L7 Anatomy of the forearm

Question 1

Elbow joint - type

Answer 1

Synovial hinge joint - flexion/extension

Question 2

Proximal radioulnar joint - type

Answer 2

• Pivot joint for supination/pronation

Question 3

Elbow ligaments

Answer 3

• Annular ligament
• Radial collateral ligament
• Ulnar collateral ligament

Question 4

What is the cubital fossa

Answer 4

• Triangle region over anterior elbow

Question 5

Clinical relevance of the median cubital vein

Answer 5

• Important for venepuncture

Question 6

Forearm compartments

Answer 6

• Flexor compartment

- Extensor compartment

Question 7

Superficial muscles of the anterior forearm

Answer 7

• 3 flexors of wrist (carpi)

- 1 pronator

Question 8

Intermediate muscles of the anterior forearm

Answer 8

• 1 flexor of digits 2-5 (digitorum)

Question 9

Deep muscles of the anterior forearm

Answer 9

• 1 flexor of digits 2-5 (digitorum)
• 1 flexor of thumb (pollicis)
• 1 pronator

Question 10

What is golfers elbow

Answer 10

• Epicondylitis at CFO(common flexor origin)

- Tendon inflammation due to overuse/excessive gripping)

Question 11

Muscle that forms the intermediate layer of the anterior forearm

Answer 11

• Flexor digitorum superficialis

Question 12

Muscles that form the deep layer of the anterior forearm

Answer 12

• Flexor pollicis longus
• Flexor digitorum profundus
  + pronator quadratus

Question 13

Muscles in extensor compartment of the posterior forearm

Answer 13

Superficial muscles:

• 3 extensors of wrist (carpi)
• 1 extensor of digits 2-5 (digitorum)
• 1 accessory extensor to digit 5 (digiti minimi)
• Brachioradialis and anconeus

Deep muscles:

• 2 Extensors of thumb (pollicis)
• 1 Abductor of thumb (pollicis)
• 1 Accessory extensor to digit 2 (indicis)
• 1 supinator

Question 14

Muscles that form the superficial layer of the extensor compartment

Answer 14

• Extensor carpi radialis longus/brevis
• Extensor digitorum
• Extensor digiti minimi (accessory to extensor digitorum)
• Extensor carpi ulnaris

Question 15

What is tennis elbow

Answer 15

• Epicondylitis at common extensor origin (tendon inflammation due to overuse/forceful extension)

Question 16

Other superficial muscles involved in the control of the forearm

Answer 16

Brachioradialis - flexor when half pronated

Anconeus - stabilises elbow

Question 17

Muscles that form the deep layer of the extensor compartment

Answer 17

• Supinator
• Abductor pollicis longus
• Extensor pollicis brevis
• Extensor pollicis longus
• Extensor indicis (accessory to extensor digitorum)

Question 18

Muscles of the deep layer of the extensor compartment that go through the anatomical snuff box

Answer 18

• Abductor pollicis longus
• Extensor pollicis brevis
• Extensor pollicis longus

Question 19

What is wrist abduction performed by

Answer 19

• Flexor carpi radialis

- Extensor carpi radialis (longus + brevis)

Question 20

What is wrist adduction performed by

Answer 20

• Flexor carpi ulnaris

- Extensor carpi ulnaris

Question 21

Muscles involved in supination

Answer 21

• Biceps brachii

- Supinator

Question 22

Muscles involved in pronation

Answer 22

• Pronator teres

- Pronator quadratus

Question 23

Joints involved in pronation and supination

Answer 23

• Proximal radioulnar joint
• Distal radioulnar joint

(During pronation, the radius rotates over the ulna)

Question 24

What is the carpal tunnel a tunnel for

Answer 24

• Tunnel for flexor tendons to digits and median nerve

Question 25

Function of flexor retinaculum (transverse carpal ligament)

Answer 25

- Prevents bowing of tendons

Question 26

Contents of the carpal tunnel

Answer 26

- Median nerve - Flexor policis longus - Flexor digitorum superficialis - Flexor digitorum profundus

Question 27

What is carpal tunnel syndrome

Answer 27

- Median nerve compression | - Due to increased pressure in carpal tunnel (associated with trauma, obesity, pregnancy)

Question 28

Purpose of extensor retinaculum

Answer 28

- Prevents bowing of tendons | - Separates tendons into compartments

Question 29

Long tendon insertions

Answer 29

Tendons to digits 2-5 Extensor digitorum - into middle + distal phalanx Flexor digitorum profundus - into distal phalanx Flexor digitorum superficialis - into middle phalanx

Question 30

Arterial supply to the forearm

Answer 30

Cubital fossa - brachial artery divides into: Radial artery - under brachioradialis Ulnar artery - under flexor carpi ulnaris, gives off common interosseous - Anastomosis around elbow joint

Question 31

What does the ulnar artery give rise to

Answer 31

- Common interosseous artery --> Posterior interosseous artery + anterior interosseous artery

Question 32

Location of the median nerve

Answer 32

- Lies mid forearm between FDS and FDP

Question 33

What does the median nerve give rise to

Answer 33

- Anterior interosseous nerve (to deep flexor muscles) - Passes through carpal tunnel - Motor supply to anterior compartment except FCU/medial part of FDP - Sensory supply to lateral palm + d1, d2, d3, 1/2 d4

Question 34

Innervation provided by the ulnar nerve

Answer 34

- Motor supply to FCU and medial part FDP | - Sensory supply to medial hand including 1/2 d4 + d5

Question 35

What is cubital tunnel syndrome

Answer 35

Cubital Tunnel Syndrome is a condition that involves pressure or stretching of the ulnar nerve (also known as the “funny bone” nerve), which can cause numbness or tingling in the ring and small fingers, pain in the forearm, and/or weakness in the hand.

Question 36

Path of radial nerve

Answer 36

- Enters forearm on lateral side under brachioradialis Divides into two branches: Superficial branch (sensory) + deep branch - posterior interosseous nerve (motor)

Question 37

Path of the superficial branch of the radial nerve

Answer 37

- Under brachioradialis | - Winds round to dorsum of hand

Question 38

Path of the deep branch of the radial nerve

Answer 38

- Passes through supinator muscle | - Enters extensor compartment

Question 39

What is wrist drop

Answer 39

Condition in which the wrist and the fingers cannot extend at the metacarpophalangeal joints. The wrist remains partially flexed due to an opposing action of flexor muscles of the forearm. As a result, the extensor muscles in the posterior compartment remain paralyzed.

Question 40

What does the deep branch of the radial nerve provide innervation to

Answer 40

- Deep branch supplies posterior compartment

Question 41

What does the superficial branch of the radial nerve provide innervation to

Answer 41

- Superficial branch supplies lat dorsum hand