lacerum, bounded laterally and posteriorly by the apex of the pyramid, which is wedged between the body of the occipital and the greater wing of the sphenoid bones.
22. Eye socket: its walls, contents and messages.
Eye socket,orbita, is a paired cavity resembling a four-sided pyramid with rounded edges. eyeball, its muscles, lacrimal gland and other formations.
The base of the pyramid faces forward and forms the entrance to the eye socket, dditus orbitae. The apex of the orbit is directed posteriorly and medially; the visual channel passes through here, canalis opticus. The orbital cavity contains the eyeball, its muscles, the lacrimal gland and other formations.
The orbital cavity is limited by four walls: superior, medial, inferior and lateral.
Top wall, paries superior (roof of the orbit), smooth, slightly concave, located almost horizontally. It is formed by the orbital part of the frontal bone and is only supplemented posteriorly by the lesser wing of the sphenoid bone.
Medial wall, paries medialis, located sagittally. It is formed by the frontal process of the maxilla, the lacrimal bone, the orbital plate of the ethmoid bone, the body of the sphenoid bone (posteriorly) and the most medial portion of the orbital part of the frontal bone (above).
Bottom wall, paries inferior (bottom of the orbit), formed by the orbital surfaces of the upper jaw and zygomatic bone; behind the wall is complemented by the orbital process of the palatine bone.
Lateral wall, paries lateralis, formed by the orbital surfaces of the greater wing of the sphenoid bone and the frontal process of the zygomatic bone, as well as a small area of the zygomatic process of the frontal bone.
Outer base of the skullbasis cranii externa, covered in front by facial bones. The posterior section of the base of the skull is formed by the outer surfaces of the occipital, temporal and sphenoid bones. Here you can see numerous holes through which arteries, veins, and nerves pass in a living person. Almost in the center of this area there is a large occipital foramen, and on its sides there are occipital condyles. Behind each condyle there is a condylar fossa with a non-permanent opening - the condylar canal. The base of each condyle is penetrated by the hypoglossal canal. The posterior section of the base of the skull ends with the external occipital protrusion with the superior nuchal line extending from it to the right and left. Anterior to the foramen magnum lies the basilar part of the occipital bone with a well-defined pharyngeal tubercle. The basilar part passes into the body of the sphenoid bone. On each side of the occipital bone, on each side, the lower surface of the pyramid of the temporal bone is visible, on which the following important formations are located: the external opening of the carotid canal, the muscular-tubal canal, the jugular fossa and the jugular notch, which with the jugular notch of the occipital bone forms the jugular foramen, the styloid process , mastoid process, and between them the stylomastoid foramen. Adjacent to the pyramid of the temporal bone on the lateral side is the tympanic part of the temporal bone, surrounding the external auditory opening. Posteriorly, the tympanic part is separated from the mastoid process by the tympanomastoid fissure. On the posteromedial side of the mastoid process are the mastoid notch and the groove of the occipital artery.
Pterygopalatine (pterygopalatine) fossa, fossa pterygopaIatina, has four walls: anterior, superior, posterior and medial. The anterior wall of the fossa is the tubercle of the maxilla, the upper wall is the inferolateral surface of the body and the base of the greater wing of the sphenoid bone, the posterior wall is the base of the pterygoid process of the sphenoid bone, the medial wall is the perpendicular plate of the palatine bone. On the lateral side, the pterygopalatine fossa does not have a bone wall and communicates with the infratemporal fossa. The pterygopalatine fossa gradually narrows downwards and passes into the greater palatine canal, canalis palatinus major, which at the top has the same walls as the fossa, and at the bottom it is delimited by the upper jaw (laterally) and the palatine bone (medially). Five openings enter the pterygopalatine fossa. On the medial side, this fossa communicates with the nasal cavity through the sphenopalatine foramen, above and posteriorly with the middle cranial fossa through the round foramen, posteriorly with the region of the foramen lacerum through the pterygoid canal, downwards with the oral cavity through the greater palatine canal. With the orbit The pterygopalatine fossa is connected through the inferior orbital fissure.
