Bones of the head (skull): how many are there and what are they called?
Our brain is protected by a series of bony plates that keep it safe. What are they?
The brain is one of the most important organs of the human body, as it governs the functioning of the rest of the body systems. Its protection is essential for survival.
Fortunately, we have different protection mechanisms, one of which is a strong bony covering that surrounds it. We are talking about the skull, which is composed of different bones..
The bony protection of the brain: the skull
When we speak of the skull, we usually imagine the totality of bones that form part of the head. This consideration is not entirely correct, since the skull as such is technically the bony structure that covers the brain.. The rest of the bones, such as those of the jaw, are part of the facial skeleton.
However, However, because of its use as a synonym for all the bones of the head, a distinction is sometimes made sometimes a distinction is made between neurocranium, which would be the skull itself, which protects the brain) and viscerocranium (which would include the bony structure that shapes the face and of which the bones of the ear, the nostrils, the eye socket, the nasal cavity and the set of bones that form the jaw are part).
In general, both neurocranial and viscerocranial both the neurocranium and the viscerocranium are solidly united.The border between one and the other is considered to be marked by the auditory canal and the upper part of the eye socket.
The adult human skull, in its meaning as neurocranium, is a set of eight bones welded and joined together throughout development throughout development by means of hardened connective tissue. Its main function is to protect the brain and to provide a basic structure to which part of the facial musculature can adhere, as well as to provide a stable position for the Blood vessels, cranial nerves and the brain itself. Likewise, the skull can be divided into cranial vault and skull base.
Bones that make up the skull
As we have seen, the skull or neurocranium is made up of a total of eight bones joined and welded together throughout the development of the individual in what are called sutures. All of them have different openings and orifices through which blood vessels and nerves circulate..
The different bones that form part of the skull, as well as some of its substructures, are described below.
Frontal bone
This bone is located above and protects the frontal lobe.. It gives shape to the forehead and reaches the upper part of the eye vault or supraorbital margin, being a point of union between the neurocranium and viscerocranium. It is joined to the parietal bones by the coronary suture, and to the nasal bones by the frontonasal suture.
2. Parietal bones
These are the largest bones of the skullThey form most of the upper and lateral region of the skull. They are connected to the frontal bone by the coronary suture, to the parietal bones by the squamous suture and to the occipital bone by the lambdoid suture. Both parietals are joined together by the sagittal suture.
3. Temporal bones
Two bones each situated below one of the parietals and joined to them by the squamosal sutures. These bones, which are irregular, can be divided into three zones: the squamous which is located around the squamous suture, the mastoid which refers to the part closest to the mandible where several muscles of the mandible and neck are located, and the petrous which is located in deeper regions, forming part of the base of the skull and containing the middle and inner ear. There is also a tympanic regionwhich surrounds the auditory canal.
4. Occipital bone
This bone mainly forms the base of the skull, where the foramen magnum or orifice where the brain and spinal cord connect. It protects part of the occipital and temporal lobe, the cerebellum and the brainstem. It has several protrusions and ridges that connect with the vertebrae. It is connected to the parietal by the lambdoid suture and to the temporal by the occipitomastoid.
5. Sphenoid
This butterfly-shaped or bat-shaped bone is located in an area at the level of the temple, connecting with the frontal, temporal and occipital bones.connecting with the frontal, temporal and occipital bones. It runs from side to side of the skull, horizontally, and is composed of body and major and minor wings and pterygoid process. The sella turcica, a structure that surrounds and protects the pituitary gland, can be found in the first wing. The greater wings form part of the dorsal wall of the ocular orbit, while the lesser wings form part of the medial part. It holds together and connects the rest of the bones of the skull.
6. Ethmoid
The bone known as the ethmoid is located between the sphenoid and the nasal bone.It participates in the formation of the ocular orbits and the nasal cavities, acting as the roof of the latter (specifically the part known as the lamina cribrosa) and the floor of the former, as well as the separation between the two (the lateral masses of the ethmoid are responsible for this).
This bone connects with the meninges through the crista galli. It has numerous cavities known as the scmoid cells..
Bones of the viscerocranium
Although the bones of the skull are properly the previous ones, it is necessary to bear in mind that there are other bones in the structure of the head more there are other bones in the structure of the head beyond them, those corresponding to the viscerocranium.those corresponding to the viscerocranium. In this case we can find a total of 14 bones, which together with the previous 8 make up the 22 bones that an adult human head has on average (to which it is possible to add those of the ear).
Below you can see them listed, each person possessing two of each of the following except the vomer and the mandible (the latter being the only movable bone structure).
- Jaw
- Maxillary bones
- Nasal bones
- Lacrimal bones
- Vomer
- Nasal turbinates
- Palatine bones
- Zygomatic bones (cheek bones)
In addition to these, within the viscerocranium we can also find the inner ossicles of the ear that allow the reverberation of sound up to the clochea: malleus, incus and stapes..
Bibliographical references:
- Rouviere, H. and Delmas, A. (2005). Human anatomy: descriptive, topographic and functional; 11th ed.
(Updated at Apr 12 / 2024)