The upper and lower limbs were evolved basically for bearing the weight of the body and for locomotion. In quadrupeds forelimbs and hindlimbs are, therefore, built on the same basic pattern.
Each limb is made up of a basal segment or girdle, and a free part divided into proximal, middle and distal segments. The girdle attaches the limb to the axial skeleton. The distal segment carries the five digits.
Following table will elicit the similarity between two limbs
However, with the evolution of the erect posture in man, the function of weight bearing was taken over entirely by the lower limbs. As a result of this the upper limbs and hands became free and gradually evolved into organs having great manipulative skill. This has become possible because of a wide range of mobility at the shoulder.The whole upper limb works as a jointed lever.
The human hand is a grasping tool. It is exquisitely adaptable to perform various complex function.
Parts of the upper limb
- Shoulder Region
- Arm (or brachium)
- Forearm (or antebrachium)
- Hand (or manus).
Shoulder region consists of following
- The pectoral or breast region, on the front of the chest
- The axilla or armpit
- The scapular region on the back comprising parts around the scapula. The bones of the shoulder girdle are the clavicle and the scapula.
The Arm (upper arm or brachium)
Arm extends from the shoulder to the elbow (or cubitus). The bone of the arm is the humerus. Its upper end meets the scapula and from the shoulder joint. The shoulder joint permits movements of the arm.
The Forearm (antebrachium)
Forearm extends from the elbow to the wrist. The bones of the forearm are the radius and the ulna. At their upper ends they meet the lower end of the humerus to form the elbow joint. Their lower ends meet the carpal bones to form the wrist joiont. The elbow joint permits movements of the forearm, namely flexion and extension. The radioulnar joints permit rotatory movements of the forearm called pronation and supination.
The hand (manus)
- The wrist or carpus
- The hand proper or metacarpus
- Five digits
The carpal bones form the wrist joint with the radius, intercarpal joints with one another, and carpometacarpal joints with the metacarpals. The phalanges form metacarpophalangeal joints with the metacarpals, and interphalangeal joints with one another. Movements of the hand are permitted chiefly at the wrist joint. The thumb moves at the first carpometacarpal joint and each finger at its metacarpophalangeal joint.