Lecture 4: Hand Flashcards
What 3 parts can the hand be subdivided into?
1) Wrist (8 carpal bones)
2) Metacarpals (5)
3) Phalanges/digits
Which is digit 1, which is digit 5?
Digit 1 = thumb
Digit 5 = little finger
How many carpal bones do we have?
8
How many phalanges are in each digit, what are they called?
Digit 1 = 2 phalanges, proximal and distal
Digits 2-5 = 3 phalanges, proximal, middle and distal
At what joint do the metacarpals articulate with the proximal phalanges?
Metacarpophalangeal joint
At what joint do the proximal phalanges articulate with the middle phalanges?
Proximal interphalangeal joint
At what joint do the middle phalanges articulate with the distal phalanges?
Distal interphalangeal joint
Where are the radial and ulnar styloid process seen?
Laterally (radial) and medially (ulnar) on the dorsal surface of the hand
What are the names of the 8 carpal bones (proximal row followed by distal row, lateral to medial)?
Scaphoid Lunate Triquetrum Pisiform Trapezium Trapezoid Capitate Hamate Some Lover Try Positions That They Cant Handle
What is the anatomical name for the wrist joint, which bones articulate here?
Radiocarpal joint
Between the radius and scaphoid and lunate carpal bones - no participation by the ulnar
What kind of joint is the radiocarpal joint?
Synovial ellipsoid joint
What strengthens the radiocarpal joint capsule anteriorly and posteriorly?
Radiocarpal ligaments
What separates the ulnar from the radiocarpal joint?
A wedge of cartilage known as the articular disc
Other than the radiocarpal joint what other joint is found in the distal forearm, what does this do?
Distal radio-ulnar joint
Assists the proximal radio-ulnar joint in pronation and supination of the hand
What are the movements of the wrist joint?
Abduction Adduction Extension Flexion Circumduction
Which kind of muscles are arranged in the anterior compartment of the forearm?
Flexors
Which type of muscles are arranged in the posterior compartment of the forearm?
Extensors
What is meant by extrinsic muscles of the hands?
Have origins outside of the hand but insert on the hand and their actions move the hand
Name the 6 extrinsic anterior flexor muscles of the hand?
1) Flexor carpi radialis
2) Palmaris longus
3) Flexor carpi ulnaris
Above all come from common tendon
4) Flexor digitorum superficialis
Above has a radial and humero-ulnar head
5) Flexor pollicis longus
6) Flexor digitorum profundus
What is meant by pollicis?
Thumb
Which nerves supply the extrinsic anterior flexor muscles of the hand?
median and ulnar nerves
What is important about the tendons of the extrinsic muscles of the hand?
They all pass over the wrist joint and act on the wrist joint
What are the extrinsic posterior extensor muscles of the hand? 8
1) Extensor carpi radialis longus
2) Extensor carpi radialis brevis
3) Extensor digitorum
4) Extensor carpi ulnaris
5) Extensor digiti minimi
6) Abductor pollicis longus
7) Extensor pollicis brevis
8) Extensor pollicis longus
Which nerve supplies the extrinsic posterior extensor muscles of the hand?
Radial nerve
What is the carpal tunnel made up of?
Posteriorly and on both sides the carpal bones
Anteriorly a sheet of cartilage known as the flexor retinaculum
What 4 things pass through the carpal tunnel?
1) Flexor digitorum superficialis tendons
2) Flexor digitorum profundus tendons
3) Flexor pollicis longus tendon
4) Median nerve
Name the intrinsic muscles of the hand? 4
1) Thenar muscles
2) Hypothenar muscles
3) Lumbricals
4) Adductor pollicis
What are the names of the 3 thenar muscles?
1) Flexor pollicis brevis
2) Opponens pollicis
3) Abductor pollicis
What are the names of the 3 hypothenar muscles?
1) Opponens digiti minimi
2) Flexor digiti minimi
3) Abductor digiti minimi
What nerves supply the intrinsic muscles of the hand?
All supplied by the ulnar nerve except the thenar muscles and 1st and 2nd lumbricals which are supplied by the median nerve
What is the thenar remnance?
Muscley area below thumb
Why is the opponens pollicis important in evolution?
Allows thumb to rotate to face fingers and form a grip - opposable thumsbs
What is unusual about the attachments of the 4 lumbricals and what implications does this have for their function?
Attached to the long tendons of the flexors on the anterior surface and pass lateral to the digits to attach to the extensor tendons on the dorsal surface giving them a dual function
Flexion of the metacarpopharyngeal joint and extension of the proximal interphalangeal joint
In movements of the hand, what is considered the midline? What implications does this have for the movements of the thumb?
In movements of the hand the midline is shifted to the middle finger
All movements relate to the middle finger rather than the body
Thumb is rotated 90 degrees to the fingers - all movements are at 90 degrees to those of the finger
What is flexion and abduction of the thumb?
Flexion is putting thumb towards palm
Abduction is moving the thumb towards the wrist
What are the 3 main branches of the median nerve, which of these are given off after the nerve has passed through the carpal tunnel?
