MSK 3.1 - Humerus, Radius And Ulna

Question 1

How should the humerus be orientated?

Answer 1

• Head should be superior and medial
• Medial epicondyle should be medial
• Olecrannon fossa should be on posterior surface

Question 2

Describe the salient features of the proximal humerus (5)

Answer 2

• Head
• Anatomical neck
• Greater tubercule
• Lesser tubercule
• Intertubercular sulcus

Question 3

Describe the salient features of the shaft of the humerus (2)

Answer 3

• Deltoid tuberosity

- Radial groove

Question 4

Describe the features of the distal humerus (5)

Answer 4

• Supraepicondylar ridges
• Later and medial epicondyles
• Trochlea
• Capitulum
• Fossae (Coronoid, Radial, Olecrannon)

Question 5

What are the 8 centres of ossification of the humerus?

Answer 5

• Head
• Shaft
• Greater and lesser tubercules
• Medial and lateral epicondyles
• Trochlea x2

Question 6

Describe the risks of a fracture to the surgical neck of the humerus

Answer 6

• Due to a fall on an outstretched hand/ direct blow
• Axillary nerve and posterior circumflex artery are at risk of damage
• Damage to Axillary nerve causes paralysis to deltoid and Teres minor

Question 7

Describe the risks of a fracture to the shaft of the humerus

Answer 7

• Mid shaft fracture can damage radial nerve and profunda brachii artery
• Results in unopposed Flexion (wrist drop)
• Can result in loss of sensation to dorsal surface of hand

Question 8

Describe the risks of a fracture to the distal humerus

Answer 8

• Due to a fall on a flexed elbow
• Can cause damage to ulnar nerve or brachial artery
• Volkmanns ischaemic contractures can lead to uncontrolled Flexion of the hand
• Damage to ulnar nerve can cause an ulnar claw

Question 9

Describe the shape of the radius

Answer 9

• Head = disc shaped

- Shaft = Triangular in cross section

Question 10

How is the radius orientated?

Answer 10

• Head is superior

- Styloid process points towards the thumb

Question 11

What are the salient features of the proximal radius? (2)

Answer 11

• Head at radio ulnar joint

- Radial tuberosity

Question 12

Describe a salient feature of the shaft of the radius

Answer 12

Middle of shaft is where pronator teres attaches

Question 13

Describe the salient features of the distal radius

Answer 13

• Styloid process

- Ulnar notch - articulates with ulna at distal radioulnar joint

Question 14

Where are the ossication centres of the radius and when do they fuse?

Answer 14

• 3 centres (shaft and at either end)
• Distal epiphysis fuses between 14-17
• Proximal epiphysis fuses between 17-19

Question 15

Describe the potential fractures of the radius (2)

Answer 15

• Caused by a fall on an outstretched hand
• Colles fracture = Distal structures are posteriorly displaced
• Radial head fracture = forced into Capitulum

Question 16

Describe the shape of the ulna

Answer 16

• Head = Lots of projections and notches

- Shaft = is triangular proximally and cylindrical distally

Question 17

How is the ulna orientated?

Answer 17

• Olecranon process and trochlea need to be superior

- Radial notch needs to be lateral

Question 18

Describe the salient features of the proximal ulna (5)

Answer 18

• Olecranon process
• Coronoid process
• Trochlear notch
• Radial notch
• Tuberosity of the ulna

Question 19

Describe the salient features of the distal ulna

Answer 19

• Styloid process

Question 20

What are the four centres of ossification of the ulna?

Answer 20

• Olecranon x2
• Shaft X1
• Distal end X1

Question 21

What is the clinical relevance to a fracture of the Olecranon process?

Answer 21

• Due to a fall on a flexed elbow

- Triceps brachii can displace a fragment proximally

Question 22

What is the clinical relevance of a Monteggias fracture?

Answer 22

• Caused by a force from behind the ulna

- Fractures proximal shaft of ulna but dislocates radial head anteriorly

Question 23

Describe the clinical relevance of a Galeazzis fracture

Answer 23

• Due to a fracture of the distal radius

- Dislocates ulna head at distal radioulnar joint

Question 24

Describe the shape of the humerus

Answer 24

• Smooth hemispheric head
• Cylindrical head
• Widens into a condyle distally