The outer base of the human skull

The human skull is a bone skeleton, which has twenty-three bones in its composition. They perform the function of protecting the brain from various injuries. The skull is a component of the bone system and the musculoskeletal system. It consists of the brain and facial departments, performing certain functions. Each department has an external and internal base.

What is the base of the skull formed from?

It is formed with the help of the orbital and nasal parts of the frontal bone, small and large wings, latticed bone and plates, temporal pyramids and the body of the main bones, lateral parts and lower portions of the occipital scales.

The base of the skull, the photo of which you see, has such a structure that some of its bones are partly connected by seams or interlayers of cartilage tissue. They are called synchondrosis.

Departments and Holes

The external base of the skull is divided into sections and has various protrusions and openings through which the nerves and blood vessels pass. The rear compartment is the location of the external occipital protrusion. From it comes down the crest of the nape. Before the scales is a large opening of the occiput. From the sides it is confined to the occipital bone, and in front - wedge-shaped. The sublingual nerve has a condylar canal passing under the processes of the occiput, behind which is located the fossa, which passes into a non-permanent canal.

Not far from the large occipital opening of the base of the skull, closer to the front, is the pharyngeal mound, and in the mastoid process there is an opening with the corresponding name, which is the exit point of the facial nerve, and the styloid process.

The lower surface of the rocky part has a jugular fossa and an aperture with the same name. Through it, cranial nerves pass. An external jugular vein emerges from this opening of the skull base . In front of him is a sleepy canal with an external hole, and a torn canal is located next to the tip of the rocky part.

The pterygoid canal passes just before the root of the pterygoid processes and opens into the pit. The oval and spinous apertures are on the sphenoid bone. The holes of the nasal cavity are called choana. They are located in front of the torn. Between the outer plate of the pterygoid process and the lower part of the surface of the large wing, located on the sphenoid bone, there is a fossa fossa.

The posterior sections of the bone skull have the same holes, which lead to the canals. The incisors have cells behind which there is an incisive hole.

Structure

The skull is a cavity formed by closely connected bones, in which are located important for human life organs: the brain of the head, the initial parts of the respiratory and digestive systems and sense organs. In the skull, the vault, or roof, and the base, which is external and internal, are distinguished. The external base of the skull is formed with the participation of its lower surfaces - the brain and facial sections, which are subdivided into anterior, posterior and middle.

The anterior part originates from the incisors and seizes the posterior edge of the palatine bones formed by horizontal plates, which in front connect with the processes of the upper jaw's skull, forming the bone skies. In its space, the incisal fossa is formed, from which the incisal canal begins. It leads to the lower courses of the nose. The structure of the base of the skull is such that a seam passes through the middle of the bone skull, and the palatal holes: small and large - lead into the canal.

The middle section occupies the space between the sky and the large occipital foramen, its front edge. The lateral borders pass through the external auditory canal up to the process of the mastoid form. The outer base of the skull has two openings that open into the nasal cavity.

The posterior part is located between the anterior edge of the occipital large opening and the outer occipital mound.

The front department

It consists of paired and unpaired bones. The first prevail. They are represented by the upper jaw, nasal, zygomatic, tear and palatine bones, lower shell of the nose. The second - a latticed bone, a vomer, a hyoid bone, a lower jaw. The skull base bones, of which the facial part consists, exert a tremendous influence on all sensory organs, respiratory and digestive systems.

A region filled with air can allow the skull to be strong. They have unpaired bones. In addition, air is involved in providing thermal insulation. Such cavities are in the wedge-shaped, frontal, latticed, temporal bones and upper jaw.

A special role in the human body is assigned to the sublingual arcuate bone located between the larynx and the lower part of the jaw and connected to the cranial bones by ligaments and muscles. With its help, the body and pair horns are formed, from which are the styloid processes.

Upper bones of the base of the skull are flat and represent plates filled with bone substance. In his cells are the brain and blood vessels that circulate. Gyrations and grooves of the brain are formed due to unevenness of some bones of the skull.

