Skull
Last reviewed: 23.04.2024
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The skull (cranium) is the skeleton of the head. This is the most complex part of the skeleton, which serves as a receptacle for the brain, organs of sight, hearing and balance, olfaction and taste, a support for the initial parts of the digestive and respiratory systems. Human skull form 23 bones (8 paired and 7 unpaired).
In the structure of the skull, the brain department, or the brain skull, and the facial or visceral skull are distinguished. The cerebral part of the skull (the cerebral skull) is located above the facial area, contains the brain. The cerebral skull (cranium cerebrale) is formed by the frontal, occipital, wedge-shaped, parietal, temporal and latticed bones and their joints. The skull's facial part - the facial skull (cranium viscer & le) is represented by the bones of the chewing apparatus: the upper and lower jaws, and also the small bones of the skull, which form part of the walls of the orbit, nasal and oral cavity. A special place is occupied by the hyoid bone located in the anterior region of the neck.
Bones of the cerebral part of the skull
The frontal bone (os frontale) participates in the formation of the anterior part of the roof (roof) of the skull, anterior cranial fossa and orbits. In the frontal bone, frontal scales, ocular and nasal parts are distinguished.
The sphenoid bone (os sphenoidale) occupies a central position at the base of the skull. It participates in the formation of the base of the skull, its lateral sections and a number of cavities and pits. In the sphenoid bone, the body, pterygoid processes, large and small wings are distinguished.
The occipital bone (os occipitale) is located in the posterior part of the brain area of the skull. In this bone, the basilar part, the two lateral parts and the occipital scales, which surround the large (occipital) foramen (foramen magnum), are distinguished.
The dark bone (os parietale) is paired, broad, convex outward, forming the upper-lateral divisions of the cranial vault. The dark bone has 4 edges: frontal, occipital, sagittal and scaly. The frontal edge borders on the posterior surface of the frontal scales, the occipital margin with the occipital scales. Using the sagittal margin, two parietal bones are connected to each other. Lower, scaly, the edge obliquely cut, covered with scales of the temporal bone. The dark bone has 4 corners: anterior-superior frontal angle, posterolateral occipital angle, anterior tapered angle and posterior mastoid angle.
The temporal bone (os temporale) is paired, it forms part of the base and lateral wall of the skull between the sphenoid bone in front and the occipital bone behind. It accommodates the organs of hearing and balance. In the temporal bone, a pyramid, a drum and a scaly part are distinguished.
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Bones of the facial skull
Upper jaw (maxilla) is a pair of bones. The upper jaw has a body and four processes: frontal, alveolar, palatine and zygomatic.
The palatine bone (os palatinum) is paired, participates in the formation of the hard palate, the orbit, the pterygoid palatine fossa. In it, two plates are distinguished - horizontal and vertical, connecting at almost a right angle, and three processes.
Lower nasal concha (concha nasalis inferior) - a pair, thin curved plate, has a body and three processes. The lateral surface of the body with its upper edge is fused with the shell crest of the upper jaw and perpendicular plate of the palatine bone. All the processes of this shell depart from its upper edge.
Vomer (vomer) - unpaired bone plate, participates in the formation of the bony septum of the nose. The lower edge of the opener fuses with the nasal crests of the maxilla and palatine bone. The rear edge of the opener separates the choana. The anterior edge of the opener is connected to the perpendicular plate of the latticed bone at the top, and at the bottom - to the cartilaginous septum of the nose.
The nasal bone (os nasale) is paired, participates in the formation of the ossicus of the nose. The upper edge of the nasal bone is connected with the nasal part of the frontal bone, the lateral margin - with the frontal process of the upper jaw. The nasal bone also participates in the formation of a pear-shaped aperture - the anterior opening of the nasal cavity.
The lacrimal bone (os lacrimale) is paired, forming the anterior part of the medial wall of the orbit. From below and from the front it is connected with the frontal process of the upper jaw, at the back - with the orbital plate of the latticed bone. Above, the teardrop border on the medial edge of the orbital part of the frontal bone. On the lateral surface of the bone there is a posterior lacrimal crest (crista lacrimalis posterior). Anterior to the lacrimal crest is a tear sulcus (sulcus lacrimalis), which together with the eponymous furrow of the upper jaw forms a fossa lacrimalis fossa (fossa lacrimalis).
The cheek bone (os zygomaticum) is paired, connects the frontal, temporal and maxillary bones, strengthening the facial skull. In the malar bone, the lateral, temporal and orbital surfaces are distinguished. The lateral surface faces forward and laterally, and contains a small, fore-sized zygomaticofacial opening. The temporal surface forms the anterior wall of the inframammary fossa, has a small pimple aperture (foramen zygomaticotemporale). On the orbital surface forming the lower-lateral wall of the orbit, there is also a small proglottid hole (foramen zygomaucoorbitale).
The lower jaw (mandibula) is the only mobile skull bone. The unpaired lower jaw has a body and two branches.
The hyoid bone (os hyoideum) is located in the anterior region of the neck, between the lower jaw at the top and the larynx below. It consists of an arcuate bent body and two pairs of processes - small and large horns. Short small horns extend to the right and left of the body of the bone up, posteriorly and laterally. Thickened at the ends, longer large horns move away from the body of the bone back and somewhat upward. The hyoid bone with the help of muscles and ligaments is suspended from the skull and connected to the larynx.
Head movements occur in the atlanto-occipital joint around the frontal, sagittal and vertical axes.
Extension of the head (deviation of the head back) is carried out: trapezoid, sternocleamus-mastoid, belt, semi-oval and longest muscles of the head, large and small posterior rectus muscles of the head, upper oblique muscles of the head.
The head is bent (tilted anteriorly) by the long muscles of the head, the forward rectus muscles of the head, the lateral rectus muscles of the head, and also by the subluxal and podpo-lingual muscles (with a fixed lower jaw).
The inclination of the head to the side (to the right, to the left) occurs with a simultaneous contraction of the extensor muscles and the flexor muscles of the corresponding side.
Rotational movements (turns) of the head along with the atlas to the right or to the left (in the middle and lateral atlantoose joints) around the tooth of the axial vertebra are performed by the following muscles: the belt muscle of the head, the longest muscle of the head, the lower oblique muscle of the head of its side and the sternocleidomastoid muscle of the opposite side.
Muscles that perform movements of the lower jaw in the temporomandibular joints. They raise the jaw: temporal muscles, chewing muscles, medial pterygoids. Lower the lower jaw: bilabial muscles, chin-sublingual muscles, maxillo-hyoid muscles, sub-lingual muscles. Movement of the lower jaw forward: bilabial muscles, chin-sublingual muscles. Movement of the lower jaw back (forward): temporal muscles (posterior fascicles). Movement of the lower jaw to the side: lateral pterygoid muscle (opposite side).
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