Unit 3
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The Skeletal System Overview
There are 206 bones in the adult human. Why do I specify adult? Because infants have MORE than 206 bones, but some of their bones fuse together as they age.
Functions of the skeletal system:
The skeleton can be divided into two parts:
There are four different shapes of bones:
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Gross Anatomy of a Long Bone
The structure of any long bone is roughly the same:
The ends of the bone are referred to as the epiphyses and the shaft of the bone is called the diaphysis. The epiphyses are covered by articular cartilage (so named because this is the place where bones articulate or join together). The articular cartilage is very strong, hard, and smooth, which reduces friction when bones rub against each other when a person moves. The outside of the bone is made of compact bone which provides a lot of strength and durability to the bone's structure. There is also spongy (cancellous) bone at the epiphyses where long bones grow. Inside the diaphysis (shaft) of the long bone is a space called the medullary cavity where bone marrow is stored. In adults this bone marrow is yellow, because it is made primarily of fats. In children, however, the bone marrow is red, because it is the site of red blood cell formation. |
Histology of a Long Bone
(Histology is the study of the structure, especially the microscopic structure, of tissues.)
Bones of the Human Skeletal System
Overview of the human skeleton:
Bones of the skull: Lateral and Frontal views
Thoracic Cage: made up of your sternum, ribs, and thoracic vertebrae
Pelvic Girdle
Bones of the lower limb: thigh, leg, and foot
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The vertebral column is divided into sections:
Upper limb: made up of your arm, forearm, and hand. Attached to the axial skeleton by the shoulder girdle (made up of your clavicle and scapula)
Bones of the hand: carpals, metacarpals, and phalanges
Bones of the foot: tarsals, metatarsals, and phalanges
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