Anatomy of the Hand Flashcards
What are the 7 layers of the palm?
- skin
- palmar aponeurosis
- thenar and hypothenar muscles
- neurovascular plane
- long flexor tendons and lumbricals
- adductor pollicis and neurovascular plane
- interossei
Why is the palmar aponeurosis difficult to perform surgery on?
because it is connected to the skin
Where is the palmar aponeurosis?
extends from the distal border of the flexor retinaculum then divides into 4 parts which insert into skin creases at the base of each finger, the flexor sheaths and the base of the proximal phalanges - does not cover the thenar or hypothenar eminences
What is dupuytren’s contracture?
thickening and scarring of palmar aponeurosis forcing a fixed flexion - seen in diabetics, alcoholics and manual workers
In what plane is abduction and adduction of the thumb?
right angles to the palm
In what plane is extension and flexion of the thumb?
in the same plane as the palm
What are the three muscles that make up the thenar eminence?
abductor pollicis brevis, flexor pollicis brevis, opponens pollicis
What are the three muscles that make up the hypothenar eminence?
abductor digiti minimi, flexor digiti minimi, opponens digiti minimi
What is the relationship of the three muscles in the thenar and hypothenar eminences?
abductors are on the outside, flexors on the inside and opponents are deep
What is the origin of the muscles of the thenar and hypothenar eminence?
the flexor retinaculum and adjacent carpal bone
What is the insertion of the abducters and flexors of the thenar and hypothenar eminence?
proximal phalynx
What is the insertion of the opponens of the thenar and hypotnear eminence?
metacarpals
What nerves and vessels are in the superficial neurovascular plane?
superficial palmar arch and the cutaneous nerve supply of the fingers
At what heigh is the superficial palmar arch?
at the level of the distal border of the outstretched thumb
Where do the fibrous sheaths covering the long flexor tendons extend from?
from the metacarpal heads to the distal phalanges
Where do the synovial sheaths covering the long flexor tendons extend from?
from the proximal wrist to the tips of the fingers but with a bare area over the palm (little finger doesn’t have a bare area)
Where do the lumbricals originate from?
from the long flexor tendons - lumbrical of 5th finger has to go through the synovial membrane
How many lumbricals are there?
4 - one for each of the long flexor tendons
How many bodies do the lumbricals have?
1st and 2nd have one body, 3rd and 4th have two bodies
Where to the lumbricals insert?
the dorsal extensor expansion on the radial side
What is the action of lumbricals?
flex the metacarpophalangeal joints and extend the interphalangeal joints
What is the deepest muscle in the hand?
adductor pollicis
What is the action of palmar interossei?
adduction
What is the action of dorsal interossei?
abduction
How many palmar interossei are there?
3 - one for the 2nd, 4th and 5th finger
What is the insertion of palmar interossei?
extensor expansion - helps with lumbricals
How many dorsal interossei are there?
4 - one on either side of the middle finger and one for the 2nd finger and one for the 4th finger - each has 2 bellies
