Forearm and Elbow

Question 1

What can be damaged by a mid humeral shaft fracture?

Answer 1

Median nerve

Profunda brachii artery

Question 2

Where does the ulnar nerve pass the medial epicondyle?

Answer 2

Posteriorly

Question 3

What movements does the capitulum allow?

Answer 3

Pronation and supination

Question 4

What movements does the trochlea allow?

Answer 4

Flexion and extension

Question 5

What movement does the radial head allow and why?

Answer 5

The rounded head of the radius allows pronation and supination

Question 6

Where is the radial styloid palpable?

Answer 6

Via the anatomical snuffbox on the lateral wrist

Question 7

What does the olecranon bursa allow?

Answer 7

Free movement of the skin over the olecranon (point of elbow)

Question 8

How might the olecranon be fractured?

Answer 8

Direct trauma, avulsion by strong triceps extension, e.g. in fall

Question 9

What bones form the elbow joint?

Answer 9

Distal humerus, radial and ulnar heads

Question 10

What movement does the lateral collateral ligament of the elbow prevent?

Answer 10

Valgus movement/ abduction

Question 11

What movement does the medial collateral ligament of the elbow prevent?

Answer 11

Varus movement/ adduction

Question 12

What 3 points make up the anconeus triangle? Why is this the safest place to inject/aspirate the elbow?

Answer 12

Radial head, olecranon and lateral epicondyl Safest place to inject into or aspirate from elbow as it contains the least structures.

Question 13

What movements do the radio-ulnar joints permit?

Answer 13

Pronation (median nerve) and supination (radial and musculocutaneous nerve) of the forearm

Question 14

What ligament supports the proximal radio-ulnar joint? What type of joint is this?

Answer 14

Annular ligament Synovial pivot joint

Question 15

Interosseous membrane forms what type of joint between the radius and ulna? What is its role?

Answer 15

Fibrous joint Transmission of forces between radius and ulna

Question 16

What is the role of the articular disc?

Answer 16

Separates the ulna from the proximal carpal bones of the hand

Question 17

What nerves supply the anterior compartment of the forearm?

Answer 17

Everything median nerve innervated except:

• Flexor carpi ulnaris
• Flexor digitorum profundus to digits 4 & 5

Question 18

How many layers does the anterior compartment of the forearm have?

Answer 18

3

Question 19

What muscles are found in layer 1 of the anterior compartment of the forearm?

What are their actions and nerve supplies?

Where do they originate from?

Answer 19

Pronator teres:

• Forearm pronator (pulls radius over ulna)
• Median nerve.
• Originates from medial epicondyle and the coronoid process of the ulna.

Flexor carpi radialis:

• Wrist flexor and abductor
• Median nerve (sits medially at wrist)
• Originates from medial epicondyle

Palmaris longus (absent in around 20%):

• Wrist flexor
• Median nerve
• Attaches into aponeuroses on palm of hand.
• Originates from medial epicondyle

Flexor carpi ulnaris:

• Wrist flexion and adduction
• Ulnar nerve
• Originates from medial epicondyle

Question 20

What muscle is found in layer 2 of the anterior compartment of the forearm? What is its action and nerve supply?

Answer 20

Flexor digitorum superficialis:

• Flexion of fingers 2-5 at PIP joint
• Median nerve
• (Attaches to both radius and ulna)

Question 21

What muscles are found in layer 3 of the anterior compartment of the forearm?

What are their actions and nerve supplies?

Answer 21

Flexor pollucis longus:

• Thumb flexor to DIP joint
• Median nerve

Flexor digitorum profundus:

• Flexion of digits 2-5 at DIP joint
• Median nerve digits 2-3, ulnar nerve digits 4-5.

Pronator quadratus:

• Forearm pronator, median nerve

Question 22

How do you test flexor digitorum profundus and ulnar nerve?

Answer 22

Flexion of digits 4 & 5 at DIP

Question 23

How do you test Flexor Digitorum Profundus and median nerve?

