MSK Session 6- The Hand Flashcards
What are the three hypo thenar muscles (lateral to medial)?
- flexor digiti minimi brevis
- abductor digiti minimi
- opponens digiti minimi
What are the three thenar muscles (lateral to medial)?
- opponens pollicis
- abductor pollicis brevis
- flexor pollicis brevis
What does the median nerve innervate in the hand?
- lumbricals 1 and 2
- opponens pollicis
- abductor pollicis brevis
- flexor pollicis brevis
What Innervates the hypothenar muscles?
The ulnar nerve
What is the role of adductor pollicis and what is it innervated by?
- adducts the thumb
- ulnar nerve
What are the two roles of the lumbricals?
- flexion of the metacarpophalangeal joints
- extension of the interphalangeal joints
Which lumbricals are innervated by the ulnar and median nerves?
- ulnar nerve= 3rd and 4th lumbricals
- median nerve= 1st and 2nd lumbricals
What is the role of the palmar interossei muscles and how many are there?
- adduct the fingers
- 3
What is the role of the dorsal interossei muscles and how many are there?
- abduct the fingers
- 4
Which nerve Innervates the interossei muscles?
Ulnar nerve
What is the palmaris longus continuous with?
The palmaris longus tendon and the flexor retinaculum
What is the function of the palmar aponeurosis?
To cover and protect underlying tissues, flexor tendons, blood vessels and digital nerves.
What is the dorsal arterial supply of the hand?
The superficial and deep palmar arches
Which structures enter the hand through Guyon’s canal?
The ulnar artery and nerve
Which nerve enters the hand through the carpal tunnel?
The median nerve
Which bones does the flexor retinaculum articulate with to form the carpal tunnel?
- lateral: scaphoid and trapezoid
- medial: pisiform and hook of hamate
What causes carpal tunnel syndrome?
A lesion that reduces the size of the tunnel, or increases the size of structures within it.
- fluid retention
- infection
- excessive exercise of the fingers
What I carpal tunnel syndrome?
Compression of the median nerve
What are the consequences of carpal tunnel syndrome?
- Parasthesia- tingling
- hyposthesia- diminished sensation
- anaesthesia- complete loss of sensation
If the median nerve is compressed, which digits are affected by carpal tunnel syndrome?
The lateral 3 1/2 digits
Does a superficial laceration if the wrist cause loss of motor function? Why/why not?
No
Because a superficial lesion will only damage the palmar cutaneous branch of the median nerve. Therefore only causes a loss of sensation to the Palm.
Does a deep laceration to the wrist cause loss of motor function? Why/why not?
Yes
Because the median nerve is damaged.
Therefore the motor function of the lateral 3 1/2 digits are affected -> ape thumb
What is boxer’s fracture?
Fracture of the 5th metacarpal due to a punch delivered with a closed, abducted fist.
Where would test the function of the median nerve?
2nd metacarpal fingertip
Where would you test the radial nerve?
The dorsum of the hand- anatomical snuffbox area.
Where would you test the ulnar nerve?
The tip of the 5th metacarpal
What is Erb’s palsy and which nerves are affected?
A upper brachial plexus injury which is caused by an excessive angle between the neck and shoulder.
It affects the musculocutaneous and axillary nerves.
It results in the ‘waiters tip’ position.
What is Klumpke palsy and which nerves are affected?
It is a lower brachial plexus injury.
The ulnar and median nerves are affected.
It results in ‘ulnar claw’
How do people with ulnar nerve damage at the elbow present?
Can’t trip paper laced between their fingers because they cannot abduct and adduct the fingers.
How do people with ulnar nerve injury at the wrist present?
Ulnar claw
How do people with median nerve damage at the elbow present?
Hand of benediction
How do people with median nerve damage at the wrist present?
Hand of benediction and a wasted thenar eminence.