Elbow, Forearm and Wrist Flashcards
What are the articular surfaces of the radius and ulna?
radius -> capitulum (lateral)
ulna -> throchlea (medial)
*The capitulum is a ball-like, rounded surface and the trochlea is a pulley-like surface
What is a styloid process?
usually acts at points of attachment of muscles
slender, pointed protrusions of bone - e.g in distal ends of radius and ulna
What is the interosseous membrane?
fibrous membrane that connects radius and ulna along the shafts - separates anterior and posterior compartments
- important for mechanical (forces transmitted between bones) and structural reasons (membrane acts as partial/ complete attachment site for muscles)
Where do the radius and ulna articulate?
distal ends of radius and ulna articulate with proximal row of bones in the wrist (except the pisiform)
- scaphoid
- lunate
- triquetrum
What is the pisiform?
sesamoid bone in the wrist - forms within a tendon (another example is the patella)
What are the muscles of the anterior compartment of the forearm?
SUPERFICIAL Anterior Compartment:
- Pronator teres (PT)
- Flexor carpi radialis (FCR)
- Palmaris longus (PL)
- Flexor digitorum superficialis (FDS)
- Flexor carpi ulnaris (FCU)
DEEP Anterior Compartment of the Forearm:
- Flexor digitorum profundus (FDP)
- Flexor pollicis longus (FPL)
- Pronator quadratus (PQ)
What are the attachments of the pronator teres?
What does it do?
proximal:
- common flexor tendon at medial epicondyle
distal:
- lateral side of radius
when contracted - pulls arm to pronate it
What are the attachments of the flexor carpi muscles?
What do they do?
proximal:
- coomon flexor tendon at medial epiconyle
distal :
- base of second and third metacarpal (radialis)
- pisiform and hook of hamate (ulnaris)
flexor of wrist on radial/ ulnar side
What are the attachments of the flexor digitorum superficialis?
What does it do?
proximal:
- medial epicondyle
- coronoid process of ulna
- anterior portion of radius
distal:
- middle phalanges of middle 4 digits
flexion of the middle phalanges of the fingers at the proximal interphalangeal joints
- under continued action it also flexes the metacarpophalangeal joints and wrist joint
What are the attachments of the flexor digitorum profundus?
What does it do?
proximal:
- upper anterior and medial surfaces of ulna
distal:
- palmar base of distal phalanx (2nd-5th digits)
flexes hands and both interphalangeal joints
What are the attachments of the flexor pollicis longus?
What does it do?
proximal:
- anterior surface of radius
distal:
- palmar side of distal phalynx of thumb
fascilitates thumb flexion
What are the attachments of the pronator quadratus?
What does it do?
anterior surfaces of distal part of shafts of ulna to radius
pronates hand
What is the significance of the palmaris longus tendon?
- most popular for use in tendon grafts for the wrist due to the length and diameter of the palmaris longus tendon, and the fact that it can be used without producing any functional deformities
fans into aponeurosis in hand - tendon not needed to have aponeurosis
What are the posterior muscles that move the wrist joint?
What are their attachments?
Extensor carpi radialis longus (ECRL) - lateral supracondylar ridge (humerus) to third metacarpal
Extensor carpi radialis brevis (ECRB) - lateral supracondylar ridge to third metacarpyl
Extensor carpi ulnaris (ECU) - lateral epicondyle of humerus to posterior border of ulna
What are the posterior muscles that move the digits?
What are their attachments?
Extensor digitorum (ED) - lateral epicondyle to middle and distal phalynges of 2nd - 5th fingers
Extensor indicis (EI) - posterior surface of ulna and interosseous membran to index finger
Extensor digit minimi (EDM) - lateral epicondyle to extensor hood of little finger
What are the posterior muscles that move the thumb?
What are their attachments?
Abductor pollicis longus (APL) - dorsal surface of radius and ulna and interosseus membrane to first metacarpal bone
Extensor pollicis brevis (EPB) - posterior side of radius and interosseous membrane to base of proximal phalynx of thumb
Extensor pollicis longus (EPL) - posterior lateral surface of the ulna and interosseous membrane to base of distal phalynx of thumb (dorsal surface)
What are the attachments of the brachoradialis and the supinator?
brachoradialis - lateral ridge of distal humerus to lateral surface of distal radius near the styloid process
flexion of elbow, supination of forearm, pronation of forearm
supinator - lateral epicondyle and supinator crest of ulna to lateral surface and posterior border of radius
supinates forearm
What is the clinical significance of the anatomical snuff box?
You have the tendons of extensor pollicis longus and extensor pollicis brevis.
It is also possible to palpate the scaphoid bone (most lateral of the proximal carpal row).
Scaphoid is commonly fractured. If you fall, you commonly put your hands out to break your fall -> scaphoid fracture. 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).
If pain is elicited during palpation of the anatomical snuffbox, this can indicate injury.
What is the elbow joint?
