6: Elbow and Forearm Flashcards
superficial muscles of anterior compartment of forearm
flexor carpi ulnaris
palmaris longus
flexor carpi radialis
pronator teres
intermediate muscles of anterior compartment of forearm
flexor digitorum superficialis
deep muscles of anterior compartment of forearm
flexor pollicis longus
flexor digitorum profundus
pronator quadratus
actions associated w anterior forearm
proantion of forearm
flexion of wrist
flexion of fingers
innervation of anterior forearm
mostly median nerve
- except for flexor carpi ulnaris and medial 1/2 of flexor digitorum profundus which are ulnar
arterial supply of anterior forearm
ulnar and radial artery
origin of all superficial muscles anterior forearm
common tendon which arises from medial epicondyle of humerus
prosection of superficial anterior forearm
prosection of intermediate layer of anterior forearm
prosection of deep layer of anterior forearm
borders of cubital fossa
lateral: medial border of brachioradialis
medial: lateral border of pronator teres
superior: horizontal line between epicondyles of humerus
roof of cubital fossa
bicipital aponeurosis
subcutaneous fat and skin
fascia
- also contains median cubital vein which connects basilic and cephalic veins which can be easily accessed for venepuncture
floor of cubital fossa
proximally: brachialis
distally: supinator
how do conditions of the elbow present
- pain
- swelling
- restriction of movement
- deformity
- different conditions common at different ages
supracondylar fracture
- up to 75% of all elbow injuries
- most common pediatric elbow fracture >10 yrs (peak age 5-7)
- more common in boys
- most common mechanism: falling from moderate height onto outstretched hand w elbow hyperextended
- presents w pain, swelling, deformity, bruising
- history of trauma
- less common mechanism: 5% - falling onto flexed elbow
classification of supracondylar fractures
describe the fracture line in a supraondylar fracture
usually extra-articular
i.e. joint not involved and the distal fragment is usually displaced posteriorly
what are the three main complications of supracondylar fractures
-
malunion
- resulting in cubtius varus - damage to median nerve (most common), radial nerve or ulnar nerve
-
ischaemic contrature: brachial artery passes v close to fracture site and can occasionally be damaged or occluded by a displaced fracture
- if reflex spasm of the collateral circulation around the elbow also occurs, there will be ischaemia of the muscles in the anterior compartment of the forearm –> oedema –> compartment sydrome –> further exacerbates ischaemia as it impedes arterial inflow
- if untreated, muscle bellies will undergo infarction
- during repair phase, dead muscle tissue = fibrotic
- fibrotic tissue contracts by myofibroblast activity –> flexion contracture aka Volkmann’s ischaemic contracture
what is Volkmann’s ischaemic contracture
- wrist is typically flexed
- fingers extended at the metacarphalangeal joints
- forearm is often pronated
- elbow is flexed
how do you minimise risk of complications in supracondylar fracture
- exmaine and document neurovascular exam
- radial pulse and capillary re-fill time
management of supracondylar fracture
- depends on your assessment of neurovascular status and how deformed elbow is
- reduce, close and gold it in position w a plaster
- closed reduction and percutaenous pinning (CRPP)
- if reducing, the frature has not restored nerve function, then surgically exploring the nerve and artery may be required
elbow dislocation
- usually occurs when a person, often child, falls on their outstretched hand w the elbow partially flexed
- 2nd most common joint to dislocate after shoulder
- casues major disruption to soft tissues - capsule and ligaments
- pain, loss of function and obvious deformity
why are elbow dislocations so common
- because of the high freqeuncy of falls onto an outstretched hand
why is elbow dislocation most likely to happen mid-flexion
- configuration of the bones contributes most to stability of the elbow in full extension and flexion whereas the stability of the elbow in mid-flexion = more reliant on the ligaments
what type of elbow dislocation is most common
posterior
how are elbow dislocations named
by the displacement of the distal fragment i.e. ulna and radius not humerus
- distal end of humerus is driven through the joint capsule anteriorly