Lecture 3: Elbow

Question 1

What 2 articulations make up the elbow joint (briefly describe them)?

Answer 1

1) Humero-ulnar - between the trochlea of the humerus and trochlear notch of the ulnar
2) Humero-radial - between capitulum and upper surface of radial head

Question 2

The capsule of the elbow joint reinforces the elbow joint in which 2 directions, using what tendons?

Answer 2

Reinforced laterally by the radial collateral ligament
Reinforced medially by the ulnar collateral ligament
The capsule is thin and loose posteriorly and anteriorly

Question 3

Why is the instability of the elbow joint capsule anteriorly and posteriorly necessary?

Answer 3

To allow for flexion and extension ie. the movements of the elbow joint

Question 4

Why is the elbow joint one of the most stable joints in the body?

Answer 4

Congruity between the trochlear notch of the ulnar and trochlea of the humerus
The radius has a flat articulation point with the humerus so does not contribute to stability

Question 5

Posterior dislocation accounts for what percentage of elbow dislocations and when this occurs in what direction do the bones involved project?

Answer 5

Accounts for 80-90%
Distal end of the humerus is driven anteriorly through the weak anterior part of the joint capsule and the ulnar and radius project posteriorly

Question 6

Sports injuries account for what percentage of elbow dislocations and in which people is it most common?

Answer 6

50%

Most common in adolescents and young people

Question 7

What are the 2 main causes of posterior dislocation of the elbow?

Answer 7

1) Fall onto hands with elbows flexed

2) Fall onto hand with elbow hyperextended - all weight goes through ulnar and drives it posteriorly or posterolaterally

Question 8

What are the 3 findings associated with a posterior dislocation of the elbow joint?

Answer 8

1) Ulnar collateral ligament torn
2) Fractures to the head of the radius, coronoid process, olecranon process
3) Ulnar nerve injury

Question 9

What are the 3 symptoms of a posterior dislocation of the elbow joint?

Answer 9

1) Severe pain in the elbow - ligaments torn - possible fracture
2) Elbow appears to have become wider
3) Prominent olecranon process - as ulnar pushed posteriorly

Question 10

What is the olecranon process?

Answer 10

The outside of the ulnar notch - bony bit of the elbow

Question 11

The ulnar nerve is a branch of what?

Answer 11

The brachial plexus

Question 12

Where does the ulnar nerve pass in the elbow joint?

Answer 12

Between the olecranon process of the ulnar and medial epicondyle of the distal end of the humerus

Question 13

What muscle in the wrist is supplied by the ulnar nerve, what is its action?

Answer 13

Flexor carpi ulnaris - involved in flexion of the wrist

Question 14

What is the sensory supply of the ulnar nerve?

Answer 14

Sensory supply to medial part of the palm and medial 1 and 1/2 fingers

Question 15

What are the symptoms of a damaged ulnar nerve?

Answer 15

1) Numbness of medial part of palm and 1 and a half fingers

2) Weakness of flexion and adduction of the wrist

Question 16

What is the difference between a simple and a complex elbow dislocation and what are the prognoses?

Answer 16

1) Simple elbow dislocation
- No fracture of the bones around the joint, normally ligamentous injury
- Good prognosis as often surgery is not required for treatment
2) Complex elbow dislocation
- Associated with fracture, usually of the forearm
- Surgery is often needed to fix the broken arm in order to maintain the elbow joint in a normal postition

Question 17

What limits extension normally so that hyperextension at the elbow joint isnt possible - why in some individuals is hyperextension possible?

Answer 17

When extended the olecranon process makes contact with the humerus
There is a fossa in the humerus called the olecranon fossa which on extension the olecranon process of the ulnar enters, limiting further extension
In some people the olecranon fossa is replaced by an olecranon foramen so that further extension is not limited and hyperextension occurs

Question 18

What is the difference between pronation and suppination of the forearm?

Answer 18

Pronation - arms facing down

Suppination - palms facing up

Question 19

What are the 3 flexors of the elbow joint?

Answer 19

1) Brachialis
2) Biceps brachii
3) Brachioradialis - note this is an accessory flexor only involved in flexion when the forearm is mid pronated

Question 20

What is the one extensor of the elbow joint?

Answer 20

Triceps brachii - has 3 heads, long head, lateral head and medial head

Question 21

Flexors of the elbow joint are part of what muscle compartment of the upper limb?

Answer 21

Anterior compartment

Question 22

Why is brachioradialis an odd muscle in terms of the compartment is classified as part of?

Answer 22

Classified as being part of the extensor compartment of the elbow but it actually passes anteriorly to end up anterior to the elbow joint

Question 23

What is the origin, insertion and innervation of the triceps brachii?

Answer 23

Origin
Long head - infraglenoid tubercle on the scapula
Lateral head - Posterolateral humerus above spinal groove
Medial head - posteromedial humerus below spinal groove
Insertion - Common tendon which inserts into the olecranon process of ulna
Innervation - radial nerve (C5-T1)

Question 24

What is the olecranon bursa?

Answer 24

Bag of sinovial fluid around the olecranon process of the ulna to protect it

Question 25

What is bursitis of the elbow, why does it occur and what are the symptoms?

