Brachial Plexus

Question 1

Brachial Plexus

Answer 1

• ventral rami or C5-T1
• provide motor, sensory, and sympathetic innervation to upper limb
• each ventral ramus has gray communicans (postganglionic sympathetic fiber) distributed via cervical sympathetic ganglia
• Passes from neck and upper thorax to upper limb via cervicoaxillary canal

Question 2

Components of Brachial plexus

Answer 2

1. roots (rami)
2. trunks
3. divisions
4. cords
5. branches

Question 3

Roots of brachial plexus

Answer 3

ventral rami of C5-T1 as they leave IV foramina in neck and upper thorax

Question 4

Trunks of brachial plexus

Answer 4

Upper- union of C5-C6
Middle- continuation of C7
Lower- Union of C8-T1

Question 5

Divisions of brachial plexus

Answer 5

Anterior- extension of trunks; contribute to lateral and medial cords

posterior- extension of all 3 trunks contribute to form posterior cord

Question 6

Cords of brachial plexus

Answer 6

• first portion of brachial plexus located in axilla
• named for relationship to axillary artery:
  lateral
  medial
  posterior

Question 7

lateral cord of brachial plexus

Answer 7

• formed by union of 2 anterior divisions:
  1. upper trunk
  2. middle trunk supplying cord level C7 to lateral cord

Question 8

Medial cord of brachial plexus

Answer 8

-direct continuation of anterior portion of lower trunk

Question 9

Posterior cord of of brachial plexus

Answer 9

• union of 3 posterior divisions

- contains fibers from ALL spinal nerves roots C5-T1

Question 10

Branches of lateral cord

Answer 10

1. Lateral pectoral nerve
2. Musculocutaneous nerve
   * contribution to median nerve carrier fibers C6 and C7 (rarely C5)*

Question 11

Lateral Pectoral Nerve

Answer 11

-innervates pectoralis major

Question 12

Musculocuntaneous Nerve

Answer 12

• C5, C6, C7
• terminal branch of lateral cord
• innervates anterior compartment of arm

Question 13

branches of medial cord

Answer 13

1. medial pectoral nerve
2. medial brachial cutaneous nerve
3. medial antebrachial cutaneous nerve
4. ulnar nerve
   * contribution to medial nerve carries fiber C8 and T1**

Question 14

Medial Pectoral Nerve

Answer 14

• innervates pectoralis major and pectoralis minor

Question 15

Medial Brachial Cutaneous Nerve

Answer 15

• cutaneous innervation to medial portion of arm

Question 16

Medial Antebrachial Cutaneous Nerve

Answer 16

• cutaneous inneration to the medial portion of forearm

Question 17

Ulnar Nerve

Answer 17

• C8, T1

- terminal branch of medial cord

Question 18

Branches of Posterior Cord

Answer 18

1. upper subscapular nerve
2. thoracodorsal nerve
3. lower subscapular nerve
4. axillary nerve
5. radial nerve

Question 19

Upper Subscapular Nerve

Answer 19

• innervates subscapularis

Question 20

Thoracodorsal Nerve

Answer 20

• innervates latissimus dorsi

* AKA middle subscapular nerve

Question 21

Lower Subscapular Nerve

Answer 21

• innervates sunscapularis and teres major

Question 22

Axillary Nerve

Answer 22

• C5 and C6
• innervates deltoid and teres minor
• 1 of 2 terminal branches of posterior cord

Question 23

Radial Nerve

Answer 23

• C5, C6, C7, C8, T1
• innervates all muscles of dorsal surface of limb
• largest
• terminal branch of posterior cord
  (T1 is inconsistent in radial nerve)

Question 24

Median Nerve

Answer 24

• C6, C7, C8, T1
• innervates most ventral antebrachial muscles and thenar muscles of hand
• terminal branch of brachial plexus
  (C5 is inconsistent nerve)

Question 25

Supraclavicular Branches of brachial plexus

Answer 25

1. dorsal scapular nerve 2. suprascapular nerve 3. nerve to subclavius 4. long thoracic nerve

Question 26

Dorsal Scapular Nerve

Answer 26

- C5 | - innervates levator scapulae, rhomboideus major and minor

Question 27

Suprascapular Nerve

Answer 27

- Formed at junction of C5 and C6 | - innervates supraspinatus and infraspinatus muscles

Question 28

Nerve to Subclavius

Answer 28

- From upper trunk C5 and C6 | - Innervates subclavius muscle

Question 29

Long Thoracic Nerve

Answer 29

- C5, C6, C7 - innervates serratus anterior * only posterior nerve off plexus*

Question 30

Dermatomes

Answer 30

- innervation from spinal cord level C4-T3 - reflects segmental innervation of body - provided by branches of brachial plexus - shoulder innervated by C4 from supraclavicular nerve pf cervical plexus - anterior, medial, and posteromedial portion of brachium innervated by intercostal brachial cutaneous nerves (T1, T2 and sometimes T3)