The Elbow Complex Flashcards
The elbow joint is made up of which 2 other joints?
Humeroulnar and humeroradial
How many degrees of freedom does the elbow joint have?
1
What type of joint is the elbow joint?
Loose hinge joint
Which plane and axis contain the elbow joint
Sagittal plane
Coronal axis
How many degrees of freedom do the PRUJ and DRUJ allow? What are the motions?
1
Supination/Pronation
What type of joint are the PRUJ and the DRUJ?
Diarthrodial pivot-type joint
Where is the trochlea located on the humerus (medial or lateral)? What kind of articulation is it (humeroradial or humeroulnar)?
Medially located
Humeroulnar articulation
What is the purpose of the coronoid fossa?
To receive the coronoid process of ulna at end of elbow flexion
When it comes to the elbow joint itself, is it proximal or distal? What kind of articulation is the capitulum (humeroradial or humeroulnar)?
Proximal humeroradial articulation
What is the function of the radial fossa?
Receives head of radius in full elbow flexion
What is the name of the structure that separates the capitulum from the trochlea?
Capitulotrochlear groove
What is the function of the olecranon fossa?
To receive the olecranon process of ulna in full elbow extension
What makes up the distal joint surface of the elbow?
Radius and ulna
What is the name of the concavity in the proximal ulna?
Trochlear notch
What structure “cuts” the trochlear notch in half?
Trochlear ridge
What is the name of the proximal end of the trochlear notch?
Olecranon process
What is the name of the distal end of the trochlear notch?
Coronoid process
What is the name of the concavity that articulates with the radial head? Where on the ulna is it located?
Radial notch
Lateral to coronoid process
What is the cup shaped surface on top of the radius called?
Fovea
The radial head is surrounded by a convex rim. Where on the humerus does it fit into?
Capitulotrochlear groove
Do the trochlear notch and the trochlea ever come in contact? If yes, how many newtons of force are required to do so?
Yes, but only when there is at least 500 N of force applied
In the humeroulnar joint in full flexion, which process goes into which fossa?
Coronoid process enters coronoid fossa
In the humeroulnar joint in full extension, which process goes into which fossa?
Olecranon process enters olecranon fossa
In the humeroradial articulation, the radial head and the capitulum articulate. Which is convex and which is concave?
Radial head: concave
Capitulum: convex
In the humeroradial joint in full flexion, which “protrusion” goes into which fossa?
Rim of radial head slides into radial fossa
In the humeroradial joint in full extension, the radial head makes contact with which area?
There is NO CONTACT between head and capitulum in full extension
The elbow joint capsule encloses which 3 joints that make up the elbow joint?
Humeroulnar joint
Humeroradial joint
Superior (proximal) radioulnar joint
The elbow joint capsule is (large or small), (tight or loose), (strong or weak)
Large
Loose
Weak
Which collection of ligaments is the joint capsule continuous with and reinforced by?
Collateral ligaments
The synovial layer in the elbow joint lines which 3 fossas?
Coronoid
Radial
Olecranon
Hypertrophy in the joint capsule can be the cause for what dysfunctions of the elbow?
Lateral epicondylalgia
Inflammation
Degenerative changes
For someone who has lateral epicondylalgia, what can aggravate their symptoms/pain?
Repetitive activities such as gripping, wrist extension, and push ups
For someone who has lateral epicondylalgia, what can improve their symptoms/pain?
Distraction of the humeroradial joint
How many bundles make up the medial (ulnar) collateral ligament, and what are they called?
3
Anterior bundle
Posterior bundle
Transverse bundle
What is the main function the anterior bundle of the UCL?
Primary restrain to valgus stress from 20-120º of flexion
Where does the Anterior bundle of the MCL attach and what does it contribute to (stability-wise)?
Attaches to capsule and radial head and it contributes to medial joint stability
What is the main function the posterior bundle of the UCL?
Limits elbow extension, and less restraint to valgus stability (than anterior bundle)
What is the main function of the transverse bundle of the UCL?
Helps to keep joint surfaces in approximation which means that it will keep those surfaces together
How many ligaments make up the lateral collateral ligament (LCL) complex, and what are they?
3
Lateral radial collateral ligament
Lateral ulnar collateral ligament
Annular ligament
What is the function of the lateral radial collateral ligament?
Reinforces humeroradial articulation
Some protection against varus stress
What is the main function of the lateral ulnar collateral ligament and the annular ligament?
Secondary restraint to combined forced varus and supination stress
What muscles work to flex the elbow?
Brachialis (in pronation)
Biceps (in supination)
Brachioradialis (in neutral)
Which muscles serve to extend the elbow?
Triceps and anconeus
What is the normal carrying angle?
Between 5-15º
What is considered cubitus valgus?
15º or Over
What is considered cubitus varus?
5º or Under
What is the elbow AROM in flexion?
135-145º
Is there more or less flexion of the elbow in supination?
More
What is the elbow PROM in flexion?
150-160º
What contributes to stability of the elbow joint in full extension?
50% from bone and 50% from LCL and capsule of varus stress
What contributes to stability of the elbow joint in full flexion?