Answer 25

Inflammation of the olecranon bursa
Caused by excess, repeated pressure and friction over the olecranon
Causes swelling of the bursa which may be visible and is painful on palpitation

Question 26

What is the anular ligament and what is its function?

Answer 26

The anular liagment wraps around the head of the radius
Maintains stability of the radius
Allows rotation of the humerus to allow pronation and suppination of the forearm

Question 27

Why is the radius more prone to subluxation or dislocation in childhood, what age of children does this tend to effect?

Answer 27

Because the annular ligament is relatively weak in childhood and cannot maintain stability of the radius, tend to affect children under 4

Question 28

What is ‘nursemaids syndrome’ or ‘pulled elbow syndrome’ and what is it commonly caused by?

Answer 28

Type of dislocation common in childhood, often results from parents swinging child or lifting child up by one arm
Get sublaxation or dislocation of the radius
When radius pulled away from the humerus the biceps brachii which is attached to it causes the head to be pulled laterally

Question 29

What other joint is contained within the capsule of the elbow joint?

Answer 29

Proximal radioulnar joint

Question 30

What is the proximal radioulnar joint?

Answer 30

This is an articulation between the head of the radius and the radial notch of the ulnar

Question 31

What are the 2 movements of the proximal radioulnar joint?

Answer 31

1) Supination. - palm up

2) Pronation. - palm down

Question 32

What happens to the radius and the radial tuberosity during pronation?

Answer 32

Radius moves up and over ulnar, so crosses over ulnar

Radial tuberosity moves from medial to lateral

Question 33

What 2 muscles contract to move the forearm from the supinated to pronated position, and what nerve innervates them?

Answer 33

1) Pronator teres (long muscle)
2) Pronator quadratus (square muscle)
Innervated by the median nerve

Question 34

Which 2 muscles contract to move the forearm from the pronated to suppinated position and what nerves innervate them?

Answer 34

1) Supinator
2) Biceps brachii
Innervated by radial nerve and musculocutaneous nerve

Question 35

What is the primary function of biceps brachii?

Answer 35

Primary function is supinator of the arm

Question 36

What are the 2 common sites on the elbow where the insertions of tendons into bones become inflamed?

Answer 36

1) Insertions of the wrist flexor tendons into the medial epicondyle
2) Insertions of the wrist extensor tendons into the lateral epicondyle

Question 37

What is golfer’s elbow?

Answer 37

When the insertions of the wrist flexor tendons into the medial epicondyle of the distal head of the humerus become inflammed

Question 38

What are the 4 wrist flexor muscles?

Answer 38

1) Pronator teres
2) Flexor carpi radialis
3) Palmaris longus
4) Flexor carpi ulnaris

Question 39

Which vessels and nerves are at risk of damage in a supracondylar fracture and what could be the consequences?

Answer 39

Anterior to the humerus have the median nerve which innervates muscles in the anterior compartment of the forearm, you also have the brachial artery anterior to the humerus which also supplies the forearm
When the humerus is pushed forward there is a risk of damage to these vessels
Hand goes blue as no blood flow, you risk necrosis unless pressure is relieved from the brachial artery and therefore emergency surgery is the treatment

Question 40

The elbow joint is composed of what 3 bones?

Answer 40

Radius, ulnar and humerus

Question 41

What is tennis elbow, what are the symptoms and treatment?

Answer 41

Inflammation of the insertions of the wrist extensor tendons into the lateral epicondyle of the distal head of the humerus
Symptoms = local tenderness, pain radiates into forearm along affected muscles
Treatment = rest or injection of corticosteroids if the pain is severe

Question 42

What is avulsion of the medial epicondyle and how can it occur?

Answer 42

When medial epicondyle is pulled out of position
Happens because:
1) Medial epicondyle ossifies separately to the rest of the humerus and is only connected by cartilage until 14-20 years when fusion occurs
2) Before fusion, severe trauma causing abduction of the elbow pulls the medial epicondyle out of position

Question 43

What is a big risk in avulsion of the medial epicondyle?

Answer 43

Stretching of the ulnar nerve

Question 44

What is one of the most common humeral fractures, especially in the elderly and what risk to nerves is associated with it, how can we test for this nerve damage?

Answer 44

Fracture of the surgical neck of the humerus (as this is the point at which the bone narrows)
Common in the elderly and may be associated with osteoporosis
The axillary nerve wraps around the surgical neck of the humerus so is at risk of damage
To test for damage to the axillary nerve - test deltoid function (supplied by the axillary nerve) and sensation in regimental badge area

Question 45

What commonly occurs in a humeral shaft fracture and what is the possible nerve damage associated?

Answer 45

1) Bone fractures along the radial/ spiral groove on the shaft of the humerus
2) Attachment for the deltoid is above the fracture line so it pulls the lateral fragment of the humerus laterally
3) Radial nerve runs in the radial/spiral groove and risks being damaged
4) The radial nerve supplies the extensors of the wrist thus these muscles may be paralysed
5) Braches to the triceps brachii have however been given off before the damage so this muscle will not be paralysed

Question 46

What is a supracondylar fracture of the humerus and who is it most common in?

Answer 46

Fracture of the humerus just above the condylar, humerus gets pushed anteriorly
Common in children