The Skull – MemoryFAQs.com

The skeletal structure enveloping a human’s or animal’s head is called a skull. It is a skeletal framework of the head of vertebrates which consists of 22 individual bones.

What’s a Skull?

The skull is the protective ‘helmet’ that wraps around the brain and protects it – a kind of a ‘house’ for the brain. Since the brain is one of the most vital body organs, the skull serves as a special guardian of all the vital functions of the body performed by the brain.

Not only does the skull shield our brain, but it also accommodates the organs of vision, hearing, smell, and taste. It also supports our facial features and plays a big role in how our face actually looks.

What Is the Skull Made Of?

Even though it looks like our ‘brain protector’, the skull, is made of a single helmet-like bone, it actually comprises two groups of bones and cartilage. One group of larger bones protects the brain. These bones are called cranial bones. They comprise the neurocranium (the protective shell of the brain and the brain stem) and are a total of 8 in number.

Cranial Bones

the ethmoid bone (a hollow bone at the root of the nose in the front-middle of the skull)
the sphenoid bone (located in the frontal mid-section of the skull, connecting almost all of the other facial bones)
the frontal bone (a single bone that forms our forehead)
the occipital bone (positioned in the back of the skull, where the spinal cord exits the skull through the foramen magnum)
two parietal bones (that make up the upper side part of the skull)
two temporal bones (the bones that sit right at the place on the skull where the hair typically first turns gray).

The other fourteen bones that comprise the second group are called facial bones, also known as the viscerocranium.

Facial Bones

There are:

- two inferior nasal concha bones (responsible for the exchange of airflow through the nose)
- two lacrimal bones (the smallest and most fragile bones of the skull, which support the eyes),

one mandible bone (a bone which supports the jaw and the lower teeth),

two maxilla bones (supporting the upper jaw, upper teeth, nasal cavity, and the palate),
two nasal bones (these bones create the ‘bridge’ of our nose, variable in size and form in different individuals),
two palatine bones (they form the back part of the palate and the back part of the nasal cavity)
a vomer bone (the singular, vertical bone that separates the nasal cavity)
two zygomatic bones (these are literally the cheekbones, giving the cheek their characteristic ‘arch’).

These bones provide support for our eyes, nose, and jaw, and as we said, directly influence how our facial structure looks.

How Are the Bones of the Skull Interconnected?

The bones of the skull are interconnected through sutures – the joints of the skull bones. There are many sutures on the skull, located exactly at the place where the bones of the skull meet, and they help the bones of the face to stick together.

There are four major sutures: the coronal, sagittal, lambdoid, and squamous sutures:

The coronal suture joins the frontal bone and the two parietal bones which are part of the bony braincase,
The sagittal suture connects the two parietal bones,
The lambdoid suture links the two parietal bones to the occipital bone, and
The squamous sutures serve as a joint between the parietal and temporal bones.

What Are Fontanelles?

When a baby is born, the bones of its skull are not firmly joined by sutures. The spaces between the bones of the skull in an infant or a fetus where the sutures are not fully formed are called fontanelles.

The fontanelles are soft, membrane-covered spaces on the skull of the fetus (the infant) where a bone is to be formed because a baby’s skull needs to be flexible during the delivery. Once the baby is born, the fontanelle slowly gets replaced by a suture after the baby’s head fully forms. This usually happens between 8 to 14 months of life.

There are two fontanelles which include:

A fontanelle in front of the skull (anterior fontanelle) – The two frontal and the two parietal bones of the skull meet at this position. The frontal fontanelle remains soft longer than the back fontanelle.
A fontanelle at the back of the skull (posterior fontanelle) – The two parietal and the occipital bone of the skull meet at this position. The back-positioned fontanelle usually closes first with a suture.

What Is the Function of the Openings in the Skull?

The skull also contains numerous openings shaped like small holes. They are called foramina. There are 21 of these special holes on the human skull, serving as passages for the cranial nerves, blood vessels, and arteries of the face that further connect to the tissues of one part of the body to another.

