The Hand SDL Flashcards
What carpal bones are in the proximal row? (radial to ulnar side)
Scaphoid, lunate, triquetral, pisiform
What carpal bones are in the distal row? (ulnar to radial side)
Hamate, capitate, trapezoid, trapezium
What carpal bones articulate with the radius to form the wrist joint?
Scaphoid and lunate
What are Heberden’s nodes? Which joints are they associated with?
Heberden’s node –> Bony bumps on the finger joint closest to the fingernail associated with the distal interphalangeal joint
What are Bouchard’s nodes?
Bouchard’s nodes are bony bumps on the middle joint of the finger –> associated with the proximal interphalangeal joint
Rheumatoid arthritis causes several marked deformities of the hands – which joints in the hands are primarily affected?
Proximal interphalangeal
Metacarpophalangeal
Beneath the skin of the palm is a triangular-shaped thickening of deep fascia. What is this fascia called and what is its function?
Palmar aponeurosis –> protects underlying structures
Some of the anterior forearm muscles insert, via long tendons, onto the palmar aspect of the bones of the hand. What are these muscles grouped as?
Extrinsic
How are intrinsic muscles of the hand different?
have both their origins and insertions within the hand.
The intrinsic muscles in the palm of the hand can be considered in 5 groups. What are these groups?
- Thenar eminence
- Hypothenar eminence
- Lumbricals
- Interossei
- Adductor pollicis
What is the thenar eminence? What muscles make it up?
describes three of the four intrinsic muscles of the thumb:
- Opponens pollicis
- Flexor pollicis brevis
- Abductor pollicis brevis
What are the actions of the 3 thenar muscles?
OP - enables opposition of the thumb
FPB - flexes the thumb at the MCPJ
APB - abducts the thumb at the MCPJ
What nerve innervates the 3 thenar muscles?
The recurrent branch of the median nerve
Adductor pollicis is an intrinsic muscle of the thumb but differs from the three thenar eminence muscles in two important ways. What 2 ways?
- it is not located in the thenar eminence
- it is not innervated by the same nerve as the thenar eminence muscles.
What is the action of adductor pollicis?
Adductor pollicis adducts the thumb.
Which nerve innervates adductor pollicis?
Deep branch of the ulnar nerve
What is the hypothenar eminence? What muscles make it up?
The hypothenar eminence describes three intrinsic muscles of the little finger that are grouped together in the same location in the palm.
- Opponens digiti minimi
- Flexor digiti minimi brevis
- Abductor digiti minimi
What are the actions of the 3 hypothenar muscles?
ODM - opposition of the little finger
FDMB - flexes little finger at MCPJ
ADM - abducts little finger at MCPJ
What nerve innervates these 3 muscles of the hypothenar eminence?
The deep branch of the ulnar nerve
How many lumbricals are there? Where do they arise from?
4
Arise from the tendons of the FDP in the palm
Where do the 1st and 2nd lumbricals arise from?
Lumbricals arise from just one FDP tendon –> described as unipennate
Where do the 3rd and 4th lumbricals arise from?
arise from two adjacent FDP tendons -> described as bipennate
Where does each lumbrical insert?
onto the extensor expansion on the lateral (so, ‘thumb side’) of its respective digit
Why are the lumbricals unique? How does this arrangement make them important?
they arise in the palm of the hand but insert onto the dorsum of the fingers via the extensor expansion
make an important contribution to extension of the fingers (i.e. extension at the PIPJs and DIPJS).
What movements do the lumbricals allow?
- make an important contribution to extension of the fingers (i.e. extension at the PIPJs and DIPJS).
- also allow a combination movement of flexion at the metacarpophalangeal joint with simultaneous extension at the PIPJs and DIPjs
What is the innervation of the lumbrical muscles?
Medial 2 –> innervated by deep branch of ulnar
Lateral 2 –> branch of median
What are the 2 groups of interossei?
Dorsal and palmar
Where do the interossei lie? Where do they insert?
They lie between the metacarpal bones and insert on the extensor expansion
What is the action of the palmar interossei?
Adduction of the fingers
What is the action of the dorsal interossei?
Abduction of the fingers
What other movements do the interossei allow?
Because they insert onto the extensor expansion, the interossei also make an important contribution to extension at the interphalangeal joints of the fingers and work with the lumbrical muscles to control the fine movements of the fingers
How many palmar interossei muscles are there?
3 - The middle (third) finger has no palmar interosseous muscle as the tendons of the palmar interossei diverge away from the middle finger.