Answer 23

Flexion of digits 2 & 3 at DIP

Question 24

What nerve supplies the entire posterior compartment of the forearm?

Answer 24

Posterior interosseous nerve (branch of radial nerve)

Question 25

What muscles are found in layer 1 of the posterior compartment of the forearm? What are their actions?

Answer 25

**Anconeous:** * Elbow extensor **Extensor Carpi Ulnaris:** * Wrist extensor and adductor **Extensor Digiti Minimi:** * 5th digit extensor to DIP **Extensor Digitorum:** * All finger extensor to DIP joint **Extensor Carpi Radialis Brevis and Longus:** * Extensors and adductors of the wrist **Brachioradialis** * Sits anteriorly but is in the posterior compartment * Elbow flexor * Moves arm to mid pronation/supination

Question 26

What muscles are found in layer 2 of the posterior compartment of the forearm? What are their actions?

Answer 26

**Extensor indices:** * Extensor of 2nd digit to PIP joint ​**Extensor pollicus longus:** * Extension of thumb at all joints **Extensor pollicus brevis:** * Thumb extension to MCP joint **Abductor pollicis longus:** * Thumb adduction ALL INNERVATED BY POSTERIOR INTEROSSEOUS NERVE (branch of radial nerve)

Question 27

What are the extensor compartments of the wrist? Which tendons do each contain?

Answer 27

1: * Extensor pollicus brevis * Adductor pollicus longus 2: * Extensor carpi radialis brevis * Extensor carpi radialis longus 3: Extensor pollicus longus 4: * Extensor digititorum * Extensor indices 5: Extensor digiti minimi 6: Extensor carpi ulnaris

Question 28

What form the borders of the cubital fossa?

Answer 28

Superior border: **inter-epicondylar line** Lateral border: **brachioradialis** Medial border: **pronator teres**

Question 29

What does the cubital fossa contain?

Answer 29

**Aponeuroses of biceps** (protects the median nerve and brachial artery) **Biceps tendon** (brachial artery and medial nerve sit medially) **Brachial artery** and its bifurcation into the ulnar and radial arteries, sits medial to the biceps tendon. **Median nerve**, sits medially to brachial artery

Question 30

Where is the brachioradialis muscle located? What are its actions? How is it tested?

Answer 30

Sits anteriorly in the forearm but is part of the posterior compartment. Flexes the elbow and moves arm to mid pronation/supination postition Forms lateral border of cubital fossa Tapping BR in the medial side of the forearm tests C5 & 6 reflex

Question 31

What are the superficial veins of the forearm? Where are they located?

Answer 31

Cephalic vein: lateral side of forearm Basilic: medial side of forearm Linked by median cubital vein

Question 32

Where are the main nerves of the forearm located?

Answer 32

**Radial nerve:** passes anterior to elbow and lateral to biceps tendon, gives off deep posterior interosseous branches which pass close to radial neck. **Ulnar nerve:** passes through cubital tunnel behind medial epicondyl before entering anterior forearm. Runs under cover of FCU and sits lateral to pisiform in the hand- potential compression point. **Median nerve:** passes medial to biceps tendon down the forearm.

Question 33

Can the radial nerve be lost?

Answer 33

The radial nerve can be harvested as long as the palmar arches of the hand join together. Test anastomoses by occluded both radial and ulnar arteries then releasing ulnar to see if it supplies the whole hand alone.

Question 34

Describe the arterial supply to the forearm

Answer 34

The radial and ulnar arteries are formed by the bifurcation of the brachial artery within the cubital fossa: **Radial artery** – * Supplies the posterolateral aspect of the forearm. * It contributes to anastomotic networks surrounding the elbow joint and carpal bones. **Ulnar artery –** * Supplies the anteromedial aspect of the forearm. * It contributes to an anastomotic network surrounding the elbow joint. * Also gives rise to the anterior and posterior interosseous arteries, which supply deeper structures in the forearm. These two arteries anastomose in the hand by forming two arches – the superficial palmar arch, and the deep palmar arch.