Elbow and forearm test questions Flashcards
what is the cubital angle? what is “normal” for men and women?
the angle formed between the long axis of the humerus and the forearm during extension of the elbow
Men: 5-10 degrees
Women: 10-15 degrees
aka: carrying angle
what is cubital valgus? what is cubital varus?
Valgus: condition in which the forearm is more LATERAL than normal (increased carrying angle)
Varus: condition in which the forearm is more MEDIAL than normal (decreased carrying angle)
What is the elbow joint capsule?
it encloses the humeralulnar, humeralradial and proximal radioulnar joints
where does the elbow joint capsule attach?
medial and lateral epicondyles, the coronoid process, the annular ligament, and the olecranon fossa
what is the elbow joint capsule strengthened by?
the oblique bands of fibrous tissue and the collateral ligaments (UCL, RCL, annular ligament )
note!: the ucl is the same as mcl, rcl=lcl
What is a osterochondritis dessican? In which population is this common in?
(1) fragmentation of the articular cartilage within the joint due to lack of blood flow
(2) in immature throwing athletes
what happens to the humeroradial joint during a throwing motion?
you have an increased lateral compressive forces which occurs in the lateral elbow at the radiocapitellar joint
what do mecahnoreceptors in ligaments do?
detects safe limits of passive tension and important for proprioception
radial collateral ligament origin and insertion
O: lateral epicondyle
I: splits into 2 parts; one set of fibers inserts onto the annular ligament; one set of fibers inserts distally on the supinator crest of the ulna
what force/s does the radial collateral ligament resist against?
varus forces
when is the RCL tight?
full flexion
What happens there there is an injury to the RCL?
results in posteriorlateral rotatory instability
note: the ulna supinates on the humerus and the radial head dislocates in the posterolateral direction
ulnar collateral ligament (UCL) origin and insertion
O: medial epicondyle
I: coronoid process and olecranon process
note: there is an anterior, posterior and oblique band
what does the posterior band of the UCL protect?
the ulnar nerve
which band of the UCL is the strongest?
anterior band
which force does the UCL protect againt?
valgus forces
When does the UCL provide the greatest stability from forces?
in full flexion
note: during extension the stability comes from UCL, capsule, and humeroradial joint
when the UCL tears what happens? (where is it instable) (what can be affected with a UCL tear)
valgus instability
can be accompanied with pain, nerve damage and bone damaged
Annular ligament origin and insertion?
O: anterior aspect of the radial notch of the ulna
I: posterior aspect of the radial notch of the ulna
what is the function of the AL?
- helps keep the radial head in the radial notch of the ulna
- allows it to rotate
How can the annular ligament be injured? (in children)
by an adult pulling on a child’s forearm forcing it into full extension
- radius can be subluxed from the annular ligament
Quadrate ligament origin and insertion?
O: inferior radial notch
I: neck of the radius
Oblique (transverse) cord origin and insertion?
O: inferior radial notch
I: inferior bicipital tuberosity of the radius
what does the quadrate ligament do?
reinforces the inferior joint capsule
what does the oblique cord do?
resists distal disarticulation of the radius during pulling movements
what is the function of the interosseous membrane?
provides longitudinal stability and transmits forces between the radius and ulna
elbow flexors
biceps, brachialis, brachialradialis, and pronator teres
when do the biceps have maximum force?
simultaneous elbow flexion and supination
when is the brachialis active? at which point does it provide the greatest torque?
(1) entire elbow flexion
(2) at 100 degrees of elbow flexion
note: contraction through a short distance causes the hand to move through a large range with high velocity
elbow extensors
triceps and anconeous
what is the difference (in recruitment) between the different heads of the triceps?
medial: active in all extension motions
lateral & long: only recruited with resisted or “fast” movements
when is the anconeous active? what is its secondary “job”?
(1) extension, pronation, and supination
(2) helps stabilize the ulna
when do the extensors have the highest torque?
when the elbow is flexed to 90 degrees
supinators
supinator and biceps
which one is stronger supinators or pronators?
supinators (but only slightly)
pronators
pronator teres and pronator quadratus
when are the supinators and pronators the strongest?
90 degrees of elbow flexion
what is tennis elbow?
tendinosus caused by overuse of the extensor tendons originating from the lateral epicondyle
what is golfers elbow?
tendinosus caused by overuse of the flexor tendons originating from the medial epicondyle
when do you commonly see a nerve injury in the elbow
when there is a fracture to the humerus
Where can the radial n. get impinged? what is this called? what will be weak? and what sport is this common in?
(1) at the supinator
(2) posterior interosseous nerve syndrome
(3) wrist extensors
(4) racquet sports
Where can the median n. get impinged? what is this called? what will be weak? what can cause this (what motion/s)?
(1) at the pronator teres
(2) pronator syndrome
(3) thumb, middle and index fingers
(4) repetitive supination and pronation motions
Where can the ulnar n. get impinged? what is this called? what will be weak (what test will be positive with this)? and what sport/population is this common in?
(1) ulnar tunnel/grove
(2) cubital tunnel syndrome
(3) patient won’t be able to pinch thumb and fingers together and hold position; positive fromont sign
(4) throwers
