Hand Flashcards
Hand muscle division
Muscles acting on the hand can be divided into two groups: extrinsic and intrinsic muscles.
The extrinsic muscles are located in the anterior and posterior compartments of the forearm. They control crude movements and produce a forceful grip.
The intrinsic muscles of the hand are located within the hand itself. They are responsible for the fine motor functions of the hand.
Thenar muscles:
Abductor pollicis brevis
Origin - tubercles of the scaphoid and trapezium; flexor retinaculum
Insertion - base of the proximal phalanx 1 (via radial sesamoid bone)
Innervation - Recurrent branch of median nerve (C8, T1)
Function - thumb abduction (moving away from the hand) at carpometacarpal joint 1
Thenar muscles:
Flexor pollicis brevis
Origin -
Superficial head: Flexor retinaculum, Tubercle of trapezium bone
Deep head: Trapezoid and capitate bones
Insertion - base of the proximal phalanx 1 (via radial sesamoid bone)
Innervation - median nerve
Function - thumb flexion (bending)
Thenar muscle:
Opponens pollicis
Origin - flexor retinaculum, tubercle of trapezium bone
Insertion - first metacarpal bone
Innervation - Recurrent branch of median nerve (C8, T1)
Function - thumb flexion, abduction, and medial rotation resulting in a combined movement called opposition
Hypothenar muscle:
Abductor digiti minimi
Origin
Pisiform bone (Pisohamate ligament, Tendon of flexor carpi ulnaris)
Insertion
Ulnar side of base of proximal phalanx of digit 5, Extensor expansion of digit 5
Action
Metacarpophalangeal joint 5: Finger abduction and flexion;
Interphalangeal joints: Finger extension
Innervation
Deep branch of ulnar nerve (C8, T1)
Hypothenar muscle:
Flexor digiti minimi
Origin Hook of hamate, flexor retinaculum Insertion Base of proximal phalanx of digit 5 Action Metacarpophalangeal joint 5: Finger flexion (+ finger lateral rotation/opposition) Innervation Deep branch of ulnar nerve (C8, T1)
Hypothenar muscles:
Opponens digiti minimi
Origin Hook of hamate bone, flexor retinaculum Insertion Ulnar aspect of metacarpal bone 5 Action Carpometacarpal joint 5: Finger flexion, finger lateral rotation/opposition Innervation Deep branch of ulnar nerve (C8, T1)
Hypothenar muscle:
Palmaris brevis
Origin Palmar aponeurosis, flexor retinaculum Insertion Dermis of skin of hypothenar region Action Tightens palmar aponeurosis, tightens grip Innervation Superficial branch of ulnar nerve (C8, T1)
Palmar interossei muscle
Origin
Medial side of metacarpal bone 2,
Lateral side of metacarpal bones 4 and 5
Insertion
1: Ulnar base of proximal phalanx/extensor expansion of digit 2
2 & 3: Radial base of proximal phalanges/extensor expansions of digits 4 and 5
Action
Metacarpophalangeal joints 2,4 & 5: Finger adduction, Finger flexion;
Interphalangeal joints 2,4 & 5: Finger extension
Mnemonic: PAD DAB (‘Use your hand to dab with a pad’) - Palmar interossei ADduct, Dorsal interossei ABduct
Innervation
Deep branch of ulnar nerve (C8-T1)
Dorsal interossei muscles
Origins
Interosseous I: adjacent surfaces of the 1st and 2nd metacarpal bones
Interosseous II: adjacent surfaces of the 2nd and 3rd metacarpal bones
Interosseous III: adjacent surfaces of the 3rd and 4th metacarpal bones
Interosseous IV: adjacent surfaces of the 4th and 5th metacarpal bones
Insertions
Interosseous I: radial side of the base of the 2nd proximal phalanx (index finger)
Interosseous II: radial side of the base of the 3rd proximal phalanx (middle finger)
Interosseous III: ulnar side of the base of the 3rd proximal phalanx (middle finger)
Interosseous IV: ulnar side of the base of the 4th proximal phalanx (ring finger)
Innervation
Deep branch of the ulnar nerve (C8-Th1)
Function
Interossei I and II: radial abduction of the index and middle fingers
Interossei III and IV: ulnar abduction of the middle and ring fingers
Assist flexion in the metacarpophalangeal joints, assist extension in the proximal and distal interphalangeal joints
Mnemonic: PAD DAB (‘Use your hand to dab with a pad’) - Palmar interossei ADduct, Dorsal interossei ABduct
Lumbricals:
Origin Radial aspects of tendons of flexor digitorum profundus Insertion Dorsal aponeurosis of digits 2-5 Innervation Lumbricals 1-2: Median nerve (C8, T1)
Lumbricals 3-4: Ulnar nerve (C8-T1)
Mnemonic: ‘1 2 me, 3 4 u’ (One to me, three for you)
Function
Metacarpophalangeal joints 2-5: Finger flexion;
Interphalangeal joints 2-5: Finger extension
Ulnar artery anatomical course
Passes through anterior compartment deep to pronator teres and runs alongside flexor carpi ulnaris with ulnar nerve running medial
Radial artery anatomical course
Passes through the anterior compartment deep to brachioradialis. It exits the forearm by passing around lateral writs to enter anatomical snuff box in the hand
Radial artery anastomoses around elbow
Radial artery gives radial recurrent artery
Profunda brachii gives radial collateral artery
Ulnar artery anastomoses around elbow
Ulnar artery give anterior and posterior recurrent
Brachial artery gives inferior and superior ulnar collateral artery
