MSK S6 The Hand Flashcards
Where do the intrinsic muscles of the hand originate?
In the hand itself
Where do the extrinsic muscles of the hand originate?
From the anterior and posterior compartments of the forearm
What is the fibrous band of connective tissue called in the palm of the hand?
The flexor retinaculum
What does the median nerve innervate?
MEAT LOAF MEdian innervates Lateral 2 lumbricala Opponens brevis Abductor pollicis brevis Flexor pollicis brevis
What does the ulnar nerve innervate?
Hypothenar muscles
Medial two lumbricals
Palmaris brevis
Interossei
What role do the lumbricals have?
They flex the fingers at the MCP joint and extend the fingers at the IP joint of each finger. (Think of a puppet movement)
What is the role of interossei? Which do which?
PAD DAB
ABduct and ADduct the fingers. Dorsal ABduct and Palmar ADduct.
What is the mneumonic used to remember the carpal bones?
Sally left the part to take cathy home
What are the carpal bones called?
Scaphoid Lunate Triquetrum Pisiform Trapezium Trapezoid Capitate Hamate
What are the 3 main fractures to the bones of the hands? Explain how they are caused and the consequences.
Fractures to the scaphoid:
Cause: FOOSH Conseq: blood supply disrupted to proximal portion of anatomical snuffbox. Can lead to vascular necrosis to proximal blood supply.
Fractures to the metacarpals:
Boxer’s fracture:
Cause: Clenched fist striking a hard object. Fracture of 5th MC neck. Conseq: Distal part displaced posteriorly, producing shortening of the affected finger.
Bennett’s fracture:
Cause: Hyperabduction of the thumb. Fracture of the 1st MC base.
From which side do you begin naming the the metacarpal bones?
From the thumb 1-5.
What property of the metacarpals allows the attachment of the interossei muscles?
The medial and lateral surfaces are concave.
Where is the flexor retinaculum located and what is it’s role?
It is found between the thenar and hypothenar muscles of the hand. It is a fibrous band of connective tissue that arches over carpal bones.
What is the palmaris brevis?
Where does it attach?
What are it’s actions?
What is it innervated by?
A small thin, muscle found very superficially in the subcutaneous tissue.
It originates from the palmar aponeurosis and flexor retinaculum and attaches to the skin on the medial margin of the hand.
It wrinkles the skin on the hypothenar eminance and deepens the curvature of the hand, improving grip.
Innervated by the ulnar nerve.
What is the extensor hood?
It is found on the fingers. It is where the extensor muscles flatten out and wrap around the phalanges. It is a bit like an aponeurosis. It is triangular shaped and acts as the site of attachment for many muscles.
What is an aponeurosis?
A flat tendon
Where do the lumbricals attach?
What are their actions?
What are they innervated by?
Originate from a tendon of the flexor digitorum profundus. Pass dorsally and laterally around each finger and insert into the extensor hood.
They flex the fingers at the MCP joint and extend the fingers at the IP joint (think of the puppet hand movement)
Innervation: medial two - ulnar, lateral 2- median
Where are the thenar muscles?
How many are there? What are they called?
What are they innervated by?
Found on the thumb side.
3 short muscles - oppenens pollicis, abductor pollicis nrevis and flexor pollicis brevis.
Median nerve.
Where is the oppenens pollicis muscle found? What does it do?
Found most radially/posteriorly or the thumb.
It is a deep muscle- think of the name opponens.
It opposes the thumb, by medially rotating and flexing the metacarpal on the trapezium