The largest one of the openings on the skull is the foramen magnum (note that even its name implies that it’s the biggest – (lat.) magnum – great, big). The foramen magnum is located at the base of the skull, on the occipital bone. It connects the brain with the spinal cord through the skull.

The foramina of the skull are of great importance because of the fact that many of the most important blood vessels and nerves pass through them in order to both supply the brain and to carry information to and from the brain, which is a highly complex process.

What Are Sinuses?

The sinuses are a butterfly-shaped void space between the bones of the nose where the air we breathe through the nose has a space to circulate. They are lined with soft tissue, and are usually empty (until we catch a cold or breathe in dust, that is).

Have you ever wondered why your nose is running even though you haven’t got a cold? Well, that’s because the sinuses are lined with cells that produce mucus, in order to prevent the nose drying out during our breathing.

Also, the mucus that the sinuses produce is responsible for filtering the pollutants we inhale, like dust and microorganisms.

This connected system of hollow cavities consists of four pairs of sinuses, named after the bones under which they are located:

Maxillary sinuses (the largest pair of sinuses, located on the left and right side right under the eyes, behind the upper part of the cheeks)
Frontal sinuses (a pair of sinuses located just above our eyebrows)
Sphenoid sinus (this is a single sinus, located in the mid-face)
Ethmoid sinuses (they are located in the upper part of the nose, near the eyes. Since they produce mucus, they give us a headache due to the pressure of the mucus when we have a cold.)

Put simply, the sinuses moisten the air we breathe in through our nose, and clear the nasal passages. They are responsible for the resonance of our voice, as well.

To Sum Up

The skull is the protective bony ‘helmet’ consisting of two groups of bones and cartilage – eight cranial bones (neurocranium) and fourteen facial bones (viscerocranium). These bones protect our brain from any injury and give support to our eyes, nose, and jaw, thus giving the face its special features.

The bones of the skull join with each other by sutures, which help the bones of the skull stay firmly connected.

The openings of the skull are called foramina, and they conduct the cranial nerves, blood vessels, and arteries from the skull to the other connective tissues of the body. The largest one among them is called foramina magnus, which is the opening where the spinal cord passes through.

There are also sinuses in the skull, which help determine the resonance of our voice but can also cause great pressure and headache when we have a cold.

Since the human brain is one of the most important organs of our body, the skull has developed all these structures and anatomical mechanisms in order to be as strong as possible to protect it.

Fun Facts

Did You Know?

The jaw bone (or the mandible) is the only bone of the skull which is not joined together with the other bones by sutures, since it’s a moveable bone.

The jaw bone is also the strongest and biggest bone in the skull. This is because a strong jaw bone is crucial for any live being that has a moveable jaw bone such as humans, since it helps us chew food.

You can easily identify an animal or a person by the ethnicity according to the shape of their skull. For instance, a bird, a bull, a dinosaur – they all have a distinct build of the skull bones.

The large suture of a newborn, called fontanelle, is soft at first, in order to prevent the skull from crushing during the baby’s delivery. After the delivery of the baby, it hardens like the other bones in order to protect the tender structure of the brain. Our bodies are truly magical, aren’t they?

Our faces are beautiful due to the symmetry of facial bones. Namely, they mostly come in equal symmetrical pairs.

Though the teeth are bony structures, they are not considered to be part of the skull bones, because – they are not actually bones!

When we have a headache, it’s mainly because of the inflammation of the sinuses – the void spaces behind the facial bones.
The male and female human skulls differ in shape, size, and thickness. Male skulls are considered to be larger, heavier, and thicker than female skulls.

Medical examiners can tell a whole story about the life of a diseased person only by the analysis of their skull. They can tell the race, ethnicity, and gender only by the measurements of the skull.

The human skull is as strong, if not stronger than steel of the same mass, but a heavy object can break it easily.