The following bones belong to the brain part of the skull. The structure of the skull bones
6. Skull: sections, bones forming them.
The skull is divided into a cerebral section (neurocranium), which contains the brain, and a facial section (splanchnocranium), in which the initial sections of the respiratory and digestive tracts are located.
Brain department. The brain skull is formed by unpaired bones: occipital, sphenoid, frontal, ethmoid, and paired bones: parietal and temporal (see Atl.). Some bones (sphenoid and ethmoid), located on the border of the brain and facial sections, are functionally involved in the formation of the latter.
Parietal bones (ossa parietalia) almost quadrangular, closing the skull from above and from the sides. Their convex parts are called parietal tubercles.
Frontal bone (os frontale) adjacent to the anterior edge of the parietal bones. It consists of scales, orbital and nasal parts (see Atl.). On her convex scales two frontal tubercles protrude in front, below them lie brow ridges, laterally ending zygomatic processes, and even lower there are two supraorbital foramina, or clippings. On the lower concave surface orbital part located at the zygomatic process fossa of the lacrimal gland, and medially – trochlear fossa, and sometimes the spine is the place of attachment of the cartilaginous block through which one of the eye muscles is thrown. Between the orbital parts is located bow part, covering lattice tenderloin. In the thickness of the frontal bone there is frontal sinus, communicating with the nasal cavity.
Occipital bone (os occipitale) participates in the formation of the base and vault of the skull, which it closes behind and below. The bone consists of a concave scales, paired side parts with jugular processes and with condyles(articulate with the atlas) and main part. These four parts limit foramen magnum. The base of each condyle laced with short canal of the hypoglossal nerve. They protrude laterally from the condyles jugular processes. Rough lines stretch across the outer surface of the scales. upper And lower nuchal lines and performs external occipital protuberance. On the brain surface of the scales rises internal occipital protuberance, from which it diverges cruciform eminence with wide grooves from the venous sinuses.
Temporal bones (ossa temporalia) adjacent to the occipital bone. They participate in the formation of the lateral wall and base of the skull, serve as a receptacle for the organs of hearing and balance, as an attachment site for the masticatory and neck muscles, and articulate with the lower jaw. Due to the variety of functions, the temporal bone has a complex structure (see Atl.). On its lateral surface there is external auditory opening, around which are located: above - the scales, behind - the mastoid part, in front and below - the tympanic part and medially - the pyramid. Scales – a slightly concave plate closing the side of the brain skull. It has a forward-facing zygomatic process, connecting to the zygomatic bone. Under its base there are the articular cavity and tubercle. Here the articulation with the head of the lower jaw occurs. Mastoid part forms the mastoid process (the place of muscle attachment), easily palpable through the skin behind the auricle. Inside, the process consists of small air-bearing cavities - cells. Unlike other pneumatized bones, they communicate with the cavity of the middle ear. Drum part smaller than other parts; it limits the external auditory canal.
Pyramid, or rocky part, contains the tympanic cavity and the cavity of the inner ear. On its back surface there is internal auditory opening, and lateral to it is a slit-like opening aqueduct of the vestibule. There is a noticeable flat surface on the anterior surface roof of the tympanic cavity and medial from it - arcuate elevation. At the top of the pyramid there is a small fossa of the trigeminal ganglion. Protrudes on the bottom surface styloid process and there is an external hole carotid artery canal. This channel runs inside the pyramid and then opens at its top with a hole of the same name. Between the styloid and mastoid processes is located stylomastoid foramen. In the corner between the scales and the pyramid it opens muscular-tubal canal, enclosing auditory tube leading into the middle ear cavity.
Sphenoid bone (os sphenoidale) lies at the base of the brain skull and connects with all its bones (see Atl.), as if wedged between them. The bone has a complex structure, since many large nerves pass through it, it participates in the formation of the orbit, the temporal and infratemporal fossa, and serves as an attachment point for the masticatory muscles.
The bones are distinguished body with an air sinus, which communicates in front with the nasal cavity (see Atl.). The depression on the upper surface of the body is called Turkish saddle, It houses the endocrine gland - the pituitary gland. Extend to both sides of the body big wings; at the base of each of them are located sequentially round, oval And spinous foramen. The anterior surface of the wings forms the lateral wall of the orbit. Above the large wings, bones extend from the body small wings, pierced at the base visual channel, in which the cranial nerve of the same name is located. Small wings are separated from large ones superior orbital fissure and participate in the formation of the orbit. Move down from the body pterygoid processes, consisting of two (medial and lateral) plates, between which there is pterygoid fossa. The base of the processes is penetrated pterygoid canal. The processes serve as attachment sites for muscles.
