Lucy Egerton
Skeletal System
Structure
The skeletal system consists of bone cells, tissues, the bones, bone joints and bone
shapes.
Bones
Skull
The bones of the cranium consist of frontal, parietal, temporal, occipital, sphenoid
and ethmoid.
Facial Bones
Spinal Column
Rib cage
Shoulder Girdle
Pelvic Girdle
Hip bone is also known as the innominate bones.
Arm Bones:
Hand Bones
Leg bones
Foot bones
Bones Joints
1. Fixed: No movement.
2. Slightly moveable
3. Freely moveable: Lubriciated with synovial fluid. Subtypes are hinge, gliding (
condyloid ), ball & socket, saddle, and pivot.
Bone Cell types:
 Osteoblasts
 Osteoclasts
 Osteocytes: mature cells
Bone Tissue:
Compact: Near surface of bone. Contains the haversian canal.
Cancellous or Spongy: Ends of long bones, inside irregular, flat and sesamoid bones.
Periosteum: white covering of bones.
Bone marrow:
Red
Found in flat bones, and cancellous tissue.
Yellow
Found in shaft of long bones
Function
The skeletal system supports the body to stay upright. It protects the brain, thorax,
heart, lungs and other viscera. It allows movement through the joints. It forms blood
cells through the bone marrow. It stores vital nutrients calcium and magnesium.
Specifically:
Bone Cell types:
 Osteoblasts: form new bone through ossisfication
 Osteoclasts: break down or reabsorbing old bone. Critical in the
maintenance, repair and rebuilding of bone cells.
Bone Tissue:
Compact: contains blood, lymph vessels and nerves.
Cancellous or Spongy: Consists of cavities which strengthen the bone. Contain bone
marrow.
Periosteum protective covering of bones.
Bone marrow:
Red
Used for blood cell production
Yellow
Used for fat storage
Bones Joints
1. Fixed: Hold cranium and innominate bones together.
2. Slightly moveable: Allow movement of spinal column
3. Freely moveable
Hinge: Movement of elbow, knee, ankle, phalanges
Gliding: Movement in the tarsal’s and carpals.
Ball & Socket: Movement in hip and shoulder
Saddle: Movement in the thumb
Pivot: Movement between atlas and axis of spine. Movement between radius
and ulna, gliding ( condyloid ), ball & socket, saddle, and pivot.
Diseases and Disorders
Osteoarthritis
85% of people over the age of 70 are affected by osteoarthritis. It is age related and
is caused by degenerative crumbling of a joint or joints. The main symptoms are joint
pain and stiffness. Other symptoms can include joint swelling, and less range of
motion. Unlike other types of rheumatoid arthritis only the joints are typically
affected. The most commonly involved joints are those near the ends of the fingers,
at the base of the thumb, neck, lower back, knee, and hips. It can affect work and
normal daily activities. It comes on usually over years but causes include previous
joint injury, abnormal joint or limb development, and inherited factors. You put
yourself at risk if you are overweight or have a job that puts a lot of stress on the
joints.
Rheumatoid Arthritis
An autoimmune disease that involves the body’s immune system attacking the
joints. This leads to inflammation and thickening of the joint capsule. Its main
symptoms are warm, swollen, and painful joints. Unlike osteoarthritis usually if one
joint is involved on one side of the body, the other will be too. Most commonly, the
wrist and hands are involved. The disease may also affect other parts of the body
causing a low blood cell count, lung inflammation, and inflammation around the
heart. It can also lead to a fever and low energy. The cause of rheumatoid arthritis is
not clear, but it is likely to be genetically and environmentally linked.