Anatomy of the Hand

Anatomy of the Hand

• The hand's structure is described, focusing on its muscles, skin, and connective tissues.
• Objectives for the study include features of hand skin, attachments, innervations, and actions of hand muscles, the flexor and extensor retinacula, carpal tunnel boundaries and contents, blood vessels and nerves of the hand, palmar aponeurosis, and synovial sheaths.

Skin of the Hand

• Palm: Thick, hairless, bound to underlying fascia by fibrous bands, characterized by creases for movement, and dense sweat gland distribution.
• Dorsum: Thin, hairy, freely mobile over tendons and bones.

Flexor Retinaculum

• Thickening of deep fascia, forming a carpal tunnel.
• Attached to pisiform and hook of hamate medially, and scaphoid and trapezium tubercles laterally.
• Holds long flexor tendons in place at the wrist.

Carpal Tunnel

• Formed by carpal bones (inferiorly) and the flexor retinaculum (superiorly).
• Contains 4 tendons of flexor digitorum profundus, 4 tendons of flexor digitorum superficialis, tendon of flexor pollicis longus, and the median nerve.

Extensor Retinaculum

• Thickening of deep fascia, forming 6 separate tunnels lined with synovial sheaths.
• Holds long extensor tendons in position.
• Attached to pisiform and hook of hamate medially, and distal end of radius laterally.

Synovial Sheaths

• Synovial sheaths surround tendons, reducing friction.
• Variations in sheath arrangement exist (e.g., intermediate bursa).
• Provide lubrication for smooth tendon movement in the hand.

Fibrous Sheaths

• Surround and support tendons of flexor digitorum superficialis and profundus muscles.
• Run anterior to metacarpophalangeal joints, extending to distal phalanges.
• Formed by fibrous arches and cruciate ligaments for support.
• Attached posteriorly to margins of phalanges, and to palmar ligaments.
• Prevent bowing of tendons during flexion.

Extensor Expansion

• Triangular attachments over proximal phalanges.
• Supports and connects tendons of extensor digitorum and extensor pollicis longus.
• Attached to distal phalanx, middle/proximal phalanx (thumb).
• Extensor hood wraps around metacarpophalangeal joints.
• Provides attachment for hand muscles.

Palmar Aponeurosis

• Triangular condensation of deep fascia covering the palm.
• Continuous with palmaris longus tendon or flexor retinaculum.
• Fibers radiate to digits, supporting and stabilizing tendons, nerves, and blood vessels that underpin the hand.

Hand Muscles

• Thumb Short Muscles: 4 comprising adductor pollicis and thenar muscles (abductor pollicis brevis, flexor pollicis brevis, opponens pollicis).
• Little Finger Short Muscles: 3 hypothenar muscles (abductor digiti minimi, flexor digiti minimi brevis, opponens digiti minimi).
• Thenar Muscles: Innervated by the median nerve.
• Adductor Pollicis: Innervated by the deep branch of the ulnar nerve.
• Lumbricals: 4 muscles, innervated by median (1st and 2nd) or ulnar (3rd and 4th) nerves.
• Palmar Interossei: 4 muscles; adduct fingers toward the third finger.
• Dorsal Interossei: 4 muscles; abduct fingers away from the third finger.

Movements of Thumb

• Movements include abduction, adduction, extension, flexion, opposition, and reposition.

Blood Vessels of the Hand

• Two interconnected vascular arches in the palm (radial and ulnar arteries): superficial and deep.
• Radial artery supplies thumb and index finger's lateral side.
• Ulnar artery supplies other digits and index medial side.

Nerves of the Hand

• Ulnar Nerve: Deep and superficial branches.
• Deep branch innervates hypothenar muscles, interossei, and medial lumbricals.
• Superficial branch innervates palmaris brevis muscle; skin on ulnar side of hand and medial half of ring finger.
• Median Nerve: Divides into recurrent branch (innervates thenar muscles) and palmar digital branches.
• Radial Nerve: Superficial branch, innervates dorsolateral aspect of palm and digits distally (over terminal interphalangeal joints).

Fascial Spaces of Palm

• Potential spaces filled with loose connective tissue (CT).
• Fibrous septa divide the palm into thenar and midpalmar spaces based on attachments to metacarpals.
• Parona's space is between FDP anteriorly and pronator quadratus/interosseous posteriorly.

Explore the intricate structure of the hand, focusing on its muscles, skin, and connective tissues. This quiz covers the features of hand skin, the flexor and extensor retinacula, carpal tunnel anatomy, and the blood vessels and nerves of the hand.