Ethmoid bone (os ethmoidale) surrounded by other bones so that only its outer part is visible on the whole skull - orbital plate, participating in the formation of the medial wall of the orbit (see Atl.). The other part of the bone is perforated plate - closes the notch of the frontal bone and is visible from the cerebral surface of the skull. From this plate a longitudinal cock's comb; its continuation into the nasal cavity is perpendicular
plate, which is involved in the formation of the nasal septum (see Atl.). Large paired part of the bone - labyrinths, consisting of bony cells hanging into the nasal cavity.
Projecting towards the perpendicular plate from the labyrinths are average And superior turbinates.
Facial section. In the facial skull, unlike the brain skull, paired bones predominate, which include the maxillary, nasal, lacrimal, zygomatic, palatine and inferior nasal conchae. There are only three unpaired bones: the vomer, the lower jaw and the hyoid bone (see Atl.).
Maxillary bone (maxilla)- a large paired bone, occupying a central place in the facial skull, has a body and four processes (see Atl.). Inside body there is a large pneumatic maxillary (maxillary) sinus, opening into the nasal cavity. The front, facial surface of the body is concave, has canine fossa, and above it - infraorbital foramen the canal of the same name, which penetrates the entire bone. The upper surface of the body forms the lower wall of the orbit, and the nasal surface forms the lateral wall of the nasal cavity. A small bone is attached to this wall - inferior nasal concha. The posterior surface of the bone faces the infratemporal fossa. Of the four processes extending from the body, frontal connects to the frontal; A zygomatic- with the cheek bone. Palatine processes together with those adjacent to them behind palatine bones (ossa palatina) form hard sky. Alveolar the process is equipped with eight holes in which the upper teeth sit.
Nasal bones (ossa nasalia) located in the bridge of the nose and closes at the top pear-shaped hole, leading into the nasal cavity. In the depths of the latter is visible vomer- a sagittally located plate that adheres to the sphenoid, ethmoid, palatine and maxillary bones.
Lacrimal bones (ossa lacrymaha) – the smallest of the facial bones. Forming part of the inner wall of the orbit, they adjoin the frontal, ethmoid and maxillary bones.
Zygomatic bones (ossa zygomatica) have three branches - frontal, temporal And maxillary, named for the bones to which they are connected. The zygomatic bones form the inferolateral edges of the orbits, and together with the zygomatic processes of the temporal bones - zygomatic arches.
Lower jaw (mandibula)– unpaired bone, consists of a body and two branches. Front on body issued chin protuberance, and on its sides - mental tubercles. On the inner surface of the body along the midline there is mental spine, from which two protruding lines stretch to the sides. There are 16 tooth sockets on the upper edge of the body. The branches extending from the body form an angle with it, on the inner and outer surfaces of which there are roughness – places of attachment of the masticatory muscles. The branches end in two shoots; of which the front one is coronary– serves as the attachment point for the masticatory muscle, and the posterior – condylar, in which the head and neck are distinguished, it articulates with the temporal bone. There is a hole on the inner surface of the branch mandibular canal, which runs along the roots of the teeth and opens on the outer surface of the body chin hole.
Hyoid bone (os hyoideum) – a small curved bone suspended from the styloid process of the temporal bone by a long ligament (Fig. 1.42). Comprises body, small And big horns. This bone can be easily felt in the neck above the larynx.
From the article you will learn about the structural features of the head skeleton. The fact is that some bones of the brain skull differ significantly in structure from the facial skull. How does this affect their functions? Let's figure it out together.
Anatomical characteristics of the human skull
The skeleton of the head, or skull, consists of 27 bones. It also includes the malleus, stirrup and incus. These are located in the middle ear cavity. As part of the sensory system, they provide the perception of sound.
Now let's look at the parts of the skull: the brain and facial parts. During the process of anthropogenesis, the size of the first of them increased. This is due to brain development. With the course of evolution, man began to create an artificial environment. He built himself a home, grew plants, and stored food. The powerful jaw lost its importance. Therefore, the size of the facial skull has decreased significantly. These differences are especially noticeable when comparing a skilled and intelligent person.
