Anatomy of the elbow

Question 1

What type of joint is the elbow joint?

Answer 1

It is a hinge, synovial joint, that moves uniaxially

Question 2

What are the bones that articulates in the elbow?

Answer 2

1) Humeroulnar articulation
- Between the “trochlea” of the humerus, & the trochlear notch of the “ulna”

2) Humeroradial articulation
- Between the capitulum of the humerus and the upper articular surface of the head of the radius

Question 3

Describe the structure of the capsule of the elbow joint

Answer 3

• Attached outside of the margins of the articular surfaces
• It is continuous with the synovial membrane and the superior radioulnar joint

1) Upper attachment (attachment to the humerus)
- Anteriorly it is attached to the margins of the coronoid and radial fossa & to the trochlea medially and the capitulum laterally

• Posteriorly, It is attached above the olecranon fossa

2) Lower attachment (attachment with the ulna & radius)

• Anteriorly, it is attached to the margins of the coronoid process & the annular ligament
• Posteriorly, it is attached to the margins of the olecranon fossa and the annular ligament

Question 4

Describe the synovial membrane of the elbow joint

Answer 4

• Lines the inner surface of the fibrous “joint” capsule
• Lines the coronoid, radial & olecranon fossae
• Continuous with the synovial membrane of the superior radioulnar joint

Question 5

What is meant by olecranon bursitis?

Answer 5

• It is the rupture/inflammation of the Olecranon bursa (closed sac filled with synovial fluid) found between the olecranon process and the skin

Question 6

What strengthens the capsule?

Answer 6

1) Ulnar collateral ligament
- Thick triangular ligament which consists of 3 bands (anterior, posterior & oblique) that are connected between the medial epicondyle of the humerus and the medial margin of the olecranon of the ulna

2) Radial collateral ligament
- A band that connects the lateral epicondyle with the annular ligament

FYI: Both ligaments control the joint movement, and prevent adduction and abduction

Question 7

Describe the different bands of the ulnar collateral ligament

Answer 7

1) Anterior:
- Strong & cord-like
- Medial epicondyle to medial margin of the coronoid process
- Remains taut during flexion and extension

2) Posterior band:
- Weak and fan-like
- Connects the medial epicondyle to the medial margin of the olecranon
- It tightens when flexed beyond 90 degrees

3) Oblique band:
- Connects the anterior (coronoid) & posterior bands (olecranon)

Question 8

Describe the radial collateral ligament

Answer 8

1) Resists excessive varus (adduction) forces

2) Triangular in shape

3) Attached above to the lateral epicondyle

4) Merges below with the annular ligament

5) Posterior fibers attaches to the supinator crest

Question 9

Which muscles flexes the elbow?

Answer 9

1) Brachialis (prime mover of the forearm)
2) Biceps brachii
3) brachiocardialis
4) pronator teres
5) common flexor origin

Question 10

Which muscle extends the elbow joint?

Answer 10

1) Triceps brachii (main extensors)

2) Anconeus

Question 11

Why is the elbow more stable during extension?

Answer 11

As the olecranon fossa is fully occupied by the olecranon process

Question 12

The stability of the elbow joint during flexion depends on what?

Answer 12

Lateral “radial collateral ligament” and the medial “ulnar collateral ligament”

Question 13

What are the different anastomosis around the elbow?

Answer 13

1) Infront of the lateral epicondyle

2) Behind the lateral epicondyle

Question 14

What is the anastomoses that occurs in-front of the lateral epicondyle?

Answer 14

• The radial collateral artery (anterior descending branch of the profunda artery) anastomoses with the radial recurrent artery in-front of the lateral epicondyle of the elbow joint

Question 15

What is the anastomoses that occurs behind the lateral epicondyle?

Answer 15

• From the posterior descending branch of the profunda artery the “middle collateral artery” anastomoses with the interosseous recurrent artery “from the posterior interosseous artery”

Question 16

What is the anastomoses that occurs in front of the medial epicondyle?

Answer 16

Anterior branch of the inferior ulnar collateral artery with the anterior ulnar recurrent artery from the “ulnar artery”

Question 17

What is the anastomoses that occurs behind the medial epicondyle?

