Nerves of the Upper Limb

Question 1

What types of nerves make up the brachial plexus?

Answer 1

ventral rami of the spinal nerves

Question 2

What does the brachial plexus provide?

Answer 2

somatomotor and somatosenstory innervation to the upper extremity

Question 3

What is the cervical enlargement?

Answer 3

ventral rami of spinal nerves C5-T1
-gives rise to brachial plexus

Question 4

What muscles does the brachial plexus pass through?

Answer 4

the anterior and middle scalene muscles

Question 5

What is the space in which the brachial plexus passes through the scalene muscles called?

Answer 5

the interscalene space

Question 6

What is the supraclavicular region?

Answer 6

the region that above the clavicle

Question 7

Where does the subclavian artery run?

Answer 7

posterior to the anterior scalene with the brachial plexus
-not with the subclavian v.

Question 8

What is an interscalene block?

Answer 8

administration of anesthesia into the interscalene space to block the brachial plexus

Question 9

What nerve can also be affected by an interscalene block?

Answer 9

the phrenic nerve
-affect breathing

Question 10

where does the axillary artery travel?

Answer 10

runs in the middle of the brachial plexus

Question 11

does the brachial plexus travel anterior or posterior to clavicle?

Answer 11

posterior

Question 12

where does the axillary vein travel?

Answer 12

“entangled” with branches of the brachial plexus

Question 13

what surrounds the brachial plexus along with the axillary a. and v. as it runs into the axilla?

Answer 13

axillary sheath
(concentration of fascia NOT a tube)

Question 14

what is an area of cutaneous sensory innervation supplied by a single spinal nerve?

Answer 14

dermatome

Question 15

what dermatome is supplied by C4?

Answer 15

supraclavicular and upper shoulder region

Question 16

what dermatome is supplied by C5?

Answer 16

upper lateral arm and shoulder

Question 17

what dermatome is supplied by C6?

Answer 17

posterolateral arm and lateral forearm

Question 18

what dermatome is supplied by C7?

Answer 18

middle of forearm and hand

Question 19

what dermatome is supplied by C8?

Answer 19

posteromedial forearm and medial hand

Question 20

what dermatome is supplied by T1?

Answer 20

medial arm

Question 21

what dermatome is supplied by T2-T4?

Answer 21

axillary region

Question 22

why is there not a 1:1 correspondence between named cutaneous nerves and dermatomes?

Answer 22

bc names nerves may be comprised of more than 1 spinal nerve and thus will span more than one dermatome

Question 23

an individual named muscle in limbs are supplied by how many spinal nerves?

Answer 23

more than one spinal nerve

Question 24

what is a group of muscles that receive motor innervation from a single spinal nerve?

Answer 24

myotome

Question 25

can myotomes overlap?

Answer 25

yes

Question 26

what myotome is supplied by C4?

Answer 26

shoulder elevation

Question 27

what myotome is supplied by C5?

Answer 27

shoulder abduction; elbow flexion

Question 28

what myotome is supplied by C6?

Answer 28

elbow flexion; wrist extension

Question 29

what myotome is supplied by C7?

Answer 29

elbow extension; wrist flexion

Question 30

what myotome is supplied by C8?

Answer 30

thumb and finger extension

Question 31

what myotome is supplied by T1?

Answer 31

intrinsic hand muscles

Question 32

what myotome is supplied by T2?

Answer 32

intercostal muscles

Question 33

what divisions do each trunk of the brachial plexus have?

Answer 33

anterior and posterior

Question 34

the anterior divisions of the brachial plexus trunks contribute to what?

Answer 34

the medial and lateral cord

Question 35

anterior divisions of the brachial plexus tend to?

Answer 35

flex

Question 36

the posterior divisions of the brachial plexus trunks contribute to what

Answer 36

the posterior cord

Question 37

posterior divisions of the brachial plexus tend to?

Answer 37

extend

Question 38

what nerve supplies the anterior compartment of the arm?

Answer 38

musculocutaneous nerve

Question 39

what nerve supplies the posterior compartment of the arm?

Answer 39

radial nerve

Question 40

what nerve supplies the anterior compartment of the forearm and hand?

Answer 40

ulnar & radial nerves

Question 41

what nerve supplies the posterior compartment of the forearm and hand?

Answer 41

radial nerve

Question 42

what innervates the shoulder (pectoral girdle) region?

Answer 42

nerves that come directly from the roots, trunks, or cords of the brachial plexus

Question 43

what innervates the arm (brachial) region?

Answer 43

nerves from the medial cord (cutaneous), the musculocutaneous n. (anterior), and the radial n. (posterior)

Question 44

what innervates the forearm (antebrachial) region?

Answer 44

a branch from the medial cord (cutaneous), the median and ulnar nn. (anterior), and the radial n (posterior)

Question 45

what supplies motor innervation to the hand?

Answer 45

median and ulnar nerves

Question 46

what supplies sensation innervation to the hand?

Answer 46

median, ulnar and radial

Question 47

what parts of the brachial plexus lie in the supraclavicular region?