At first glance it may seem that it is formed by one large bone. In fact, its structure is like a mosaic. Some bones have their own exact copy. They are paired, there are eight of them in total. The remaining seven are unpaired. Each of them has its own name, in most cases related to its location. So, the frontal is an unpaired bone of the skull. And the temporal and zygomatic areas have their own analogues.
Facial skeleton
This part of the skull consists of 15 bones. The largest of them are the zygomatic and jaw. Let's list the unpaired skull bones of this section:
- vomer;
- sublingual;
- lower jaw.
The paired bones of the facial region include:
- upper jaw;
- zygomatic;
- nasal;
- lacrimal;
- palatal;
- inferior nasal concha.
The seam
They have different connection types. They depend on the functions performed. For example, the bones of the limbs form joints - movable joints. Elbow, knee, ankle, etc. They make possible the movement of individual parts and the entire body in space. The vertebrae are connected semi-movably. Between them are cartilaginous plates. This structure provides elasticity and shock absorption.
But the bones of the skull are connected motionlessly. Thanks to this, the brain is reliably protected from mechanical damage. This type of connection is called a seam. It is also characteristic of the pelvic bones.
Seams in children have an elastic structure. With age they ossify and become stronger. Depending on the pattern that is formed along the connection of the bones, flat, scaly and jagged sutures are distinguished.
An exception
All bones of the brain skull, like the facial skull, are connected motionlessly, except for the lower jaw. It is an unpaired bone of the skull. Despite the fact that there is, we were not mistaken. How is this possible? The upper jaw consists of two identical bones connected by a suture. Thus, it is a pair in itself.
The lower jaw is attached movably - using a joint. This is very important for human life. Thanks to the movements of the lower jaw, a person is able to chew food and pronounce sounds. These functions are associated with a decrease in the size of this bone during evolution. After all, its massiveness would significantly complicate chewing and speed of pronunciation. In addition, people began to eat chopped and thermally processed food. This is how the lower jaw acquired its optimal size.
What are fontanelles
During a person's life, the skeleton of the head undergoes significant changes. As the body grows, its weight increases from 300 to 1400. In addition, the baby’s brain region is much larger than the facial region. The jaws are still underdeveloped during this period. Between the bones of the occipital region there are areas consisting of cartilaginous tissue. These are fontanelles. These areas have important biological significance. They ensure a narrowing of the cranial vault during the movement of the fetus through the narrow reproductive tract.
In the areas of the fontanelles, the baby's brain is protected only by soft connective tissues. Therefore, any impact or deformation can be fatal. There are only two of them. The large one is located between the frontal, which is an unpaired bone of the skull, and the parietal. The size of this fontanel reaches 2 cm in diameter. In colloquial speech, its location is called the “top of the head.”
Located on the back of the head. In children born on time, it is already closed. Otherwise, it will be overgrown by a maximum of three months. The large fontanelle will close by about the time the child is one year old. The intensity of this process depends on the degree of fetal development and its calcium supply.
Another meaning of fontanelles is heat regulation. Illnesses in children are often accompanied by a significant increase in body temperature. This is very dangerous, since at high values it can lead to protein coagulation. In the area of the fontanelles, brain tissue cools naturally.
Skull: brain section
This part of the head skeleton is more massive. Here the unpaired bone of the skull is:
- occipital;
- frontal;
- lattice;
- wedge-shaped.
The paired ones include the parietal and temporal. The brain region is divided into a base and a fornix.
Despite the general structural plan, the skulls of men and women have their own distinctive features. Thus, in the former, the paranasal sinuses are more pronounced and larger than the orbit. And the skull bones themselves in the male half of humanity are thick. Women have less cranial capacity. But this is not connected with mental abilities, but with the general size of organisms.
Sections of the skull. The skull (cranium) consists of brain And facial departments. All bones are connected to each other relatively motionlessly, except for the lower jaw, which forms a combined joint, and the movable hyoid bone, which lies freely on the neck. The bones of the cranium form the container for the brain, cranial nerves and sensory organs.
TO brain section The skull (neurocranium) includes 8 bones:
- unpaired- occipital, sphenoid, ethmoid, frontal;
- doubles- parietal and temporal.
TO facial area The skull (splanchnocranium) includes 15 bones:
- unpaired- lower jaw, vomer, hyoid bone;
- doubles- upper jaw, palatine, zygomatic, nasal, lacrimal, inferior nasal concha.