Ganglion pterygopalatinum, pterygopalatine ganglion, located in the pterygopalatine fossa medially and inferiorly to the point maxillaris. In the node related to the autonomic nervous system, parasympathetic fibers coming from the autonomic nucleus n are interrupted. intermedius to the lacrimal gland and glands of the mucous membrane of the nose and palate as part of the nerve itself and further in the form of n. petrosus major (branch of the facial nerve).
Ganglion pterygopalatinum gives off the following (secretory) branches: 1) rami nasales posteriores go through the foramen sphenopalatinum to the glands of the nasal mucosa; the largest of them, n. nasopalatinus, passes through the canalis incisivus, to the glands of the mucous membrane of the hard palate; 2) nn. palatini descend along the canalis palatinus major and, exiting through the foramina palatina majus et minus, innervate the glands of the mucous membrane of the hard and soft palate. The nerves extending from the pterygopalatine ganglion contain, in addition to secretory fibers, also sensitive (from the second branch of the trigeminal nerve) and sympathetic fibers. Thus, fibers n. intermedius (parasympathetic part of the facial nerve), passing along n. petrosus major, through the pterygopalatine ganglion innervates the glands of the nasal cavity and palate, as well as the lacrimal gland. These fibers come from the pterygopalatine ganglion through n. zygomaticus, and from it to n. lacrimalis.
Veins of the lower limb.
As on the upper limb, veins of the lower limb are divided into deep and superficial, or subcutaneous, which pass independently of the arteries. The deep veins of the foot and leg are double and accompany the arteries of the same name. V. poplitea, composed of all the deep veins of the leg, represents a single trunk, located in the popliteal fossa posteriorly and somewhat laterally from the artery of the same name.
V. femoralis is single, initially located lateral to the artery of the same name, then gradually moves to the posterior surface of the artery, and even higher - to its medial surface and in this position passes under the inguinal ligament in the lacuna vasorum.
Tributaries v. femoralis are all double. Of the saphenous veins of the lower limb, the largest are two trunks: v. saphena magna and v. saphena parva. Vena saphena magna, the great saphenous vein of the leg, originates on the dorsal surface of the foot from the rete venosum dorsale pedis and arcus venosus dorsalis pedis. Having received several inflows from the side of the sole, it is directed upward along the medial side of the lower leg and thigh.
In the upper third of the thigh, it bends onto the anteromedial surface and, lying on the fascia lata, goes to the hiatus saphenus. At this point v. saphena magna flows into the femoral vein, spreading over the lower horn of the falciform margin. Quite often v. saphena magna is double, and both of its trunks can flow separately into the femoral vein.
Of the other subcutaneous tributaries of the femoral vein, mention should be made of v. epigastrica superficialis, v. circumflexa ilium superficialis, vv. pudendae externae, accompanying the arteries of the same name. They flow partly directly into the femoral vein, partly into the v. saphena magna at its confluence with the hiatus saphenus region.
V. saphena parva, the small saphenous vein of the leg, begins on the lateral side of the dorsal surface of the foot, bends around the lateral malleolus from below and behind and rises further along the posterior surface of the leg; first it runs along the lateral edge of the Achilles tendon, and then upward in the middle of the posterior part of the tibia, corresponding to the groove between the heads of m. gastrocnemia. Having reached the lower angle of the popliteal fossa, v. saphena parva flows into the popliteal vein. V. saphena parva is connected by branches to v. saphena magna.
The human skull is the bony base of the head, consisting of twenty-three bones, in addition to which there are three paired bones located in the cavity of the middle ear. The base of the skull consists of that part that is located below the edge that runs in front on the border of the infraorbital margin, behind along the frontal bone, in particular, its zygomatic process, and the infratemporal crest of the bone in the form of a wedge, the upper border of the external auditory canyon, as well as external protuberance of the occiput. External and are distinguished. Today we will look at the internal foundation. But before we begin to study this issue, let us consider what structure and functions the skull has, as well as its shape.
