Before studying of upper limb you have to know what is upper limb. You may think it is silly question., but can you define the upper limb?  This is the definition:

upper limb:  the limb of the body extending from the deltoid region to the hand; it is specialized for functions such as grasping and manipulating

In human anatomy, the upper limb (also upper extremity) refers to the region distal to the deltoid.

In formal usage, the term "arm" only refers to the structures from the shoulder to the elbow, explicitly excluding the forearm, and thus "upper limb" and "arm" are not synonymous. However, in casual usage, the terms are often used interchangeably. The term "upper arm" is redundant in anatomy, but in informal usage is used to distinguish between the two terms.


The upper limb includes the following structures:


Bones of the upper limb.

The following bones are considered to be part of the upper limb:

                                                             Fig 1.1 The general plain of the upper limb 

The upper limb is associated with the lateral aspect of the lower portion of the neck. It is suspended from the trunk by muscles and a small skeletal articulation between the clavicle and the sternum-the sternoclavicular joint. Based on the position of its major joints and component bones, the upper limb is divided into shoulder, arm, forearm, and hand 


The shoulder is the area of upper limb attachment to the trunk

The arm is the part of the upper limb between the shoulder and the elbow joint; the forearm is between the elbow joint and the wrist joint; and the hand is distal to the wrist joint.

The axilla, cubital fossa, and carpal tunnel are significant areas of transition between the different parts of the limb Important structures pass through, or are related to, each of these areas.

The axilla is an irregularly shaped pyramidal area formed by muscles and bones of the shoulder and the lateral surface of the thoracic wall. The apex or inlet opens directly into the lower portion of the neck. The skin of the 'armpit' forms the floor. All major structures that pass between the neck and arm pass through the axilla.

The cubital fossa is a triangularly shaped depression formed by muscles anterior to the elbow joint. The major artery, the brachial artery, passing from the arm to the forearm passes through this fossa, as does one of the major nerves of the upper limb, the median nerve.

The carpal tunnel is the gateway to the palm of the hand. Its posterior, lateral, and medial walls form an arch, which is made up of small carpal bones in the proximal region of the hand. A thick band of connective tissue, the flexor retinaculum, spans the distance between each side of the arch and forms the anterior wall of the tunnel. The median nerve and all the long flexor tendons passing from the forearm to the digits of the hand pass through the carpal tunnel.

Positioning the hand

Unlike the lower limb, which is used for support, stability, and locomotion, the upper pimb is highly mobile for positioning the hand in space.

The shoulder is suspended from the trunk predominantly by muscles and can therefore be moved relative to the body. Sliding (protraction and retraction) and rotating the scapula on the thoracic wall changes the position of the glenohumeral joint (shoulder joint) and extends the reach of the hand . The glenohumeral joint allows the arm to move around three axes with a wide range of motion. Movements of the arm at this joint are flexion, extension, abduction, adduction, medial rotation (internal rotation), lateral rotation (external rotation), and circumduction .

The major movements at the elbow joint are flexion and extension of the forearm . At the other end of the forearm, the distal end of the lateral bone, the radius, can be flipped over the adjacent head of the medial bone, the ulna. Because the hand is articulated with the radius, it can be efficiently moved from a palm-anterior position to a palm-posterior position simply by crossing the distal end of the radius over the ulna . This movement, termed pronation, occurs solely in the forearm. Supination returns the hand to the anatomical position.

At the wrist joint, the hand can be abducted, adducted, flexed, extended, and circumducted . These movements, combined with those of the shoulder, arm, and forearm, enable the hand to be placed in a wide range of positions relative to the body. Positioning the hand

Unlike the lower limb, which is used for support, stability, and locomotion, the upper pimb is highly mobile for positioning the hand in space.

The shoulder is suspended from the trunk predominantly by muscles and can therefore be moved relative to the body. Sliding (protraction and retraction) and rotating the scapula on the thoracic wall changes the position of the glenohumeral joint (shoulder joint) and extends the reach of the hand . The glenohumeral joint allows the arm to move around three axes with a wide range of motion. Movements of the arm at this joint are flexion, extension, abduction, adduction, medial rotation (internal rotation), lateral rotation (external rotation), and circumduction 

The major movements at the elbow joint are flexion and extension of the forearm . At the other end of the forearm, the distal end of the lateral bone, the radius, can be flipped over the adjacent head of the medial bone, the ulna. Because the hand is articulated with the radius, it can be efficiently moved from a palm-anterior position to a palm-posterior position simply by crossing the distal end of the radius over the ulna . This movement, termed pronation, occurs solely in the forearm. Supination returns the hand to the anatomical position.

At the wrist joint, the hand can be abducted, adducted, flexed, extended, and circumducted . These movements, combined with those of the shoulder, arm, and forearm, enable the hand to be placed in a wide range of positions relative to the body.

                                                               


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