The Skeletal The Skeletal SystemSystem

The Human SkeletonThe Human Skeleton● Made up of 206 bones● Bones come in many different forms● Many parts of the body are made up of several

bones joined together i.e. Each hand is made up of 27 bones

● Skeletal is hard and durable– Bones are composed primarily of calcium– Bones are able to repair themselves (with the help

of casts, splints, pins, etc.)

Role of the SkeletonRole of the Skeleton● Provides structural support for the body● Protects vital organs i.e. Rib cage protects the

lungs and heart● Red blood cells and platelets are produced in the

marrow of bones● Bones serve as a reservoir to regulate calcium

and other minerals● Works in conjunction with the muscular system to

cause movement● *Table 2.1 – page 10

The Structure of the The Structure of the SkeletonSkeleton

● Divided into two main parts– Axial skeleton– Appendicular skeleton

Axial-->Appendicular-->

The Axial Skeleton● 80 bones● Made up of the vertebral column (spine), the

skull, and the rib cage● Vertebrae protect the spinal cord● The skull/cranium protects the brain● Ribs protect the lungs and heart

– 7 “true” pairs– 3 “false” pairs– 2 “floating” pairs

The Appendicular Skeleton

● 126 bones● Includes movable limbs and supporting

structures● Upper limbs are attached to the shoulder girdle

– Two scapulae and two clavicles– The humerus attaches to move the arms

● Lower limbs are attached to the pelvic girdle– Two hip bones and the sacrum– The femur attaches to move the legs

Types of BonesTypes of Bones● 1. Long bones – found in the arms and legs● 2. Short bones – most common in the wrists and

ankles● 3. Flat bones – are flat and thin, often protect

vital organs from injury● 4. Irregular bones – odd-looking bones such the

vertebrae● 5. Sesamoid bones – small, flat bones wrapped

within tendons that move over bony surfaces i.e. The patella

Types of Bones

Short

Long

Flat

Irregular

Sesamoid

Anatomy of a Long Bone

● Articulating cartilage: located on both ends of the bone. Allows for smooth movement within joints

● Periosteum: outer connective tissue, covers entire length of bone. Does not unite with articulating cartilage.

● Medullary cavity: found inside the shaft of the bone. Filled with red (blood-cell formation) and yellow (adipose tissue) bone marrow.

Continued...● Compact bone: more dense part of the bone.

Responsible for the bone's structural integrity● Diaphysis: shaft of the bone● Cancellous/spongy bone: filled with marrow● Epiphysis: the very ends of a long bone.