"The Hand" Questions Flashcards
What are the names of the 5 fingers?
Thumb Index Middle Ring Little - don't number them
What is the palmar fascia, where is it, and what does it form?
Fascia of the hand that lies in the palm
- forms specialisations = palmar aponeurosis and fibrous digital sheaths
What is the palmar aponeurosis, what does it overlie and what structures is it continuous with?
Specialisation of palmar fascia
- overlies the long flexor tendons (hand)
- continuous with flexor retinaculum + palmaris longus tendon proximally
- continuous with fibrous digital sheaths
What are the fibrous digital sheaths?
Tubes which contain the flexor tendons and their synovial sheaths
How are the compartments of the hand divided up and what are the compartments?
Space between palmar aponeurosis and bones of the hand are separated by extensions of fascia (aka septa)
- hypothenar
- central (midpalm)
- thenar
- adductor
- interosseous
(viewed through cross-section of the hand distal to the wrist, (moving from medial to lateral) hypothenar, central, thenar, adductor (just below thenar), interosseous (bottom of the palm))
What are the 3 grips the hand is capable of?
Power
Precision
Hook
What is the neuromuscular basis of the power grip?
Fingers are pressed against palm with counter pressure from the thumb (e.g. grasping a rod) Muscles needed: - long flexors of fingers/thumb - intrinsic muscles of the palm - extensors of the wrist joint
What is the neuromuscular basis for the precision grip?
Wrist and fingers held rigidly, intrinsic muscles of the hand carry out fine movements needed (e.g. unbuttoning a shirt)
Muscles needed:
- long flexors/extensors of wrist/thumb/fingers (hold joints rigid)
- intrinsic muscles of the hand (fine movements)
What is the neuromuscular basis for the hook grip?
Consumes little energy, mainly involves long flexors of the digits (e.g. carrying shopping bag/briefcase)
Muscles needed:
- long flexors of the digits
What are the bones involved in the wrist and hand?
Radius Ulna Carpal bones Metacarpal bones Phalanges
What are the carpal bones and the mnemonic to remember them?
So Long To Pinky Here Comes The Thumb - Scaphoid - Lunate - Triquetrum - Pisiform (sesamoid bone) - Hamate - Capitate - Trapezoid - Trapezium
What bones does the radius articulate with in the wrist?
Proximal row
- scaphoid, lunate, triquetrum
How does the ulna interact with the wrist?
Does not itself articulate with any carpal bones.
Articulates with triangular fibrocartilage which extends from the distal radius to the ulna
What is unusual about the scaphoid bone and why is this clinically relevant?
Has an unusual blood supply where the vessels pass from distal to proximal (back to front)
- clinically relevant as fracture of the waist of the scaphoid bone can damage/cut off this blood supply causing avascular necrosis
What are the features of the metacarpal bones and how many are there?
Body (shaft), base (proximal), head (distal)
- 5, numbered 1 to 5 (1 = thumb, 5 = little finger)
What are the features of the phalanges, how many are there in each finger and what are each phalanx called?
Body (shaft), base (proximal), head (distal)
- 3 in each finger, 2 in the thumb
- proximal, middle, distal (thumb does not have a middle phalanx)
What are the 4 compartments of the intrinsic hand muscles?
Hypothenar
Interossei + lumbricals
Thenar
Adductor
What muscles are in the hypothenar compartment of the hand?
Abductor digiti minimi
Flexor digiti minimi
Opponens digiti minimi
What muscles are in the interossei + lumbricals compartment of the hand?
Lumbricals (4 muscles)
Palmar interossei
Dorsal interossei
What muscles are in the thenar compartment of the hand?
Abductor pollicis brevis
Flexor pollicis brevis
Opponens pollicis
What muscles are in the adductor compartment of the hand?
Adductor pollicis
What is the outlier muscle that is part of the intrinsic muscles of the hand and what does it do?
Palmaris brevis
- improves grip
Innervated by superficial branch of the ulnar nerve
What are the actions of the muscles of the hypothenar compartment and what nerve innervates these muscles?
Abductor digiti minimi - abducts little finger at MCP joint
Flexor digiti minimi - flexes little finger at MCP joint
Opponens digiti minimi - laterally rotates metacarpal 5 (allows opposition of little finger with thumb)
All supplied by the deep branch of the ulnar nerve
What are the actions of the muscles of the interossei + lumbricals compartment of the hand and what nerve innervates these muscles?
Lumbricals - flex MCP joints while extending IP joints (straight fingers)
Palmar interossei - adduction of thumb, index, ring, and little fingers at MCP joints
Dorsal interossei - abduction of thumb, index, ring, and little fingers at the MCP joints
Lumbricals divided into 2+2, lateral 2 by deep branch of the ulnar nerve, medial 2 by digital branches of median nerve
What are the actions of the muscles of the thenar compartment of the hand and what nerve innervates these muscles?
Abductor pollicis brevis - abducts thumb at MCP joint
Flexor pollicis brevis - flexes thumb at MCP joint
Opponens pollici - medially rotates thumb (allows opposition with little finger)
All supplied by the recurrent branch of the median nerve
What are the actions of the muscles of the adductor compartment of the hand and what nerve innervates these muscles?
Adductor pollicis - adducts the thumb
Supplied by deep branch of the ulnar nerve (all other thumb muscles are recurrent branch of median but adductor is NOT)
What two spinal roots are being tested in the test of any of the intrinsic muscles of the hand?
C8 and T1 (roots for literally all the muscles)
What are the fibrous digital sheaths and where do they extend?
The fibrous digital sheaths are condensations or specialisations of the palmar fascia
- they extend from the level of the metacarpal head to the base of the distal phalanx in each digit (so the whole finger basically)
What do the fibrous digital sheaths form with the underlying bone and what runs through these?
Form OSSEO-FIBROUS TUNNELS through which the long flexor tendons and their synovial sheaths run
What do parts of the fibrous digital sheaths form and what is the function of these structures?
Further condensations called PULLEYS
- allow for more functional use of the long flexor tendons
Annular and Cruciform pulleys