Brain bones. The bones of the brain skull, unlike the bones of the facial skull, have a number of features: on their inner surface there are imprints of the convolutions and grooves of the brain. The canals for veins lie in the spongy substance, and some bones (frontal, sphenoid, ethmoid and temporal) have air sinuses.
Occipital bone(os occipitale) consists of scales, two side parts And main part. These parts limit the large opening through which the cranial cavity communicates with the spinal canal. The main part of the occipital bone fuses with the sphenoid bone, forming a slope with its upper surface. On the outer surface of the scales there is an external occipital protuberance. On the sides of the foramen magnum are the condyles (articular surfaces that are connected by synastosis to the articular surface of the first vertebra). At the base of each condyle there is a canal for the hypoglossal nerve.
Occipital bone(outside). 1 - foramen magnum; 2 - scales; 3 - side part; 4 - condyle; 5 - canal of the hypoglossal nerve; 6 - body (main part); 7 - external occipital crest; 8 - external occipital protuberance
Wedge-shaped, or mainbone(os sphenoidale) consists of a body and three pairs of processes - large wings, small wings and pterygoid processes. On the upper surface of the body there is the so-called sella turcica, in the fossa of which the pituitary gland is located. At the base of the lesser wing there is an optic canal (optic opening).
Both wings (small and large) limit the superior orbital fissure. The large wing has three openings: round, oval and spinous. Inside the body of the sphenoid bone there is an air sinus, divided into two halves by a bony septum.
Wedge-shaped (main) And ethmoid bone. 1 - cockscomb of the ethmoid bone; 2 - perforated plate of the ethmoid bone; 3 - labyrinth of the ethmoid bone; 4 - hole leading into the sinus of the sphenoid bone; 5 - sinus of the sphenoid bone; 6 - small wing; 7 - large wing; 8 - round hole; 9 - oval hole; 10 - spinous foramen; 11 - perpendicular plate of the ethmoid bone; 12 - sella turcica of the sphenoid bone; 13 - back of the sella turcica; 14 - tubercle of the sella turcica; 15 - superior orbital fissure; 16 - visual channel
Ethmoid bone(os ethmoidae) consists of a horizontal or perforated plate, a perpendicular plate, two orbital plates and two labyrinths. Each labyrinth consists of small air-bearing cavities - cells separated by thin bone plates. Two curved bony plates hang from the inner surface of each labyrinth - the superior and middle turbinates.
Frontal bone(os frontale) consists of scales, two orbital parts and a nasal part. The scales have paired projections - frontal tubercles and brow ridges. Each orbital part anteriorly passes into the supraorbital margin. The air sinus of the frontal bone (sinus frontalis) is divided into two halves by a bony septum.
Parietal bone(os parietale) has the shape of a quadrangular plate; on its outer surface there is a protrusion - the parietal tubercle.
Temporal bone(os temporale) consists of three parts: the scales, the stony part, or pyramid, and the drum part.
The temporal bone contains the organ of hearing, as well as canals for the auditory tube, internal carotid artery and facial nerve. On the outside of the temporal bone there is the external auditory canal. Anterior to it is the articular fossa for the articular process of the lower jaw. The zygomatic process extends from the scales, which connects with the process of the zygomatic bone and forms the zygomatic arch. The stony part (pyramid) has three surfaces: anterior, posterior and inferior. On its posterior surface there is the internal auditory canal, in which the facial and vestibulocochlear (stato-auditory) nerves pass. The facial nerve exits the temporal bone through the stylomastoid foramen. A long styloid process extends from the lower surface of the petrous part. Inside the petrous part is the tympanic cavity (middle ear cavity) and the inner ear. The stony part also has a mastoid process (processus mastoideus), inside of which there are small air-bearing cavities - cells. The inflammatory process in the cells of the mastoid process is called mastoiditis.
Temporal bone(right). A - outside view; B - view from the inside; 1 - scales; 2 - zygomatic process; 3 - front surface of the rocky part; 4 - articular fossa; 5 - sigmoid groove; 6 - top of the pyramid; 7 - in the top picture - the drum part; in the lower picture - the internal auditory opening; 8 - styloid process; 9 - external auditory opening; 10 - mastoid process; 11 - mastoid foramen
text_fields
text_fields
arrow_upward
The brain skull is formed
unpaired bones:
- occipital,
- wedge-shaped
- frontal,
- lattice,
paired dice:
- parietal and
- temporal
Some bones (sphenoid and ethmoid), located on the border of the brain and facial sections, are functionally involved in the formation of the latter.
