Anatomy of the brachial plexus

Question 1

What are the roots of the upper trunk?

Answer 1

C5 & C6

Question 2

What is the root of the middle trunk?

Answer 2

C7

Question 3

What are the roots of the lower trunk?

Answer 3

C8 & T1

Question 4

What are the divisions of all of the trunks?

Answer 4

Anterior and posterior division

Question 5

Which divisions forms the lateral cord?

Answer 5

The joining of the anterior division of the upper and middle trunk

Question 6

Which divisions forms the posterior cord?

Answer 6

formed by the joining of all posterior division of all of the trunks

Question 7

Which divisions forms the medial cord?

Answer 7

Formed by the anterior division of the lower trunk

Question 8

What are the branches of the roots of the brachial plexus?

Answer 8

1) Long thoracic nerve (C5-7), it innervates the serratus anterior muscle in the medial wall of the axilla

2) Phrenic nerve from C5

3) Dorsal scapular nerve (C5), innervates the rhomboids responsible for retraction

Question 9

What are the branches of the trunk of the brachial plexus?

Answer 9

From the upper trunk:

1) Nerve to subclavius muscle

2) Subscapular nerve (innervates supra & infraspinatus muscle)

Question 10

What are the branches of the lateral cord of the brachial plexus?

Answer 10

1) Lateral pectoral nerve (innervates pectoralis major & minor)

2) Lateral root of median nerve (root value C5,6,7,8 & T1) largest nerve in the whole upper build

3) Musculocutaneous nerve (root value C5,6, &7), supplies major muscles (like the biceps) & also the skin

Question 11

What are the branches of the medial cord?

Answer 11

1) Medial pectoral nerve (supplies the pectoralis major and minor)

2) medial root of Median nerve (root value C5,6,7,8 & T1) largest nerve in the whole upper build

3) Medial cutaneous nerve of arm (root value C8 & T1)

4) Medial cutaneous nerve of forearm (root value C8 & T1)

5) Ulnar nerve (root value C7, 8 & T1)

Question 12

What are the branches of the posterior cord of the brachial plexus?

Answer 12

1) Upper subscapularis nerve (supplies the subscapularis muscle)

2) Thoracodorsal nerve (supplies the latissimus dorsi muscle)

3) Lower subscapularis nerve (supplies the subscapularis and teres major muscle)

4) Radial nerve (root value C5, 6, 7, 8 & T1

5) Axillary nerve (Root value C5 & 6) supplies the deltoid and teres minor

Question 13

In which operation is the long thoracic nerve most commonly injured?

Answer 13

Mastectomy (causes winging of the scapula)

Question 14

What is the root value of the musculocutaneous nerve?

Answer 14

C5, 6 & 7

• Ends in our forearm

Question 15

What is the root value of the medial nerve?

Answer 15

C5, 6, 7, 8, T1

• It reaches to our hand

Question 16

What is the root value of the ulnar nerve?

Answer 16

C7, 8, T1

• It reaches to our hand

Question 17

What is the root value of the radial nerve?

Answer 17

C5, 6, 7, 8 & T1

Question 18

What is the root value of the axillary nerve?

Answer 18

C5 & 6

• Ends in our upper arm

Question 19

What is the deformity that is caused by a lesion to the radial nerve?

Answer 19

Wrist/finger drop

Question 20

What is the deformity caused by a lesion to the axillary nerve?

Answer 20

Flat shoulder (paralyzed deltoid muscle which will be paralyzed then will atrophy)

• the deltoid is responsible for abduction, flexion & extension

Question 21

What is meant by Erb’s palsy?

Answer 21

It is a lesion/avulsion to the upper trunk (C5 & 6)

• Common when delivering the head of the baby in a wrong way (seen after 2-3 weeks from delivery), or falling between the head and shoulder

Question 22

What is the deformity caused by Erbs palsy?

Answer 22

Police man tip position/waiters position

Where:
1) The shoulder is adducted & medially rotated

2) The elbow is extended

3) Forearm is pronated

Question 23

What is klumpke’s paralysis?

Answer 23

• A lesion/avulsion to the lower trunk (C8 & T1),mainly to the ulnar nerve
• Resulting in a claw hand

Question 24

What are the problems that are caused by Klumpke’s paralysis?

Answer 24

1) Winged scapula
2) Wrist drop
3) Flat shoulder
4) Claw hand

Question 25

What are the conditions that can cause compression of the cervical nerves?

Answer 25

1) Extra rib

2) Cervical arthritis (inflammation of the disk)

3) Cervical disc prolapse

4) Cervical spondylosis