IMG_0024

Introduction to the Upper Limb

• The upper limb is attached to the pectoral girdle, which consists of:

  • Scapula

  • Clavicle

• Articulation:

  • Scapula and clavicle articulate at the acromioclavicular joint.

  • The sternoclavicular joint is the sole bony connection between the axial skeleton and the upper limb.

• All upper limb muscle attachments to the pectoral girdle are via muscles.

Anatomy of the Axilla

• The axilla (armpit) is a pyramid-shaped, fat-filled structure located between the chest wall and the upper limb.

• Contains critical structures:

  • Brachial plexus

  • Axillary artery and vein

  • Lymph nodes

• Functions as a funnel for neurovascular structures to/from the upper limb.

Segmentation of the Upper Limb

• The upper limb segments include:

  • Arm: between shoulder and elbow

  • Forearm: from elbow to wrist

  • Hand: connects to forearm at the wrist (carpus).

Mobility of the Upper Limb

• The upper limb is characterized by high mobility, allowing a range of controlled movements.

• The hand is specifically noted for its refined grasping ability and sensory function.

Bone Structure of the Upper Limb

• Key long bones include:

  • Humerus (arm)

  • Radius and Ulna (forearm)

• Smaller but critical bones:

  • Carpal bones (wrist): scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, hamate

  • Metacarpals (5 total: I-V)

  • Phalanges (14 total: 2 in the thumb, 3 in each finger)

Muscular Structure

• The deep fascia supports the upper limb, divided into anterior and posterior compartments by intermuscular septa and interosseous membranes.

• Muscle functions:

  • Anterior compartment: primarily contains flexors

  • Posterior compartment: primarily contains extensors.

Nerve Supply

• The brachial plexus supplies nerves to the upper limb:

  • Main terminal branches include:

    • Musculocutaneous

    • Median

    • Ulnar

    • Axillary

    • Radial

• Function of nerves:

  • Musculocutaneous, median, ulnar nerves supply anterior flexors.

  • Radial nerve supplies posterior extensors.

  • Axillary nerve supplies deltoid and teres minor muscle.

Blood Supply and Vascular Structures

• Arterial Supply:

  • The axillary artery has six branches:

    • Superior thoracic artery

    • Thoraco-acromial artery

    • Lateral thoracic artery

    • Subscapular artery

    • Posterior circumflex humeral artery

    • Anterior circumflex humeral artery

• The axillary artery transitions to the brachial artery at the teres major muscle.

  • The brachial artery divides into radial and ulnar arteries at the elbow.

Venous and Lymphatic Structures

• Veins:

  • Deep veins follow arteries toward the axilla.

  • The axillary vein becomes the subclavian vein, merging with the internal jugular to form the brachiocephalic vein.

  • The cephalic vein drains the superficial venous blood from the upper limb.

  • The basilic vein arises from the medial limb of the dorsal venous arch.

• Lymphatics:

  • Lymphatic drainage follows unnamed vessels from the hand, with superficial drainage along superficial veins and deep drainage along deep arteries.

• Lymph reaches the axillary lymph nodes.

Breast and Pectoral Region

• Located on the anterior and superior part of the thorax.

• Contains:

  • Mammary glands that secrete milk.

  • Pectoral muscles that assist in upper limb movement.

• Structural support by the upper eight ribs.

Muscles of the Pectoral Region

• Pectoralis Major:

  • Fan-shaped muscle originating from the anterior rib cage and inserting onto the humerus

  • Functions: adducts, flexes, and medially rotates the arm.

• Pectoralis Minor:

  • Stabilizes scapula by pulling it inferiorly and anteriorly.

• Subclavius:

  • Pulls clavicle inferiorly and anteriorly.

• Serratus Anterior:

  • Major protractor of the upper limb.

Nerve and Blood Supply

• Nerves:

  • Supplied by brachial plexus branches (medial and lateral pectoral nerves) for motor innervation.

  • Supraclavicular and intercostal nerves provide sensory innervation.

• Blood Supply:

  • Internal thoracic artery supplies the medial pectoral region; lateral part supplied by axillary artery branches (thoraco-acromial and lateral thoracic arteries).

Venous and Lymphatic Drainage

• Superficial and deep venous drainage occurs alongside arteries.

• Lymphatic drainage:

  • Drains into axillary nodes and has clinical relevance for cancer spread.

Clinical Correlations

• Breast Mass:

  • Abnormal lump; common causes include fibroadenoma (benign) and breast cancer.

  • Breast cancer symptoms differ from benign masses, often hard, adhered to tissue, and immobile.

• Diagnosis approaches:

  • Clinical examination, mammography, biopsy options (fine needle, core, open).

  • Surgical intervention often considers axillary nodes to check for metastasis.