The Skeletal System

Skeletal System•The skeletal system provides the bony framework.•Movement occurs in the joints but movement per se is done by the muscles.•The bones will not move unless the muscle makes them moves.•The essential purpose of physical movement is to:

Obtain food and foodAvoid injury and reproduce

•Most of the body movements done by an individual is controlled by the will expect for some movements like the beating of the heart, digestion and respiration. The phenomenon know as reflex action is done before the individual becomes aware of it.

•The bones of the skeleton is divided into

two: Axial skeletonAppendicular skeletons

•The axial skeleton is compose of:

SkullVertebral columnRibsSternum

The Human Skull

Cranium – is formed by irregular bones that provide protection for the brain.

Base of the skull-where the brain rests

Vault-surrounds and protects

the brain

• The bones of the cranium are:FrontalParietalTemporalOccipitalSphenoidEthmoid bones

The Vertebral Bones

•Verbal column is composed of:

24 separateMovableIrregular bones5 sacrum bones4 coccyx

•The 24 separate bones are divided into three groups:

7 cervical groups12 thoracic bones5 lumbar bones

Kinds of Bones

• The appendicular skeleton is composed of:

Shoulder girdle with the upper limbs

Pelvic girdle with the lower limbs

• Compact Bone - has a large number of Haversian canals which contain blood, lymph vessels and nerves.• Haversian Canal – is surrounded by concentric plates of bones called lacunae (spaces).• Cancellous Bone – is similar to a honeycomb in appearance. It contains the red bone marrow and its haversian canals are larger those in the compact bones.

• Osteoblasts - are the cells responsible for bone formation which develop into osteocytes.

- are mature bone cells that developed from osteoblasts.

• Osteoblasts can be seen present at:1. The deeper layer of the periosteum2. The centers of ossification3. The ends of the diaphyses and4. The sites of fracture

The Functions of BonesAside from providing the frame work of the

body, the bones still perform other functions such as:

1. Provide attachment for muscles and tendons,

2. From a boundary at the cranial, thoracic and pelvic cavities,

3. They also provide protection for the different organs located at these cavities,

4. Contain the red bone marrow where hematopoiesis occurs and

5. They serve as reservoir for calcium, phosphorous and fats.