Elbow, forearm and wrist Flashcards
What are the carpal bones?
proximal: scaphoid, lunate, triquetrium, pisiform
distal: trapezium, trapezoid, capitate, hamate
Which side is the capitulum and which side is the trochlea?
capitulum - lateral
trochlea - medial
What is the importance of the radial tuberosity?
Th biceps brachii attaches here
What is the structure of the capitulum and trochlea?
Capitulum - ball like
Trochlea - pulley shape
What is the name of the part of the ulna that articulates with the humerus and where does it fit in?
coronoid process into the coronoid fossa
Which fossa does the radius fit into in the ulna?
radial fossa
What fossa is found posteriorly on the humerus and what fits in there?
Olecranon fossa - olecranon process
What do both the ulna and radius have at their distal ends?
styloid prcoess
Which membrane connects the ulna and radius?
interosseous membrane
What is the importance of the interosseous membrane?
mechanical - forces are transmitted between the bones
structural - attachment site for muscles and seperates the anterior and posterior forearm compartments
What is the annular ligament?
Strong band of fibres that encircles the head of the radius and retains it in contact with the radial notch of the ulna
Which carpal bone (proximal row) doesn’t articulate with the radius or ulna?
pisiform
What type of bone is the pisiform?
sesamoid bone - a bone that forms within a tendon e.g. the patella
What forms from the biceps and attaches to the radial tuberosity?
bicipital tendon
biceps also forms a biceps aponeurosis
Describe the attachment of the brachialis muscle
It attaches to the mid-distal part of the shaft of the humerus and then crosses over the elbow joint and attaches to the coracoid process of the ulna
What is the role of brachialis?
flexor
What does the triceps form and what does it attach to?
Three heads converge to form a tendon that crosses the elbow and attaches to the olecranon process of the ulna
What is the attachment of anconeus?
Lateral epicondyle of the humerus and the lateral and upper part of the ulna shaft
What is the role of the anconeus?
A small muscle that is important in stabilisation during some movements
How is the forearm divided?
Anterior - divided into superficial and deep
Posterior
Where do the forearm muscles originate?
the distal humerus, radius and ulna
Where are the flexors , pronators and extensors, supinators found?
flexors and pronators - anterior
extensors and supinators - posterior
What is found in the superficial anterior compartment of the forearm?
- pronator teres
- flexor carpi radialis
- palmaris longus
- flexor digitorum superficialis (not everyone has this)
- flexor carpi ulnaris
What is found in the deep anterior compartment of the forearm?
- flexor pollicis longus
- flexor digitorium profundus
- pronator quadratus
Where do the superficial muscles originate?
distal humerus (medial epicondyle) - the common flexor tendon
Where is pronator teres and what does it do?
wraps around radius, pronates the arm
Where is flexor carpi radialis and what does it do?
Flexor on the radial side
Where is flexor carpi ulnaris and what does it do?
Flexor on the ulnar side
Where is flexor digitorium superficialis?
second layer beneath flexor carpi radialis/ulnaris and pronator teres
What is in the third layer (deep)?
- flexor digitorium profundus
- flexor pollicis longus
What is found deep to the third layer?
pronator quadratus
What does pronator quadratus do?
Small quadratus muscle that attaches at the anterior surface of the distal parts of the ulnar and radial shaft
What forms the roof of the carpal tunnel?
flexor retinaculum (transverse ligament)
What is the antebrachial fascia?
continuous with the brachial fascia - it is a deep fascia of the arm
Describe the antebrachial fascia
Dense, membrane which forms a sheath for the muscles in the region
What are the attachments of the antebrachial fascia?
olecranon and the dorsal border of the ulna
What merges with the antebrachial fascia?
bicipital aponeurosis
What is found at the wrist to hold down the tendons?
retinaculum
Where are the extensor muscles found?
posterior compartment
What are the muscles that move the wrist joint?
- Extensor carpi radialis longus
- Extensor carpi radialis brevis
- Extensor carpi ulnari
What are the muscles that move the digits?
- Extensor digitorum
- Extensor indicis
- Extensor digit minimi
What are the muscles that move the thumb?
- Abductor pollicis longus
- Extensor pollicis brevis
- Extensor pollicis longus
What are the other extensor muscles?
brachioradialis and supinator
What are the attachments for supinator?
Lateral epicondyle of the humerus and the supinator crest of the ulna
Attaches to lateral and posterior surface of radius
Where is the attachment for some of the extensors?
common extensor tendon on the lateral epicondyle
Where else may extensor muscles originate?
interosseous membrane, ulnar and radial shafts
What is the role of supinator?