1.1. Parietal bones
Parietal bones (ossa parietalia) almost quadrangular, closing the skull from above and from the sides. Their convex parts are called parietal tubercles.
1.2. Frontal bone
Frontal bone (os frontale) adjacent to the anterior edge of the parietal bones.
It consists of
- scales,
- orbital part
- bow part.
On her convex scales two frontal tubercles protrude in front, below them lie brow ridges, laterally ending zygomatic processes, and even lower there are two supraorbital foramina, or clippings. On the lower concave surface orbital part located at the zygomatic process fossa of the lacrimal gland, and medially – trochlear fossa, and sometimes the spine is the place of attachment of the cartilaginous block through which one of the eye muscles is thrown. Between the orbital parts is located bow, covering lattice tenderloin. In the thickness of the frontal bone there is frontal sinus, communicating with the nasal cavity.
1.3. Occipital bone
Occipital bone (os occipitale) participates in the formation of the base and vault of the skull, which it closes behind and below (Fig. 1.40).
Rice. 1.40. Occipital bone from outside1 – jagged edge;
2 – scales;
3 – foramen magnum;
4 – condyle;
5 – canal of the hypoglossal nerve;
6 – main part;
7 – top and
8 – lower nuchal lines;
9 – external occipital protrusion;
10 – external occipital crest;
11 – jugular process
Bone is made up of
- concave scales,
- paired side parts with jugular processes and with condyles(articulate with the atlas),
- main part.
These four parts limit foramen magnum. The base of each condyle laced with short canal of the hypoglossal nerve. They protrude laterally from the condyles jugular processes. Rough lines stretch across the outer surface of the scales. upper And lower nuchal lines and performs external occipital protuberance. On the brain surface of the scales rises internal occipital protuberance, from which it diverges cruciform eminence with wide grooves from the venous sinuses.
1.4. Temporal bones
Temporal bones (ossa temporalia) adjacent to the occipital bone. They participate in the formation of the lateral wall and base of the skull, serve as a receptacle for the organs of hearing and balance, as an attachment site for the masticatory and neck muscles, and articulate with the lower jaw.
Due to the variety of functions, the temporal bone has a complex structure. On its lateral surface there is
- external auditory opening,
around which are located:
- on top - scales,
- behind – mastoid part,
- in front and below – the drum part,
- medially – pyramid.
- Scales – a slightly concave plate closing the side of the brain skull. It has a forward-facing zygomatic process, connecting to the zygomatic bone. Under its base there are the articular cavity and tubercle. Here the articulation with the head of the lower jaw occurs.
- Mastoid part forms the mastoid process (the place of muscle attachment), easily palpable through the skin behind the auricle. Inside, the process consists of small air-bearing cavities - cells. Unlike other pneumatized bones, they communicate with the cavity of the middle ear.
- Drum part smaller than other parts; it limits the external auditory canal.
- Pyramid, orrocky part, contains the tympanic cavity and the cavity of the inner ear. On its back surface there is internal auditory opening, and lateral to it is a slit-like opening aqueduct of the vestibule. There is a noticeable flat surface on the anterior surface roof of the tympanic cavity and medial from it - arcuate elevation. At the top of the pyramid there is a small fossa of the trigeminal ganglion. Protrudes on the bottom surface styloid process and there is an external hole carotid artery canal. This channel runs inside the pyramid and then opens at its top with a hole of the same name. Between the styloid and mastoid processes is located stylomastoid foramen. In the corner between the scales and the pyramid it opens muscular-tubal canal, enclosing auditory tube leading into the middle ear cavity.
1.5. Sphenoid bone
Sphenoid bone (os sphenoidale) lies at the base of the brain skull and connects with all its bones, as if wedged between them. The bone has a complex structure, since many large nerves pass through it, it participates in the formation of the orbit, the temporal and infratemporal fossa, and serves as an attachment point for the masticatory muscles.
The bones are distinguished body with the air sinus, which communicates in front with the nasal cavity. The depression on the upper surface of the body is called Turkish saddle, It houses the endocrine gland - the pituitary gland. Extend to both sides of the body big wings; at the base of each of them are located sequentially round, oval And spinous foramen. The anterior surface of the wings forms the lateral wall of the orbit. Above the large wings, bones extend from the body small wings, pierced at the base visual channel, in which the cranial nerve of the same name is located. Small wings are separated from large ones superior orbital fissure and participate in the formation of the orbit. Move down from the body pterygoid processes, consisting of two (medial and lateral) plates, between which there is pterygoid fossa. The base of the processes is penetrated pterygoid canal. The processes serve as attachment sites for muscles.
