UPPER EXTRIMITIES REGION

Anatomical Features of Upper Limb

The upper limb is divided into several regions including the pectoral region, axilla, back, intermuscular spaces around the scapula, arm, cubital fossa, forearm, and palmar spaces.

Contents of Regions of Upper Extremity

• Pectoral region: Contains pectoralis major and minor muscles.
• Axilla: Contains axillary artery, vein, and nerves, as well as lymph nodes and fat.
• Back: Contains trapezius, latissimus dorsi, rhomboids, and levator scapulae muscles.
• Intermuscular spaces around scapula: Contain suprascapular and subscapular nerves and vessels.
• Arm: Contains biceps brachii, brachialis, and triceps brachii muscles.
• Cubital fossa: Contains median nerve, brachial artery, and biceps tendon.
• Forearm: Contains flexor and extensor muscles of the wrist and fingers.
• Palmar spaces: Contain palmar aponeurosis, palmar arteries, and nerves.

Attachments, Nerve Supply, and Actions of Muscles

1. Pectoralis major: Originates from clavicle, sternum, and ribs → Inserts into humerus → Supplied by lateral and medial pectoral nerves → Acts in flexion, adduction, and medial rotation of arm.
2. Latissimus dorsi: Originates from lower back → Inserts into humerus → Supplied by thoracodorsal nerve → Acts in extension, adduction, and lateral rotation of arm.

Main Joint, Blood Vessels, and Nerves in the Region

• Main joint: Shoulder joint (ball and socket joint).
• Blood vessels: Axillary artery and vein, brachial artery and vein.
• Nerves: Axillary, musculocutaneous, median, radial, and ulnar nerves.

Surface Landmarks for Surface Marking

1. Pectoral region: Clavicle, pectoralis major muscle.
2. Axilla: Axillary fold, axillary tail of breast.
3. Back: Scapula, spinous processes of vertebrae.
4. Arm: Biceps brachii muscle, cubital fossa.
5. Forearm: Flexor and extensor muscles, wrist creases.
6. Palmar spaces: Palmar aponeurosis, palmar creases.

Developmental Process

The development of the upper limb involves the formation of limb buds → Differentiation into upper arm, forearm, and hand → Development of muscles, bones, and nerves.

Nerve Supply

The nerve supply to the upper limb involves the brachial plexus → Formation of nerves (musculocutaneous, median, radial, ulnar, and axillary) → Innervation of muscles and skin.

Blood Supply

The blood supply to the upper limb involves the subclavian artery → Axillary artery → Brachial artery → Radial and ulnar arteries → Digital arteries.

Pathway of Blood Flow

Subclavian artery → Axillary artery → Brachial artery → Radial and ulnar arteries → Digital arteries → Return through venous system.

Lymph Drainage

The lymph drainage of the upper limb involves the axillary lymph nodes → Subclavian lymph trunk → Thoracic duct → Emptying into venous system.

Muscle Action Sequence

1. Flexion of arm: Pectoralis major and minor → Biceps brachii → Brachialis.
2. Extension of arm: Latissimus dorsi → Triceps brachii.
3. Flexion of forearm: Flexor muscles of forearm.
4. Extension of forearm: Extensor muscles of forearm.

Anatomical Organisation

The upper limb is organised into several layers:

• Skin and fascia
• Muscles (superficial and deep)
• Nerves and blood vessels
• Bones and joints