Nerve supply of upper arm: Brachial plexus

Question 1

Does the brachial plexus supply the upper limbs or lower limbs?

Answer 1

Upper limbs

Question 2

Does the brachial plexus innervate the skin or muscles of upper limbs?

Answer 2

Innervates muscles and skin

Question 3

Which 5 spinal segmental levels form the brachial plexus, and do the nerves originate from the anterior or posterior rami roots?

Answer 3

C5
C6
C7
C8
T1

Nerves originate from anterior rami of each segmental level

Question 4

What are the 5 parts of the brachial plexus, and what are the functional differences between these divisions?

Answer 4

Roots, trunks, divisions, cords, branches

No functional differences, just easier to explain routes of brachial plexus

Question 5

What are the 5 anterior roots that form the brachial plexus?

Answer 5

C5
C6
C7
C8
T1

Question 6

What are the names of the 3 trunks of the brachial plexus, and how do they relate to the 5 roots?

Answer 6

Superior trunk: Formed by combination of C5 and C6

Middle trunk: Formed by C7

Inferior trunk: Formed by combination of C8 and T1

Question 7

Which brachial plexus trunk is not formed by a combination of multiple anterior roots?

Answer 7

Middle trunk: Only formed by C7

Question 8

How are the divisions of the brachial plexus formed from trunks?

Answer 8

Each trunk splits into anterior (move towards front of body) and posterior division (moves towards back of body)

Question 9

How many divisions are in the brachial plexus in total, and which ones supply the front/back of body?

Answer 9

6 divisions in total, as each trunk splits into anterior and posterior divisions

3 anterior divisions to supply front

3 posterior divisions to supply back

Question 10

Where in the body do the cords of the brachial plexus form from divisions, and how are they named?

Answer 10

In axilla, divisions combine to form lateral, posterior, medial cord

Named in relative position to axillary artery

Question 11

Which 2 brachial plexus divisions combine to form the lateral cord, and where is this positioned relative to the axillary artery?

Answer 11

Anterior division of superior trunk

Anterior division of middle trunk

Furthest and behind axillary artery (closest to back of body)

Question 12

Which 3 brachial plexus divisions combine to form the posterior cord, and where is this positioned relative to the axillary artery?

Answer 12

Posterior divisions of superior, middle, inferior trunks

Directly behind axillary artery, in front of lateral cord

Question 13

Which brachial plexus divisions combine to form the medial cord, and where is this positioned relative to the axillary artery?

Answer 13

Only anterior division of inferior trunk

In front of axillary artery

Question 14

Which 5 major nerves are formed from the cords of the brachial plexus, to innervate the upper arm?

Answer 14

Musculocutaneous
Axillary
Ulnar
Radial
Median

Question 15

Which brachial plexus cord forms the musculocutaneous nerve, and what roots innervate it?

Answer 15

Formed from terminal branch of lateral cord, only carries nerves from C5,C6,C7

Question 16

Which compartment of the upper arm is innervated by musculocutaneous nerve, and what 3 muscles are these?

Answer 16

Anterior (flexor) compartment muscles:
Coracobrachialis

Biceps brachii

Brachialis

Question 17

Does the musculocutaneous nerve only supply the upper arm?

Answer 17

No

Emerges lateral to biceps brachii and brachialis to enter forearm, becomes lateral cutaneous nerve

Question 18

In which part of the forearm does the musculocutaneous nerve become the lateral cutaneous nerve and provide sensory innervation?

Answer 18

Lateral half of anterior forearm

Small part of posterior forearm

Question 19

Which brachial plexus cords form the axillary nerve, and what roots innervate it?

Answer 19

Direct continuation of posterior cord, only carries nerves from C5,C6

Question 20

How many branches does the axillary nerve have?

Answer 20

Anterior branch

Posterior branch

Articular branch

Question 21

Which 2 muscles does the posterior branch of axillary nerve supply motor innervation to?

Answer 21

Posterior aspect of deltoid

Teres minor

Question 22

Where in the arm does the posterior branch of axillary nerve provide sensory/cutaneous innervation, and what is the name of this nerve now?

Answer 22

Skin over inferior region of deltoid: Regimental badge area

Upper lateral cutaneous nerve

Question 23

Which muscle does the anterior branch of the axillary nerve provide motor innervation to?