Forms and functions of the skull
The human skull performs several functions:
Protective, which is characterized by the ability to protect the human brain and sensory organs from various damages;
Supportive, consisting in the ability to accommodate the brain and the initial parts of the respiratory and digestive systems;
Motor, characterized by articulation with the spinal column.
The human skull can be represented by one of the following forms: standard (cranial index), acrocephaly (tower-shaped) and craniosynostotic (fusion of the sutures of the cranial vault).
To better understand the anatomy of the skull, let's take a closer look.
Outer base of the skull
This is the customary name for the one that faces down and is covered in front by the bones of the face, and at the back the outer base is formed by the bony palate, processes in the form of wings, and medial plates that limit the choanae, separated by the vomer. Behind the pterygoid processes, the base is formed by a wedge-shaped bone, the lower part of the pyramid, the tympanic part, as well as the anterior part of the occipital bone. External base of the skull, anatomical atlas its location will tell you, it has three parts: front, middle and back. Let's look at each of them in more detail.
Posterior part of the base of the outer
In the posterior section there is a vault of the nasopharynx, which is limited by the pharynx. The fascia is attached to the base of the skull, which has a direction from the pharyngeal tubercle to the side, in front of the carotid canal of the pyramid of the temple bone to the lower jaw. In the posterior part of the base there is a large occipital fissure and emissaries that connect the sinuses of the dura mater with the plexus of suboccipital veins, the vertebral vein and the subclavian artery.
Anterior section of the base of the outer
There are gaps here, through which nerves and blood vessels pass. The largest foramina, the role of which is very important, are located along the border that connects the stylomastoid fissure and the incisive foramen. The section of the base, which is located in front, includes the bony palate with the incisive and greater palatine canals. The choanae extend backward from the nasal cavity.
Middle section of the outer base
This area includes a torn gap that is located between bones such as the temporal, occipital and sphenoid. There is also a jugular ostium, located between the occipital bone and the temporal bone. In the same area there are such fissures as the sphenoid-petrosal and occipital.
Inner surface of the base of the skull
The base of the skull on the inside contains three fossae: anterior, middle and posterior. In its location, the anterior fossa is above the middle one. And this, in turn, fit over the back. The cerebrum is located in the first two fossae, and the cerebellum is located in the posterior fossa. The demarcations between the fossae are represented by the edges of the sphenoid bone, which are located behind, as well as the upper level of the pyramids of the temple bones. IN the internal base of the skull is the surface of the skull, which is concave and has irregularities, it repeats the structure of the brain that is adjacent to it. Let's look at its structure in more detail.
Anterior fossa of the skull
The anterior cranial fossa is the deepest. It is formed by the edges of the wings of the bone in the form of a wedge and a protrusion that is located between the visual openings. The frontal sinuses adjoin this fossa in front, and below are the recesses of the ethmoid bone, the nasal cavity and sinuses. In front of the cock's crest there is a blind orifice, through which a small vein follows, which connects the superior sagittal sinus with the nasal veins. On both edges of the ethmoid bone there are olfactory bulbs, where the olfactory nerves enter through the plate from the nasal cavity. Arteries, nerves, and veins also pass through the ethmoid bone to provide the lining of the anterior fossa. IN internal base of the skull involves the placement of the frontal lobes of the cerebral hemispheres of the human brain in this pit.
