The Elbow Complex Flashcards by David Hanna

The elbow joint is made up of which 2 other joints?

Humeroulnar and humeroradial

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How many degrees of freedom does the elbow joint have?

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What type of joint is the elbow joint?

Loose hinge joint

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Which plane and axis contain the elbow joint

Sagittal plane
Coronal axis

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How many degrees of freedom do the PRUJ and DRUJ allow? What are the motions?

1
Supination/Pronation

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What type of joint are the PRUJ and the DRUJ?

Diarthrodial pivot-type joint

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Where is the trochlea located on the humerus (medial or lateral)? What kind of articulation is it (humeroradial or humeroulnar)?

Medially located
Humeroulnar articulation

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What is the purpose of the coronoid fossa?

To receive the coronoid process of ulna at end of elbow flexion

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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

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What is the function of the radial fossa?

Receives head of radius in full elbow flexion

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What is the name of the structure that separates the capitulum from the trochlea?

Capitulotrochlear groove

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What is the function of the olecranon fossa?

To receive the olecranon process of ulna in full elbow extension

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What makes up the distal joint surface of the elbow?

Radius and ulna

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What is the name of the concavity in the proximal ulna?

Trochlear notch

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What structure “cuts” the trochlear notch in half?

Trochlear ridge

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What is the name of the proximal end of the trochlear notch?

Olecranon process

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What is the name of the distal end of the trochlear notch?

Coronoid process

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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

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What is the cup shaped surface on top of the radius called?

Fovea

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The radial head is surrounded by a convex rim. Where on the humerus does it fit into?

Capitulotrochlear groove

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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

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In the humeroulnar joint in full flexion, which process goes into which fossa?

Coronoid process enters coronoid fossa

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In the humeroulnar joint in full extension, which process goes into which fossa?

Olecranon process enters olecranon fossa

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In the humeroradial articulation, the radial head and the capitulum articulate. Which is convex and which is concave?

Radial head: concave
Capitulum: convex

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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?

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