M Upper limb 2 - The elbow joint Flashcards
What 3 bones is the elbow joint composed of?
- humerus
- ulna - medial
- radius - lateral
What are the 2 articulations of the elbow joint?
- humero-ulnar
2. humero-radial
What is involved in humero-ulnar articulation? (2)
- trochlea of the humerus
2. trochlear notch of the ulna
What is involved in the humero-radial articulation? (2)
- the capitulum
2. the upper surface of the radial head - flat
What ligaments reinforces the capsule of the elbow joint? (2)
1.LATERALLY
radial collateral ligament
2.MEDIALLY
ulnar collateral ligament
What aspect of the capsule allows for flexion and extension to occur? (2)
- thin
2. loose anteriorly and posteriorly
Why is the elbow joint one of the most stable joints in the body?
- good congruity between humero-ulnar joint
- the trochelar notch of the ulna and the trochlea of the humerus
How much force is required to dislocate the elbow?
a lot
What age range and activities tend to cause dislocation of the elbow joint?
AGE
young adults
ACTIVITIES
sports
What happens during elbow dislocation? (4)
- humerus moves forwards
- humerus projects anteriorly
- ulnar projects posteriorly
- radius projects posteriorly
What percentage of elbow dislocations are posterior elbow dislocations?
80-90%
What happens in posterior elbow dislocation?
distal end of humerus is driven through the weak anterior part of the joint capsule
What are the causes of posterior elbow dislocation?
falling onto hands with elbows flexed
HYPEREXTENSION - drives the ulnar posterolaterally
What ligament can be torn in posterior elbow dislocation?
ulnar collateral ligament
What fractures can occur in posterior elbow dislocation?
- head of radius
- coronoid process
- olecranon process
What nerve could get injured during posterior dislocation of the elbow?
ulnar nerve
What are the symptoms of posterior elbow dislocation?
- severe pain in elbow region
- Elbow appears to be widened
- prominent olecranon process (lump of elbow)
What plexus is the ulnar nerve a part of?
brachial plexus
What does the ulnar nerve travel down posteriorly?
medial epichondyle
What feeling do you get when you hit the ulnar nerve?
funny bone feeling
What happens when you injure the ulnar nerve? (4)
- numbness of the medial part of the palm
- numbness of medial 1 and 1/2 fingers
- weakness in flexion
- weakness of adduction of the wrist
What muscle is bound to wrist on the ulnar/medial side of the forearm?
flexor carpi ulnaris
How elbow dislocations classified? (2)
- simple elbow dislocation
2. complex elbow dislocation
Is surgery required for a simple elbow dislocation?
no
What is the prognosis like for simple elbow dislocation?
good
What is a simple elbow dislocation?
ligamentous injury only
no fracture
What is complex dislocation?
fracture of bone in the forearm
Is surgery required for complex elbow dislocation and why?
yes - to maintain elbow in normal position
What are the movements of the elbow?
flexion/extensions
Why can hyperextension occur?
olecranon process has a hole in it = OLECRANON FOREAMEN
What muscles are flexors of the elbow joint? (3)
- brachialis
- biceps brachii
- brachioradialis
NOTE
know innervation and attachments of flexors of elbow joint
What is an accessory flexor of the elbow joint when the forearm is mid-pronated?
brachioradialis
What is the extensor of the elbow joint? (1)
triceps brachii
What are the 3 heads of triceps brachii? (3)
- lateral head
- medial head
- long head
What is triceps brachia innervated by?
radial nerve
What does the olecranon bursa protect?
Olecranon process of the ulnar
What is a bursa full of and what does it do?
full of synovial fluid
- reduce friction
Why can inflammation of the olecranon bursa occur?
excessive and repeated pressure and friction over the olecranon
What are the symptoms and signs of olecranon bursitis? (3)
- swelling of bursa
- visible bursa
- painful on palpation
What is olecranon bursitis also known as?
student elbow
Where is the proximal radio-ulnar joint?
with the capsule of the elbow joint
What does the articulation of the proximal radial-ulnar joint involve?
- head of the radius
2. radial notch of the ulnar
Where does the annular ligament wrap around?
head of the radius
What does the annular ligament do? (2)
- maintains stability of the radius
2. allows for rotation of the forearm during supination and pronation
What is supination?
palm up
What is pronation?
palm down
What age group makes your annular ligament weak?
children - kids under 4 yrs
What can a weak annular ligament cause the radius to do?
to under go subluxation or dislocation
What is subluxation or dislocation of the radius commonly caused by in kids and what is the name given to it?
- adults swinging kids by their arms / lifting the child by one arm
- Nursemaids elbow/ Pulled elbow syndrome
What are the movements of the proximal radioulnar joint? (2)
- supination
2. pronation
What muscle rotates the proximal radio-ulanr joint?
Pronator terres
What muscle helps rotate the radius?
biceps brachii
What is golfer’s elbow?
insertion of wrist flexor tendons into the medial epicondyle becomes inflamed
What is tennis elbow?
insertion of the wrist extensor tendons into the lateral epicondyle become inflamed
What are the symptoms of epicondyltis? (2)
- local tenderness
2. pain radiating into forearm along affected muscles
What is the treatment of epicondyltis? (2)
- rest
2. injections of corticosteroids if pain is severe
What ossifies separately from the rest of the humerus and what is it only connected by?
Medial epicondyle
- connected by cartilage
When does fusion of the medial epicondyle occur?
14-20 years
What causes avulsion of the medial epicondyle?
- severe trauma
- causes abduction of the elbow
- stretches the ulnar collateral ligament which pulls the medial epicondyle out of position
What nerve may be damaged in the avulsion of the medial epicondyle?
ulnar nerve
Where are humeral fractures likely to occur?
surgical neck of humerus
What age group are humeral fractures likely to happen in and why?
elderly
osteoporosis
What nerve amy be injured in a humeral surgical neck fracture?
axillary
In a humeral shaft fracture, what muscle pulls the proximal fragment laterally?
deltoid
What is at risk of being injured in a humeral shaft fracture?
radial nerve
What age group is supracondylar fracture common in?
children
Which nerve and artery are prone to injury in a supracondylar fracture?
NERVE
median
ARTERY
brachial
What happens to the hand if the brachial artery is blocked?
turns blue
may necrose
What direction does the humerus displace in a supracondylar fracture?
displaces forwards