1) Palmar cutaneous branch - given off first
2) Recurrent branch
3) Digital branch - given off most distally after passing through carpal tunnel
What does the palmar cutaneous branch of the median nerve innervate?
Sensory supply to lateral side of palm
What does the recurrent branch of the median nerve innervate?
Motor to the thenar muscles
What does the digital branch innervate?
1st and 2nd lumbricals - motor
Palmer - sensory to lateral 3 and 1/2 digits
Dorsal - sensory to distal half of 3 and 1/2 digits
What does carpal tunnel commonly result from?
Repetitive wrist motion
What is the flexor retinaculum also known as?
Transverse carpal ligament
What are the medial and lateral attachments of the flexor retinaculum?
Medial - Pisiform and hook of hamate
Lateral - Scaphoid tuberosity and trapezium
The carpal tunnel is a fibro-oseous tunnel, what is meant by this?
Has a bony bottom and fibrous roof
What are the symptoms of carpal tunnel caused by?
Build up of fluid or inflammation in the carpal tunnel leading to compression of the median nerve
What are the 3 symptoms of carpal tunnel syndrome?
1) Pins and needles in the cutaneous distribution of digital branches of median nerve
2) Weakness of thumb and muscle atrophy in thenar region
3) Inability to oppose thumb
How is carpal tunnel cured?
By carpal tunnel release surgery - cut the flexor retinaculum to release the pressure
Other than carpal tunnel syndrome how else may the median nerve be damaged?
By lunate dislocation - this most commonly occurs as result of a fall on an outstretched hand (FOOSH) extended at the wrist
What is the most commonly dislocated carpal bone?
The lunate bone
In which direction does the lunate bone dislocate?
Anteriorly
What are the 4 main branches of the ulnar nerve?
1) Palmar branch
2) Dorsal branch
3) Superficial branch
4) Deep branch
Where does the ulnar nerve pass in relation to the flexor retinaculum?
Passes superficial to the flexor retinaculum
Is the ulnar nerve lateral or medial to the median nerve?
Medial
What does the palmar branch of the ulnar nerve innervate?
Sensory to the medial side of palm
What does the dorsal branch of the ulnar nerve innervate?
Sensory to the lateral side of the dorsum of the hand and the lateral 1 and 1/2 digits
What does the superficial branch of the ulnar nerve innervate?
Sensory to palmer surface of lateral 1 and 1/2 digits
Motor to palmaris brevis
What does the deep branch of the ulnar nerve innervate?
Hypothenar muscles, adductor pollicis, interossei and 4th and 5th lumbricals
What is Guyon’s canal and where does it lie in relation to the flexor retinaculum?
Tunnel that the ulnar nerve and artery pass through
Lies superficial to the flexor retinaculum on the medial side
What is ‘handlebar neuropathy’ caused by?
Compression of the ulnar nerve at the wrist
What are the 3 clinical features of handlebar neuropathy?
1) sensory loss to the palmer surface of the lateral 1 and a 1/2 digits
2) Motor weakness in the intrinsic muscles of the hand (except thenar eminence and lateral 2 lumbricals)
3) Hyperextension of metacarpophalangeal joints of digits 4 and 5
Why does hyperextension of the metacarpophalangeal joints of digits 4 and 5 occur in handlebar neuropathy?
The action of the powerful extrinsic extensor muscles of than in the forearm are unopposed due to paralysis of lumbrical muscles
What tendons mark the lateral and medial borders of the anatomical snuff box?
Lateral border - Extensor pollicis brevis tendon
Medial border - Extensor pollicis longus tendon
What can be palpated in the anatomical snuff box?
The radial pulse
A scaphoid fracture is typical in who and typically presents with what?
Common injury in young adults
Presents with tenderness in the anatomical snuff box
What does a scaphoid fracture normally result from and where does it normally break?
Results from a fall on an outstretched hand when the hand is abducted
Scaphoid bone has a narrow waist which is normally fractured
What is unusual about the blood supply to the scaphoid bone and what complications can these lead to in a fractured scaphoid?
Blood enters the scaphoid distally and then travels through the bone to the proximal part, therefore, in the event of a fracture, blood supply to the proximal part may be disrupted
This could lead to avascular necrosis
What is the blood supply to the scaphoid bone?
The palmar carpal branch of the radial artery
What is a colles fracture, what is it associated with?
Fracture of the distal end of the radius - this gets displaced posteriorly
Most common in older people, particularly women due to osteoporosis
Usually the result of falling on a outstretched upper limb
Often the ulnar styloid process is avulsed (pulled away from ulnar)
Why does a Colles fracture normally heal well?
There is a rich blood supply to the distal radius
What are epiphyses?
Growth plates found in bone
What are the complications of a fracture/separation of the distal radial epiphysis, who is it common in?
Common in children
Good prognosis with reduction of the epiphysis back to normal position
rarely, damage leads to premature fusion
