6.1 2.2.2 human skeleton  (Page 2/4)

In a newborn baby the entire vertebral column curves backwards probably because of the confines of the uterus.

Initially a baby cannot support the weight of its head.. When after about 3 months it is able to support its head, the cervical forward curve is complete .

The lumbar forward curve is complete when the baby is able to stand on its own and ready to learn to walk.

These curves of the vertebral column provide some of the resilience and spring so essential in balance and movement. Abnormal curves may be due to poorposture, congenital disease or bone disease.

FUNCTIONS OF VERTEBRAL COLUMN

• Supports the skull
• Surrounds and protects the spinal cord.
• Provides attachment for ribs, girdles, and back muscles
• Separate vertebrae and S-shaped curvature provide flexibility allowing humans to bend backwards, forwards and sideways.
• Cartilage discs act as shock absorbers

RIB CAGE

The rib cage consists of 12 thoracic vertebrae, 12 pairs of ribs and the sternum or breastbone

• All 12 pair of ribs are attached to the thoracic vertebrae
• The first 7 pairs are attached to the sternum by cartilage. These are the true ribs
• The next 3 pairs are each attached .to the rib above by means of cartilage. These are the false ribs.
• The last 2 pairs are not attached at all to in the front and are called floating ribs.
• Between each pair of ribs are external and internal intercostal muscles
• The sternum is a flat dagger shaped bone at the front of the rib cage.

Functions of rib cage

• Protection of the heart and lungs
• With the help of the diaphragm and the intercostals muscles they increase. And decrease the volume of the thoracic cavity thereb allowing inhalation andexhalation to take place.

APPENDICULAR SKELETON

This part consists of the pectoral girdle with arms and pelvic girdle with legs

Appendicular skeleton animation

http://www.wisc-nline.com/objects/ViewObject.aspx?ID=AP13404

The pectoral girdle and arms

The pectoral girdle consists of 2 clavicles (collar bones) and 2 scapulae (shoulder blades). Each clavicle is attached to the sternum in the front andthe scapulae at the sides and they help to support they help to support the shoulders. The clavicle is the most frequently broken bone in the body as itoften takes the full impact of falls on outstretched arms or of blows to the shoulder. Each scapula has a socket into which the upper arm fits

Each upper arm has a single bone called the humerus which fits into the Glenoid cavity on the scapula to form a ball and socket joint. This cavity is very shallow which allows the arms to move in almost any direction for forms an elbow joint with the forearm

The forearm consists of two bones namely the ulna in line with the little finger and the radius which lies above the thumb. The joint at the elbow is a hinge joint.

The wrist consists of 8 small carpal bones arranged in two rows of four.

The palm of the hand consists of 5 metacarpal bones. Their rounded ends at the base of the fingers form the knuckles

There are 14 finger bones or phalanges in each hand, two in each thumb and three in each of the fingers