Brain skull

It protects the brain from damage and is its protective framework. The brain of the skull is above the facial and has the shape of an ellipse. Its volume is 1500 cm. It consists of paired, parietal and temporal, bones, and unpaired - occipital, wedge-shaped and frontal. The latter consists of two scales, a bow. It is airborne. Here the forehead and frontal hillocks form, due to which the walls of the eye sockets, the nasal cavity, the pits on the temples and in the anterior part are formed. With the help of the parietal bone , arches are formed, and with the help of the occipital bone - the base of the skull, the photo of which is presented to your attention.

The twin bone is a complex airborne temporal part. It carries out the formation of the cranial vault, it contains the organs of hearing. This bone forms a pyramid with a drum cavity and an inner ear.

Sphenoid bone

It is located where the base of the skull is, in its very center. The sphenoid bone has a body with outgrowths with the corresponding name, with large and small wings. The body has six surfaces that perform certain functions. This is the front, back, top, bottom and two side.

At the base of the large wing there are holes of round, oval and spinous shape. There are four surfaces of the wing, which are called the temporal, maxillary, ophthalmic and cerebral. Arterial furrows and impressions are located on them. The medial aspect of the small wing has an inclined process. The space between the large and the small wing occupies the upper orbital gap.

Occipital bone

It consists of basilar, lateral parts and scales. When they are joined, a large hole is formed, which is called the occipital. The lower surface of the lateral part is provided with a condyle, above which is a hyoid canal. Behind it is a fossa with condylar canal at the bottom.

The center of the outer surface of the scales has an occipital protrusion. From it down comes a crest with the same name.

Frontal bone

The external base of the skull occupies the greater part of the arch and has a frontal bone, which includes the nasal, orbital parts and frontal scales. The fore part in the front and sides is limited to the trellised notch, which separates the right and left eye sockets. The anterior part of the frontal part in the middle has a line that passes into the nasal awn. On either side of it (horizontally) is the aperture of the sinus of the frontal part of the skull.

Functional features of the skull

Being a complex bone organ, the skull performs the following functions:

• It protects the brain, all sensory organs from damage.
• Cranial bones connect the chewing, mimic and cervical muscles.
• Participates in the speech process, and with the help of jaws and airborne sinuses a sound is formed.
• The skull plays a big role in the digestive system, namely: with the jaws, the chewing function is performed and the oral cavity is limited.

The base of the human skull: formation

In a newborn baby, the jaw bones are flat, they represent a congestion of a huge number of bone bunches without a clearly defined organization. Between them is a loose connective tissue. There is no compact bone along the peripheral zones, it is replaced by a periosteum, represented by a thick layer.

Over time, the beams merge. A continuous compact plate forms: first at the sides, then in the frontal and distal areas of the jaw. The size of the facial bones increases. Great importance in the growth of facial bones has the base of the skull. The anatomy of their structure is such that the anterior cranial fossa is elongated by the sutures that divide the frontal and latticework, the last and basic bones.

The growth in the 10-11 year of human life ends. Later, the frontal bone is pneumatized, and bone formation occurs on the outer surface. In girls, this occurs before age 13, and in boys - up to 14. As the base of the skull grows, the angle between the cranial fossa decreases: the posterior and anterior ones. This explains the fact that the vertical dimension of a person's face predominates over the horizontal one.

Features of the structure of the skull: sex and age

All the bones of the skull begin to develop with a membranous stage, then the cartilage and the final bone marrow. Facial bones in their development pass the middle stage. A feature of the structure of the skull in a newborn child is the presence of remnants of a webbed skull - ferns, which are front, back and side.

On the anterior fontanel (the largest), one can observe respiratory movements, intracranial pressure (if it increases, the fontanel swells), dehydration of the baby's body (in the disease, the fontanelle sinks).

The back fontanelle is smaller and quickly overgrown. A full-term newborn child usually lacks lateral fontanelles, which are present in pre born children. But they are over 2-3 years of life overgrown.

The second feature is that both the inner and outer surface of the base of the skull has cartilaginous layers that are located between the individual parts of the bones.

The third feature. In newborns, airborne sinuses, processes, bumps, jaws are not developed, there are no teeth.

The formation of the seams of the skull occurs to 3-5 years of human life. In general, it finishes growing at 25-30 years.

The skull is distinguished by gender, but it does not matter much. Age changes can spread to the entire base of the skull. The anatomy of its structure is such that the crests and the bone substance of the spongy structure begin to dissolve, the cranial bones become light and brittle. The shape of the skull can change under the influence of mechanical factors.