The occipital bone of the skull, the photo of which is presented in the article, is unpaired. It is located in the back of the lower part of the head. This element forms part of the arch and is involved in the formation of the base. You can often hear the question from schoolchildren: "Is the occipital bone of the skull flat or tubular?" In general, all solid elements of the head have the same structure. The occipital bone, like the others, is flat. It includes several elements. Let's take a closer look at them.
Occipital bone of the skull: anatomy
This element is connected to the temporal and parietal by means of seams. The occipital bone of the human skull includes 4 parts. It is of cartilaginous and membranous origin. The occipital bone of the animal skull includes:
- Scales.
- Two articular condyles.
- Body.
- Two jugular processes.
There is a large hole between the indicated parts. Through it there is a message between the brain cavity and the spinal canal. The occipital bone of the human skull articulates with the wedge-shaped element and the 1st cervical vertebra. It includes:
- Scales.
- Condyles (lateral masses).
- Body (basilar part).
There is also a large hole between them. They connect the cranial cavity with the spinal canal.
Scales
It is a spherical plate. Its outer surface is convex, and its inner surface is concave. Considering the structure of the occipital bone of the skull, the structure of the plate should be studied. On its outer surface are present:
- Protrusion (inion). It is presented in the form of an elevation in the center of the scale. On palpation, it can be felt quite well.
- Occipital area. It is represented by a patch of scales above the ledge.
- Drawing highest line. It starts from the upper boundary of the inion.
- Outer top line. It runs at the level of the ledge between the lower and highest edge.
- Bottom line. It runs between the top edge and the foramen magnum.
Inner surface
It contains:
- Cruciform elevation. It is located at the intersection of the internal crest and the grooves of the transverse and superior sagittal sinuses.
- Inner ledge. It is located at the junction of the venous sinuses.
- Inner comb.
- Furrows: one sagittal and two transverse sinuses.
- Opistion. This is the identification point. It corresponds to the center of the posterior margin of the foramen magnum.
- Basion. This is a conditional stitch, which corresponds to the center of the anterior edge of the occipitalholes.
The inner surface of the scales has a relief, which is determined by the shape of the brain and the membranes adjacent to it.
Lateral masses
They include:
- Jugular processes. They limit the hole of the same name from the sides. These elements correspond to the transverse vertebral processes.
- Hyoid canal. It is located on the side and in front of the occipital foramen. It contains the XII nerve.
- Condylar canal located behind the condyle. It has an emissary vein.
- Jugular tubercle. It is located above the hypoglossal nerve canal.
Body
It is the very front part. From above and in front the body is beveled. It distinguishes:
- Bottom surface. It has a pharyngeal tubercle, a site of attachment of the pharyngeal suture.
- Two outer lines (edges). They are connected to the pyramids of the temporal element.
- Slope (upper surface). It is directed into the cranial cavity.
In the lateral part, a groove of the stony lower sinus is distinguished.
Articulations
The occipital bone of the skull is connected to the elements of the vault and base. It acts as a link between the head and spine. As mentioned above, in the considered part of the head, the wedge-shaped element and the occipital bone of the skull are connected. Articulation type - synchondrosis. Connection is via the frontbody surface. The occipital bone is articulated with the parietal bone by a suture. A conditional point is located at the junction. It's called "lambda". In some cases, interparietal bone is found here. It is formed from the upper part of the scale and separated from it with a transverse seam. The occipital bone of the skull is articulated with the temporal element by sutures:
- Petro-jugular. The jugular process articulates with the notch of the same name in the temporal bone.
- Petro-basilar. The lateral part of the base connects to the pyramid of the temporal element.
- Occipital-mastoid. The mastoid part articulates with the posterior inferior plane of the temporal element.
With the atlas, the lower convex surface of the condyles is connected to the concave parts of the 1st vertebra of the neck. Here a joint of the type of diarthrosis is formed. It contains a capsule, synovia, cartilage.
Bundles
They are presented in the form of membranes:
- Front. It is located between the base of the bone and the arch of the atlas.
- Back. This ligament is stretched between the back of the first vertebra of the neck and the foramen magnum. It is included in the composition of the corresponding surface of the spinal canal.
- Lateral. This membrane connects the jugular process with the transverse vertebral.
