Brachial Plexus

Question 1

What is the brachial plexus?

Answer 1

The brachial plexus is a network of nerves that supplies motor and sensory innervation to the upper limb.

Question 2

Which spinal nerve roots contribute to the brachial plexus?

Answer 2

The brachial plexus arises from the ventral rami of spinal nerves C5, C6, C7, C8, and T1.

Question 3

How is the brachial plexus anatomically divided?

Answer 3

The brachial plexus is divided into roots, trunks, divisions, cords, and terminal branches.

Question 4

What are the names of the five roots of the brachial plexus?

Answer 4

The five roots of the brachial plexus are C5, C6, C7, C8, and T1.

Question 5

Which nerves arise directly from the roots of the brachial plexus?

Answer 5

The dorsal scapular nerve (C5) and long thoracic nerve (C5-C7) arise directly from the roots.

Question 6

What is the function of the dorsal scapular nerve, and which root does it arise from?

Answer 6

The dorsal scapular nerve (C5) innervates the rhomboid major, rhomboid minor, and levator scapulae muscles.

Question 7

What is the function of the long thoracic nerve, and which roots does it arise from?

Answer 7

The long thoracic nerve (C5-C7) innervates the serratus anterior muscle and prevents scapular winging.

Question 8

How many trunks are in the brachial plexus, and what are their names?

Answer 8

The brachial plexus has three trunks: superior, middle, and inferior.

Question 9

Which roots contribute to the superior trunk of the brachial plexus?

Answer 9

The superior trunk is formed by the union of C5 and C6 roots.

Question 10

Which roots contribute to the middle trunk of the brachial plexus?

Answer 10

The middle trunk is a continuation of the C7 root.

Question 11

Which roots contribute to the inferior trunk of the brachial plexus?

Answer 11

The inferior trunk is formed by the union of C8 and T1 roots.

Question 12

What are the two major branches from the superior trunk of the brachial plexus?

Answer 12

The superior trunk gives rise to the suprascapular and nerve to subclavius.

Question 13

What is the function of the suprascapular nerve, and which trunk does it arise from?

Answer 13

The suprascapular nerve (C5-C6) innervates the supraspinatus and infraspinatus muscles.

Question 14

What are the divisions of the brachial plexus?

Answer 14

Each trunk divides into an anterior and posterior division.

Question 15

What is the purpose of the anterior and posterior divisions of the brachial plexus?

Answer 15

The anterior divisions supply flexor muscles, and the posterior divisions supply extensor muscles.

Question 16

How many cords are in the brachial plexus, and what are their names?

Answer 16

The brachial plexus has three cords: lateral, medial, and posterior.

Question 17

How are the cords of the brachial plexus named?

Answer 17

The cords are named based on their position relative to the axillary artery.

Question 18

Which divisions contribute to the lateral cord?

Answer 18

The anterior divisions of the superior and middle trunks form the lateral cord.

Question 19

Which divisions contribute to the medial cord?

Answer 19

The anterior division of the inferior trunk forms the medial cord.

Question 20

Which divisions contribute to the posterior cord?

Answer 20

The posterior divisions of all three trunks form the posterior cord.

Question 21

What are the branches of the lateral cord?

Answer 21

The lateral cord gives rise to the musculocutaneous nerve and lateral root of the median nerve.

Question 22

What are the branches of the medial cord?

Answer 22

The medial cord gives rise to the ulnar nerve, medial root of the median nerve, and medial cutaneous nerves.

Question 23

What are the branches of the posterior cord?

Answer 23

The posterior cord gives rise to the axillary and radial nerves.

Question 24

What is the function of the lateral pectoral nerve, and which cord does it arise from?

Answer 24

The lateral pectoral nerve (C5-C7) innervates the pectoralis major.

Question 25

What is the function of the medial pectoral nerve, and which cord does it arise from?

Answer 25

The medial pectoral nerve (C8-T1) innervates the pectoralis major and minor.

Question 26

What are the five major terminal branches of the brachial plexus?

Answer 26

The five major terminal branches are the musculocutaneous, median, ulnar, axillary, and radial nerves.

Question 27

Which cord gives rise to the musculocutaneous nerve?

Answer 27

The lateral cord gives rise to the musculocutaneous nerve.

Question 28

What is the function of the musculocutaneous nerve?

Answer 28

The musculocutaneous nerve innervates the anterior arm muscles and provides sensory innervation to the lateral forearm.

Question 29

Which cords contribute to the median nerve?

Answer 29

The lateral and medial cords contribute to the median nerve.

Question 30

What is the function of the median nerve?

Answer 30

The median nerve innervates most forearm flexors and thenar muscles.

Question 31

Which cord gives rise to the ulnar nerve?

Answer 31

The medial cord gives rise to the ulnar nerve.

Question 32

What is the function of the ulnar nerve?

Answer 32

The ulnar nerve innervates intrinsic hand muscles and flexor carpi ulnaris.

Question 33

Which cord gives rise to the axillary nerve?

Answer 33

The posterior cord gives rise to the axillary nerve.

Question 34

What is the function of the axillary nerve?

Answer 34

The axillary nerve innervates the deltoid and teres minor.

Question 35

Which cord gives rise to the radial nerve?

Answer 35

The posterior cord gives rise to the radial nerve.

Question 36

What is the function of the radial nerve?

Answer 36

The radial nerve innervates the extensor muscles of the upper limb.

Question 37

What is Erb-Duchenne palsy, and which part of the brachial plexus is affected?

Answer 37

Erb-Duchenne palsy results from injury to the upper brachial plexus (C5-C6).

Question 38

What are the common causes of Erb-Duchenne palsy?

Answer 38

Common causes of Erb-Duchenne palsy include shoulder dystocia and trauma.

Question 39

What is Klumpke’s palsy, and which part of the brachial plexus is affected?

Answer 39

Klumpke’s palsy results from injury to the lower brachial plexus (C8-T1).

Question 40

What are the common causes of Klumpke’s palsy?

Answer 40

Common causes of Klumpke’s palsy include birth trauma and excessive arm traction.

Question 41

What is "winged scapula," and which nerve is affected?

Answer 41

"Winged scapula" occurs due to long thoracic nerve injury, affecting the serratus anterior muscle.

Question 42

What are the symptoms of a musculocutaneous nerve injury?

Answer 42

Musculocutaneous nerve injury causes weakness in elbow flexion and sensory loss in the lateral forearm.

Question 43

What are the symptoms of a median nerve injury?

Answer 43

Median nerve injury leads to "ape hand" and loss of thumb opposition.

Question 44

What are the symptoms of an ulnar nerve injury?

Answer 44

Ulnar nerve injury leads to "claw hand" and loss of intrinsic hand function.

Question 45

What are the symptoms of an axillary nerve injury?

Answer 45

Axillary nerve injury leads to deltoid atrophy and shoulder weakness.

Question 46

What are the symptoms of a radial nerve injury?

Answer 46

Radial nerve injury leads to "wrist drop" and loss of extension.

Question 47

How does the brachial plexus contribute to the autonomic nervous system?

Answer 47

The brachial plexus contributes sympathetic fibers to the upper limb.

Question 48

What is the significance of the interscalene triangle in brachial plexus anatomy?

Answer 48

The interscalene triangle is a potential site for nerve compression.

Question 49

What is the clinical importance of the infraclavicular region in brachial plexus block?

Answer 49

The infraclavicular region is important for brachial plexus blocks in anesthesia.

Question 50

What are the anatomical variations of the brachial plexus that may have clinical significance?

Answer 50

Anatomical variations include prefixed (C4-C8) and postfixed (C6-T2) plexuses.