The elbow joint is the joint between the capitulum and trochlea of the distal humerus, and the head of radius and proximal part of ulna
The radius articulates with the capitulum (lateral) and the ulna with the trochlea. It is a synovial joint
- Movements: flexion and extension
What ligaments are associated with the elbow joint?
collateral ligaments (both ulnar and radial) – they prevent deviation (adduction and abduction)
radial annular ligament that wraps around the neck of radius, allowing for rotation
- arranged to stabilise the joint, but allow pronation/supination movements
What are sex differences in the carrying angle at the elbow?
greater in women than men - may be due to differences in width of hips (pelvis) - arms of women needs to deviate more
What is the proximal radio-ulnar joint?
the head of radius is held close to the proximal part of ulna
It has an articular surface that articulates with the capitulum as part of the elbow joint (head of radius)
The JOINT also has a trochlear articulating surface (proximal part of ulna)
On the joint is a rim, allowing the head of radius to also articulate with the radial notch of ulna
When radius is pronated (by pronator teres and pronator quadratus), it is held in place at the proximal RUJ and crosses over ulna to bring about pronation
What is the distal radio-ulnar joint?
We see the ulna and radius articulating 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
- the articular disc, during pronation and supination, changes position slightly. It moves over a bit, but still is acting as the surface for the articulation with the carpal bones. The bones cross over, and the orientation of the hand is essentially changed by 180 degrees going from pronation to supination
Which muscles are involved in the movement of the elbow joint?
FLEXION:
- brachialis
- biceps
- brachioradialis
- pronator teres
EXTENSION:
- triceps (mainly)
- anconeus
What muscles are involved in the movement of the radio-ulnar joints?
SUPINATION:
- supinator
- biceps
- EPL
- ECRL
PRONATION:
- pronator quadratus
- pronator teres
- FCR
- PL
- brachioradialis
- 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.
Which muscles are involved in the movement of the wrist joint?
Flexion:
- FCR and FCU – important
- Long flexors of thumb and fingers, (PL, APL)
Extension:
- ECRL, ECRB, ECU – important
- Long extensors of the thumb and fingers
Radial deviation (abduction):
- APL
- FCR
- ECRL
- ECRB
Ulnar deviation (adduction):
- ECU
- FCU
- 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. It is the combinations of activities that determine the movement.
*** In order to get abduction or adduction, there is a flexor and an extensor working. Flexors work together to carry out flexion; extensors work together to carry ou
What are the arteries of the region?
At the elbow, the brachial artery divides into the ulnar and radial arteries
The ulnar artery branches almost immediately to give a common interosseous branch - common interosseous branch immediately branches to give anterior & posterior interosseous arteries
The radial artery continues down the forearm to the wrist.
The posterior interosseous artery pierces the upper part of the interosseous membrane to supply the posterior compartment. The anterior artery supplies deep structures.
arteries go down to palmer arches (deep and superficial)
What are veins of the region?
Superficial and deep systems
- Cephalic vein (superficial) runs up lateral border of arm
- Basilic vein (superficial) runs up the medial border of arm
Basilic veins joins venae comitantes to form the axillary vein in the arm
Cephalic vein joins axillary vein in the axilla
Axillary vein becomes the subclavian vein at the level of the first rib
Cephalic and Basilic veins arise from the dorsal venous arch of the hand
Commonly connected at the cubital fossa by the median cubital vein (not always present or prominent)
- Median cubital vein is commonly used in phlebotomy
- When median cubital vein is absent, cephalic or basilic in the region are used to take blood
** There is the dorsal venous arch, giving the cephalic vein laterally and the basilic vein medially. The median cubital vein joins them. It is not always present, or when it’s present it may be a very small, weedy vein. When present, it is the vein of choice for routinely taking blood
*** Deep drainage follows the arteries. Particularly in the more distal parts of the limb, veins accompanying the artery are often not a single vein (that’s why they’re called the venous comitantes). This is seen both anteriorly and posteriorly
Describe the lymphatic drainage of the region?
Superficial and deep systems, running with veins
Cubital lymph nodes drain the forearm (usually 3 or 4 lymph nodes, often on the medial side)
Cubital lymph nodes are very important – if they are enlarged, this may indicate HIV status, they may also get inflamed is due to syphilis
Axillary nodes are also draining nodes for the distal parts of the upper limb
What does the musculocutaneous nerve supply?
C5, 6, 7
Supplies all the anterior compartment of the upper arm
Sensory to the lateral forearm (as the lateral cutaneous nerve of the forearm – terminal branch
What does the median nerve supply?
C6, 7, 8, T1
Courses through the anterior compartment of the arm (no significant branches)
Lies anterior to the elbow, with the brachial artery (easily damaged) – found in cubital fossa
- Main nerve to the muscles of the forearm
The median nerve supplies LOADS of the flexors, but only HALF of the flexor digitorum profundus
What does the ulnar nerve supply?
C8, T1
Courses via the posterior compartment of the upper arm
No significant branches in the upper arm
Lies behind the medial epicondyle at the elbow (easily damaged)
The main nerve of the hand
What does the radial nerve supply?
C5, 6, 7, 8, T1
Supplies all the muscles of the posterior compartments of the upper arm and forearm
Passes around the body of the humerus at its mid-shaft in the radial groove (easily damaged)
Supplies triceps in the arm
Courses via the anterior compartment of the upper arm more distally
Divides just above the level of the elbow into:
- Deep branch – the posterior interosseous nerve (motor – mainly extensor muscles)
- Superficial branch – the superficial radial nerve (sensory)
What is the retinaculum?
As we get towards the hand, we see a retinaculum. It is the flexor retinaculum of the wrist (also the transverse carpal ligament)
It is a structure that forms the roof of the carpal tunnel. The carpal tunnel allows lots of tendons and the median nerve to pass through to the hand
This arrangement can be problematic