Middle cranial fossa
The middle cranial fossa is separated from the posterior one with the help of the sella turcica and the tops of the pyramids of the temple bones. In the middle of the fossa there is a sella turcica, which is covered by a diaphragm that has a slit through which a depression appears, which has an ending in the form of a cerebral appendage. On the diaphragm in front of the funnel there is a chiasm of the optic nerves, on the sides of which there are so-called siphons of the carotid arteries. From them, in turn, the orbital arteries move away; they, together with the optic nerves, pass into the optic canyons. Thus, it involves placement in the middle fossa of the cavernous sinus, which is located away from the sella turcica. The internal carotid artery passes through this place and above the carotid artery, the following nerves are located in the walls of the sinuses: trigeminal, cranial and oculomotor. They pass through the superior opening into the orbit. On the side of these nerves there are veins of the orbits and the eyeball, which then enter the cavernous sinus. Behind the sella turcica, on the vagus nerve, between the sheets of one of the three meninges, the motor nerve is located. Its branches go through the cracks of the round and oval shape of the cranial pit, which is located in the middle. At the back of the form there is a spinous fissure, through which the anterior artery of the dura mater passes into the cranial cavity. It also suggests the presence on both sides of the sella turcica in the fossa, which is located in the middle, of the brain. In front of the inner part of the temple bone, which has the shape of a pyramid, there is a cavity of the middle ear, an intraauricular cavity and a cavity in the mastoid process of the temporal bone.
Posterior cranial fossa
The posterior cranial fossa contains the cerebellum, medulla oblongata and pons. In front of the fossa on the inclined surface there is a bridge, the main artery with all its branches. There is a plexus of veins and stony sinuses. Everything is connected. The posterior fossa is almost entirely occupied by the cerebellum; above and on the sides of it there are sinuses: sigmoid and transverse. The cranial cavity and the posterior fossa are separated by the cerebellar tentorium, through which the brain passes. Let's consider what role it has.
Behind the pyramid of the temple bone is the auditory orifice, through which the facial and auditory nerves and the membranous labyrinth pass. Below the auditory canyon, the glossopharyngeal, accessory nerves, vagus, and also the jugular vein pass through the ragged fissure. If you look below in the atlas, you can see that the hypoglossal nerve and its canal, as well as a plexus of veins, pass through the mouth of the hypoglossal nerve. In the middle of the posterior fossa there is a large occipital fissure, through which the medulla oblongata and its membranes, spinal arteries and the spinal nerve root extend. Along the edge of the groove of the sigmoid sinus, several orifices open into the fossa located behind, allowing emissary veins and the meningeal branch of the occipital artery to pass through. The mouths and slits that connect the posterior fossa with other areas are located in its anterior parts. Thus, they are presented in three types: front, middle and rear.
Finally...
The features of the shape and structure of the human skull cannot be studied without analyzing its functions, just as it is impossible to imagine the functions of any organ without understanding its structure. Knowledge of the anatomy of the skull in medicine is undeniable. This science uses modern diagnostic methods. The structure of the skull was learned through examination, dissection, study, and other things. Today we have the opportunity to study the external thanks to medical atlases that were created many years ago. This knowledge is of particular importance in medical sciences, since it makes it possible to study abnormalities in the development of the skull, the structure of the veins and blood vessels of the brain. Studying the anatomy of the skull is especially important for neurosurgeons, traumatologists and maxillofacial surgeons. Knowledge helps them make the correct diagnosis and prescribe proper treatment in case of various defects or diseases. And this, in turn, can save a person’s life.
Now we know what human scull. Anatomy of the internal base of the skull considered when studying at medical universities. The base is a concave surface, which follows the structure of the brain. It contains many channels and holes and consists of three pits. The inner base of the skull is the surface of the skull where the frontal lobes of the cerebral hemispheres are located, as well as the cerebellum, medulla oblongata and pons. Arteries, vessels, and nerves are also located here. All of them play a huge role in the normal functioning of the human body.
In the external base, three sections are distinguished: anterior, middle and posterior, the relief of which is formed by the bones of the facial and cerebral skull.
The anterior region or base of the facial skull.
· In the middle there is a bony palate made up of the palatine processes of the upper jaws and horizontal plates of the palatine bones, bounded along the edge by the alveolar processes. The bony palate separates the cavities of the nose and mouth and the muscles of the soft palate are attached to it behind. The gums are located along the alveolar processes.
· Between the palatine processes of the upper jaws and the horizontal plates of the palatine bones there are palatine median and transverse flat sutures.
