FUNCTION OF HUMAN SKELETON
SKELETON:
The framework around which the body of an organism is build is called skeleton.
The shape of an organism depends upon the skeleton. At the time of the birth each child has 350 bones but when the child grows. Some of these bones fused together and only 206 bones are remained.
Parts of human skeleton:
Human skeleton is divided into two parts.
(1) Axial skeleton
(2) Thoracic skeleton
(3) Appendicular skeleton
(1) Axial skeleton:
The skeleton that forms the main axis of the body is called asexual skeleton. It consists of skull, backbone etc.
(i) Skull:
Skull is divided into two parts.
A. Cranium:
The cranium consists of 8 bones. Out of them 4 bones namely frontal, occipital, solenoid and ethmoid are unpaired bones where 2 bones are paired namely parietal and temporal. Cranium protects the brain.
B. Facial bone:
Facial bone consist of 14 bones which make our face. Out of these 14 bones, 2 bones are unpaired and 6 bones are paired. The unpaired bones are mandible and vomer. The paired is maxilla, zygomatic, nasal, lacrimal, palatine and inferior concha.
(ii) Vertebral column:
Vertebral column extends from skull to the pelvis. It consists of 33 vertebra. These vertebra are named according to their location in the body. These are:
A. Cervical vertebra. 7 bones
B. Thoracic vertebra. 12 bones
C. Lumber vertebra. 5 bones
D. Sacrum vertebra. 5 bones
E. Coccyx vertebra. 4 bones
2. Thoracic skeleton:
Rib cage and sternum:
Rib cage composed of 12 pair of ribs. These are attached on dorsal side with the thoracic vertebrae. Out of 12 pairs of ribs, upper 10 paired are connecting with sternum bone and lower two pair of ribs are not attached to sternum called floating ribs. Ribs provide supporting to thoracic cavity in which vital organs like heart, lungs are present.
2. Appendicular skeleton:
These are the skeletons that forms outside of the body. It consist of,
(i) Girdle (ii) Limbs
(i) Girdle:
There are two types of girdle in human skeleton.
A. Pectoral girdle:
Pectoral girdle is composed of bone called scapula, super scapula and clavicle.
B. Pelvic girdle:
Pelvic girdle attached the hind Limb to the vertebral column. It consists of two coxal bone. The pelvic girdles support the pelvic region.
(ii) Limb:
Limb are differentiated into,
A. Fore Limbs
B. Hind Limbs
A. Fore limbs:
Limbs consists of 1 humer, 1 radius and 1 ulna, 8 carpals, 5 metacarpal and 14 phalanges.
B. Hind Limb:
Hind Limb of human beings consists of 1 femur, 1 tibia, 8 tarsal, 5 metatarsal and 14 phalanges.
Composition of Skeleton
Human skeleton is made of two types of material,
1. Bones
2. Cartilages
1. Bone:
●Bones are hard and rigid form of connective tissue.
●Bones are tough and not flexible.
●These are made from special type of cells called collagen fiber.
●Bones are hardened by the deposition of calcium phosphate.
Examples:
Femur, humorous, ulna, tibia, fibula etc.
2. Cartilages:
●Cartilages are the soft form of connective tissue.
●Cartilages are soft and flexible.
●These are made from special type of cell called chondrocyte.
●In embryonic life the whole skeleton is made of cartilages which are then replaced by bone in adulthood.
Examples:
Air pinna, nose, trachea, esophagus and end of jointed bones.
Joint:
The point where one bone attaches to another bone is called a joint. It helps in the movement of skeleton without damaging the bones. Joints help in movement and locomotion of the body. Body moves with the help of muscles acting across the joint.
Types of joints:
(i) Immoveable (fixed) Joints
(ii) Slightly moveable joints
(iii) Freely moveable joints
(i) Immovable joints:
Those joints that fit together tightly or fused orbital together and don't allow any type of movement, are called immovable joints. The cranial bones of the skull form immovable joints.
(ii) Slightly moveable Joints:
Those joints which allow a very limited or slight movement are called slightly moveable Joints, e.g. Joints between the vertebrae.
(iii) Freely moveable joints:
These joints show free movements. There are two types of freely moveable joints.
(a) Hinge joints
(b) Ball and socket joints
(a) Hinge joints:
Hinge joints in elbow and knees. These joints produce movement in forward and backward direction just like opening and closing of a door.
(b) Ball and socket joints:
Ball and socket joints in shoulder and hips These joints can move freely in all direction. A ball located at the end of one bone that fits into a socket in other. This allows a circular moment in a direction.
Repair of broken bones:
Although bones are quite strong and tough yet they may fracture due break or automobile accident, sports, old age and many other causes. It is a painful event and must be treated properly.
When a bone breaks, the blood vessels in the bone are teared. As a result, a hematoma or a mass of clotted blood, forms at the fracture site.
Some chemicals are released by the injured bone.
(i) If a crack in the bone is like hairline and the bone remains in one piece, it may heal after sometime. It should be bandaged and needs a little support.
ii) If a bone like ulna breaks. Then broken ends need to be brought together carefully and held firmly by a plaster. It takes a long time to heal.
iii) If bone is broken badly then steel rods are inserted to hold the bone pieces together.
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