Bones of the head (skull): how many are there and what are they called?

The brain is one of the most important organs of the human body, governing the functioning of the rest of the body systems. Being protected is essential for survival.

Fortunately, we have different protection mechanisms, one of which is a strong bone covering that surrounds it. We are talking about the skull, which is made up of different bones.

• Related article: "Parts of the human brain (and functions)"

Bony protection of the brain: the skull

When talking about the skull, the totality of bones that are part of the head is usually imagined. 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, like those of the jaw, are part of the facial skeleton.

However, given its use as a synonym for the set of bones of the head Sometimes a distinction is made between neurocranium, which would be the skull itself, which protects the brain) and viscerocranium (which would include the bone 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 make up the mandible).

In general both neurocranium and viscerocranium are solidly attached, considering that the border between one and the other is 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 together and joined together throughout development through hardened connective tissue. Its main function is to protect the brain and allow a basic structure in which part of the facial muscles can adhere, in addition to providing a stable position to the blood vessels, cranial nerves and the brain itself. Likewise, the skull can be divided into the cranial vault and the base of the skull.

• You may be interested: "The lobes of the brain and their different functions"

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 throughout the development of the individual in what are called sutures. All of them have different openings and holes through which blood vessels and nerves circulate.

The different bones that are part of the skull, as well as some of its substructures, are exposed below.

1. Frontal bone

This bone sits on and protects the frontal lobe. It allows to shape the forehead and reaches the upper part of the vault of the eye or supraorbital margin, being a point of union between the neurocranium and the viscerocranium. It joins with the parietal bones by the coronary suture, and with the nasal bones by the frontonasal suture.

• Related article: "What is the frontal lobe and how does it work?"

2. Parietal bones

Is about the largest bones of the skull, which form most of the upper and lateral region of this. It is connected to the frontal one by the coronary suture, with the parietal by the squamous suture and with the occipital one by the lambdoid suture. Both parietals are joined together by the sagittal suture.

3. Temporal bones

Two bones each located under one of the parietals and joined to them by squamous sutures. These irregular bones can be divided into three areas: the squamous one that is located around the squamous suture, the mastoid that refers to the part closest to the jaw in the one where various muscles of the neck and neck are located and the stone that is located in deeper regions, forming part of the base of the skull and having inside the middle ears and internal. There is also a tympanic region, which surrounds the ear canal.

4. Occipital bone

This bone mainly configures the base of the skull, placing the foramen magnum in it or hole in which brain and spinal cord they connect. It protects part of the occipital and temporal lobe, the cerebellum, and the brain stem. It has several protrusions and ridges that connect with the vertebrae. It connects with the parietal through the lambdoid suture and with the temporal through the occipitomastoid.

5. Sphenoid

This bone shaped like a butterfly or bat It is located in an area at the height of the temple, connecting with the frontal, temporal and occipital bones. It goes from side to side of the skull, horizontally, and is made up of the body and major and minor wings and the pterygoid process. In the first one can be found the sella turcica, a structure that surrounds and protects the pituitary. The greater wings form part of the dorsal wall of the ocular orbit, while the lesser ones form part of the medial part. It holds the rest of the bones of the skull together and connected.

6. Ethmoid

The bone known as the ethmoid lies between the sphenoid and the nasal bone, participating in the formation of the eye orbits and the nostrils, acting as a ceiling for the seconds (specifically the part called the cribriform lamina) and the ground of the former, as well as the separation between them (the lateral masses of the ethmoid).

This bone connects with the meninges through the crista galli. It has numerous cavities called turtle cells.

Bones of the viscerocranium

Although the bones of the skull are properly the previous ones, it must be taken into account that there are other bones in the head structure beyond them, 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 that the head of an adult human has on average (to which it is possible to add those of the ear).

Below you can see them listed, each person having two of each of the following except the vomer and the jaw (the latter being the only movable bone structure).

• Mandible
• Maxillary bones
• Nasal bones
• Tear bones
• Vomer
• Turbinates
• Palatal bones
• Zygomatic bones (cheekbones)

In addition to these, within the viscerocranium we can also find the internal ossicles of the ear that allow the reverberation of sound until clucking: hammer, anvil and stirrup.

Bibliographic references:

• Rouviere, H. and Delmas, A. (2005). Human anatomy: descriptive, topographic and functional; 11th ed.; Masson.