Why Is the Skull Vital for Human Anatomy and Protection?
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.
FAQs on Skull: Structure and Importance in Biology
1. What is the human skull and what are its primary functions?
The human skull is the bony framework of the head in vertebrates. Its two primary functions are to provide a protective cavity for the brain and to form a structural framework for the face, supporting sensory organs like the eyes, ears, nose, and mouth.
2. What is the difference between the skull and the cranium?
While often used interchangeably, the terms have distinct meanings in anatomy. The cranium refers specifically to the part of the skull that encloses and protects the brain. The skull is a more comprehensive term that includes both the cranium and all the facial bones.
3. How many bones are in the adult human skull and how are they categorised?
The adult human skull is composed of 22 bones. These are divided into two main categories:
- Cranial Bones (8): These bones form the protective case for the brain. They include the frontal, parietal (2), temporal (2), occipital, sphenoid, and ethmoid bones.
- Facial Bones (14): These bones form the structure of the face. They include the maxillae (2), zygomatic (2), mandible, nasal (2), lacrimal (2), palatine (2), vomer, and inferior nasal conchae (2).
4. Which is the only movable bone in the skull and what is its importance?
The only movable bone in the skull is the mandible, or the lower jawbone. Its mobility, through the temporomandibular joint (TMJ), is crucial for essential functions like chewing (mastication), speaking, and facial expression. All other skull bones in an adult are fused by immovable joints.
5. Why is the sphenoid bone often referred to as the “keystone” of the skull?
The sphenoid bone is called the “keystone” because of its unique, central location within the skull. It is the only bone that articulates with all the other cranial bones. This connection helps to bind the cranial skeleton together, providing significant structural stability and forming a large part of the skull's base and sides.
6. What are sutures in the skull, and how do they change from infancy to adulthood?
Sutures are immovable fibrous joints that connect the bones of the cranium. In infants, these joints are not fully fused and are separated by soft, membranous gaps called fontanelles. This flexibility is critical for two reasons:
- It allows the bony plates of the skull to overlap, enabling the head to pass through the birth canal.
- It accommodates the rapid growth and expansion of the brain during the first few years of life.
7. What is the significance of the foramina in the base of the skull?
The foramina are openings or holes in the bones of the skull, particularly concentrated at its base. They serve as critical passageways for vital structures to enter and exit the cranial cavity. Their primary importance is to allow for the passage of cranial nerves, major blood vessels like arteries and veins, and the spinal cord (through the foramen magnum), connecting the brain to the rest of the body.
