Week 4

Question 1

Name the superficial, intermediate, and deep muscles of the anterior compartment of the forearm

Answer 1

Superficial: flexor carpi ulnaris, palmaris longus, flexor carpi radialis, pronator teresIntermediate: flexor digitorum superficialisDeep: flexor digitorum profundus, flexor pollicus longus, pronator quadratus

Question 2

The superficial muscles in the anterior compartment of the forearm all originate from where?

Answer 2

They all originate from a common tendon, which originates from the medial epicondyle of the humerus (they hence all cross the elbow joint)

Question 3

What is the action of the flexor carpi ulnaris? What is its innervation?

Answer 3

Flexion and adduction at the wrist; ulnar nerve

Question 4

What is the action of the palmaris longus? What is its innervation?

Answer 4

Flexion at the wrist; median nerve

Question 5

Which structure is just underneath the palmaris longus? In what percentage of the population is the palmaris longus absent?

Answer 5

Median nerve; 15%

Question 6

What is the action of the flexor carpi radialis? What is its innervation?

Answer 6

Flexion and abduction at the wrist; median nerve

Question 7

What is the significance of the pronator teres with regard to the cubital fossa?

Answer 7

The lateral border of the pronator teres forms the medial border of the cubital fossa

Question 8

What is the action of the pronator teres? What is its innervation?

Answer 8

Pronates the forearm; median nerve

Question 9

Which two structures can be found passing between the two heads of the flexor digitorum superficialis?

Answer 9

The median nerve and ulnar artery

Question 10

To where do the four distal tendons of the flexor digitorum superficialis attach?

Answer 10

The middle phlanges of the four fingers

Question 11

What are the actions of the flexor digitorum superficialis?

Answer 11

Flexes the metacarpophalangeal joints, and proximal interphalangeal joints at the 4 fingers, and flexes the wrist

Question 12

What is the innervation of the flexor digitorum superficialis?

Answer 12

The median nerve

Question 13

The tendons of which two muscles pass through the carpal tunnel?

Answer 13

Flexor digitorum superficialis and flexor digitorum profundus

Question 14

To what do the tendons of the flexor digitorum profundus attach?

Answer 14

The distal phlanges of the four fingers

Question 15

What are the actions of the flexor digitorum profundus?

Answer 15

It is the only muscle that can flex the distal interphalangeal joints at the wrist; it also flexes the metacarpophalangeal joints and at the wrist

Question 16

What is the innervation of the flexor digitorum profundus?

Answer 16

Medial half is innervated by the ulnar nerve; the lateral half is innervated by the median nerve

Question 17

Describe the position of the flexor pollicis longus relative to the flexor digitorum profundus

Answer 17

The flexor pollicis longus lies laterally to the flexor digitorum profundus

Question 18

What are the actions of the flexor pollicis longus?

Answer 18

Flexes the interphalangeal joint and metacarpophalangeal joint of the thumb

Question 19

What is the innervation of the flexor pollicis longus?

Answer 19

Median nerve

Question 20

Describe the shape and location of the pronator quadratus

Answer 20

Square shaped muscle, lies deep to the tendons of the flexor digitorum profundus and flexor pollicis longus

Question 21

What is the action of the pronator quadratus? What is its innervation?

Answer 21

Acts to pronate the forearm; median nerve

Question 22

Which bones and what else form the carpal tunnel?

Answer 22

Pisiform, triquetrum, lunate, capitate, trapezoid trapezium, flexor retinaculum

Question 23

Which structures are of importance within the carpal tunnel?

Answer 23

Median nerve, tendons of the flexor digitorum superficialis, flexor digitorum profundus and flexor pollicis longus (9 tendons)

Question 24

What is carpal tunnel syndrome?

Answer 24

Compression of the median nerve within the carpal tunnel; thought to be due to increased pressure/thickening of tendon sheaths

Question 25

What are the typical signs of carpal tunnel syndrome?

Answer 25

Pins and needles in the sensory distribution of the median nerve and weakness of thenar muscles

Question 26

Why is some median nerve function retained in carpal tunnel syndrome?

Answer 26

The palmar cutaneous branch of the median nerve travels superficial to the flexor retinaculum

Question 27

Where is there sensation loss for people with Erb’s palsy?

Answer 27

The sensory areas that are supplied by the axillary and musculotaneous nerves; down the lateral side of the arm

Question 28

Does the musculotaneous nerve have any sensory function?

Answer 28

Lateral cutaneous nerve provides sensory function to the lateral side of the forearm

Question 29

Where would there be loss of sensation with a lesion of the musculotaneous nerve?

Answer 29

Lateral side of the forearm

Question 30

What sensory function does the axillary nerve contribute to?

Answer 30

Gives rise to lateral cutaneous nerve of arm; innervates the skin over the posterior deltoid, the ‘regimental badge’ area

Question 31

What sensory loss will occur with an injury to the axillary nerve?

Answer 31

If the lateral cutaneous nerve supply is interrupted, there will be loss of sensation over the regimental badge area

Question 32

Which to muscles does the median nerve travel in between as it passes through the forearm?

Answer 32

Flexor digitorum profundus and flexor digitorum superficialis

Question 33

Describe two important branches of the median nerve as it passes through the forearm, and their functions

Answer 33

Anterior interosseous nerve, supplying deep flexor muscles, and palmar cutaneous nerve, which innervates skin on the palmar, lateral aspect of the hand

Question 34

What are the respective areas supplied by the radial and ulnar arteries?

Answer 34

Radial: posterior aspect, Ulnar: anterior aspect

Question 35

What are some common risk factors for carpal tunnel syndrome?

Answer 35

TRAMP; trauma, rheumatoid arthritis, acromegaly, myxoedema, pregnancy

Question 36

Which myotome performs abduction of the arm at the glenohumeral joint?

Answer 36

C5

Question 37

Which myotome performs flexion of the forearm at the elbow joint?

Answer 37

Primarily C6 (some C5)

Question 38

Which myotome performs extension of the forearm at the elbow joint?

Answer 38

Mainly C7 (some 6/8)

Question 39

Which myotome performs flexion of the forearm of the fingers?

Answer 39

C8

Question 40

Which myotome performs abduction and adduction of the index, middle and ring fingers?

Answer 40

T1

Question 41

What is the cubital tunnel?

Answer 41

Formed by tendinous arch joing humeral and ulnar heads of the attachment of flexor carpi ulnaris; the median nerve enters the forearm through it

Question 42

Which myotome performs adduction at the shoulder?

Answer 42

C6, C7, (C8)

Question 43

Which myotome performs pronation?

Answer 43

C7, C8

Question 44

Which myotome performs supination?

Answer 44

C6

Question 45

What are the medial and lateral attachments of the flexor retinaculum?

Answer 45

Medially attached to the pisiform and hook of hamate; laterally attached to the tubercle of the scaphoid and trapezium bones

Question 46

Give causes of carpal tunnel syndrome

Answer 46

Tenosynovitis (thickening of synovium), repetitive trauma (compression forces and stretching), oedema, fractures, dislocations, inherited small bone fractures