When forearm is pronated, it supinates it
What does pollicis, indicis and digiti minimi mean?
pollicis (thumb)
indicis (index finger) digiti minimi (little finger)
What is the anatomical snuff box and its importance?
What is found in it?
Tendons of extensor pollicis longus and extensor pollicis brevis - within the depression is the radial artery, the scaphoid can be palpated too
Important in determining if the scaphoid might be fractured: a common injury.
Why is it important to determine a scaphoid injury?
Can fracture when putting hands out to break fall
- Its blood supply comes from arteries that have entered the wrist, gone past scaphoid and then given branches back
- So a scaphoid fracture can result in an interruption of blood supply to a more proximal part (e.g. part involved in the wrist joint) -> avascular necrosis of the bone (can be very debilitating)
What are the joints of the forearm?
Elbow joint, proximal radio-ulnar joint, distal radio-ulnar joint, wrist joint
What kind of a joint is the elbow joint?
What movements can it do?
hinge
flexion and extension
What are the ligaments associated with the elbow and what are their roles?
collateral (ulnar and radial collateral ligaments) - prevents deviation
radial annular ligament - allows rotation for supination and pronation
What is the difference in the sexes in the elbow carrying angle?
The carrying angle (the angle that the forearm deviates from vertical compared to the arm) is greater in women than in men. One obvious reason for this may be the difference in the relative width of the hips (the pelvis).
Proximal radio-ulnar joint
- Head of radius is held close to the proximal part of ulna
- Head of radius articulates with the capitulum as part of the elbow joint
- On the joint is a rim, allowing the head of radius to also articulate with the radial notch of ulna
- When radius is pronated it is held in place at the proximal RUJ and crosses over ulna to bring about pronation
Distal radio-ulnar joint
- Ulna and radius articulates with the 3 bones of the proximal row of carpals (not pisiform)
- On an x-ray, there is a bigger gap between the ulna and the bones because there is an intervening articular disc
- The ulna actually articulates with this disc, that in turn articulates with the proximal carpal bones
Does the distal ulna articulate with the triquetrium carpal bone directly?
No it attaches to the articular disc - this moves a bit during pronation and supination
What causes flexion and extension at the elbow joint?
Flexion: brachialis, biceps, brachioradialis and pronator teres
Extension: triceps and anconeus
What causes supination and pronation?
supination: supinator, biceps (EPL, ECRL)
pronation: pronator teres, pronator quadratus (FCR, PL and brachioradialis)
What happens in the supine and prone positions and to which muscles?
- In the supine position the pronator teres is stretched around the bone
- It is attached to the lateral side of the shaft of the humerus
- Pronator quadratus is stretched into its approximately quadrate shape
- Supinator has contracted here, and has pulled the radius round so that the bones are parallel again
- In the prone position, the pronator teres has contracted and has rotated the radius round, as has pronator quadratus
What are the muscles causing flexion, extension, abduction and adduction at the wrist?
Flexion –FCR, FCU, PL, APL
Extension –ECU, ECRL, ECRB
Abduction –FCR, ECRL, ECRB, APL
Adduction –FCU, ECU
Describe wrist movement
- There is a combination of muscles involved in the various movements of the wrist joints
- If the flexor muscles work together, you’ll get straightforward flexion
- If just one of them works, you’ll get slight deviation one way or the other
- In order to get abduction or adduction, there is a flexor and an extensor working
GO OVER WRIST ABDUCTION, ADDUCTION, FLEXION AND EXTENSION
learn what they look like
What are the arteries in the forearm and what do they come from?
- At the elbow, the brachial artery divides into the ulnar and radial arteries
- Ulnar passes anteriorly then down the ulnar side and is medial to wrist joint
- Radial descends down lateral arm
- The ulnar artery branches almost immediately to give a common interosseous branch
- Common interosseous branch immediately branches to give anterior & posterior interosseous arteries
What is the cubital fossa?
Space anterior to the elbow joint
What type of joints are the proximal and distal radio-ulnar joints?
pivot type synovial
How is the biceps tested for?
flex arm against resistance
How is the triceps tested for?
extend forearm against reisistance
How is the brachioradialis tested for?
elbow flexed against resistance with forearm in midprone position
How is flexor carpi radialis, flexor carpi ulnaris and palmaris longus tested for?
wrist flexed against resistance
What are the wrist joint movements?
- flexion, extension
- radial deviation and ulnar deviation (abduction and adduction)
What kind of joint is the wrist joint?
ellipsoid synovial joint
Which ligaments stabilise the wrist?
- The ulnar collateral ligament
- The radial collateral ligament
- The palmar radio-carpal ligament
- The palmar ulnocarpal ligament
- The dorsal radio-carpal ligament
- The inter-carpal ligaments
What does the ulnaar artery supply?
medial muscles of forearm
Where does the ulnar artery end?
