Nerves of the upper limb

Question 1

What does the brachial plexus supply?

Answer 1

The brachial plexus is the nervous supply to the upper limb including all but 1 extrinsic back muscle
Containing both sensory and motor components

Question 2

What is the brachial plexus derived from

Answer 2

The brachial plexus is derived from the anterior rami of C5-C8 and T1

Question 3

What is the pattern of the brachial plexus?

Answer 3

Roots
Trunks
Divisions
Cords
Branches(nerves)

Question 4

What does brachial plexus mean

Answer 4

Brachial – refers to the arm
Plexus – intricate network or arrangement

Question 5

What are dermatomes

Answer 5

Dermatomes are areas of skin innervated by a spinal segment

Question 6

What are 3 useful dermatome landmarks in the upper limb?

Answer 6

1) Thumb is C6
2) Middle finger is C7
3) Little finger is C8

Question 7

What are myotomes?

Answer 7

Myotomes are a group of muscles innervated by a single spinal segment, usually with a common action

Question 8

What muscles do the brachial plexus emerge from?

Answer 8

The brachial plexus emerges from between the scalenus medius and the scalenus anterior muscles in the root of the neck

Question 9

Where does the brachial plexus pass underneath?

Answer 9

Passes underneath the clavicle and out into the axilla

Question 10

What does the brachial plexus surround in the axilla?

Answer 10

The brachial plexus raps around the axillary artery in the axilla

Question 11

What structures wrap around the front of the brachial plexus?

Answer 11

The subclavian artery and clavicle wrap around the front of the brachial plexus

Question 12

What structures pass over the top and in between the brachial plexus?

Answer 12

The dorsal scapular artery and the suprascapular artery pass over the top and in between parts of the brachial plexus

Question 13

What can the roots of the brachial plexus be used for

Answer 13

A regional anaesthesia target

Question 14

How is the brachial plexus found?

Answer 14

The brachial plexus is found by looking for the scalene groove between the scalenus anterior and medius

Question 15

Draw the brachial plexus

Answer 15

Question 16

How many roots form how many trunks?

Answer 16

5 roots become 3 trunks

Question 17

What does each trunk divide into?

Answer 17

Each trunk has an anterior and posterior division (3 trunks become 6 divisions)

Question 18

Where do of the brachial plexus divisions take place?

Answer 18

Behind the clavicle

Question 19

What 3 ways do these divisions come together and what do they form?

Answer 19

1) The anterior division of the superior and middle trunk come together to form the lateral cord
2) All of the posterior divisions come together to form the posterior cord
3) The anterior division of the inferior trunk continues on by itself to form the medial cord

Question 20

What are 5 major terminal branches of the brachial plexus and what do they form

Answer 20

1) Musculocutaneous nerve
2) Median nerve
3) Radial nerve
4) Axillary nerve
5) Ulnar nerve

Question 21

What sensory function does the musculocutaneous nerve provide?

Answer 21

Lateral cutaneous nerve of the forearm

Question 22

What motor function does the musculocutaneous nerve provide?

Answer 22

Anterior compartment muscles of the arm

Question 23

What sensory function does the median nerve provide?

Answer 23

Area on the lateral side of the palm

Question 24

What motor function does median nerve provide?

Answer 24

• Anterior compartment muscles of the forearm
• Thenar muscles of the hand

Question 25

What sensory function does the radial nerve provide?

Answer 25

- Posterolateral skin of the forearm - Dorsal skin of the hand

Question 26

What motor function does the radial nerve provide?

Answer 26

Posterior compartment muscles of the arm

Question 27

What sensory function does the axillary nerve provide?

Answer 27

Supra-lateral arm

Question 28

What motor function does the axillary nerve provide?

Answer 28

- Deltoid and teres minor muscle

Question 29

What is sensory function of the ulnar nerve

Answer 29

1/2 skin of the hand

Question 30

What is the motor function of the ulnar nerve?

Answer 30

- Flexor carpi ulnaris - Medial half of the flexor digitorum profundus - Rest of small muscles of the hand

Question 31

What are the roots associated with each of the major branches of the brachial plexus

Answer 31

1) Musculocutaneous nerve – C5-C7 2) Axillary nerve – C5 and C6 3) Median nerve – C6 to T1 4) Radial nerve – C5 to T1 5) Ulnar nerve – C7, C8 and T1

Question 32

What are 2 minor branches of the brachial plexus do not innervate the upper limb?

Answer 32

1) Phrenic nerve 2) 1st intercostal nerve

Question 33

Describe the Long thoracic nerve

Answer 33

* Takes origin from C5, C6 and C7 * Passes down behind the roots very medially * Passes down the lateral aspect of the thoracic wall, supplying a muscle called the serratus anterior * Runs along side the lateral thoracic artery (branch of axillary artery) * Relatively easy to find in mid-axillary line

Question 34

Describe the dorsal scapular nerve

Answer 34

* Comes off C5 * Very proximal * Can be difficult to find * Comes off between scalene muscles

Question 35

Describe the suprascapular nerve

Answer 35

* Goes down the same way the suprascapular artery does, except when it reaches the suprascapular notch, it goes underneath and upper transverse scapular ligament * The suprascapular artery goes over the top and around the suprascapular foramen

Question 36

Describe the subclavian nerve

Answer 36

* Supplies one muscle underneath the clavicle * Very small and difficult to find

Question 37

Describe the Lateral pectoral nerve

Answer 37

* Supplies one of the pectoral muscles * Comes from the lateral cord

Question 38

What are the 3 minor branches of the posterior cord of the brachial plexus

Answer 38

1) Upper scapular nerve 2) Thoracodorsal nerve 3) Lower subscapular nerve

Question 39

What does the upper scapular nerve supply?

Answer 39

Subscapularis

Question 40

What does the thoracodorsal nerve supplu?

Answer 40

Latissimus dorsi

Question 41

What does the lower subscapular nerve supply?

Answer 41

Supplies more of subscapularis

Question 42

What are the 3 branches of the medial cord of the brachial plexus?

Answer 42

1) Medial pectoral nerve 2) Medial brachial 3) Medial antebrachial cutaneous nerve

Question 43

What does the medial nerve supply?

Answer 43

Pectoral muscles

Question 44

What do the medial brachial cutaneous nerve and the medial antebrachial cutaneous nerve supply?

Answer 44

Skin on the medial side of the arm

Question 45

What are the two main causes of brachial plexus injury?

Answer 45

- obstetric - traumatic

Question 46

What roots does an upper brachial plexus injury affect?

Answer 46

C5 and C6

Question 47

What 3 things will the patient be unable to do if they have an upper brachial plexus injury?

Answer 47

1) Flex elbow (C5 and C6) 2) Laterally rotate elbow 3) Abduct shoulder

Question 48

What 3 things will the upper limb present with if C5 and C6 nerve roots are injured and what is this position called?

Answer 48

* The upper limb will present: 1) Adducted 2) Internally rotated 3) Extended at the elbow * This position is known as waiters tip palsy

Question 49

What condition does upper brachial plexus injury cause?

Answer 49

Erbs palsy

Question 50

What roots does a lower brachial plexus injury affect?

Answer 50

C8 and T1

Question 51

How does a lower brachial plexus injury affect the hand and what condition is this?

Answer 51

This leads to problems with intrinsic muscles of the hand, leading to movements being difficult, and the hand ending up like a claw condition: Klumpkey’s Palsy