Answer 47

roots (rami) and trunks

Question 48

what parts of the brachial plexus lie in the infraclavicular region?

Answer 48

divisions, cords, and branches

Question 49

what is the order of the brachial plexus segments?

Answer 49

roots --> trunks --> divisions --> cords --> branches Real Texans Drink Cold Beer

Question 50

the upper trunk of the brachial plexus is made up of which roots?

Answer 50

C5 and C6

Question 51

the middle trunk of the brachial plexus is made up of which roots?

Answer 51

C7

Question 52

the lower trunk of the brachial plexus is made up of which roots?

Answer 52

C8 and T1

Question 53

which divisions make up the lateral cord of the brachial plexus?

Answer 53

anterior divisions of upper and middle trunks

Question 54

which divisions make up the medial cord of the brachial plexus?

Answer 54

anterior division of the lower trunk

Question 55

which divisions make up the posterior cord of the brachial plexus?

Answer 55

posterior divisions of upper, middle, and lower trunks

Question 56

which cords make up the musculocutaneous branch of the brachial plexus?

Answer 56

lateral cord

Question 57

which cords make up the median branch of the brachial plexus?

Answer 57

lateral and medial cords

Question 58

which cords make up the ulnar branch of the brachial plexus?

Answer 58

medial cord

Question 59

which cords make up the radial branch of the brachial plexus?

Answer 59

posterior cord

Question 60

which cords make up the axillary branch of the brachial plexus?

Answer 60

posterior cord

Question 61

what additional nerves does the lateral cord of the brachial plexus give rise to?

Answer 61

lateral pectoral n.

Question 62

what additional nerves does the medial cord of the brachial plexus give rise to?

Answer 62

medial pectoral n. medial brachial cutaneous n. medial antebrachial cutaneous n.

Question 63

what additional nerves does the posterior cord of the brachial plexus give rise to?

Answer 63

upper subscapular n. lower subscapular n. thoracodorsal n.

Question 64

what additional nerves does the upper trunk of the brachial plexus give rise to?

Answer 64

subclavius n. suprascapular n.

Question 65

what additional nerves does the C5 root of the brachial plexus give rise to?

Answer 65

dorsal scapular n. long thoracic n.

Question 66

an injury to superior trunk (C5 and C6) can be called?

Answer 66

Erb's palsey

Question 67

what are potential causes of Erb's palsey?

Answer 67

-results from excessive, forceful increase in angle b/w neck and shoulder -most common obstetric brachial plexopathy -can also occur in adults from a fall onto the shoulder

Question 68

what is the clinical presentation of Erb's palsey?

Answer 68

-arm will be adducted -arm will be internally (medially) rotated at the elbow -there will be pronation -there will be extension

Question 69

what are the nerve deficits & affected muscles of Erb's palsey?

Answer 69

-axillary n. (weakness in deltoid and teres minor) -suprascapular n. (weakness in supraspinatus and infraspinatus) -musculocutaneous n. (weakness in biceps) -radial n. (weakness in brachioradialis and supinator, and wrist extensors)

Question 70

an injury to the axillary region affects which nerves?

Answer 70

C5-T1 (radial nerve)

Question 71

what are common causes of injury to axillary region?

Answer 71

improper use of crutches can compress and injure the nerve in the axilla

Question 72

what is the clinical presentation of an injury to the radial nerve in the axillary region?

Answer 72

-weakness when trying to push something away with arm -difficulty extending the wrist -difficulty extending the fingers and opening the hand -"wrist drop" posture

Question 73

an injury at the spinal groove of humerus affects which nerves?

Answer 73

C5-T1 (compression of the radial nerve)

Question 74

what is the clinical presentation of an injury at the spiral groove of humerus?

Answer 74

-difficulty extending the wrist -difficulty extending or straightening the fingers and opening the hand -triceps retains strength because nerve fibers entering this muscle branch off proximal to the mid shaft of the humerus -also causes "wrist drop" posture

Question 75

what are common causes of injury at spiral groove of humerus?

Answer 75

-compression of the radial nerve along the midshaft of the humerus in certain postions -humeral fracture at midshaft (spiral groove fracture)

Question 76

what are common causes of injury to the axillary nerve?

Answer 76

-fracture to surgical neck of humerus -anterior dislocation of glenohumeral joint -rotator cuff repair surgery

Question 77

what is the clinical presentation of an injury to the axillary nerve?

Answer 77

-numbness in posterior deltoid region -difficulty abducting arm -diminished lateral rotation of arm -deltoid muscle wasting (prolonged injury)

Question 78

an injury to the axillary nerve affects which nerves?

Answer 78

C5 and C6

Question 79

an injury to the long thoracic nerve affects which nerves?

Answer 79

C5, C6, and C7 (innervation to the serratus anterior muscles)

Question 80

what are common causes of an injury to the long thoracic nerve?

Answer 80

-penetrating wound to the axillary region -surgical removal of axillary lymph nodes

Question 81

what is the clinical presentation of an injury to the long thoracic nerve?

Answer 81

-cannot raise arms above 90 degrees -"winged scapula"