MST 2 - upper limb muscles and movements

Question 1

What is the role of fascia?

Answer 1

Fascia separates anterior and posterior muscle compartments, as well as separating muscles within that compartment.

Question 2

The interosseous membrane, retinaculae, aponeurosis and digital sheaths all have what in common?

Answer 2

They are examples of specialised fascia. Other examples include the brachial fascia and the antebrachial fascia.

Question 3

What is the role of the interosseous membrane?

Answer 3

It binds the radius and the ulna together, provides an attachment for muscles and directs force between the radius and the ulna in a fall.

Question 4

What is the job of retinaculae?

Answer 4

It is a specialised deep fascia at the wrist, whose job is to bind down tendons to prevent bow stringing and to protect nerves and vessels.

Question 5

What is special about the flexor retinaculum?

Answer 5

It spans between the scaphoid and the pysoform bones and forms the roof of the carpal tunnel. The carpal bones form the base of the carpal tunnel. Contained within the tunnel are tendons and their synovial sheaths, and the median nerve. When compressed in carpal tunnel syndrome the median nerve results in pain, pines and needles and muscle atrophy. The base of the flexor retinaculum is the most distal wrist crease.

Question 6

Muscles may have one of four functions. List them.

Answer 6

Prime movers, antagonists, synergists or fixators (stabilisers).

Question 7

Where do the superficial (extrinsic) muscles of the back attach to, and what do they act upon?

Answer 7

They attach to the shoulder girdle and act on the upper limb.

Question 8

Name the 4 extrinsic back muscles.

Answer 8

Trapezius (names for its shape), latissimus dorsi, rhomboids (named for its shape) and levator scaplae (names for its function)

Question 9

What is the role of trapezius?

Answer 9

It elevates and depresses the shoulder, and can pull back the scapula to retract the shoulder.

Question 10

What is the role of latissimus dorsi?

Answer 10

It attaches to the arm and extends the shoulder, as well as internal rotation.

Question 11

What is the role of rhomboids?

Answer 11

Attaches to the scapula and allows retraction.

Question 12

What is the role of levator scapulae?

Answer 12

It elevates the scapula.

Question 13

Name the 3 muscles of the shoulder/scapula. that attach to and act on the upper limb.

Answer 13

Pectoralis major, pectoralis minor and serratus anterior.

Question 14

What is the role of pectoralis major?

Answer 14

It is involved in shoulder flexion

Question 15

What is the role of pectoralis minor?

Answer 15

It attaches to the choricoid process of the scapula and allows protraction.

Question 16

What is the role of serratus anterior?

Answer 16

Scapula protraction

Question 17

Name the muscles of the shoulder/scapula that are known as the scapulo-humerus muscles.

Answer 17

The deltoids, the biceps and the rotator cuff muscles.

Question 18

What is the role of the deltoids?

Answer 18

They attach to the scapula and the humerus and allow flexion, some extension and abduction.

Question 19

Name the four rotator cuff muscles.

Answer 19

Supraspinatous, infraspinatous, teres minor and subscapularis.
(Supraspinatous is about the spine of the scapula, infraspinatous is below the spine of the scapula, subscapularis sits infront of the scapula, and teres minor is below infraspinatous)

Question 20

What is the role of the rotator cuff muscles?

Answer 20

All the tendons of the rotator cuff muscles wrap around the glenohumerus and act as fixators.

Question 21

Name the muscles of the anterior compartment of the arm

Answer 21

Biceps brachii, coracobrachialis and brachialis

Question 22

What is the role of the anterior compartment of the arm?

Answer 22

Elbow flexion

Question 23

List the main features of biceps brachii

Answer 23

It has two heads, one long and one short.

Question 24

Where is brachialis found?

Answer 24

Under the biceps

Question 25

Where is coracobrachialis and what is its function?

Answer 25

It is a vestigial muscle running under the arm which is used for adduction when climbing trees. It is highly variable in todays humans.

Question 26

What muscle is in the posterior compartment of the arm? What is its function?

