MSK - Brachial Plexus And Axillary

Question 0

Describe the features of the Musculocutaneous nerve?

HINT : Which roots, what it innervates

Answer 0

Descends between the biceps brachii and brachialis
From roots C5 C6 C7
Innervates the muscles of the anterior compartment of arm
(Biceps, brachialis)

Question 1

What are the 5 regions of the brachial plexus?

Answer 1

Roots
Trunks
Divisions 
Cords
Terminal nerves

Question 2

What are the features of the Axillary nerve?

Answer 2

Winds around the surgical neck deep into deltoid.

Innervates the Teres minor, deltoid muscle

Question 3

What are the features of the median nerve?

Answer 3

Lateral and medial cords merge to form this.
Innervates muscles of the anterior forearm compartment
C5 C6 C8 T1

Question 4

What are the features of the radial nerve?

Answer 4

Larger terminal branch of the posterior cord
Innervates all muscles of the posterior compartment of arm/forearm
Skin of posterior arm

Question 5

What are the features of the ulnar nerve?

Answer 5

Large terminal branch of the medial cord
Supplies forearm muscles, intrinsic hand muscles
C8 T1

Question 6

What is the Axilla?

Answer 6

The pyramidal shaped area providing a passageway for the neurovascular structures that serve the upper limb

Question 7

What are the 6 boundaries of the Axilla called?

Answer 7

Apex, base, anterior wall, posterior wall, medial wall, lateral wall.

Question 8

How is the apex formed?

Answer 8

Bounded by 1st rib

Clavicle and superior scapula edge.

Question 9

What is the base boundary?

Answer 9

Formed by the concave skin, subcutaneous tissue, and Axillary fascia

Question 10

What is the anterior wall bounded by?

Answer 10

The pectoralis minor and major

Question 11

What is the posterior wall bounded by?

Answer 11

Scapula, and subscapularis and Teres major and latissmus dorsi

Question 12

What is the medial wall formed by?

Answer 12

The thoracic wall (1st-4th ribs) and serratus anterior.

Question 13

What this the lateral wall formed by?

Answer 13

Intertubercular sulcus in humerus

Question 14

What are the Axillary lymph nodes?

Answer 14

Fibrofatty connective tissue containing many lymph nodes

They drain the lymph from the arm, breast, chest wall

Question 15

What would a tearing injury to the superior brachial plexus result in?

Answer 15

Injures superior roots (C5, C6)
Waiters tip position limb hangs by side in medial position.
Deltoid, biceps and brachialis are affected

Question 16

What happens after a long period of holding arm above head?

Answer 16

The cords are compressed between the coraciod process of spacula and pectoralis minor tendon.
This leads to pain down the arm, tingling

Question 17

What is the venous supply of the Axilla region?

Answer 17

The cephalic vein runs up under the deltoid
The basilic vein carries blood up from the arm to the Axilla
They both join the Axillary vein

Question 18

What is the arterial supply of the Axilla?

Answer 18

The subclavian artery travels down the arm and becomes the Axillary artery.
The artery is posterior to the vein.

Question 19

What is an example of a fist class lever?

Answer 19

The seesaw like movement of the neck with the force in the opposite side to the load.

Question 20

What is an example of a second class lever?

Answer 20

Wheelbarrow like mechanism with the force and the load to the left of the fulcrum. E.g ball of foot

Question 21

What is the third class lever?

Answer 21

Fishing rod mechanism. The force and the load on right of fulcrum.
E.g the forearm

Question 22

What are agonists?

Answer 22

Prime movers (main muscle responsible for movement)

Question 23

What are antagonists?

Answer 23

Muscles that oppose prime movers

Question 24

What are synergists?

Answer 24

Assist in prime movers

Question 25

What are fixators?

Answer 25

These stabilise action of prime mover

Question 26

What is isotonic muscle contraction?

Answer 26

Muscle changes length with constant tension
Concentric - muscle shortens e.g arm
Eccentric - muscle extends e.g walking downhill

Question 27

What is isometric contraction?

Answer 27

Constant muscle length e.g hand grip

Question 28

What is muscle tone?

Answer 28

Muscles resistance to passive stretch during rest.

Question 29

What are the 4 things that cause hypotonia?

Answer 29

Cerebral spinal neural shock
Lesion of lower motor neurone
Lesion of sensory afferents from muscle
Myopathy of primary muscle.