1.6. Ethmoid bone
Ethmoid bone (os ethmoidae) surrounded by other bones so that only its outer part is visible on the whole skull - orbital plate, participating in the formation of the medial wall of the orbit. The other part of the bone is perforated plate - closes the notch of the frontal bone and is visible from the cerebral surface of the skull. From this plate a longitudinal cock's comb; its continuation into the nasal cavity is perpendicularplate, which is involved in the formation of the nasal septum. Large paired part of the bone - labyrinths, consisting of bony cells hanging into the nasal cavity.
Projecting towards the perpendicular plate from the labyrinths are average And superior turbinates.
Facial part of the skull
text_fields
text_fields
arrow_upward
In the facial skull, unlike the brain skull, paired bones predominate, which include the maxillary, nasal, lacrimal, zygomatic, palatine and inferior nasal conchae. There are only three unpaired bones: the vomer, the lower jaw and the hyoid bone.
2.1. Maxillary bone
Maxillary bone (maxilla)- a large paired bone, occupying a central place in the facial skull, has a body and four processes. Inside body there is a large pneumatic maxillary (maxillary) sinus, opening into the nasal cavity. The front, facial surface of the body is concave, has canine fossa, and above it - infraorbital foramen the canal of the same name, which penetrates the entire bone. The upper surface of the body forms the lower wall of the orbit, and the nasal surface forms the lateral wall of the nasal cavity. A small bone is attached to this wall - inferior nasal concha. The posterior surface of the bone faces the infratemporal fossa. Of the four processes extending from the body, frontal connects to the frontal; A zygomatic- with the cheek bone. Palatine processes together with those adjacent to them behind palatine bones (ossa palatina) form hard sky. Alveolar the process is equipped with eight holes in which the upper teeth sit.
2.2. Nasal bones
Nasal bones (ossa nasalia) located in the bridge of the nose and closes at the top pear-shaped hole, leading into the nasal cavity. In the depths of the latter is visible vomer- a sagittally located plate that adheres to the sphenoid, ethmoid, palatine and maxillary bones.
2.3. Lacrimal bones
Lacrimal bones (ossa lacrymaha) – the smallest of the facial bones. Forming part of the inner wall of the orbit, they adjoin the frontal, ethmoid and maxillary bones.
2.4. Zygomatic bones
Zygomatic bones (ossa zygomatica) have three branches - frontal, temporal And maxillary, named for the bones to which they are connected. The zygomatic bones form the inferolateral edges of the orbits, and together with the zygomatic processes of the temporal bones - zygomatic arches.
(mandibula)– unpaired bone, consists of a body and two branches (Fig. 1.41). Rice. 1.41. Lower jaw:A – outside;
B – from the inside;
1 – body;
2 – branch;
3 – chin protuberance;
4 – digastric fossa;
5 – angle;
6 – chewing tuberosity;
7 – pterygoid tuberosity;
8 – maxillary-hyoid line;
9 – coronoid process;
10 – condylar process;
11 – opening of the mandibular canal;
12 – chin hole
Front on body issued chin protuberance, and on its sides - mental tubercles. On the inner surface of the body along the midline there is mental spine, from which two protruding lines stretch to the sides. There are 16 tooth sockets on the upper edge of the body. The branches extending from the body form an angle with it, on the inner and outer surfaces of which there are roughness – places of attachment of the masticatory muscles. The branches end in two shoots; of which the front one is coronary– serves as the attachment point for the masticatory muscle, and the posterior – condylar, in which the head and neck are distinguished, it articulates with the temporal bone. There is a hole on the inner surface of the branch mandibular canal, which runs along the roots of the teeth and opens on the outer surface of the body chin hole.
Rice. 1.42. Hyoid bone:
A – position in relation to the skull and spine;
B – top view;
1 – body;
2 – small and
3 – big horns
Hyoid bone (os hyoideum) – a small curved bone suspended from the styloid process of the temporal bone by a long ligament (Fig. 1.42).
Comprises body, small And big horns. This bone can be easily felt in the neck above the larynx.
