The axilla and brachial plexus

Question 1

Medial border of the axillary region =

Answer 1

Serratus anterior muscles

Question 2

Posterior border of the axillary region =

Answer 2

Subscapularis, teres major and latissimus dorsii

Question 3

Anterior border of the axillary region =

Answer 3

Pectoral muscles (pectroalis major, pectoralis minor, subclavius)

Question 4

What forms the apex of the axilla

Answer 4

Lateral border of 1st rib, superior border of the scapula, posterior border of clavicle

Question 5

Contents of the axilla:

Answer 5

• Axillary artery
• Axillary vein
• Brachial plexus
• Axillary lymph nodes
• Biceps brachii (short head) and Coracobrachialis

Question 6

Axillary lymph node groups:

Answer 6

Lateral, subscapular, pectoral, cental, apical

Question 7

Which type of rami does the brachial plexus include?

Answer 7

Ventral/anterior rami of C5-T1

Question 8

Roots of brachial plexus:

Answer 8

C5-T1

Question 9

Read that damn cadavar book

Answer 9

Roots, trunks, divisions, cords, branches

Question 10

Superior trunk =

Answer 10

C5 + C6

Question 11

Middles trunk =

Answer 11

C7

Question 12

Inferior trunk =

Answer 12

C8 + T1

Question 13

Trunks split into…

Answer 13

Anterior and posterior divisions

Question 14

Lateral cord =

Answer 14

Anterior division of superior trunk + Anterior division of middle trunk

Question 15

Posterior cord =

Answer 15

Posterior divisions of superior, middle and inferior trunks

Question 16

Medial cord =

Answer 16

The anterior division of the inferior trunk

Question 17

Anterior divisions supply which types of muscle?

Answer 17

Flexors and adductors

Question 18

Posterior divisions supply which type of muscles?

Answer 18

Extensors and abductors

Question 19

Cords:

Answer 19

Lateral, posterior, medial

Question 20

Lateral cord splits into which branches?

Answer 20

Musculocutaneous

Median

Question 21

Posterior cord splits into which branches?

Answer 21

Axillary

Radial

Question 22

Medial cord splits into which branches?

Answer 22

Median

Ulnar

Question 23

Which 2 nerves supply the majority of extensors and abductors?

Answer 23

Axillar and radial nerves

Question 24

Which 3 nerves supply the majority of flexors and adductors?

Answer 24

Musculocutaneous
Median
Ulnar

Question 25

The anterior nerves ‘supply in the order they are derived’ for the most part - what does this mean?

Answer 25

Musculocutaneous = arm
Median = forearm 
Ulnar = hand

Question 26

What does the musculocutaneous nerve supply?

Answer 26

Flexors of the upper arm: coracobrachialis, brachialis, biceps brachii
Sensory = lateral half of the anterior forearm

Question 27

What does the axillary nerve supply?

Answer 27

Teres minor and deltoid muscles, superior lateral cutaneous nerve of arm (sargent’s stripes)

Question 28

What does the median nerve supply?

Answer 28

Anterior compartment flexors of forearm and hand (radial side)
Sensory = Palmar cutanous branch, lateral 3 and a half fingers on palmar surface of hand.

Question 29

What does the radial nerve supply?

Answer 29

Triceps brachii and muscles in posterior compartment of forearm (mostly extensors of the wrist and fingers),

Sensory = posterior aspect of arm and forearm, posteroateral aspect of hand.

Question 30

What does the ulnar nerve supply?

Answer 30

Innervates muscles of the hand, 2 muscles in forearm = flexors carpi ulnas and medial half of flexor digitorum profundus

Sensory = Anterior and posterior surfaces of the medial one and half fingers and associated palm area

Question 31

What would happen to a patient with a radial nerve injury?

Answer 31

• Wrist drop (weakness of extensors)

- Loss of sensation over dorsal web between thumb and index finger

Question 32

Dermatome =

Answer 32

Area of skin supplies by a single spinal nerve

Question 33

Myotomes =

Answer 33

Group of muscles that a single spinal nerve innervates

Question 34

Shoulder myotomes

Answer 34

Abduct and laterally rotate = C5

Adduct and medially rotate = C6, 7, 8

Question 35

Elbow myotomes

Answer 35

Flex = C5, 6
Extend = C7, 8

Question 36

Forearm myotomes

Answer 36

Pronate and supinely = C6

Question 37

Wrist myotomes

Answer 37

Flex and extend = C6, 7

Question 38

Fingers and thumb myotomes

Answer 38

Flex and extend = C7, 8

Hand intrinsic muscles (fine movement) = T1

Question 39

Example of upper brachial plexus injury

Answer 39

Erb’s palsy

Question 40

Erb’s palsey

Answer 40

Upper myotomes and dermatomes affected.
Tear of C5 nerve root.
Loss of sensation over lateral arm, loss of muscles of shoulder.

Question 41

Example of lower brachial plexus injury

Answer 41

Klumpke’s paresis

Question 42

Klumpke’s paresis

Answer 42

Tear to lower roots of brachial plexus.

All fine movement of hands is lots, sensation over medial side of forearm lost.