[Biology Class Notes] on Skull Pdf for Exam

Skull is a bunch of bones that create the head in vertebrates. The structure of the face is supported by the skull. Skull also protects the brain cavity. Skull is an English word and it is derived from the old world “skulle”. Skull includes two parts, one is the cranium and the other is the mandible. All living beings on earth have different kinds of skeleton according to the face and size of the brain. In human beings, the skull includes the neurocranium and viscerocranium. The mandible is the largest bone of the human face structure that is placed in the viscerocranium. The anterior-most portion of the body is formed by the skull and it is a product of cephalization that includes both housings of sensory structures and the brain. Humans have sensory structures like eyes, ears, mouth, nose and all are included in the facial skeleton.

Importance of the Skull

Well, have you ever thought about how important the skull is? Brain protection is the main function of the skull. In addition, it also fixes the eye balls’ distance to get proper stereoscopic vision. Skull fixes the ears position to enable sound localization of distance and direction of sounds. Some mammals with hooves (horned ungulates animals), skull offers the mount for horns as a defensive structure. The skull consists of foramina, processes, and fossae, sinuses or cavities, and various fused flat bones. Openings of the skull are known as fenestrae in zoology.

Human Skull: What is a Skull? 

As we have discussed earlier in this article, all living beings have different skulls and the human skull diagram includes brain housing and protective structure for sensory organs like eyes, nose, and ears. Well, the framework of the human skull consists of cartilage or bones that protect sense organs and the brain too. Moreover, the lower jaw is not the part of the human skull but the upper jaw is the part of the human skull. The part of the skull that protects the brain is the human cranium and it is globular and large concerning face size. The facial structure of the skull is relatively larger than the brain skeleton structure in other animals. Atlas is the highest vertebra of the human skull that permits nodding motions. The side-to-side motion is possible as the atlas move on the next-lower vertebra called axes. Let’s look at the human skull diagram to know more about the structure of the human skull.

Human Skull Diagram: Structure of Human Skull

In humans, the base of the cranium is the occipital bone, which has a central opening (foramen magnum) to admit the spinal cord. The base of the cranial includes ethmoid and sphenoid bones. Temporal and parietal bones form the forehead. The facial bones include zygomatic, cheekbones that joints with maxillary and temporal bones that make the zygomatic arch of the eye socket. Turbinates bones, lachrymal, nasal, and vomer form the nasal cavity. Human beings change the skull structure many times as they grow older. Such as in infants, sutures or space between various skull bones are loose but they change with age. Many mammals, such as the dog, have a sagittal crest down the centre of the skull; this provides an extra attachment site for the temporal muscles, which close the jaws.

Fun Facts

The bones of the skull are divided into two parts, cranium and face bones. Cranium has eight bones whereas facial bones are fourteen. But teeth are not part of skull bones. It includes only the upper jaw, not teeth, and lower jaw.

The skull bone structure has many holes that are called foramina. Holes are for blood vessels and nerves to pass through the face. Space, where the vertebral column and skull base are joined, is the largest hole of the structure of the skull. The largest hole of the skull is called the magnum.

Even in human beings, the skull is different in size and shape depending upon gender, male and female. Also, the country or place of human beings is a factor that affects the shape of the structure of the human skull.