The human skull, due to the development of its brain, is larger in volume than the facial skull, while in all other representatives of the animal world the facial skull is larger than the brain. The bones of the brain skull are flat in shape (parietal, occipital) or air-bearing (frontal, sphenoid, ethmoid, temporal).
The inner surface of the bones that form the brain skull has large, fingerprint-like depressions that alternate with protrusions. The depressions and protrusions correspond to the convolutions and grooves of the outer surface of the brain. In addition, on the inner surface of the skull bones there are grooves in which the arteries of the dura mater pass.
Occipital bone of the skull takes part in the formation of the base of the skull and the posterior part of the roof of the skull. It is made up of four parts located around the large opening: in front - the basilar part, on the sides - paired lateral parts, and in the back - the occipital scales. The foramen magnum contains the medulla oblongata, vertebral arteries and accessory nerves. By the age of 18-20, the basilar part of the occipital bone fuses with the body of the sphenoid bone. The layer between them changes from cartilaginous to bone (synchondrosis turns into synostosis). The upper surface of the basilar part of the occipital bone faces the cranial cavity and has a flat platform, which, together with the sphenoid bone, forms the clivus, where parts of the brain stem are located. The lateral parts of the occipital bone merge posteriorly into the occipital squama. They have ellipsoidal occipital condyles on their lower surface, connecting to the atlas. The hypoglossal nerve canal passes through the condyles. On their lateral edge is the jugular notch, which forms with the same notch the temporal vagus, glossopharyngeal and accessory veins and the internal jugular vein. On the upper surface of the lateral parts of the occipital bone is the sigmoid sinus groove, where the sigmoid venous sinus is located. The occipital scales have the appearance of a wide plate convex back and down, on the outer surface of which there is an external occipital protrusion, and above and below it there are nuchal lines for muscle attachment. On the inner surface of the squama of the occipital bone there is an internal occipital protrusion. It divides the entire inner surface of the scales into four depressions, the lower two of which correspond to the position of the cerebellar hemispheres, and the upper two are adjacent to the occipital lobes of the cerebral hemispheres. Upward from the internal occipital protrusion there is an unpaired groove of the superior sagittal sinus, and to the sides there are grooves of the transverse sinus, where the venous sinuses of the dura mater of the brain are located.
Sphenoid bone of the brain skull
consists of a body and three pairs of processes. Small wings extend to the sides and upwards, large wings extend laterally to the sides, and pterygoid processes extend downward. The body of the sphenoid bone has a cuboid shape. It contains an air sinus that communicates in front with the nasal cavity. On the upper surface of the sinus there is a depression - the sella turcica, where the endocrine gland - the pituitary gland - is located. The sella turcica has grooves on the sides in which the internal carotid arteries lie. At the base of each of the small wings there is an optic canal. The optic nerve and ophthalmic artery pass through it into the orbit. The large wings of the sphenoid bone face one, concave, surface into the cranial cavity, the other, flat, into the cavity of the orbit, and the third, somewhat concave, outward, into the temporal fossa, the bottom of which they form. At the base of the large wings there are openings: round (for the passage of the second branch of the trigeminal nerve), oval (for the passage of the third branch) and spinous (for the passage of the middle artery of the dura mater). The lower surface of the large wings faces the infratemporal fossa. Between the greater and lesser wings there is the superior orbital fissure, through which the oculomotor, trochlear, orbital, abducens and ophthalmic veins pass. Pterygoid processes
The sphenoid bones run vertically downward from its body. Each of them has medial and lateral plates; the medial one ends in a small hook at the bottom.
Frontal bone of the skull participates in the formation of the roof and base of the skull. It is divided into four parts: the frontal scales directed upward, 2 orbital parts located horizontally, and the nasal part lying between the orbital parts. The frontal scales face forward with their outer surface, and with their inner surface facing the cranial cavity. The outer surface is smooth, at the bottom it has a sharp supraorbital edge, above which there are elevations on the right and left - the brow ridges. Above the brow ridges are the frontal tubercles, and between the brow ridges there is a depression, the glabella. On the inner surface of the frontal squama, along the midline there is a groove of the superior sagittal sinus next to the depressions corresponding to the cerebral gyri. The lateral, temporal, surface of the frontal scales connects below with the large wings of the sphenoid bone, and behind and above with the parietal bones. The orbital parts of the frontal bone are thin plates, the lower surface of which faces the orbit and forms its upper wall, and the upper surface - into the cranial cavity. On the lateral part of the orbital part there is a depression - the fossa of the lacrimal gland. Between the orbital plates there is a ethmoidal notch. The nasal part of the frontal bone closes the ethmoidal notch in front. In the nasal part there are two openings leading to the frontal sinus.