Coronoid process with fossa and rim of radial head
What contributes to stability of the elbow joint in 90º of flexion?
Anterior part of MCL resists valgus and distraction stress
Resistance to varus stress mostly osseus, but some from LCL and capsule
In which angle does the Brachialis have the greatest moment arm?
100º
In which angle does the Biceps have the greatest moment arm?
80-100º
In which angle does the Brachioradialis have the greatest moment arm?
100-120º
When is the biceps the least effective elbow flexor?
In full extension
Of the 3 flexors of the elbow, which are mobility muscles and which are compressing muscles?
Mobility: Biceps & Brachialis
Compressing: Brachioradialis
In which position is the triceps in its active insufficiency?
Full extension of elbow and hyperextension of the shoulder
What is the PRUJ composed of?
Radial notch
Annular ligament
Radial head
Radial fovea
Humeral capitulum
What is the DRUJ composed of?
Ulnar notch
Radioulnar disc (TFCC - triangular fibriocartilage complex)
Head of ulna
What ligaments are found in the PRUJ?
Annular ligament
Quadrate ligament
Oblique cord
Where is the annular ligament and what is the purpose of it?
Encircles radial head
Adds stability and has NO LIMITATIONS
What is the purpose of the quadrate ligament?
Reinforces inferior aspect of joint capsule
Helps maintain radial head to radial notch
Limits spin of radial head in supination and pronation
In which direction does the oblique cord run and what is the main purpose of it?
Fibers run at right angles to fibers of interosseous membrane
May assist in preventing separation of radius and ulna
Which ligaments and discs are part of the DRUJ?
Dorsal and palmar ligaments
TFCC and DRUJ capsule
Interosseous membrane
Where do the dorsal and palmar ligaments insert? And where do they run
They insert into ulnar fovea and base of ulnar styloid
They extend along margins of TFCC
What is the purpose of the TFCC and DRUJ capsule?
To provide stability to carpals
Transmit compression and tension forces
What is the purpose of the interosseous membrane?
To stabilize PRUJ and DRUJ
Force transmission especially through weight-bearing
When does the interosseous membrane become taut?
During rotation to keep radius and ulna from splaying
During weightbearing
Which muscles serves to pronate the forearm, and which one is a 2 joint* muscle?
Pronator teres*
Pronator quadratus
Which muscles serve to supinate the arm?
Biceps
Supinator
Which Pronator muscle stabilizes proximal joint?
Pronator teres
Which Pronator muscle dynamically stabilizes distal joint?
Pronator quadratus
In which positions is the supinator active?
In all positions
What limits supination?
Tension in palmar radioulnar ligament and oblique cord
What limits pronation?
Bone on bone
Dorsal radioulnar ligament and posterior fibers of MCL
What is the ROM for pronation/supination?
150º
Is supination/pronation measured in elbow flexion or extension?
Flexion
Extension could induce shoulder IR/ER
What muscles in the DRUJ contribute to radioulnar stability?
PQ
ECU tendon
Which muscle stabilizes the forearm in pro/sup and gripping activities?
ECRB
How much joint play is allowed at the radioulnar joint before full resistance from the ligaments ensues?
~5mm
In which position is the dorsal radioulnar ligament taut?
Pronation
In which position is the palmar radioulnar ligament taut?
Supination
During weight-bearing on the hand, where do the forces go?
Forces go thru hand to radius, then to the interosseous membrane, then then the ulna, then humerus
What is the functional ROM required for most activities?
100º of elbow flexion (30-130º)
100º of forearm rotation (50º each pro/sup)
In children, which is stronger: bone or ligaments?
Ligaments
In adults, which is stronger, bone or ligaments?
Bone
What are the ossification centers of the elbow in order of age of ossification?
Capitulum
Radial head
Internal (medial) epicondyle
Trochlea
Olecranon
External (lateral) epicondyle
What is the age of ossification for the capitulum?
6 months - 2 years
What is the age of ossification for the radial head?
3-6 years
What is the age of ossification for the internal (medial) epicondyle?
4-7 years
What is the age of ossification for the trochlea?
7-10 years
What is the age of ossification for the olecranon?
6-12 years
What is the age of ossification for the external (lateral) epicondyle?
10-14 years
What can result in compression injuries of the elbow?
Bony: FOOSH with elbow in extension
Muscular: repetitive contractions of flexor carpi ulnaris may compress ulnar nerve
What can result in distraction injuries of the elbow?
Nursemaid’s elbow - radius is pulled inferiorly from annular ligament
What can result in varus/valgus injuries of the elbow?
- UCL and medial joint instability secondary to repetitive valgus stresses, such as with pitching
- Compression of one side and distraction of the other
- Ulnar neuritis
- Medial/lateral epicondylitis
- Ulnar collateral ligament instability causes increased carrying angle and radial head compression on capitulum (ex. Throwing) – can lead to avascular necrosis of capitulum
Why does the elbow have the highest incidence rate of peripheral neuropathy?
The superficial positioning of nerves and mechanical/repetitive stress on elbow
