Anatomy of the arm

Question 1

In a patient with difficulty retracting the scapula, which muscle is most likely affected?

Answer 1

Rhomboid minor

Question 2

Which of the following can extend, adduct and medially rotate the arm?

Answer 2

Latissimus dorsi

Question 3

Which muscle is responsible for retracting the scapula and is often strengthened during exercise like rowing?

Answer 3

Rhomboid major

Question 4

What is the name of the bone of the skeleton?

Answer 4

Humerus

Question 5

What are the different structures in the humerus?

Answer 5

1) Head of the humerus
2) Neck of the humerus
3) Surgical neck of the humerus
4) Shaft of the humerus
5) Lateral epicondyle
6) Medial epicondyle
7) Bicipital groove
8) Greater tubercle
9) Lesser tubercle
10) Deltoid tuberosity

Anteriorly:
1) Capitulum (where the head of the radius articulate)
2) Trochlea (articulates with the trochlear fossa of the ulna)
3) Coronoid fossa
4) Radial fossa

Posteriorly:
1) Olecranon fossa (for the olecranon process of the ulnar)

2)

Question 6

The ulnar nerve is behind which structure of the humerus?

Answer 6

The medial epicondyle

Question 7

Define the elbow joint

Answer 7

The combination of the trochlea with the trochlear fossa of the ulna & capitullem with head of the radius

Question 8

What type of joinT is the elbow join?

Answer 8

Synovial hinge joint

• Only flexes and extends uniaxially

Question 9

The rotation that happens in the arm/forearm are due to which structure?

Answer 9

Between the radius and the ulna

Question 10

What are the compartments of the arm?

Answer 10

Anterior and posterior

• Divided by the humerus and 2 intermuscular septa
• Each compartment has its own muscle nerves and arteries
• Anterior compartment contains the flexor group which flexes the elbow and shoulder joint, while the posterior contains the extensors

Question 11

What connects the deep fascia with the lateral border of the humerus?

Answer 11

Lateral intermuscular septa

Question 12

What connects the deep fascia to the medial border of the humerus?

Answer 12

Medial intermuscular septa

Question 13

In which compartment of the arm is the triceps found?

Answer 13

Posterior compartment

Question 14

In which compartment of the arm are the biceps, brachialis & coracobrachialis found?

Answer 14

Anterior compartment

Question 15

What is a brachium?

Answer 15

It is another name of the humerus

Question 16

What is the landmark of the ulnar nerve?

Answer 16

It is behind the medial epicondyle

Question 17

What is the landmark of the musculocutaneous nerve?

Answer 17

It pierces the coracobrachialis muscle

Question 18

What is the change that occurs to the musculocutaneous nerve once it pierces the fascia?

Answer 18

It becomes the cutaneous nerve

Question 19

Which muscles will be supplied by the axillary nerve?

Answer 19

It loops around the surgical neck and supplies the deltoid and teres minor

Question 20

What is the origin of the bicep brachii?

Answer 20

1) Long head:
- Supraglenoid tubercle of the scapula within the shoulder joint

2) Short head:
- Tip of the coracoid process in common with the coracobrachialis

Question 21

Where is the bicep brachii inserted?

Answer 21

1) Via a strong tendon it is inserted into the posterior rough part of the radial tuberosity

2) via bicipital aponeurosis (arises from the tendon of the biceps) which blends with the deep fascia of the forearm

Question 22

What is the nerve supply of the bicep brachii?

Answer 22

Musculocutaneous nerve

Question 23

What are the different actions of the bicep brachii?

Answer 23

Both heads:
- Supination of the flexed forearm
- Flexion of the elbow joint

Short head:
- Weak flexor of the shoulder joint

Long head:
- Prevents the upward dislocation of the shoulder joint

Question 24

What is the origin of the coracobrachialis muscle?

Answer 24

Tip of the coracoid process, common with the short head of the biceps

Question 25

What is the place of insertion of the coracobrachialis muscle?

Answer 25

Medial border of the humerus

Question 26

What is the nerve supply of the humerus?

Answer 26

Musculocutaneous nerve

Question 27

What is the action of the coracobrachialis muscle?

Answer 27

Flexion and adduction of the arm

Question 28

What is the origin of the brachialis muscle?

Answer 28

1) Lower 1/2 of the front of the humerus

2) Lateral and medial intermuscular septa

Question 29

What is the site of insertion of the brachialis muscle?

Answer 29

Ulnar tuberosity

Question 30

What is the nerve supply of the brachialis muscle?

Answer 30

1) Musculocutaneous nerve
2) Radial nerve supplies a small part of its lateral side

Question 31

What is the action of the brachialis muscle?

Answer 31

Flexion of the elbow

• Main flexor of the elbow joint

Question 32

What is the origin of the long head of the triceps?

Answer 32

Infraglenoid tubercle of the scapula

Question 33

What is the site of origin of the lateral head of the biceps?

Answer 33

Upper 1/2 of the posterior surface of the shaft of the humerus above the spiral groove of the scapula

Question 34

What is the site of origin of the medial head of the triceps?

Answer 34

1) Posterior surface of the lower 1/2 of the shaft of the humerus below the spiral groove

2) Back of the lateral & medial intermuscular septa

Question 35

What is the site of insertion of the triceps brachii?

Answer 35

The 3 heads fuses together in a common tendon attaching to the posterior part of the upper surface of the olecranon process of the ulna

Question 36

What is the nerve supply of the triceps brachii?

Answer 36

• Each head receives a separate branch from the radial nerve

Question 37

What is the action of the triceps brachii?

Answer 37

• Powerful extensors of the elbow joint
• Main function is to keep the elbow extended when someone is pushing an object

Question 38

What are the nerves of the anterior compartment of the arm?

Answer 38

1) Musculocutaneous nerve (the nerve that pierces the coracobrachialis muscle)
2) Median nerve
3) Ulnar nerve

Question 39

What are the muscles supplies by the musculocutaneous nerve?

Answer 39

all anterior compartment muscles (brachialis, coracobrachialis, and biceps)

Question 40

Describe the root of the musculocutaneous nerve through the anterior compartment of the arm

Answer 40

It enters through the coracobrachialis muscle, moves across the biceps and pierces the deep fascia to become the lateral cutaneous nerve of the forearm

Question 41

What is the origin of the brachial artery?

Answer 41

It is a continuation of the axillary at the lower border of the teres major

Question 42

Describe the course of the brachial artery

Answer 42

Passes downwards and laterally from the medial side of the humerus to the front of the arm

Question 43

Where is the brachial artery terminated?

Answer 43

Opposite to the neck of the radius by dividing into the radial and ulnar arteries

Question 44

What are the branches of the brachial artery

Answer 44

1) Profunda brachii (biggest branch the supplies the posterior compartment)

• Leaves the anterior compartment through the lower triangular space and then runs in the posterior compartment in the spiral groove, and terminates as it branches into anterolateral-descending & posterolateral descending
• It will give muscular branch to the triceps, nutrient artery branch to the humerus & lateral descending which will share anastomosis around the humerus from the lateral epicondyle

2) Superior ulnar collateral (share anastomoses with the ulnar)

3) Inferior ulnar collateral (shares anastomoses around the elbow)

• superior and inferior will share anastomoses around the medial epicondyle

4) Muscular (from the profunda brachii branch)

5) Nutrient artery (from the profunda brachii branch to the humerus)

6) Terminal artery (radial and ulnar arteries)