- Integumentary. It is a continuation of the longitudinal posterior membrane towards the anterior part of the large opening. This ligament passes into the periosteum of the skull base elements.
Besides this, there are:
- Pterygoid ligaments. They go to the lateral parts of the large hole.
- Bundle of tooth. It runs from the process of the 2nd vertebra of the neck to the anterior border of the foramen magnum.
- Superficial aponeurosis. It is attached along the top line of the neckline.
- Deep aponeurosis. It is anchored at the base of the occipital bone.
Muscles
They attach to:
- Occipital highest line. Here the abdomen is fixed from the supracranial muscle.
- Occipital top line. Here the belt, sternocleidomastoid, trapezius muscles are fixed. The occipital bundle of muscles is fixed in the same place.
Fixed on the bottom line:
- Straight back muscle of the head. It is attached to the spinous process of the 1st vertebra of the neck.
- Rear big straight line. They are fixed on the spinous process of the 2nd vertebra of the neck.
- Oblique superior muscle of the head. It is attached to the transverse process of the 2nd cervical vertebra.
Merebral (dura mater) and nerves
The cerebellum is attached to the edges of the transverse sulcus. The crescent of the brain is fixed with its back. It is anchored at the edges of the sulcus on the superior sagittal sinus. The cerebellar falx is fixed on the occipital crest. Pairs of nerves pass through the jugular foramen:
- Glossopharyngeal (IX).
- Wandering (X).
- Additional (XI). Its spinal roots pass through the foramen magnum.
At the level of the condyles, the XII pair passes through the hypoglossal canalnerves.
Injuries
The structure of the occipital bone of the skull is such that it is highly susceptible to mechanical damage. However, they can be accompanied by serious, in some cases, fatal consequences. This is due to the fact that the occipital bone of the skull protects the optic nerve. And damage to it can lead to a complete or partial loss of the ability to see.
Types of injury
The following damage exists:
- Depressed fracture of the occipital bone of the skull. It appears from the mechanical impact of a blunt object. In such situations, usually most of the load falls on the brain.
- Shrapnel damage. It is a violation of the integrity of the element, accompanied by the formation of fragments of various sizes. This may cause damage to the brain structure.
- Linear fracture of the occipital bone of the skull. It is also a violation of the integrity of the element. In this case, damage is often accompanied by fractures of other bones, concussion and bruising of the brain. Such an injury on an x-ray looks like a thin strip. She shares the skull, namely his occipital bone.
The last damage is different in that the displacement of the elements in relation to each other is no more than a centimeter. This fracture may go unnoticed and not manifest in any way. This injury is especially common in children during active play. If a child has a headache and nausea after a fall, a doctor should be consulted.
Specialcase
The skull can take damage that affects the foramen magnum. In this case, the brain nerves will also be injured. The clinical picture is characterized by bulbar symptoms. It is accompanied by disorders of the respiratory and cardiovascular systems. The consequences of such an injury are quite serious. It can be a violation of certain functions of the brain, and an osteoma of the neck bone, and even death.
TBI
There are three main types of brain damage:
- Concussion.
- Squeezing.
- Bruised.
The most common signs of a concussion condition include fainting lasting from 30 seconds. up to half an hour. In addition, a person has nausea, vomiting, dizziness, pain in the head. Possible short-term memory loss, irritability to noise and light. With simultaneous damage to the occipital bone and concussion, a complex of symptoms is noted. A slight bruise is manifested by loss of consciousness. It can be short (a few minutes) or last several hours. Often there is paralysis of facial muscles, speech disorders. With a moderate bruise, a poor reaction of the pupils to light is noted, nystagmus occurs - involuntary twitching of the eyes. With a severe degree of damage, the victim may fall into a coma for several days. In this case, compression of the brain may also occur. This is due to the development of a hematoma. However, in some cases, compression can cause swelling or bone fragments. This condition usually requires emergency surgery.intervention.
Consequences
Injuries to the occipital bone can cause unilateral visuospatial agnosia. Doctors call this condition violations of different types of perception. The victim, in particular, cannot see and understand the space to the left of him. In some cases, people believe that the skull injuries they have received do not pose a danger to them. However, with any damage to it, regardless of the severity, you must go to the hospital. With no symptoms, a condition that does not manifest itself in the early stages can cause serious consequences.
