Anatomy of Upper Limb Muscles and Blood Supply of Upper and Lower Limbs
Upper Limb Muscles - Major Groups
The upper limb contains approximately 20 distinct muscles organized into functional compartments:
Shoulder Region
- Deltoid - primary shoulder abductor
- Rotator cuff muscles (supraspinatus, infraspinatus, teres minor, subscapularis) - shoulder stabilization and rotation
- Pectoralis major and minor - shoulder adduction and internal rotation
Arm (Brachium)
- Anterior compartment: Biceps brachii (typically 2 heads, though a third head occurs as an anatomical variant 1), coracobrachialis, brachialis
- Posterior compartment: Triceps brachii (3 heads) - elbow extension
Forearm
The forearm contains the highest density of muscles with an average of 264 muscular vascular pedicles per forearm 2:
Anterior (Flexor) Compartment:
- Superficial layer: Pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris
- Intermediate: Flexor digitorum superficialis
- Deep: Flexor digitorum profundus, flexor pollicis longus, pronator quadratus
Posterior (Extensor) Compartment:
- Superficial: Brachioradialis, extensor carpi radialis longus/brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris
- Deep: Supinator, abductor pollicis longus, extensor pollicis brevis/longus, extensor indicis
Hand
- Thenar muscles (thumb)
- Hypothenar muscles (little finger)
- Lumbricals (4 muscles with complex blood supply from multiple sources) 3
- Interossei (palmar and dorsal)
Blood Supply of Upper Limb
Arterial Supply - Proximal to Distal
Subclavian artery → Axillary artery → Brachial artery (begins at inferior border of teres major)
The brachial artery is the primary vessel supplying the upper limb. Classical anatomy shows the brachial artery bifurcating at the cubital fossa into radial and ulnar arteries, though variations are common - including high divisions occurring 10+ cm proximal to the elbow 4.
Forearm Arterial Anatomy
The forearm receives blood from multiple arterial sources creating overlapping territories (angiosomes):
- Radial artery - lateral forearm, supplies multiple muscles
- Ulnar artery - medial forearm, largest terminal branch
- Common interosseous artery → anterior and posterior interosseous arteries
- Median artery (when persistent) - can contribute to palmar circulation 4
- Anterior oblique artery - constant vessel accompanying pronator teres 2
Critical anatomical principle: Most forearm muscles receive blood from at least 2 different angiosomes, with connections occurring within tissues rather than between them 5. This redundancy explains why circulation can be reconstituted after arterial injury.
Hand Circulation
Superficial palmar arch - formed primarily by ulnar artery, completed laterally by:
- Superficial branch of radial artery (most common)
- Princeps pollicis artery
- Median artery (when present)
Deep palmar arch - formed primarily by radial artery, completed by deep branch of ulnar artery
The lumbrical muscles have 4 separate blood supply sources: superficial palmar arch, common palmar digital arteries, deep palmar arch, and dorsal digital arteries 3.
Blood Supply of Lower Limb
Arterial Anatomy - Levels 6
The lower extremity arterial system is divided into three anatomical levels:
Aortoiliac level: Infrarenal abdominal aorta → common iliac arteries → external and internal iliac arteries
Femoropopliteal level: Common femoral artery → profunda femoris (deep femoral) and superficial femoral artery → popliteal artery
Infrapopliteal level: Tibial-peroneal trunk → anterior tibial artery, posterior tibial artery, peroneal (fibular) artery → plantar pedal loop → pedal vessels (common plantar, medial plantar, lateral plantar arteries)
Key Concepts
Angiosome-based blood flow refers to uninterrupted arterial flow to the anatomic territory of a source artery, particularly important in the foot where specific infrapopliteal arteries supply distinct skin regions and underlying tissues 6.
In-line (pulsatile) blood flow means uninterrupted arterial flow via named infrapopliteal arteries to the foot - this is the therapeutic goal in revascularization procedures 6.
Clinical Relevance
Patients commonly have multilevel arterial disease across multiple segments 6. The profunda femoris serves as a critical collateral pathway when superficial femoral artery is occluded. Understanding these anatomical levels is essential for:
- Localizing disease
- Planning revascularization strategies
- Predicting outcomes in peripheral artery disease
Important Clinical Variations
Upper limb arterial variations are extremely common and include:
- High brachial artery bifurcations 4
- Persistent median artery 1, 4
- Superficial brachial arteries
- Variations in palmar arch formation
The pronator teres muscle uniquely receives blood from virtually all anterior arteries of the upper limb 2, making it highly resistant to ischemia but complicating surgical approaches.