In the hand to form the palmar arches with the radial artery
Describe the lymphatic drainage of the forearm
- Superficial and deep systems, running with veins
- Cubital lymph nodes drain the forearm (usually 3 or 4 lymph nodes, often on the medial side)
- Axillary nodes are also draining nodes for the distal parts of the upper limb
Why may cubital lymph nodes be enlarged?
If they are enlarged, this may indicate HIV status or syphilis
What are the main nerves of forearm?
- median
- ulnar
- radial
Describe the venous drainage of the forearm
- Major superficial veins: cephalic vein and the basilic vein
- The cephalic vein ascends the upper limb on its lateral side, whilst the basilic vein runs medially
- Arise from the lateral and medial sides, respectively, of the dorsal venous arch on the posterior surface of the hand
- Median cubital vein connects the cephalic and basilic veins at the level of the elbow
- Deep veins (venae comitantes) accompany the radial and ulnar arteries
- They eventually flow to the brachial vein in the arm
What is the importance of the median cubital vein?
It is a common site for venepuncture and is variable in its anatomy. If it isn’t found cephalic or basilic can be used instead
What is important about venous connections between superficial and deep veins?
Valves allowing one-way flow from the superficial to the deep system
At which place does the axillary vein become the subclavian?
at level of the first rib
What is the pathway of the ulnar nerve?
Which spinal nerves is it made of ?
C8, T1
- It has no branches in the arm and initially descends in its anterior compartment, but distally passes into the posterior compartment to lie superficially, posterior to the medial epicondyle of the elbow (risk of damage)
- It enters the forearm passing between the heads of flexor carpi ulnaris, and then descends on the medial side of the forearm,
- At the wrist, the ulnar nerve lies between the FCU (medially) and the ulnar artery (laterally) and then passes into the hand
What does the ulnar nerve do?
- Supplies the more medial muscles in the anterior compartment
- Supplies: flexor carpi ulnaris (FCU), medial portion of flexor digitorum profundus (FDP) i.e. to the ring and little finger
- Gives sensory supply to the medial aspect of the ventral forearm
- It supplies most of the intrinsic muscles of the hand
Which nerves make up the median nerve?
Describe its pathway
C6,7,8, T1
- It descends in the anterior compartment of the arm, within which it does not give any branches
- Anterior to the elbow, it lies medial to the brachial artery, where it is at risk of damage by supracondylar fractures of the humerus
- The median nerve then descends into the forearm between the heads of pronator teres
- At the anterior wrist, the median nerve lies quite superficially between the tendons of FDS and FDP and deep to palmaris longus, prior to entering the hand through the carpal tunnel
What does the median nerve do?
- Principal motor nerve of the anterior compartment
- In the forearm it supplies: pronator teres, FDS, lateral portion of FDP (to the index and middle fingers), FCR, pronator quadratus and palmaris longus
- Supplies half of flexor digitoruium profundus
Which nerves make up the radial nerve?
Describe its pathway
C5,6,7,8 and T1
- It lies on the humerus in the radial (spiral) groove where it is at risk in humeral shaft fractures
- Just superior to the elbow it divides into the superficial radial nerve (cutaneous sensory) and the deep branch of the radial nerve (motor), which descends into the forearm between the heads of supinator, to become the posterior interosseous nerve
- It ends as a pseudoganglion below the extensor retinaculum
What does the radial nerve do?
- Supplies the posterior (extensor) compartment of the arm
- Supplies triceps
- Divides above elbow to deep branch (mposterior interosseous nerve -motor to mainly extensors) and superficial (superficial radial nerve - sensory)
What are the boundaries of the cubital fossa?
- Brachioradialis muscle (lateral)
- Pronator teres muscle (medial)
- The line between the humeral epicondyles (superior)
What do the radial, ulnar and median nerve supply briefly?
Radial Nerve supplies all posterior compartment muscles.
Ulnar Nerve supplies only FCU and the Ulnar half of FDP.
Median Nerve supplies all of the remaining anterior compartment muscles.
What are the anterior compartment superficial flexors?
Pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris, flexor digitorum superficialis
What are the anterior compartment deep flexors?
Flexor policis longus, flexor digitorum profundus, pronator quadratus.
What are the posterior compartment superficial muscles?
Brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris, anconeus
What are the posterior compartment deep muscles?
Supinator, abductor pollicus longus, extensor pollicis brevis, extensor pollicis longus, extensor indicis
What is found in the cubital fossa?
- radial nerve
- biceps tendon
- brachial artery
- median nerve
(lateral to medial)
What muscles cause flexion and extension at the elbow?
Brachialis, Brachioradialis & Biceps Brachii
Triceps
