2.1.3. Muscles of the Posterior (Extensor) Compartment of the Upper Arm

Question 1

Where does the Arm extend:
1. From?
2. To?

Answer 1

1. Shoulder
2. Elbow

Question 2

What are the 2 Compartments of the Arm?

Answer 2

1. Anterior (Flexor)
2. Posterior (Extensor)

Question 3

What are the 2 Muscles of the Posterior (Extensor) Compartment?

Answer 3

1. Triceps Brachii
2. Anconeus

Question 4

What is the Arterial Supply to the Triceps Brachii?

Answer 4

Profunda Brachii Artery

Question 5

How many Heads does the Triceps Brachii have?

Answer 5

3

Question 6

What are the 3 Heads of the Triceps Brachii?

Answer 6

1. Medial Head
2. Lateral Head
3. Long Head

Question 7

1. Which of the Heads of the Triceps Brachii sits Deepest?
2. Where do the other 2 sit?

Answer 7

1. The Medial Head of the Triceps Brachii
2. They Lateral and Long Heads cover the Medial Head of the Triceps Brachii

Question 8

Where does the Medial Head of the triceps Brachii originate from?

Answer 8

The Humerus, inferior to the Radial Groove

Question 9

Where does the Lateral Head of the Triceps Brachii originate from?

Answer 9

The Humerus, superior to the Radial Groove

Question 10

Where does the Long Head of the Triceps Brachii originate from?

Answer 10

The Infraglenoid Tubercle

Question 11

What happens to the Triceps Brachii as they converge?

Answer 11

They form one Tendon

Question 12

Where does the Tendon of the Triceps Brachii attach Distally?

Answer 12

Olecranon of the Ulna

Question 13

What is the function of the Triceps Brachii?

Answer 13

Extension of the Arm at the Elbow

Question 14

What is the innervation of the Triceps Brachii?

Answer 14

1. Radial Nerve
2. In some individuals, the Triceps Brachii are innervated by the Axillary Nerve

Question 15

What is the Biceps Tendon Reflex testing?

Answer 15

C7

Question 16

Where is the Anconeus located?

Answer 16

Medially and Superiorly to the Extensor Compartment of the Forearm

Question 17

What are the Fibres of the Anconeus blended with?

Answer 17

The Fibres of the Triceps Brachii (The two muscles can be indistinguishable)

Question 18

Where does the Anconeus originate from?

Answer 18

Lateral Epicondyle of the Humerus

Question 19

What does the Anconeus attach to distally?

Answer 19

Posterior and Lateral Part of the Olecranon

Question 20

What is the function of the Anconeus?

Answer 20

1. Extends the Elbow Joint
2. Stabilizes the Elbow Joint
3. Abducts the Ulna during Pronation of the Forearm

Question 21

What is the innervation of the Anconeus?

Answer 21

Radial Nerve

Question 22

What does the Radial Nerve arise from?

Answer 22

It is the Terminal Branch Posterior Cord of the Brachial Plexus

Question 23

What is the function of the Radial Nerve?

Answer 23

It is the Nerve of the Extensor Compartment of the Forearm

Question 24

What does the Radial Nerve innervate?

Answer 24

All the Extensor Muscles of the Elbow and Wrist Joints

Question 25

How does the Radial Nerve enter into the Arm?

Answer 25

Anterior to the Long Head of the Triceps Brachii

Question 26

1. What does the Radial Nerve travel alongside?
2. Where does the Radial Nerve travel?

Answer 26

1. Profunda Brachii Artery (Deep Artery of the Arm)
2. Curves around the Midshaft Region of the Humerus, in the Radial Groove

Question 27

What is the Profunda Brachii Artery a Branch of?

Answer 27

Brachial Artery

Question 28

What is the Segmental (or Root) Value of this Nerve?

Answer 28

1. C5
2. C6
3. C7
4. T1

Question 29

Which Branch of the Brachial Artery accompanies the Radial Nerve in the Radial Groove?

Answer 29

Profunda Brachii

Question 30

1. What is the Characteristic Clinical Sign of a Radial Nerve Injury?

Answer 30

Wrist Drop (due to this Nerve Supplying the Extensors of the E;bows and Wrists)