The Hand Flashcards
Why is the skin of the dorsum (back) of the hand is looser and more mobile compared to the palmar aspect of the hand?
The reason for this is that is structure and stability is provided to the palmar aspect of the hand by the palmar fascia.
These are fibres which provide a lattice structure, protecting the deep muscles and neurovascular structures.
Which muscle of the forearm (not found in everyone) is continuous with the fascia of the palm shown above?
Palmaris longus
The small, intrinsic muscles of the hand allow for what?
For fine movements of the fingers, often working in combination with each other.
What are the 5 compartments of the hand? From superficial to deep
Thenar compartment
Hypothenar compartment
Lumbricals and long flexor tendons – central compartment
Adductor compartment
Interosseous compartment
What do the thenar muscles form?
Form the fleshy muscle belly (thenar eminence) on the lateral aspect of the palm.
They are composed of 3 muscles, 2 lying superficial, and 1 immediately deep to these.
What is the nerve supply from the thenar emincnece derived from?
Median nerve, however, the exception to this is the deep belluy of FPB which is supplied by the ulnar nerve
Which nerve segment from the brachial plexus serves to provide the majority of the innervation to the thenar muscle?
C6-T1 and part of C5
The hypothenar muscles form?
The fleshy muscle belly (hypothenar eminence) on the lateral aspect of the palm.
Which nerve innervates the hypothenar muscles?
Ulnar nerve
Which nerve root from the brachial plexus serves to provide the majority of the innervation to the hypothenar muscles?
C8-T1
What do opponens do?
Opposition is the movement of the thumb (pollicis), or little finger (digiti minimi) towards the other fingers.
Lying deep to the thenar and hypothenar eminence is what?
The central compartment
What does the central compartment contain?
The flexors tendons passing distally from the forearm to the digits, with their respective synovial sheathes.
These are: Flexor digitorum profundus, Flexor digitorum superficialis and Flexor pollicis longus
Additionally, 4 small muscles of the hand originate here the lumbricals
What do the lumbricals arise from?
Medial and lateral aspects of the FDP tendon, between the 1st to 5th metacarpals
The lumbricals flex what?
The fingers at the metacarpophalangeal joints and extend the interphalangeal joint of 2nd to 5th digits
What do the median two lumbricals innervated by?
Ulnar nerve
What do the lateral two lumbricals innervated by?
Median nerve
Where does the adductor pollicis lie?
Lying in the hand below the neurovascular structures, this muscle has 2 heads
What does the contraction of the adductor pollicis do?
Adducts the thumb - the explanation of abduction, adduction, with its other movements is given here
Which nerve innervates adductor pollicis?
Ulnar nerve
What are the interossei muscles deep do?
Deepest in the hand and lie between the metacarpal bones (hence interossei); there are 4 dorsal and 3 palmar interossei.
A mnemonic is used to remember the action of dorsal and palmar interossei muscles on the fingers
DAB – Dorsal Interossei ABduct the Fingers
PAD – Palmar Interossei ADduct the Fingers
Which nerve innervates the dorsal and palmar interossei muscles?
Ulnar nerve
Which spinal segment contributes the most to the innervation of the interossei?
C8-T1
What does the ulnar and radial artery do once it provides blood supply to the hand?
Once they reach the palm they form the superficial and deep palmar arch.
These arches anastomose with each other, therefore if one artery becomes blocked the other can maintain blood supply via. its collateral circulation.
Which artery is the main contributor of superficial palmar arch?
Ulnar
Which artery is the main contributor of the deep palmar arch?
Radial
Where does the deep palmar arch lie?
Deep in the palm as the terminal branch of the radial artery.
After it crosses the anatomical snuff box, passing between the 2 heads of the 1st dorsal interossei and 2 heads adductor pollicis.
What are venous arches associated with?
Respective arterial arches
What do the median and ulnar nerves supply?
Muscles of the hand
The median nerve enters the hand through?
Through the carpal tunnel and proceeds to supply the majority of the thenar eminence apart from the deep belly of flexor pollicis brevis, and the 1st and 2nd lumbricals
Ulnar nerve innervates the rest of the intrinsic muscles of the hand
What do the median and ulnar nerves carry?
The segmental fibres of C 6 and T 1 to innervate the respective intrinsic muscles of the hand
The ulnar nerve is a branch of which cord of the brachial plexus?
Medial cord
What is the motor testing action of the axillary?
Abduct the shoulder (deltoid)
What is the motor testing action of the musculocutanoeus
Flex the elbow (biceps, brachialis)
What is the motor testing action of the
Extend your wrist (posterior compartment of the forearm
What is the motor testing action of the ulnar
Spread your fingers (intrinsic muscles of the hand)
What is the motor testing action of the median?
Move your thumb towards your nose (abductor pollicis brevis)
What is the sensory testing action of the axillary?
Outer aspect of shoulder
What is the sensory testing action of the radial?
Posterior arm, froearm and dorsal aspect of lateral 3 and a half fingers
What is the sensory testing action of the musuclocutanous nerve
Lateral aspect of forearm
What is the sensory testing action of the median nerve
Palmar aspect of lateral 3 and a half fingers
What is the sensory testing action of the ulnar nerve?
Palmar and dorsal aspect of medial 1 and a half fingers
