Week 4 - Musculoskeletal

Question 1

There are two muscles which are innervated by the accessory nerve (CNXI). What are they?

Answer 1

Trapezius and sternocleidomastoid

Accessory nerve (CNXI)

= posterior triangle of neck & nerve crosses it

Question 2

The superficial muscles in the flexor compartment of the forearm share a tendinous proximal attachment; this is referred to as the common flexor origin/tendon. This is located on the:

Answer 2

Anterior compartment of forearm = FLEXORS

Common flexor origin = the medial epicondyle of the humerus

The common flexor tendon is the convergence of 5 muscles:

1. pronator teres
2. flexor carpi radialis
3. palmaris longus
4. flexor digitorum superficialis
5. flexor carpi ulnaris.

Medial epicondylitis = golfers elbow

Common extensor origin (posterior compartment of forearm) = Lateral epicondyle (Tennis elbow)

Question 3

Which nerve from the brachial plexus innervates the three muscles of the anterior (flexor) compartment of the arm?

Answer 3

Musculocutaneous nerve

Question 4

List the three muscles with their origin at the landmark marked with the green arrow.

Answer 4

Landmark = the coracoid process of the scapula.

1. Pectoralis minor
2. Coracobrachialis
3. Biceps brachii (short head)

Question 5

Which commonly fractured carpal is found on the floor of the anatomical snuffbox?

Answer 5

= Scaphoid

Anatomical Snuffbox

Borders - As the snuffbox is triangularly shaped, it has three borders, a floor, and a roof:

• Ulnar (medial) border: Tendon of the extensor pollicis longus.
• Radial (lateral) border: Tendons of the extensor pollicis brevis and abductor pollicis longus.
• Proximal border: Styloid process of the radius.
• Floor: Carpal bones; scaphoid and trapezium.
• Roof: Skin.

Contents

1. Radial artery
2. Superficial branch of the radial nerve
3. Cephalic vein

Question 6

What are the carpal bones?

Answer 6

Question 7

An elderly lady with cervical spine osteoarthritis has foraminal narrowing at the C5/6 intervertebral foramen causing compression of the C6 nerve root. The ideal location to test this dermatome is:

1. First digit (thumb)
2. Tip of shoulder
3. Third digit (middle finger)
4. Fifth digit (little finger)
5. Above the medial epicondyle

Answer 7

1. First digit (thumb)
2. Tip of shoulder
3. Third digit (middle finger)
4. Fifth digit (little finger)
5. Above the medial epicondyle