What are the anatomical compartments of the hand?

Hand Compartments: Anatomical Overview

The hand contains 10 distinct anatomical compartments that are critical for understanding hand pathology, particularly compartment syndrome and surgical planning.

The Ten Compartments of the Hand

Based on anatomical studies, the hand compartments are organized as follows 1:

Intrinsic Muscle Compartments

1. Thenar compartment(s) - Contains the thenar muscles (abductor pollicis brevis, flexor pollicis brevis, opponens pollicis). This space demonstrates 2 or more discrete subcompartments in 52% of hands 1.

2. Hypothenar compartment(s) - Houses the hypothenar muscles (abductor digiti minimi, flexor digiti minimi, opponens digiti minimi). At least 2 subcompartments are present in 76% of specimens 1.

3. Adductor compartment - Contains the adductor pollicis muscle. This forms a discrete compartment in 71% of hands 1.

4. Four interosseous compartments - Each contains the dorsal and palmar interosseous muscles:

   • First interosseous compartment (includes first dorsal interosseous, forms discrete space in 71% of hands) 1
   • Second interosseous compartment (dorsal and palmar interossei are discrete in 48% of hands) 1
   • Third interosseous compartment (discrete separation in 67% of hands) 1
   • Fourth interosseous compartment (discrete separation in 33% of hands) 1

Critical Anatomical Considerations

The fascial anatomy of the hand differs significantly from traditional teaching 2. Key findings include:

• No well-defined tough fascia overlies the thenar muscles, hypothenar muscles, or adductor pollicis 2
• Areolar tissue exists between individual thenar and hypothenar muscles rather than distinct fascial planes 2
• A distinct fascial band covers the entire length of the ulnar three dorsal interosseous muscles 2
• Fascia over palmar interossei is present distally but absent proximally 2

Clinical Implications for Compartment Syndrome

The unyielding overlying skin may serve as the primary constricting layer in hand compartment syndrome, rather than fascia alone 2. This has important implications for:

• Recognizing that thin filmy fascia only partially encases some muscles and is unlikely to solely cause compartment syndrome 2
• Understanding that subcompartmentalization should be anticipated when performing fasciotomy 1
• Ensuring thorough inspection within anatomic areas or generous release of muscular origins along the metacarpal during fasciotomy 1

Surgical Relevance

When treating deep hand infections, surgeons must understand how infection spreads through these compartments 3. The compartmental anatomy guides surgical drainage and debridement approaches, particularly in diabetic foot infections where similar principles apply to foot compartments 3.

Dorsal Hand Anatomy

The dorsal hand has a distinct three-layer structure 4:

• Subcutaneous superficial fatty lamina (no traversing structures)
• Intermediate lamina (contains dorsal veins and sensory nerves)
• Deep lamina (contains extensor tendons)

These layers are separated by thin fascia with 8-10 perforating vessels traveling within fascial septa 4.