Why does skull have joints

Cartiliginous Joints. Joints that unite bones with cartilage are called cartilaginous joints. There are two types of cartilaginous joints: 1 A synchrondosis is an immovable cartilaginous joint. One example is the joint between the first pair of ribs and the sternum.

This type of joint allows for some movement. The hip bones, connected by the pubic symphysis, and the vertebrae, connected by intervertebral discs, are two examples of symphyses.

Synovial Joints. Synovial joints are characterized by the presence of an articular capsule between the two joined bones. Bone surfaces at synovial joints are protected by a coating of articular cartilage. Synovial joints are often supported and reinforced by surrounding ligaments, which limit movement to prevent injury. There are six types of synovial joints:. Major gliding joints include the intervertebral joints and the bones of the wrists and ankles.

These joints allow for flexion and extension. The sphenoid bone, from the outside, appears to contribute to only a small portion of the cranium, but when the parietal bones are removed and the interior of the cranial cavity where the brain would be housed is viewed, you can see the butterfly-like shape of the sphenoid bone makes a large contribution to the floor of the cranial cavity.

The ethmoid bone, which from the outside is only visible in the eye sockets and as the upper conchae internal bumps of the nasal cavity, also contributes to the floor of the cranial cavity. The contributions of these two bones to the floor of the cranial cavity are shown in Figure 6. There are three prominent bone markings on the temporal bones.

The external acoustic meatus is the opening that leads to the organs of the inner ear. The styloid process is a thin, pen-like projection where muscles and ligaments of the neck are attached. The mastoid process is a wide and rough projection that serves as another attachment point for neck muscles.

Structural classification is determined by how the bones connect to each other, while functional classification is determined by the degree of movement between the articulating bones. In practice, there is significant overlap between the two types of classifications.

Fibrous Joints : The adult skull is normally made up of 22 bones. Except for the mandible, all are joined together by sutures, semi-rigid articulations formed by bony ossification. Fibrous joints are connected by dense connective tissue consisting mainly of collagen.

Your frontal bone forms your forehead, and the tops of your eye sockets. Most of the top and sides of your head are formed by two parietal bones. And the back of your skull is formed by your occipital bone which has an opening in it where your spinal cord connects to your brain. The fourteen bones at the front of your skull hold your eyes in place and form your facial features.

Your mandible, or jawbone, is the largest, strongest bone in your face. It holds your lower teeth in place and you move it to chew your food. Apart from you mandible and your vomer, all your facial bones are arranged in pairs. That's why your face is symmetrical.