Skull Bones
It is one of the components of the skeletal system of the head and is located in the upper part of the body and attached to the neck.
Functions of the skull
The main functions of the skull are:
- Shelter and protect the brain and sensitive organs of the head;
- Protect nerves and blood vessels;
- Allow air and food to pass through existing openings;
- Act in the chewing process through the action of the maxilla, mandible and teeth.
Skull anatomy
The skull is divided into three parts, which are the neurocranium, viscerocranium and middle ear. Learn more about each of them below.
Neurocranium
The neurocranium corresponds to the upper and lower posterior part of the skull, it is the rounded framework that surrounds the brain and the inner ears. It can also be called the cranial box.
See the table below for the main bones of the neurocranium:
| Bones of the neurocranium | Description |
|---|---|
| Occipital | It has a large, oval perforation responsible for allowing communication between the brain and the spinal canal. |
| Sphenoid | It is an odd, irregular bone located at the base of the skull before the temporal bones and the basilar portion of the occipital bone. |
| Parietal | It is a paired bone, responsible for forming the roof of the skull. Its shape is flat and has two faces, four edges and four angles. |
| Temporal | It is an extremely important paired bone for our body, as the hearing aid is located inside it. |
| Front | This is a wide, flat bone that is located forward and upward. It has two portions, one vertical and the other horizontal, where the orbital and nasal cavities are located. |
| Ethmoid | It is a light, spongy bone, which has an irregular shape and is located in the anterior part of the skull. |
Viscerocranium
The viscerocranium contains the bones of the face that are related to the respiratory, digestive and sensory systems.
Also known as the splanchnocranium, the viscerocranium is composed of the bones shown in the table below.
| Bones of the viscerocranium | Description |
|---|---|
| Lacrimal | It is the bone that houses the lacrimal sac and is responsible for supporting the contents of the orbit. |
| Vomer | It is a bone that makes up the nasal septum, thus creating a division between the two sides of the nasal cavity. |
| Jaw | It is the bone that forms the largest portion of the face and contains the majority of muscle tissue. It is responsible for facial expressions. |
| Nasal | It is a pair of bones located in the face that forms the initial contour of the nose. |
| Palatine | It is a bone located between the maxilla and the sphenoid bone. It is L-shaped and is responsible for forming the posterior portion of the hard palate and the floor of the nasal cavity. |
| Zygomatic | It is the bone responsible for bridging the gap between the neurocranium and the viscerocranium. It is the bone that forms the cheekbones. |
| Jaw | It is the bone that forms the chin and the lower contour of the face. It is what allows the person to open their mouth to eat, chew and speak. |
| Inferior nasal concha | It is located along the lateral wall of the nasal cavity. |
Middle ear
The middle ear is made up of three double bones. Learn about each of them in the table below.
| Bones of the middle ear | Description |
|---|---|
| Hammer | It is the largest ossicle in the ear. It is connected to the eardrum by the tympanic membrane and the incus. |
| Anvil | It is located between the hammer and the stirrup. |
| Stirrup | It is the smallest bone in the human body, measuring about 3 millimeters. Its function is to provide support and is connected to the anvil and the inner ear. |
Cranial sutures
Cranial sutures are joints that allow mobility to the bones of the skull, in addition to serving to connect one bone to another.
The sutures are closed from the age of 30 or 40.
The table below describes the most important sutures.
| Suture | Description |
|---|---|
| Coronal | Located between the frontal and parietal bones. |
| Sagittal | Separates the parietal bones. |
| Lambdoid | It occurs horizontally between the occipital bone and the parietal bones. |
Cranial fossae
In addition to the sutures, the skull also contains holes, which are the places where nerves and blood vessels pass through. Most of these holes are located at the base of the skull.
The skull also has cranial fossae, which are described in the table below.
| cranial fossa | Description |
|---|---|
| Anterior cranial fossa | Composed of the frontal, sphenoid and ethmoid bones. |
| Middle cranial fossa | Formed by the sphenoid and temporal bones. |
| Posterior cranial fossa | Composed of the temporal and occipital bones. |
Bone malformation of the skull
Below, find out about some anomalies related to the malformation of the skull bones.
Craniofacial stenosis
Also known as craniosynostosis, this is a bone malformation in the skull. The cause is related to the absence or premature closure of the cranial and facial sutures.
It is not known exactly why this occurs, but it is estimated that it affects on average one in every 2,000 children in the world. Diagnosis is made through radiological examinations or tomography scans.
Treatment can be performed according to the severity of the craniofacial stenosis. If the impact is related to aesthetics, surgery is optional, but if closing the cranial sutures puts the child’s life at risk, surgery becomes essential.
cleft palate
Popularly known as cleft lip, a cleft lip is an anomaly caused by the failure of the structures in the palate or lip region to close. It is a malformation that occurs between the fourth and tenth week of pregnancy.
The opening can reach different sizes, and can reach the entire roof of the mouth (hard palate) and base of the nose or just part of them.
The cause of cleft palate is not known for sure, but some factors are considered risk factors, such as: nutritional deficiency and maternal diseases during pregnancy, use of certain medications and use of alcohol and tobacco.