When they contract, they pull the 2nd, 4th and 5th digits towards the middle finger – this is adduction
Is there an adductor in the hypothenar eminence? What adducts the little finger instead?
The third palmar interosseous muscle adducts the little finger – there is no adductor in the hypothenar eminence.
How many dorsal interossei are there? Where do they originate from?
There are 4 dorsal interossei. Each originates from two adjacent metacarpals. Their tendons converge towards the middle finger.
What happens when the dorsal interossei contract?
they pull digits 2 and 4 away from the middle finger – this is abduction
How many dorsal interossei does the middle finger have attached to it?
2 –> can therefore be independently moved to either side
Do the interossei have any effect on the thumb?
No - the thumb as it’s own abductors and adductor
Which muscles abduct and adduct the thumb?
Abduct –> abductor pollicis longus and abductor pollicis brevis
Adduct –> adductor pollicis
Which nerve innervates all the interossei?
Deep branch of the ulnar nerve
What do the extensor expansions cover?
Extensor expansions cover the dorsum and sides of the distal metacarpal bones and proximal phalanges and maintain the extensor tendons in the midline of the digits
What is the function of the extensor expansion?
It helps anchor the long extensor tendons, and is also the insertion point for the interossei and lumbrical muscles
What movement occurs when the interossei and lumbricals act together?
When the interossei and lumbricals act together, because they insert on the extensor expansion, they allow flexion at the MCPJ and extension at the IPJ to occur simultaneously
Appearance of superficial veins in the dorsum of the hand
Why does a torniquet make the superificial veins easier to see?
restricts venous return from the hand and distends the superficial veins, making them easier to see and access
What veins form the dorsal venous network?
The cephalic vein and basilic vein form from the dorsal venous network
What structure does the cephalic vein run through?
The cephalic vein runs through the anatomical snuffbox and can be accessed in this location.
What forms the arterial supply of the hand ?
The radial and ulnar arteries supply blood to the hand. The ulnar artery predominantly supplies the medial part of the hand, and the radial predominantly supplies the lateral part.
What happens when the radial and ulnar arteries reach the palm?
They anastamose –> forming the superficial and deep palmar arches
What forms the superficial palmar arch?
The superficial arch is the terminal part of the ulnar artery with input from the radial artery
What forms the deep palmar arch?
the terminal part of the radial artery with input from the ulnar artery
What is the function of the radial and ulnar arteries anastamosing?
ensure that if one of the arteries is compromised, the hand will still be perfused providing the other artery is patent
What is The Modified Allen’s Test?
a simple test that allows a clinician to assess the adequacy of the blood flow within the ulnar artery before the radial artery is accessed for procedures like arterial blood gas sampling, inserting an arterial line (for continuous blood pressure monitoring and taking regular arterial blood gas samples) or for minimally invasive procedures like coronary angiography
Why is it vital to perform the Modified Allen’s test before accessing the radial or ulnar artery?
USE THE MODIFIED Allen test to assess the integrity of the ulnar artery before your patient undergoes radial artery puncture or cannulation. You must verify ulnar collateral circulation to ensure blood flow to the hand if embolization or a thrombus occludes the radial artery.
What is the skin of the hand supplied by?
the ulnar, median and radial nerves.
What sensory innervation does the median nerve supply in the hand?
- the middle and lateral palm
- the palmar surface of the lateral 3 ½ digits
- the dorsum of the lateral 3 ½ digits distal to DIPJ of the fingers and IPJ of the thumb
What sensory innervation does the radial nerve supply in the hand?
- the ASB
- the dorsum of the lateral hand and lateral 3 digits as far as the DIPJs of the 2nd and 3rd digits and the IPJ of the thumb
What sensory innervation does the ulnar nerve supply in the hand?
- the medial palm and dorsum of the hand
- the palmar surface medial 1 ½ digits
- the dorsum medial 2 digits excluding lateral ½ of tip of the 4th digit, distal to DIPJ
Contraction of muscle B brings about which one of the following movements?
Abduction of the 4th digit - These muscles are the dorsal interossei, which abduct the fingers. This muscle can be seen arising from the 4th and 5th metacarpals and inserting on the proximal phalanx of the 4th digit - it therefore acts upon the 4th and not the 5th digit.
Identify carpal bone D.
Lunate
Identify muscle E.
Abductor pollicis brevis
What is muscle B?
Flexor pollicis brevis
What are the muscles indicated in this image?
