Hand Compartments: Palmar, Deep, and Dorsal

• The hand is divided into 5 compartments: three palmar compartments, a deep compartment, and a dorsal compartment.
• The palmar (superficial and deep) and dorsal (superficial and deep) fasciae divide the hand into compartments.

Palmar Compartments

• The palmar compartments include:
• Lateral palmar compartment (thenar)
• Medial palmar compartment (hypothenar)
• Middle palmar compartment, occupied by flexor muscle tendons

Deep Compartment

• Metacarpals divide this compartment.
• Interosseous spaces contain palmar and dorsal interosseous muscles.

Dorsal Compartment

• Extensor muscle tendons run through it.

Lateral Palmar Compartment: Thenar Muscles

• 4 muscles occupy this area, from superficial to deep:
• Abductor pollicis brevis
• Opponens pollicis
• Flexor pollicis brevis (superficial and deep bundles)
• Adductor pollicis
• The median nerve and the deep branch of the ulnar nerve innervate this compartment.

Medial Palmar Compartment: Hypothenar Muscles

• Contains from superficial to deep:
• Palmaris brevis
• Abductor digiti minimi
• Flexor digiti minimi brevis
• Opponens digiti minimi
• This compartment is innervated by the deep branch of the ulnar nerve.

Middle Palmar Compartment

• The flexor muscle tendons and the four lumbrical muscles occupy it.
• The median nerve innervates the 1st and 2nd lumbricals.
• The deep branch of the ulnar nerve innervates the 3rd and 4th lumbricals.
• Actions:
• Flex P1, extends P2 and P3
• No movement of laterality
• The first two lumbricals are

Deep Compartment: Interosseous Spaces

• Interosseous muscles occupy the intermetacarpal spaces.
• They divide into palmar and dorsal interosseous muscles.
• The deep branch of the ulnar nerve innervates all of them.
• These muscles flex P1 and extend P2 and P3.
• The dorsal interossei abduct fingers; the palmar interossei adduct fingers.