Lecture 9 - Hand Flashcards
What is the wrist?
Transition between forearm & hand
What tendons of extrinsic muscles of the hand pass through the wrist?
- Flexor retinaculum
- Extensor retinaculum
What is the retinaculum?
A band of thickened tissue that stabilises tendons around joints, preventing them from popping up when the joint is flexed or extended
What is the hand?
Distal to the wrist
Blood supply/venous drainage through networks (arches)
What are carpals, metacarpals and phalanges?
- Wrist joint
- Metacarpophalangeal joints
- Interphalangeal joinits
What are intrinsic muscles?
- Fine movements of the hand
- Act on digit joints
What is the arterial supply of the hand?
Arch of the aorta –> L/R subclavian artery –> axillary artery –> brachial artery –> radial & ulnar arteries –> superficial and deep palmar arches + dorsal carpal arch
What is the venous supply from the hand?
From digits: digital veins –> palmar venous arches + dorsal venous arch –> cephalic & basilic veins (superficial) + radial & ulnar veins (deep) –> brachial vein (deep) –> axillary vein –> L/R subclavian vein –> L/R brachiocephalic vein –> SVC (superior vena cava)
What are the bones of the hand?
Carpals (8)
- Proximal row
- Distal row
Metacarpals (5)
- 1 to 5 (as digits)
Phalanges (14)
- Digits 2-5 have 3 (proximal, middle and distal)
- Digit 1 has 2 (proximal and distal)
What is the proximal row of the carpal bones?
- Scaphoid
- Lunate
- Triquetrum
- Pisiform
What is the distal row of the carpal bones?
- hamate
- capitate
- trapezoid
- trapezium
What are the hand joints?
- MCP (metacarpophalangeal) joints
- Interphalangeal (IP) joints
What are features of MCP (metacarpophalangeal) joints?
- between metacarpal and proximal phalanx
- 5 MCP joints
- allows flexion, extension, adduction, abduction and circumduction (*very limited)
What are features of Interphalangeal (IP) joints?
- between phalanges
- Digit 1 has 1 IP joint
- Digits 2-5 have IP joints each
- Only allow flexion and extension
What are the basic movements of the hand?
- Flexion
- Extension
- Abduction
- Adduction
- Opposition
- Digits 2-5 flexion/extension at MCP/IP joints
- Digits 2-5 abduction/adduction from longitudinal axis
- Digit 1 flexion/extension
- Digit 1 abduction/adduction
- Digit 1 opposition
What are eminences on the palm of the hand?
Thenar eminence - digit 1 (pollicis)
Hypothenar eminence - digit 5 (digit minimi)
What are the different parts of the thenar eminence?
Abductor pollicis brevis - Action: abducts digit 1
Flexor pollicis brevis - Action: flexes digit 1
Opponens pollicis - Action: opposes digit 1
(blood supply - superficial palmar arch)
(innervation - median nerve)
What are the different parts of the hypothenar eminence?
Abductor digiti minimi - Action: abducts digit 5
Flexor digiti minimi - Action: flexes digit 5
Opponens digiti minimi - Action: opposes digit 5
Blood supply - ulnar artery
Innervation - ulnar nerve
What are other intrinsic muscles in the palm of the hand?
Palmaris brevis - Action: pulls on skin over hypothenar eminence, deepening the cup of the palm and so improving grip.
Adductor pollicis - Action: adducts digit 1
Palmar interossei - Action: adducts digits 2,4,5 towards longitudinal axis
Blood supply - deep palmar arch
Innervation - ulnar nerve
What is the Lumbricals?
Other intrinsic muscles of the palm of the hand
- action: on digits 2-5 they flex MCP joints, extends IP joints.
(blood supply - superficial and deep palmar arches)
(innervation - ulnar and median nerve)
What is the dorsum of the hand?
Dorsal interossei - Action: abducts 2-4 away from the hand’s longitudinal axis (middle finger). Assist in flexion at the MCP joints and extension at the IP joints of digits 2-4.
PAD (palmar interossei adduct) & DAB (dorsal interossei abduct)
Blood supply - dorsal carpal arch
Innervation - ulnar nerve
What is a summary of the hand?
- Hand - 8 carpals, 5 metacarpals & 14 phalanges. They articulate through metacarpophalangeal (MCP) and interphalangeal (IP) joints.
- The carpals are arranged in proximal and distal rows. The proximal row (except the pisiform) articulates with the radius and the ulna at the wrist joint.
- The palm of the hand has 2 major muscle groups in the thenar and hypothenar eminences. Each group has an abductor, a flexor and an opponens, acting on either digit 1 or 5. Ither intristic muscles in the palm of the hand are the palmaris brevis, adductor pollicis, the lumbricals and the palmar interossei.
- The dorsal interossei are the only muscles on the dorsum of the hand
- the hand is innervated by the median and ulnar nerves
- the hand is supplied by the radial and ulnar arteries, which form arches in the palm (superficial and deep palmar arches) and the dorsum of the hand (dorsal carpal arch).
- The venous drainage of the hand is achieved by the palmar and dorsal venous arches, which drain into the cephalic and basilic veins
