Lecture 6: The hand Flashcards
What do grips of the hand provide us with?
Manipulation of objects, dexterity
Precise application of force from the upper limb
What are the 5 joints of the hand?
Distal interphalangeal (DIP)
Proximal interphalangeal (PIP)
Interphalangeal joint of the thumb
Metacarpophalangeal (MCP)
Carpometacarpal (CMC)
What are the bones of the hand?
- Distal phalanges
- Intermediate phalanges
- Proximal phalanges
- Metacarpals
- Carpals
Which groups of muscles are the movements of the fingers and thumbs brought about by?
- Extrinsic
- Intrinsic
What are the extrinsic muscles?
muscles in the anterior and posterior forearm whose tendons travel down into the hand. The tendons of these muscles are vulnerable to injury at the wrist or in the hand.
What are the intrinsic muscles?
muscles located in the hand; their origins and insertions are within the hand. These are, by definition, short, or small muscles. Many of them have the term ‘brevis’ in their name.
Where do the intrinsic muscles lie?
Almost all of them lie in the palm of the hand (the dorsum of the hand has just one set)
What are the groups of muscles and one singular muscle in the intrinsic muscles?
- thenar eminence
- hypothenar eminence
- The lumbrical muscles
- The interosseous muscles
Single muscle: Adductor pollicis
What is the thenar eminence?
3 muscles, lie in the palm below the thumb, move the thumb
What are the 3 muscles in the thenar eminence?
Opponens pollicis (deeper)
Flexor pollicis brevis
Abductor pollicis brevis
Where does the thenar eminence originate?
Origins = carpal bones (centred on the trapezium and scaphoid)
Where does the thenar eminence insert?
OP = 1st metacarpal
APB and FPB = base of the proximal phalanx of the thumb
what innervates the thenar eminence?
recurrent branch of
the median n.
What is the hypothenar eminence?
3 muscles, lie in the palm below the little finger, move the little finger. They mirror the thenar eminence muscles
What are the 3 muscles in the hypothenar eminence?
Opponens pollicis (deeper)
Flexor pollicis brevis
Abductor pollicis brevis
Where does the hypothenar eminence originate?
carpal bones
(centred on the hamate and pisiform)
Where does the hypothenar eminence insert?
ODM on the 5th metacarpal
ADM and FDM = base of the proximal phalanx of the 5th digit
What innervates the hypothrnar eminence?
deep branch of the ulnar n.
What are the lumbrical muscles?
4 of these; each one is attached to an FDP tendon
where do the lumbrical muscles originate?
tendons of FDP
Where do the lumbrical muscles insert?
base of proximal phalanges & extensor expansion
What is the action of lumbrical muscles?
MCPJ flexion, PIPJ and DIPJ extension
What innervates the lumbrical muscles?
medial 2 = ulnar n.; lateral 2 = median n. (i.e. innervated by the same nerve as their ‘parent’ FDP muscle / tendon)
What is the adductor pollicis?
is a single muscle that lies in the palm and adducts the thumb
Where does the adductor pollicis originate?
3rd metacarpal and capitate
where does the adductor pollicis insert?
base of proximal phalanx of thumb
Adducts the thumb
what innervates the adductor pollicis?
deep branch of the ulnar n.
Is there an adductor minimi?
No
There isn’t an adductor digiti minimi, equivalent to adductor pollicis; because one of the interosseous muscles adducts the little finger
Where does the palmar interossei orginiate?
metacarpals.
Where does the palmar interossei insert?
base of proximal phalanges & extensor expansion
What does PAD stand for?
Palmar adduct fingers
What do the PADs contribute to?
Palmar adduct fingers (= PAD) and contribute to flexion at the MCPJs and extension at the PIPJs and DIPJs via their insertion onto the extensor expansion
What innervates the palmar interossei?
deep branch of the ulnar n.
Where does the dorsal interossei originate?
metacarpals.
Where does the dorsal interossei insert?
base of proximal phalanges & extensor expansion
What does DAB stand for?
Dorsal abduct fingers
What does the dorsal interossei contribute to?
and contribute to flexion at the MCPJs and extension at the PIPJs and DIPJs via their insertion onto the extensor expansion
What innervates the dorsal interossei?
deep branch of the ulnar n.
What do the radial and ulnar arteries anastomose in the palm to form?
palmar arches.
What arises from the palmar arches?
Metacarpal and digital arteries arise from these
Does the median or the ulnar nerve travel through the carpal tunnel?
Median
What do the superficial veins on the dorsum of the hand form?
The cephalic and basilic veins
Where does the cephalic vein formed in the ASB course to?
up the lateral forearm towards the cubital fossa
Where does the basilic vein formed on the medial aspect of the forearm travel to?
Cubital fossa
What forms the axillary veins in the axilla?
The basilic vein joining with the deep veins
Where does the cephalic vein drain into?
axillary vein
Why is the dorsal venous network clinically important?
A site for IV cannulation
What is atrophy of the thumb?
Atrophy (wasting) and
weakness of the thumb
What does atrophy of the thumb cause?
Sensory disturbance (e.g. pain, diminished sensation, pins and needles) in the distribution of the median n.
What does the ulnar nerve injury at the wrist cause?
Sensory disturbance (e.g. pain, diminished sensation, pins and needles) in the distribution of the ulnar n.
What is the typical appearance of injury to the ulnar nerve (Claw hand)?
Describes the typical appearance of the hand after injury to the ulnar n.
Hyperextension of MCP joints of 4th and 5th
Flexion at PIP and DIP joints of 4th and 5th
Guttering between the metacarpals