Answer 26

Triceps brachii. It extends the elbow. Has 3 heads, a long head which hides a medial head and a lateral head. It attaches to the process of the ulna distally.

Question 27

How many layers of muscle are there in the anterior compartment of the forearm? Name them

Answer 27

3. Superficial, intermediate and deep.

Question 28

What is the common origin of the anterior muscles of the forearm?

Answer 28

The medial epicondyle of the humerus

Question 29

What is the common origin for the posterior muscles of the forearm?

Answer 29

The lateral epicondyle of the humerus

Question 30

Anterior muscles generally perform which function?

Answer 30

Flexion

Question 31

Posterior muscles generally perform what function?

Answer 31

Extension

Question 32

List the features of the muscles in the superficial layer of the anterior compartment of the forearm.

Answer 32

They are long, and most cross at the wrist. They all arise from the medial epicondyle (common flexor origin)

Question 33

Name the muscles in the superficial layer of the anterior compartment of the forearm.

Answer 33

Pronator teres (doesn’t do flexion, pronates), flexor carpi radialis (on the radius side), palmaris longus (20% of people don’t have, claw retractor), flexor carpi ulnaris (on ulnar side).

Question 34

What is the muscle in the intermediate layer of the anterior compartment of the forearm? List its function and main features.

Answer 34

Flexor digitorum superficialis. It flexes the digits. It is a very powerful muscle and has a unique splitting of the tendons at the wrist, and then further as it enters the digits. It arises from the medial epicondyle of the humerus (the common flexor origin), the radius and the ulna.

Question 35

What are the muscles of the depp layer of the anterior compartment of the forearm? Where do they all arise from?

Answer 35

Flexor pollicis longus (attaches onto the thumb only), flexor digitorum profundus (deepest muscle) and pronator quadratus. They all arise from the radius and the ulna, and some are also attached to the interosseous membrane.

Question 36

What is the relevance of the carpal tunnel to the anterior muscles of the forearm?

Answer 36

All their tendons go through it, except for flexor pollicis longus which is just intimately associated with the carpal tunnel. When pressure in the carpal tunnel increases, as often happens during pregnancy with increased fluid retention, carpal tunnel syndrome results as the median nerve is compressed.

Question 37

How many layers are there in the posterior compartment of the forearm? What is their common origin?

Answer 37

There are 2 layers; superficial and deep. The muscles attach to the lateral epicondyle, known as the common extensor origin.

Question 38

What muscles are in the superficial layer of the posterior compartment of the forearm?

Answer 38

• brachioradialis; doesn’t cross the wrist, its main action is as an elbow extendor
• 3 muscles extend the wrist; extensor carpir radialia longus, extensor carpi radialis brevis and extensor carpi ulnaris
• 2 muscles extend the digits; extensor digitorum communis (the common extensor), extensor digiti minimi (extends the little finger)

Question 39

What are the muscles in the deep layer of the posterior compartment of the forearm? Where do they originate from?

Answer 39

Supinator, abductor pollicis longus, extendor pollicis brevis, extensor pollicis longus and extensor indicis. They all originate from the ulna/radius/interosseous membrane

Question 40

The tendons of which muscles form the anatomical snuff box borders? What bone forms the snuff box base?

Answer 40

The tendons of abductor pollicis longus forms one edge, the tendons of extensor pollicis longus and extensor pollicis brevis form the other edge. The scaphoid bone forms the base.

Question 41

The tendons of which muscles pass under the extensor retinaculum?

Answer 41

The muscles in the posterior compartment of the forearm.

Question 42

As tendons pass under retinaculum they are encased by what?

Answer 42

Synovial sheaths

Question 43

How many groups of intrinsic muscles in the hand are there? Name them

Answer 43

4. Thenar muscles (x 3), hypothenar muscles (x 3), lumbricals (x 4) and interossei (x 7)

Question 44

List the special structures of the hand

Answer 44

Palmar aponeurosis (source of cupping of the palm), and digital sheaths (like retinaculae for the fingers)