Flashcards in MSK S6 The Hand Deck (48):
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?
Lateral 2 lumbricala
Abductor pollicis brevis
Flexor pollicis brevis
What does the ulnar nerve innervate?
Medial two lumbricals
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?
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?
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:
Cause: Clenched fist striking a hard object. Fracture of 5th MC neck. Conseq: Distal part displaced posteriorly, producing shortening of the affected finger.
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.
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
Where is the abductor pollicis brevis found? What does it do?
Middle 3 out of the thumb muscles.
Originates from the tubercles of the scaphoid and trapezium.
Abducts the thumb.
Where is the flexor pollicis brevis found? What does it do?
It is the muscle out of the 3 thumb muscles which is found nearest to the palm.
Its role is to flex the metacarpal phalangeal joint of the thumb.
Where are the hypothenar muscles found? What is their important prefix/words used? How many are there are what are they called? What are they innervated by?
They are found on the side of the hand where the little finger is.
Prefix = digiti minimi
3- opponens digiti minimi, abductor digiti minimi, flexor digiti minimi brevis.
Innervated by the ulnar nerve.
How many interossei are there? Are there different types? How do you remember them?
Dorsal: 4 on the door
Where do the dorsal interossei originate/attach? What is their role?
They originates from the lateral and medial sides of the metacarpals. They attach to the extensor hoods
What is the palmar aponeurosis?
A sheet of fascia under the skin of the palm surrounding muscles.
What are interossei innervated by?
What does the word opponens tell you?
That the muscle is deep
Which side of the hand does the median nerve innervate?
Lateral (not medial - MEDIAN NERVE DOESN'T INNERVATE MEDIAL SIDE)
What mnemonic can you use for naming the thenar and hupothenar muscles?
OAF from deep/outside in
You can follow the OAF principle for naming the thenar and hypothenar muscles but what changes between them other than the pollicis/digiti minimi?
In the thenar muscles brevis follows abductor pollicis.
In the hypothenar muscles, however, it is just abductor digiti minimi
Where is opponens digiti minimi found? What does it do?
Found deep in the little finger on the outside (most medial) of the hand
Originates from the hook if hamate and associated flexor retinaculum and inserts into the medial margin of MC 5
Produces opposition of the little finger
Where is abductor digiti minimi found? What does it do?
Found as the middle of the 3 little finger muscles
Originates from the pisiform and the tendon of the flexor carpi ulnaris and attaches to the proximal phalanx of the little finger.
Abducts the little finger
Where is flexor digiti minimi brevis found? What does it do?
Found on the inside of the 3 little finger muscles
Originates from the hook of hamate and adjacent flexor retinaculum and inserts into the bas of the proximal phalanx of the little finger
Flexes the MCP joint of the little finger
What is the muscles called that cause adduction of the thumb?
Where does the adductor pollicis muscle originate/attach?
One head from metacarpal 3 and the other from the capitate bone. Attach to the base of the proximal phalanx of the thumb.
How do you test for the interossei of the hand?
Adduction- ask someone to prevent a piece of paper being tugged away by holding it with their fingers.
Abduction- open fingers whilst you press on them externally.
How do the ulnar nerve and ulnar artery enter the hand?
Via guyon's canal
What is the blood supply of the hand?
Lots of anastomosing arteries
Ulnar and radial arteries interconnect to form two arches - deep and superficial palmar.m
What are the attachments of the flexor retinaculum?
Medially: Pisiform and hamulus of hamate
Laterally: Tubercle of scaphoid and ridge of trapezium
What are the two layers of the carpal tunnel?
Deep carpal arch
Superficial flexor retinaculum
What is the deep carpal arch formed from?
The carpal bones:
Laterally: scaphoid and trapezium tubercles
Medially: hook of hamate and pisiform
What is the role of the flexor retinaculum in the carpal tunnel?
It turns the carpal arch into the caroal tunnel by bridging the space between the medial and lateral parts of the the arch
What are the contents of the carpal tunnel?
Tendon of flexor pollicis longus
4 tendons of flexor digitorum profundus
4 tendons of flexor digitorum superficialis
Which nerves give sensory supply to the hand?
Median, ulnar and radial nerves
What is the sensory supply of the median nerve on the hand?
Lateral 3.5 digits on palmar side and associated palm area
Tips of lateral 3.5 digits on dorsal side.
What is the sensory supply of the ulnar nerve on the hand?
Dorsal and palmar sides of the palmar 1.5 fingers and associated palm area.
What is a good tip to think about when considering the sensory innervation of the hand?
Think what nerves innervate what muscles and then think of the skin overlying them