HAND & ARM Flashcards
What are the 3 types of bones in the hands?
Carpal bones
Metacarpal bones
Phalanges
What are the carpal bones?
Scaphoid
Lunate
Triqetrum
Pisiform
Trapezium
Trapezoid
Capitate
Hamate
“Some Lovers Try Positions That They Can’t Handle”
Which of the carpal bones is a sesamoid bone?
The pisiform - it is formed within the tendon of the flexor carpi ulnaris
What are the metacarpal bones?
Metacarpal 1-5 for each finger
They articulate proximally with the carpals and distally with the proximal phalanges
What are the phalanges?
Bones of the fingers
Each digit has a proximal, middle and distal phalanx apart from the thumb which only has a proximal and distal phalanx.
What are the extrinsic and intrinsic muscles of the hand?
Extrinsic - located in anterior and posterior compartments of the forearm. Control crude movements and produce a forceful grip
Intrinsic - located within the hand itself. Responsible for the fine motor functions of the hand
What innervates the thenar muscles?
Median nerve
What are the thenar muscles?
Opponens pollicis
Abductor pollicis brevis
Flexor pollicis brevis
Function of opponens pollicis?
Opposes the thumb by medially rotating and flexing the metacarpal on the trapezium
Function of abductor pollicis brevis?
Abducts the thumb
Function of flexor pollicis brevis?
Flexes the MCP joint of the thumb
What innervates the hypothenar eminence?
Ulnar nerve
What are the hypothenar muscles?
Opponens digiti minimi
Abductor digiti minimi
Flexor digiti minimi brevis
Function of opponens digiti minimi?
Rotates the metacarpal of the little finger towards the palm, producing opposition
Function of abductor digiti minimi?
Abducts the little finger
Function of flexor digiti minimi brevis?
Flexes the MCP joint of the little finger
What innervates the lumbricals?
Lateral 2 - median nerve
Medial 2 - ulnar nerve
What hand muscles does the median nerve innervates?
LOAF
The lateral 2 lumbricals, opponens pollicis, abductor pollicis brevis and flexor pollicis brevis
All others are ulnar
Function of the lumbricals?
Flexion at MCPJ and extension at IPJs of each digit
Denervation of the lumbricals causes what…?
Ulnar claw
Hand of benediction
What is hand of benediction?
When there is a lesion of the median nerve so the middle and index fingers cannot flex at the MCP and IP joints
This is due to paralysis of the lateral 2 lkmbricals and the lateral half of flexor digitorum profundus
What is ulnar claw?
Lesion of an ulnar nerve which causes unopposed extension at the MCPjs and flexion at IPJs in the little and ring fingers
This is due to paralysis of the medial 2 lumbricals
What are the interossei muscles?
These are the muscles located between the metacarpal bones of the hand
They are divided into dorsal and planar
What innervates the interossei muscles?
Ulnar nerve
Function of dorsal interossei muscles?
Abduction of digits
Assists in flexion at MCPJs and IPJs
Function of palmar interossei muscles?
Adduction of digits
Assists in flexion at MCPJs and extrension at IPJs
What is the palmaris brevis?
A small, thin muscle found superficially in the subcutaneous tissue of the hypothenar eminence
It originates from the palmar aponeurosis and flexor retinaculum and attaches to the dermis of the skin
What innervates palmaris brevis?
Ulnar nerve
Fnction of palmaris brevis?
Wrinkles the skin of the hypothenar eminence and deepens the curvature of the hand, improving grip
Function of adductor pollicis?
Adducts thumbs
Innervation of adductor brevis?
Ulnar nerve
What is the carpal tunnel bounded by?
Bounded on 3 sides by the carpal bones and on the palmar side by the transverse carpal tigament
What is contained within the carpal tunnel?
The median nerve and flexor tendons
Pathophysiology of carpal tunnel syndrome?
Reduction in dimensions of carpal tunnel or increase in the volume of its contents -> increased pressure in the tunnel -> ischaemia of median nerve which impairs nerve confection -> pain and paraesthesia in median nerve distribution
Risk factors for carpal tunnel syndrome?
Activities with high hand/wrist repetitive rate e.g. gardening, vibrating hand tools
Obesity
Pregnancy
OA of MCP joint of thumb (due to osteophytes)
Inflammatory joint disease e.g. RA
Ganglion cysts
Scar tissue e.g. lunate fracture
Hypothyroidism
DM
Oedema e.g HF
Symptoms of carpal tunnel syndrome?
In the distribution of the median nerve (thumb, index, middle finger) there may be…
Intermittent paraesthesia, numbness, altered sensation
Burning or pain
May be worse at night
Shaking the wrist can help relieve pain
Examination signs of carpal tunnel syndrome?
Weakness of thumb abduction (abductor pollicis brevis)
Wasting of thenar eminence only
Tinels sign
Phalens sign
Durkan’s test
What is tinels sign?
tapping the wrist over the median nerve causes paraesthesia in cubital tunnel syndrome
What is phalens sign?
Flexing the wrist for 60 seconds causes paraesthesia in cubital tunnel syndrome