Answer 23

Anterior aspect of deltoid

Question 24

Which part of the arm does the anterior branch of the axillary nerve provide sensory/cutaneous innervation to?

Answer 24

anterior, anterolateral shoulder

Question 25

What is supplied by the articular branch of the axillary nerve?

Answer 25

Upper part of triceps brachii Glenohumeral joint

Question 26

In the brachial plexus, the median nerve carries nerves from which roots?

Answer 26

C5,C6,C7,C8,T1

Question 27

Does the median nerve provide motor innervation in the upper arm?

Answer 27

No, It provides motor innervation to all muscles in the anterior forearm except flexor carpi ulnaris and flexor digitorum profundus And thenar muscles and 2 lateral lumbrical muscles in hand

Question 28

Which muscles in the anterior forearm receive motor innervation from the median nerve?

Answer 28

All except flexor carpi ulnaris and flexor digitorum profundus

Question 29

Which 3 muscles in the hand receive motor innervation from the median nerve?

Answer 29

2 lateral lumbricals Thenar (thumb) muscle

Question 30

Which 2 branches does the median nerve give off to supply cutaneous innervation in hand?

Answer 30

Palmar cutaneous nerve: Lateral aspect of palm Digital cutaneous nerve: Lateral 3.5 fingers on palmar/anterior surface

Question 31

Which branch of the median nerve in the hand provides motor innervation to the 2 lateral lumbricals?

Answer 31

Motor branch

Question 32

Which branch of the median nerve in the hand provides motor innervation to the thenar muscle?

Answer 32

Thenar/recurrent branch

Question 33

The radial nerve of the brachial plexus carries nerves from with roots?

Answer 33

C5,C6,C7,C8,T1

Question 34

Which muscle in the posterior upper arm receives motor innervation from the radial nerve?

Answer 34

Triceps brachii

Question 35

How many muscles in the posterior forearm are supplied by radial nerve?

Answer 35

All of them

Question 36

Before the radial nerve becomes the deep branch, which 2 posterior forearm muscles does it supply motor innervation to?

Answer 36

Radial nerve supplies brachioradialis and extensor carpi radialis Before terminating as deep branch and supplying rest of posterior forearm muscles

Question 37

How many muscles in the posterior upper arm are supplied motor innervation by the radial nerve?

Answer 37

Triceps brachii This is the only muscle in the posterior upper arm compartment

Question 38

Which 2 cutaneous branches does the radial nerve give off to provide sensory innervation to the upper arm in 2 areas?

Answer 38

Lower lateral cutaneous nerve: Lateral aspect of upper arm, inferior to deltoid Posterior cutaneous nerve: Posterior surface of upper arm

Question 39

Which cutaneous branch does the radial nerve give off to provide sensory innervation to the forearm?

Answer 39

Posterior cutaneous nerve of forearm: Strip of skin down middle of posterior forearm

Question 40

Which cutaneous branch does the radial nerve give off to provide sensory innervation to the hand?

Answer 40

Superficial/dorsal radial sensory nerve: Dorsal (posterior) surface of lateral 3.5 digits

Question 41

The ulnar nerve of the brachial plexus carries nerves from which roots?

Answer 41

C8 and T1

Question 42

Which 2 muscles in the anterior forearm receive motor innervation from the ulnar nerve?

Answer 42

Flexor carpi ulnaris Medial half of flexor digitorum profundus

Question 43

Which branch of the ulnar nerve in the hand supplies motor innervation to the hypothenar muscles?

Answer 43

Deep branch

Question 44

Which branch of the ulnar nerve in the hand supplies motor innervation to the 2 medial lumbricals?

Answer 44

Deep branch

Question 45

Which branch of the ulnar nerve in the hand supplies motor innervation to the palmar and dorsal interosseous?

Answer 45

Deep branch

Question 46

Which branch of the ulnar nerve in the hand supplies motor innervation to adductor pollicis?

Answer 46

Deep branch

Question 47

What are the 3 cutaneous branches that arise from the ulnar nerve in the hand?

Answer 47

Superficial branch: Palmar surface of medial 1.5 fingers Palmar cutaneous branch: Medial half of palm Dorsal cutaneous branch: Dorsal surface of medial 1.5 fingers and associated area