Dorsal interossei:
- abduct the fingers away from the midline (middle finger)
- insert upon the extensor expansions
- are innervated by the deep branch of the ulnar nerve
What is B a tendon of? Would the part of the muscle that gives rise to this tendon would be affected by median nerve damage at the wrist? Would the part of the muscle that gives rise to this tendon would be affected by ulnar nerve damage at the elbow?
B is a tendon of FDS
The part of the muscle that gives rise to this tendon would be unaffected by median nerve damage at the wrist
The part of the muscle that gives rise to this tendon would be unaffected by median nerve damage at the wrist
What are the muscles shown in this image?
Palmar interossei:
- innervated by the deep branch of the ulnar nerve
- adduct the fingers towards the midline
- contribute to flexion at the MCPJs and extension at the IPJs
Bone C articulates with which other carpal bones?
- Capitate (D)
- Trapezium (A)
- Lunate (E)
- Trapezoid (B)
The muscles labelled X act to simultaneously:
Flex the metacarpophalangeal joints and extend the interphalangeal joints
The muscles labelled X arise from which one of the following structures?
The flexor digitorum profundus tendons
Palpation of vessel C can sometimes be difficult because in life it lies deep to and partly covered by the tendon of what?
Flexor carpi ulnaris
What structures travel through Guyon’s Canal?
Ulnar nerve and ulnar artery
Name muscles A, B and D
A - Abductor digiti minimi
B - Opponens digiti minimi (lies deep)
D - Flexor digiti minimi
Which nerve travels in the region circled A?
Ulnar nerve
Identify bone F
Trapezoid
Muscle D is innervated by which nerve?
D is adductor pollicis –> innervated by the deep branch of the ulnar nerve
Tendon B and its muscle contribute to flexion at all of the following joints EXCEPT the…
DIPJ
Nerve B contains fibres from which spinal cord segments?
C8-T1
A patient with an injury affecting structure G would develop which one of the following:
- Wrist drop?
- Weakness of small muscles of the hand?
- Thumb atrophy?
Weakness of the small muscles of the hand
What is main contributor for superficial palmar arch?
Its main source is the ulnar artery, with a smaller contribution from the radial artery.
In the diagram below, the examiner (white hand) is making an assessment of a patient’s hand. The patient is able resist the examiners attempt to pull the paper from between the 4th and 5th digits. The examiner is able to confirm the functioning of which muscle?
3rd palmar interosseous
What is vessel C?
Ulnar artery
What is the preferred vessel for arterial blood gas sampling?
ABG sampling is usually performed on the radial artery because the superficial anatomic presentation of this vessel makes it easily accessible. However, this should be done only after it has been demonstrated that there is sufficient collateral blood supply to the hand.
The examiner (white hand) is performing an assessment of a patient (purple). Which nerve is the examiner assessing with the test below?
Radial nerve
Identify carpal bone C
Hamate
The muscles labelled A, B and C insert on the extensor expansions of which digits?
2, 4 and 5 (NOT the middle finger)
Which muscle flexes the interphalangeal joint of the thumb?
Flexor pollicis longus
In the diagram below, the examiner (white hand) is making an assessment of a patient’s hand. The patient is able resist the examiners attempt to pull the paper from between the 4th and 5th digits. The examiner is able to confirm the functioning of which muscle?
3rd palmar interosseous
Dislocation of bone E in an anterior / palmar direction could cause compression of which nerve?
Median nerve
Identify the vessel indicated by the letter D.
Median cubital vein
What is vessel A?
- Radial artery
- Is a major contributor to the deep palmar arch
- Passes between the 2 heads of the 1st dorsal interosseous muscle
What is extensor digitorum supplied by?
Posterior interosseous branch of the radial nerve
A patient with a right side radial nerve lesion resulting in ‘wrist drop’ could extend her elbow joint - but this movement was weak when compared to the left side. At approximately what level does the radial nerve lesion lie?
Mid-arm
Match the letter to the correct carpal bone on this X-ray of a right hand.
A - trapezium
B - trapezoid
C - scaphoid
D - capitate
E - lunate
F - hamate
G - pisiform
H - triquetral
What is tendon E? Where does it travel?
Flexor pollicis longus - travels through the carpal tunnel
The photograph shows an examiner (on the left) assessing the function of a patient’s right hand (on the right). The examiner is is trying to push the patient’s fingers together. The patient’s ability to resist this demonstrates the functioning of what nerve and what muscles?
- Dorsal interossei
- Ulnar nerve
What major nerve has been lacerated here?
Median nerve
What are the muscles labelled x?
Lumbricals - can see arising from FDP tendons
