The Mechanics of The Neck and Skull
This Structure Protects The Most Vital Organs in The Body
Jan 12, 2009
Apart from acting as a protective casing for the brain, the head has many more important jobs. The bones and muscles of the skull, face and neck help movements such as:
- turning
- nodding
- chewing
- swallowing
- looking
- listening
- breathing
- talking and
- subtle facial expressions.
The bones of the skull are separated into two main groups. There are eight bones that form the cranial vault which protect and support the brain. The cranium is held together by bands of fibrous tissue called sutures. Fourteen other bones are responsible for structuring the skeleton of the jaw, cheeks, eyes, ears and nose.
Cavities that are full of air, known as the sinuses, and a honeycomb of air-filled pockets in the mastoid process, help to lighten the weight of the skull. Little holes in the cranium allow blood vessels and nerves to move through to structures on the skulls surface.
The Structure of the Nasal Cavity
The nasal cavity is separated by a bone and cartilage septum. Bony projections called conchae disrupt the flow of incoming air, meaning it will bounce around the cavity, dropping dust and germs in the mucus lining. Draining into the cavity is a number of air-filled chambers lined with mucus secreting membranes.
There are three tiny bones that conduct sound waves between the ear drum and the inner ear. These are known as the ossicles, with the smallest of these, the malleus, measuring just 8mm in length.
The Mechanism of the Jaw Bones
The jaw bones consist of a large lower bone, the mandible and two upper bones called the maxillae. How the jaw bones fit together is known as occlusion. The temporomandibular joints allow the lower jaw bone to connect to the skull meaning opening, closing and sideways movements can be made when talking or chewing. These are the only moveable joints within the skull structure.
The teeth are held in a fixed position in the jawbone with fibrous sheets of connective tissue. Each tooth is covered in a hard outer shell of enamel above the gum, with a bone like cementum forming the outer layer of the tooth below the gum.
The spinal cord passes out of the head through a hole at the bottom of the skull and down the vertebrae in the neck. The throat is made up from the trachea and larynx and is supported by a group of small bones and cartilage rings in the front of the neck.
The Bones that Help to Form the Neck
The neck contains seven cervical vertebrae, including two specialised vertebrae, the atlas and the axis, at the top of the spine. The atlas helps to support the weight of the head and takes it name from the mythological giant Atlas, who was thought to carry the weight of the world on his shoulders. This vertebra allows the movement of nodding of the head. The axis vertebra forms a pivot joint around which the skull can rotate from side to side.
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