Answer 17

The superior ulnar collateral artery & posterior branch of the inferior ulnar collateral artery with the posterior ulnar recurrent artery (from the ulnar artery

Question 18

Describe the superior radio-ulnar joint

Answer 18

• Type: Synovial pivot
• Articulation: Head of the radius and the radial notch on the ulna
• Ligaments: Annular & quadrate ligaments

Question 19

What are the ligaments of the superior radio-ulnar joint?

Answer 19

1) Annular ligament

2) Quadrate ligament

• These ligaments have no attachment to the radius bone, they just keep it in place, so the radius can freely rotate inside it but can’t dislocate

Question 20

What are the functions/description of the annular ligament?

Answer 20

1) Stabilizes the radial head at the superior radio-ulnar joint
2) U-shaped
3) Forms 4/5 of osseofibrous ring
4) Attached medially to the anterior and posterior margins of the radial notch
5) Laterally winds around the head and neck of the radius
6) Continuous with the capsule from above

Question 21

Describe the quadrate ligament

Answer 21

Extends medially from the medial surface of the neck of the radius to the lower margin of the radial notch of the ulna

Question 22

Describe nursemaids elbow

Answer 22

• Radial head dislocates from the annular ligament
• Its a common injury seen most often in children between the ages of 1-3 years
• Usually it involves an incidents where the extended arm was pulled, like when a child falls and the person catching his hand does not let go, or when he is swinging while being held by the hands
• Then the head slips out of the hold in a sudden accidental pull of the forearm of the child
• Most common in children as their epiphysis is noy yet ossified

Question 23

What are the movements of the superio-radioulnar joint?

Answer 23

1) Pronation

2) Supination

• FYI: In these movements it is the radius that moves and not the ulna

Question 24

Which muscle is responsible for the pronation movement?

Answer 24

1) Pronator teres

2) Pronator quadrants

Question 25

Which muscles are responsible for the supination movement?

Answer 25

1) Supinator

2) Bicep muscles

Question 26

Describe the tennis elbow condition (lateral epicondylitis)

Answer 26

It is a common condition caused by inflammation of the common extensor origin at the back of the lateral epicondyle

• Associated with the overuse of gripping & lifting activities

Question 27

Describe golfer’s elbow (medial epicondylitis) condition

Answer 27

• Less common
• Associated with inflammation of the common flexor origin at the front of the medial epicondyle

Question 28

How do you identify elbow dislocation using surface anatomy?

Answer 28

Normally when the arm is flexed there is a equilateral triangle between the olecranon apex, medial and lateral epicondyle and they form a straight line when extended, if a dislocation occurs and it is usually the ulna due to a fall on a outstretched arm, causing a deformity, extreme pain & swelling, & loss of configuration of the the triangle

Question 29

Describe the cubital fossa

Answer 29

• Triangular space in front of the elbow
• Common site above the elbow joint for blood sampling and transfusion
• Choosing the median cubital vein usually or the basilic vein
• It has a base (formed by an imaginary line between the two epicondyles of the humerus) and two borders (medial “formed by the lateral border of the pronator teres muscle” & lateral “formed by the medial border of brachioradialis muscle)
• Apex of the triangle is directed downwards where the brachioradialis overlaps with the pronator teres
• Its roof is formed by skin, superficial fascia (median cubital vein, part of cephalic lateral & basilic vein medially, & Medial and lateral cutaneous nerves of the forearm) and deep fascia (bicipital aponeurosis “protects the underlying content”)
• The floor
  1) Brachialis medially
  2) Supinator laterally

Question 30

What connects the cephalic and basilic veins?

Answer 30

The median cubital vein

Question 31

What are the contents of the cubital fossa?

Answer 31

1) Tendon of biceps

2) Termination of the brachial artery (medial to the tendon)

3) Median nerve (medial to the artery)

4) Radial nerve (Lateral most structure might be hidden by the brachioradialis muscle)

From Medial to Lateral:
MBBR
M: Median nerve
B: Brachial artery
B: Tendon of biceps
R: Radial nerve