Ethmoid bone The shape is similar to a laterally flattened cube. This bone is light and fragile. It consists of two plates - ethmoid and perpendicular - and a latticed labyrinth. The cribriform plate is located horizontally in the ethmoidal notch of the frontal bone. It has a large number of holes, and in the median plane a bony protrusion, the cock's crest, extends from it, facing upward, to which a process of the dura mater is attached. The olfactory nerves pass from the nasal cavity into the cranial cavity through the openings of the cribriform plate. The perpendicular plate of the ethmoid bone is located in the median plane and runs vertically downward from the cribriform plate, taking part in the formation of the nasal septum. The right and left ethmoid labyrinths are built from thin plates that run in different directions, forming the walls of ethmoid cells containing air and communicating with the nasal cavity. The cells on the side of the nasal cavity are closed by curved bone plates, the superior and middle nasal turbinates, between which is located the superior nasal passage (orbital plate), which makes up the medial wall of the orbit.
The parietal bone is a paired bone of the brain skull. It makes up the central part of the cranial vault and is a quadrangular plate, convex on the outside and concave on the inside. On its convex surface there is an elevation - the parietal tubercle, easily palpable under the skin. Laterally and below the tubercle runs the rough temporal line, which serves as one of the origins of the temporalis muscle. The inner concave surface of the parietal bone faces the cranial cavity, has arterial grooves, digital impressions, as well as a groove for the superior sagittal sinus running along its sagittal edge. These sagittal grooves of both parietal bones, complementing each other, form one common groove, which serves as the location of the superior sagittal sinus of the dura mater.
Temporal bone - paired bone of the brain skull. It takes part in the formation of the base of the skull and partly its roof. This bone consists of three parts: petrosal, or pyramid, squamosal and tympanic. The petrous part has the shape of a three-sided pyramid, to which the mastoid process of the bone is attached posteriorly. This part faces its lower surface downward, towards the outer base of the skull, and the anterior and posterior faces into the cranial cavity. On the front surface of the pyramid, at its apex, there is a trigeminal depression. The anterior surface takes part in the formation of the roof of the tympanic cavity, being one of the walls of the middle ear. On the posterior surface of the petrous part is the internal auditory foramen, through which the facial and vestibulocochlear nerves pass. It leads into the internal auditory canal. On the lower surface of the petrous part there is an external carotid foramen, through which the internal carotid artery enters the canal of the same name. At the apex of the petrous part, corresponding to the anterior end of the carotid canal, there is an internal carotid foramen; here the internal carotid artery enters the cranial cavity. On the lower surface of the stony part, at the posterior edge of its base, there is a jugular fossa. Behind and outside of it is the stylomastoid foramen, through which the facial nerve exits the skull. In front of this opening is the styloid process. At the top of the petrous part of the temporal bone, in addition to the carotid canal, the muscular-tubal canal opens, in which the auditory tube and the tensor tympani muscle are located. The facial canal, where the facial nerve is located, also passes through the petrous part of the temporal bone. This canal begins deep in the internal auditory canal and ends at the stylomastoid foramen. The stony part of the temporal bone includes the mastoid process, located behind the external auditory canal and easily palpable under the skin. It serves as the attachment point for the sternocleidomastoid muscle and contains air cells. On its inner surface there is a mastoid notch, from which the digastric muscle originates, and on the brain surface there is a wide groove of the sigmoid sinus, which is a continuation of the groove of the same name in the occipital bone and the location of the sigmoid sinus of the dura mater. The scaly part of the temporal bone has the appearance of a semicircular, vertically located plate, which takes part in the formation of the roof of the skull. Its inner surface faces the cranial cavity, and its outer surface forms the bottom of the temporal fossa. The zygomatic process departs from it, forming, together with the temporal process of the zygomatic bone, a zygomatic arch that is easily palpable under the skin. At the base of this process on the temporal bone there is a mandibular fossa, which serves for articulation with the head of the lower jaw. Anterior to the fossa is the articular tubercle. The tympanic part of the temporal bone is a curved plate that limits the external auditory canal below and in front.
