Upper Limb Anatomy Overview

Study Notes

Overview of Upper Limb Anatomy

The upper limb, attached to the axial skeleton via the pectoral girdle, comprises the shoulder, arm, forearm, and hand.
Its primary function is manipulation and skilled dexterity.
The region exhibits a diverse range of movements enabled by multiple joints and muscle groups.
Detailed knowledge of bony landmarks, articular surfaces, and muscle attachments is crucial for understanding biomechanics and clinical considerations.

Shoulder Girdle

The pectoral girdle consists of the clavicle and scapula.
The clavicle connects the sternum to the scapula, providing stability and attachment for muscles.
The scapula is a flat, triangular bone articulating with the humerus at the glenohumeral joint and the clavicle at the acromioclavicular joint.
Key bony landmarks include the acromion, coracoid process, glenoid cavity, and various facets for muscle attachment.
The glenoid cavity, shallow in comparison to other joints, results in a wide range of motion but also higher risk of dislocation.
Important muscles include the deltoid (abduction of arm), supraspinatus (initiation of abduction), infraspinatus and teres minor (external rotation), subscapularis (internal rotation), and rotator cuff muscles enabling stability and mobility.

Humerus

The humerus is the long bone of the arm.
Distal humerus articulates with the radius and ulna at the elbow joint.
Important bony landmarks include the head, greater and lesser tubercles, anatomical neck, surgical neck, deltoid tuberosity, medial and lateral epicondyles, capitulum, and trochlea.
The articulating surfaces of the distal humerus and proximal radius and ulna are crucial for elbow joint movements.

Elbow Joint

The elbow joint is a hinge joint formed by the articulation of the distal humerus with the proximal radius and ulna.
The joint allows flexion, extension, and supination (palm facing up) and pronation (palm facing down) movements.
The radius and ulna articulate to form the proximal and distal radioulnar joints, supporting pronation and supination movements, vital for hand positioning.
The ulna and radius articulate at proximal and distal radioulnar joints, enabling rotational movements crucial for hand movements.

Forearm

The forearm comprises the radius and ulna.
The radius and ulna are parallel to each other, permitting specific movements in the forearm.
Proximal and distal ends articulate with other bones enabling hand movement.
Muscles of the forearm are responsible for wrist and finger movements (flexion/extension and abduction/adduction).
Multiple flexor and extensor muscles reside in the anterior and posterior compartments of the forearm.

Wrist and Hand

The wrist is a complex structure with eight carpal bones arranged in two rows that articulate with the radius and ulna distally and metacarpals proximally.
The carpal bones form the wrist joint, crucial for wrist flexion/extension and radial/ulnar deviation.
Metacarpals directly connect to the carpals, forming the palm.
Phalanges form the fingers and thumb, enabling delicate manipulation and grasp.
Intrinsic muscles of the hand originate and insert within the hand, allowing for specific finger movements.
Individual fingers are composed of three phalanges (proximal, middle, and distal) with the thumb possessing only two.

Neurovascular Supply

The upper limb receives its nerve supply from the brachial plexus, a complex network of nerves arising from cervical spinal nerves (C5-T1).
Major nerves include the musculocutaneous nerve (anterior compartment arm), median nerve (anterior forearm and hand), ulnar nerve (posterior forearm and hand), and radial nerve (posterior arm and forearm).
Arterial blood supply is mainly through the brachial artery, branching to supply the upper limb with oxygenated blood.
Venous drainage mirrors the arterial system, returning venous blood to the heart via the subclavian vein.

Clinical Correlations (brief)

Common injuries include fractures of the clavicle, humerus, radius, and ulna.
Dislocations of the shoulder, elbow, and wrist joints are common injuries.
Nerve injuries, such as carpal tunnel syndrome and ulnar nerve entrapment, can occur.
Rotator cuff tears are common injuries, particularly in overhead athletes.
Understanding anatomical structures aids accurate diagnosis and treatment of upper limb injuries.

Description

This quiz provides a comprehensive overview of upper limb anatomy, focusing on the shoulder girdle, arm, forearm, and hand. It highlights the key bony landmarks, joint articulations, and muscle attachments necessary for understanding movement and clinical considerations. Test your knowledge on the complex functions and structures of the upper limb.