Week 5: The Hand Flashcards
What types of joints are the small joints of the hand?
synovial
What happens when you flex the MCP, PIP and DIP joints?
makes a fist
Which two groups of muscles allow movement of the fingers and thumbs?
- Extrinsic muscles: muscles in the anterior and posterior forearm whose tendons travel down into the hand
- Intrinsic muscles: muscles located in the hand
There are 4 groups of intrinsic hand muscles and 1 single muscle. What are they?
- The Thenar Eminence
- The hypothenar eminence
- The lumbrical muscles
- The interosseous muscles (interossei)
Single muscles: adductor pollicis
What is the thenar eminance?
- group of 3 muscles
- lie in the palm below the thumb
- move the thumb
What is the hypothenar eminence?
- group of 3 muscles
- lie in the palm below the little finger
- move the little finger
How many lumbrical muscles do we have?
4 - each one is attached to an FDP tendon
What is the interosseous muscles (interossei)?
- muscles that lie between adjacent metacarpals
- there are 3 in the palm and 4 in the dorsum
What is the adductor pollicis?
a single muscle that lies in the palm and adducts the thumb
Which intrinsic muscles does the ulnar nerve innervate?
- the hypothenar eminence muscles
- all the interossei
- the medial 2 lumbrical muscles (to the 4th and 5th digits)
- adductor pollicis
Which intrinsic muscles does the median nerve innervate?
- thenar eminence muscles
- lateral 2 lumbricals
Which 3 muscles make up the thenar eminence and what are their functions?
- Abductor pollicis brevis - abductor
- Flexor pollicis brevis - flexor
- Opponens pollicis (deeper) - opposer
Where do the thenar eminence muscles originate
carpal bones
Where does each thenar eminance muscle insert
- APB = base of proximal phalanx of thumb
- FPB = base of proximal phalanx of thumb
- OP = 1st metacarpal
How does the OP lie in relation to the APB?
Deep
Which nerve innervates the thenar eminence?
recurrent branch of the median nerve
What are the 3 muscles in the hypothenar eminence?
- Abductor digiti minimi
- Flexor digiti minimi
- Opponens digiti minimi (deeper)
Where do the hypothenar eminence muscles originate?
carpal bones (centred on the hamate and pisiform)
Where do the hypothenar eminence muscles insert?
- ADM and FDM = base of the proximal phalanx of the 5th digit
- ODM = 5th metacarpal
Which nerve innervates the hypothenar eminence?
deep branch of the ulnar nerve
Where does the adductor pollicis originate?
3rd metacarpal and capitate
Where does the adductor pollicis insert?
base of the proximal phalanx of thumb
What is the function of the adductor pollicis?
adducts the thumb
What nerve is the adductor pollicis innervated by
deep branch of the ulnar
Where do the lumbrical muscles originate?
tendons of FDP
Where do the lumbrical muscles insert?
base of proximal phalanges and extensor expansion
What is the action of the lumbrical muscles?
- MCJP flexion
- PIPJ and DIPJ extension
Which nerves innervate the lumbrical muscles?
medial 2 = ulnar nerve
lateral 2 = median nerve
innervated by the same nerve as their parent FDP
where do the palmar interossei originate?
metacarpals
Where do the palmar interossei insert?
base of proximal phalanges and extensor expansionn
What is the action of the palmar interossei?
- adducts fingers
- contribute to flexion at MCJPs and extension at the PIPJs and DIPJs via their insertion onto the extensor expansion
Which nerve innervates the palmar interossei?
deep branch of ulnar nerve
How many palmar interossei are there?
3
Where do the dorsal interossei originate?
metacarpals
Where do the dorsal interossei insert?
base of proximal phalanges and extensor expansion
What is the action of the dorsal interossei?
- abduct fingers
- contribute to flexion at the MCPJs and extension at the PIPJs and DIPJs via their insertion onto the extensor expansion
Which nerve innervates the dorsal interossei?
deep branch of ulnar nerve
The radial and ulnar arteries anastomose in the palm to form what?
palmar arches
What arises from the palmar arch?
metacarpal and digit arteries
Which carpal bone is most commonly dislocated?
lunate
What is meant by a ‘claw hand’?
- describes a hand after injury to the ulnar nerve
- hyperextension of MCP joints of the 4th and 5th digits
- flexion at PIP and DIP joints of 4th and 5th
what are the possible movements of the fingers?
flexion, extension, abduction and adduction
Which joints are predominately affected in osteoarthritis?
proximal and distal interphalangeal joints
Which joints are characteristically affected in rheumatoid arthritis?
metacarpals
Where do the palmar interossei lie in relation to lumbricals and FDP?
Deep to
Where does the 1st dorsal interossei lie?
in the web space between the thumb and the 1st digit
What is the Allens test?
- arterial blood gas at the radial artery
- Occlude arteries and squeeze hand - hand will turn whiter
- Release one finger on the radial side and hand will turn red - radial artery repurfuses
- Release one finger on the ulnar side and hand will turn red - ulnar artery reperfuses
