Chapter 7 Skeletal Organization

Number of Bones Average number of bones is 206 – People may have varying numbers of bones Ex – sutural bones, sesamoid bones in tendons

Divisions of the Skeleton Axial skeleton – Bony and cartilaginous parts that support and protect the organs of the head, neck, and trunk Appendicular skeleton – Bones of the upper and lower limbs and the bones that anchor the limbs to the axial skeletion

Divisions of the Skeleton

Axial Skeleton Skull – Includes cranium and facial bones Hyoid Bone – Located in neck between lower jaw and the larynx – Does not articulate with any other bones (held in place by muscles and ligaments) – Supports the tongue – Serves as an attachment point for muscles associated with the tongue

Axial Skeleton Vertebral Column – Consists of vertebrae separted by cartilaginous vertebral discs – Five vertebrae near the distal end are fused to form the sacrum (part of the pelvis) – Four vertebrae are fused to form the tailbone (coccyx) below the sacrum Thoracic Cage – Protects the organs of the thorax and upper abdomen – Consists of 12 pairs of ribs (which articulate with the thoracic vertebrae) and the sternum (with which most ribs articulate anteriorly)

Appendicular Skeleton Pectoral Girdle – Formed by the scapula and the clavicle – Connects the bones of the upper limbs to the axial skeleton – Aid in upper limb movements Upper Limbs – Consists of humerus, radius, ulna, and hand bones The humerus, radius, and ulna articulate at the elbow joint The hand consists of 8 carpals, 5 metacarpals, and 14 phalanges

Appendicular Skeleton Pelvic Girdle – Formed by two hipbones (coxae) which attach to the sacrum posteriorly and each other anteriorly – Connects the bones of the lower limbs to the axial skeleton – Forms the pelvis with the sacrum and coccyx Protects the lower abdominal and reproductive organs Lower Limbs – Consists of the femur, tibia, fibula, and foot The femur and tibia articulate at the knee joint which is covered by the patella The foot contains 7 tarsals, 5 metatarsals, and 14 phalanges

Terms used to describe skeletal structures: