Upper Limb - Muscles (1)

Question 1

In the muscles of the upper arm, what separates the anterior compartment from the posterior compartment? Describe this structure.

Answer 1

The intermuscular septum, which is continuous with the deep fascia of the upper arm, which surrounds all the muscles of the upper arm. The lateral intermuscular septum is separated from the medial intermuscular septum by the humerus bone.

Question 2

Name the three muscles in the anterior comparment of the upper arm. How are these muscles innervated?

Answer 2

Biceps brachii. Coracobrachialis. Brachialis muscle. All innervated by the musculocutaneous nerve.

Question 3

Describe the attachments of the biceps brachii.

Answer 3

The long head of biceps originates from the supraglenoid tubercle of the scapula, then runs down through the intertubercular groove of the humerus. The short head of biceps originates from the coracoid process of the scapula. The biceps then inserts mostly as the bicipital aponeurosis onto the fascia of the forearm, but also as the radial tuberosity.

Question 4

Describe the attachments of the coracobrachialis. What lies superficially to the coracobrachialis?

Answer 4

The coracobrachialis originates from the **coracoid process **of the scapula, and inserts at the mid-shaft of the humerus. The coracobrachialis lies deep to the biceps brachii.

Question 5

Describe the attachments of the brachialis muscle.

Answer 5

The brachialis originates from the mid-shaft of the humerus and inserts at the ulnar tuberosity.

Question 6

Describe the muscles of the posterior compartment of the arm, including attachments.

Answer 6

There is just the triceps brachii. The long head originates from the infraglenoid tuberosity of the scapula, the lateral head originates from the upper shaft of the humerus, and the medial head lies just deep to this, originating just a little more distally. All three heads converge to form the triceps tendon, which inserts onto the olecranon process of the ulna.

Question 7

What is the innervation to the triceps brachii?

Answer 7

The Radial Nerve.

Question 8

What is meant by the mnemonic “The Lady between two Majors”

Answer 8

The insertion of the Latissimus dorsi is on the intertubercular groove of the humerus, in between the insertion sites of the Teres Major and the Pectoralis Major.

Question 9

Name the origins of the pectoralis major.

Answer 9

Medial half of clavicle, Anterior surface of sternum, Aponeurosis of external oblique.

Question 10

Name the distal attachment of pectoralis major.

Answer 10

Lateral lip of intertubercular groove of humerus.

Question 11

Name the origins of the pectoralis minor.

Answer 11

3rd-5th ribs, near their costal cartilages.

Question 12

Name the distal attachment of the pectoralis minor. Which muscle overlies the pectoralis minor?

Answer 12

Coracoid process of scapula. Pectoralis major overlies it.

Question 13

What causes a winged scapula?

Answer 13

Injury to the long thoracic nerve, causing paralysis of the serratus anterior muscle.

Question 14

What are the proximal attachments (origins) of the trapezius muscle?

Answer 14

Nuchal ligament, Spinous processes of C7-T12 vertebrae.

Question 15

What are the distal attachments of the trapezius muscle?

Answer 15

Lateral third of clavicle, Spine of scapula.

Question 16

Name two major adductors of the humerus.

Answer 16

Latissimus dorsi. Teres major.

Question 17

What are the technical terms for these movements of the scapula:

1. Shrug
2. Hug
3. Star jumps

Answer 17

1. Elevation/Depression
2. Protraction/Retraction
3. Upward rotation / Downward rotation

Question 18

Name the deep muscles that retract the scapulae.

Answer 18

Rhomboids.

Question 19

Name the deep muscles that allow you to shrug your shoulders.

Answer 19

Levator scapulae.

Question 20

During the first 15 degrees of abduction of the arm, which muscle is required to assist the deltoid?

Answer 20

Supraspinatus.

Question 21

The deltoid muscle is innervated by the _______ nerve.

Answer 21

Axillary.

Question 22

Name the muscles of the following walls of the axilla:

1. Medial wall
2. Anterior wall
3. Posterior wall

What is the bony structure making up the lateral wall?

Answer 22

1. Serratus anterior
2. Pectoralis major and minor
3. Subscapularis

The intertubercular groove of the humerus.

Question 23

What holds the tendon of the long head of biceps in the intertubercular groove?

Answer 23

The transverse humeral ligament.

Question 24

What is the anconeus muscle?

Answer 24

A small, triangular muscle on the posterolateral aspect of the elbow.

Question 25

What is the main flexor of the elbow?

Answer 25

Brachialis.

Question 26

What are the names of the two compartments of the forearm, and where are the situated?

Answer 26

Flexor-pronator compartment (positioned antero-medially), and Extensor-supinator compartment (positioned postero-laterally)

Question 27

Name the four muscles in the superficial layer of the flexor-pronator muscles of the forearm.

Answer 27

From lateral to medial: Pronator teres, Flexor carpi radialis, Palmaris longus, Flexor carpi ulnaris.

Question 28

What is the common flexor attachment?

Answer 28

This is the proximal attachment of all four muscles in the superficial layer of the flexor-pronator muscles of the forearm, as well as the flexor digitorum superficialis (of the intermediate layer), and it is at the medial epicondyle.

Question 29

Name the muscles of the intermediate layer of the flexor-pronator muscles of the forearm.

Answer 29

One muscle: flexor digitorum superficialis

Question 30

Name the muscles of the deep layer of the flexor-pronator muscles of the forearm.

Answer 30

Flexor digitorum profundus, Flexor pollicis longus, Pronator quadratus.

Question 31

Which nerve supplies most of the muscles of the anterior compartment of the forearm? Which nerve supplies the minority of these muscles?

Answer 31

Most by the median nerve. The ulnar nerve supplies flexor carpi ulnaris, and the medial half of flexor digitorum profundus.

Question 32

Which flexor muscle of the forearm is absent in approximately 14% of people?

Answer 32

Palmaris longus

Question 33

What is the only muscle that can flex the distal interphalangeal joints of the fingers?

Answer 33

Flexor Digitorum Profundus.

Question 34

Which tendons of the forearm are ensheathed in synovial tendon sheaths, and why?

Answer 34

The extensor tendons as they pass over the dorsum of the wrist, the synovial tendon sheaths reduce friction.

Question 35

Where is the common extensor origin?

Answer 35

Lateral epicondyle of humerus.

Question 36

Name the muscles of the superficial layer of the extensor compartment of the forearm.

Answer 36

From lateral to medial: Brachioradialis, Extensor carpi radialis longus, Extensor carpi radialis brevis, Extensor digitorum, Extensor digiti minimi, Extensor carpi ulnaris.

Question 37

Name the five muscles of the deep layer of the posterior compartment of the forearm.

Answer 37

In order of their origins, from proximal to distal: Supinator, Abductor pollicis longus, Extensor pollicis longus, Extensor pollicis brevis, Extensor indicis.

Question 38

Which two tendons form the borders of the anatomical snuff box?

Answer 38

Laterally: Extensor Pollicis Brevis. Medially: Extensor Pollicis Longus.

Question 39

Which artery lies in the floor of the anatomical snuff box?

Answer 39

Radial artery.

Question 40

Which nerve gives off the posterior interosseous nerve? Where does this happen? Which muscle does it penetrate? What is the name for this nerve *before* it has penetrated this muscle?

Answer 40

Radial nerve. At the cubital fossa. Penetrates the supinator muscle. Called the **deep branch of the radial nerve** until it penetrates the supinator, at which point it becomes named the **posterior interosseous nerve**

Question 41

Which is more medial, the short head of biceps or the long head of biceps?

Answer 41

The short head.

Question 42

Name the two heads of the flexor digitorum superficialis, and their origins.

Answer 42

Humeroulnar head: Medial epicondyle (common flexor origin) and coronoid process of ulna. Radial head: Anterior surface, just below the tuberosity.

Question 43

What is the bicipital aponeurosis?

Answer 43

It is part of the distal attachment of the biceps brachii.

Question 44

Where does the extensor pollicis longus insert? Where does the extensor pollicis brevis insert?

Answer 44

Longus: base of distal phalynx. Brevis: base of proximal phalynx.