Hand Flashcards
What are the muscles called that are found on the dorsum of the hand?
The dorsal interosseous muscles.
Creases on the hand are found in places where the skin is firmly bound to the _______.
fascia
The deep fascia of the palm is continuous proximally with the ______ ______ (fascia of the forearm) and forms a thick fascia in the palm called the _______ ________ and in the digits called the ______ _______ ______.
antebrachial fascia. Thick part on palm is the palmar aponeurosis and on the digits it forms the fibrous digital sheaths.
How is the space in the palm divided anatomically?
Floor, two walls, roof
What forms the floor of the palm?
Interossei muscles (four dorsal and three palmar interossei muscles) + the adductor pollicis muscle of the thumb.
What is the action of the palmar interossei muscles? What is the action of the dorsal interossei muscles?
Palmar interossei: Adduction of the 2nd, 4th and 5th fingers.
Dorsal interossei: Abduction of the 2nd through 5th fingers.
PADs and DABs
The intrinsic muscles of the thumb (______ eminence) and little finger (________ eminence) form the walls of the palm.
Thumb: Thenar eminence
Little finger: Hypothenar eminence
How many muscles comprise each of the thenar and hypothenar eminences? Describe them.
Three each: An abductor, a flexor, and an opponens.
They are arranged alphabetically from superficial to deep.
Which nerve innervates the interossei muscles of the hand?
Ulnar nerve innervates all of them.
Where do the hypothenar and thenar muscles get innervation from?
Hypothenar: Ulnar nerve
Thenar: Recurrent branch of the median nerve
What is a Dupuytren’s contracture?
Progressive fibrosis of the palmar aponeurosis that results in shortening and thickening of the fibrous bands, pulling the digits into flexion at the MP joints. Mostly affects the 4th and 5th digits.
What structure forms the roof of the carpal tunnel? Which structures does it span?
The flexor retinaculum (transverse carpal ligament). Spans the tubercles of the trapezium and scaphoid on the thumb side and the pisiform and hook of hamate on the little finger side.
Name five structures that do NOT run inside the carpal tunnel.
- Ulnar nerve
- Ulnar artery
- Palmaris longus tendon
- Palmar cutaneous branch of the median nerve
- Flexor carpi radialis
What are the three divisions (groups) of the intrinsic muscles of the hand?
- Thumb/thenar muscles in the thenar compartment.
- Little finger/hypothenar muscles in the hypothenar compartment.
- Lumbrical muscles in the central compartment and the interosseous muscles between the metacarpal bones.
Define thumb abduction.
Thumb abduction is movement away from the plane of the other fingers.
Which nerves innervate the intrinsic muscles of the hand?
Branches of the ulnar and median nerves.
Name the three thenar muscles. What is their action? What is their innervation?
Abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis.
Responsible for opposition of the thumb.
Supplied by the recurrent branch of the median nerve.
The adductor pollicis is a fan-shaped muscle in the _____ compartment of the hand. It has two heads that are separated by a gap through which the ______ _______ passes. Its action is to: _____________________. It is innervated by the _______ nerve.
adductor compartment
radial artery passes through the gap
it adducts the thumb
ulnar nerve innervation
Does carpal tunnel syndrome affect cutaneous sensation of the palm of the hand? Explain why or why not.
No, the median nerve sends out the palmar cutaneous branch to the palm proximal to the carpal tunnel.
Fracture of the medial epicondyle, with subsequent claw hand (ring, little fingers are hyperextended at the MP joints and flexed at the PIP joint), loss of abduction and adduction of the digits and flexion at the MP joints, and wasted hyporthenar eminence due to paralysis of the adductor pollicis muscle suggests injury to which nerve?
Ulnar nerve
Name the three hypothenar muscles. What is their nerve supply?
- Abductor digiti minimi
- Flexor digiti minimi
- Opponens digiti minimi
Deep motor branch of the ulnar nerve
Which nerves supply the lumbrical muscles?
Lumbricals 1 and 2 (index, middle fingers): Median nerve.
Lumbricals 3 and 4 (ring, little fingers): Deep branch of the ulnar nerve.
Through which structure do the long flexor tendons of the extrinsic muscles enter the hand?
Through the common synovial sheath deep to the flexor retinaculum in the carpal tunnel.
Which tendons (either from the flexor digitorum superficialis, or from the flexor digitorum profundus) split near the base of the proximal phalanxes?
Tendons from from the flexor digitorum superficialis splits and attaches to the margins of the middle phalanxes while the tendons from the flexor digitorum profundus passes under the tendons from the flexor digitorum superficialis to attach on the extensor expansion hoods at the base of the distal phalanxes.