· Anteriorly in the bony palate lies the incisive foramen, which passes into the incisive canal for the nasopalatine vessels and nerve. On the surface there are transverse palatine grooves and between them palatine ridges, which smooth out with age.
· At the back there are large palatine foramina, which pass into the same canals - for the vessels and nerves of the same name.
· The pyramidal process of the palatine bone contains openings for the small palatine tubules for the vessels and nerves of the same name.
The lateral sections of the base of the facial skull (right and left) consist of the pterygopalatine fossa, the inferior orbital fissure and the infratemporal crest, the infratemporal fossa.
In the middle section (from the posterior edge of the bony palate and pterygoid processes to the anterior edge of the foramen magnum, styloid processes and external auditory foramina of the temporal bones) there are:
· posterior edges of the nasal septum, vomer and nasal ridge with the posterior spine, the sphenoid process of the palatine bone to delimit the choanae;
· pterygoid processes of the sphenoid bone with medial and lateral plates, a pterygoid fossa between them, a pterygoid notch and a pterygoid hook for attachment of the pterygoid masticatory muscles and pharynx;
Choanae - for transmitting air into the nasopharynx;
· body of the sphenoid bone - external carotid and lacerated foramen - for the internal carotid artery and nerve, large wings with holes: oval - for the second branch of the Y pair, spinous - for the middle meningeal artery;
· the pterygoid canal at the base of the pterygoid processes - for the corresponding autonomic nerves and vessels;
· spine of the sphenoid bone - attachment of the temporomandibular joint ligament;
· in the lateral sections – the infratemporal fossa and the mandibular fossa of the temporal bone, the retromandibular fossa,
· on the temporal bone - the mandibular fossa, the base of the zygomatic process - the articular tubercle for the temporomandibular joint, the sphenoid-petallous and petrotympanic fissures;
· at the apex of the temporal pyramid there is a muscular-tubal canal for the auditory tube and the muscle of the tympanic membrane;
· basilar part of the occipital bone - pharyngeal tubercle - beginning of the pharynx.
In the posterior section (from the anterior edge of the foramen magnum to the external occipital protuberance and the superior nuchal line) there are:
· bottom surface of the pyramid; the tympanic part of the temporal bone is the lower edge of the external auditory opening;
· styloid, mastoid processes of the temporal bone;
· jugular fossa, jugular notch, jugular foramen - for the internal jugular vein and IX, X, XI pairs of cranial nerves;
· stylomastoid foramen - exit of the facial nerve canal - UII pair;
· occipital condyles, condylar fossae behind them, canals of the hypoglossal nerves at the base of the occipital condyles;
Foramen magnum for the spinal cord and vertebral vessels;
· stony-occipital fissure filled with cartilage - synchondrosis;
· external nuchal crest and protuberance, inferior nuchal line for attachment of ligaments and muscles.
The temporal fossa is located in the anterolateral part of the vault, bounded above by the inferior temporal line and below by the infratemporal crest of the sphenoid bone. On the lateral side the temporal fossa has the zygomatic arch, and on the front there is the temporal surface of the zygomatic bone. It is filled with the temporal muscle and fiber of the interaponeurotic, subaponeurotic and deep temporal space. The superficial temporal vessels are located above the muscle. Downwards, i.e. at the lateral edge of the outer base of the skull, it passes into the infratemporal fossa. The border between them is the infratemporal crest of the sphenoid bone.
The infratemporal fossa has:
· upper border along the infratemporal ridge;
· lower – along the base and lateral plate of the pterygoid process;
· anterior border – along the orbital edge of the sphenoid bone;
Posterior – along the edge of the base of the zygomatic process of the temporal bone.
On the side, the fossa is limited by the inner surface of the ramus of the lower jaw.
In the infratemporal fossa there is tissue of the temporopterygoid, interpterygoid and pterygomaxillary space, the pterygoid muscles and the maxillary artery pass nearby, part of the pterygoid venous plexus and the maxillary vein lie. Through the pterygomaxillary fissure, the fossa communicates with the pterygopalatine fossa.
