Upper Limb Anatomy

Upper Limb Anatomy

The upper limb, comprising the upper arm, forearm, and hand, is crucial for performing various tasks and movements in humans. It contains 30 bones and a complex system of muscles, nerves, and blood vessels that enable flexibility, strength, and dexterity. Let's explore the anatomy of each region of the upper limb.

Arm (Brachium)

The arm, in an anatomical sense, refers to the proximal part of the upper limb above the elbow. It consists of the humerus bone, which is the largest bone in the arm and lies between the shoulder and elbow joints. The humerus has a head that articulates with the glenoid cavity of the scapula to form the glenohumeral joint. The humerus also has an anatomical neck, which serves as a common site of arm fractures. Additionally, the humerus contains greater and lesser tubercles, which serve as attachment sites for muscles acting across the shoulder joint, and a deltoid tuberosity on the lateral side for muscle attachments.

Forearm

The forearm is the region between the elbow and wrist joints and contains two bones: the ulna medially and the radius on the lateral side. The ulna articulates with the trochlear notch of the humerus, forming part of the elbow joint. The proximal radioulnar joint is the articulation between the head of the radius and the radial notch of the ulna, allowing for supination and pronation of the hand.

Hand

The hand consists of five metacarpal bones that form the palm and eight carpal bones that make up the base of the hand. The fingers contain phalanges, with each finger having three phalanges except for the thumb, which has only two. The bones of the hand are arranged in such a way that they allow for various movements and grasping abilities.

Muscles

Muscles play a crucial role in moving the upper limb. For example, the rotator cuff muscles include the supraspinatus, infraspinatus, teres minor, and subscapularis, which surround the shoulder joint and provide stability and mobility. The deltoid muscle covers the lateral side of the arm and provides abduction and flexion of the arm. The triceps brachii extends the elbow, while the biceps brachii and brachialis flex the elbow. There are also muscles responsible for wrist extension, such as the extensor carpi radialis brevis and the extensor carpi ulnaris.

The upper limb's anatomy allows for a unique range of motion, including flexion, extension, rotation, and complex movements like grasping objects. Understanding this anatomy is essential for various daily activities and for medical professionals in diagnosing and treating injuries or disorders of the upper limb.