Lecture 15: Upper Extremity Neurology

Question 1

What innervates the skin of the neck and shoulder?

Answer 1

Supraclavicular Nerves

(Nerves of the Cervical Plexus)

Question 2

What are the three major divisions of the Lateral Cord of the Brachial Plexus?

Answer 2

Lateral Pectoral Nerve

Musculocutaneous Nerve

1/2 of the Median Nerve

Question 3

What are the branches and terminal divisions of the Posterior Cord of the Brachial Plexus?

Answer 3

Branches: Inferior Subscapular, Superior Subscapular, and Thoracodorsal

Terminal Branches: Axillary Nerve, Radial Nerve

Question 4

What are the three branches and two terminal branches of the Medial Cord?

Answer 4

Branches: Medial Pectoral, Medial Brachial Cutaneous, Medial Antebrachial Cutaneous.

Terminal Branches: Ulnar Nerve and 1/2 of the Median Nerve

Question 5

What Nerves come directly off the Root of C5?

Answer 5

Dorsal Scapular Nerve

Long Thoracic

Question 6

Dorsal Scapular Nerve

1. What does it innervate?
2. Where does it come off of the brachial plexus?
3. What roots contribute to it?

Answer 6

1. What does it innervate?

Rhomboid Muscles and Levator Scapulae Muscle

2. Where does it come off of the brachial plexus?

Root of C5

3. What roots contribute to it?

C5 only

Question 7

Long Thoracic Nerve

1. What does it innervate?
2. Where does it come off of the brachial plexus?
3. What roots contribute to it?

Answer 7

1. What does it innervate?

Serratus Anterior Muscle

2. Where does it come off of the brachial plexus?

Root of C5

3. What roots contribute to it?

C5, C6, C7

Question 8

What two Nerves come directly off of the Superior Trunk?

Answer 8

Suprascapular Nerve and Subclavian and Nerve

Question 9

Suprascapular Nerve

1. What does it innervate?
2. Where does it come off of the brachial plexus?
3. What roots contribute to it?

Answer 9

1. What does it innervate?

Supraspinatus Muscle and Infraspinatus Muscle

2. Where does it come off of the brachial plexus?

Superior Trunk

3. What roots contribute to it?

C5 and C6

Question 10

Subclavian Nerve

1. What does it innervate?
2. Where does it come off of the brachial plexus?
3. What roots contribute to it?

Answer 10

1. What does it innervate?

Subclavius Muscle

2. Where does it come off of the brachial plexus?

Superior Trunk

3. What roots contribute to it?

C5 and C6

Question 11

Lateral Pectoral Nerve

1. What does it innervate?
2. Where does it come off of the brachial plexus?
3. What roots contribute to it?

Answer 11

1. What does it innervate?

Pectoralis Major Muscle

2. Where does it come off of the brachial plexus?

Lateral Cord

3. What roots contribute to it?

C5, C6, and C7

Question 12

Thoracodorsal Nerve

1. What does it innervate?
2. Where does it come off of the brachial plexus?
3. What roots contribute to it?

Answer 12

1. What does it innervate?

Latissimus Dorsi Muscle

2. Where does it come off of the brachial plexus?

Posterior Cord

3. What roots contribute to it?

C6, C7, and C8

Question 13

Superior Subscapular Nerve

1. What does it innervate?
2. Where does it come off of the brachial plexus?
3. What roots contribute to it?

Answer 13

1. What does it innervate?

Subscapularis Muscle

2. Where does it come off of the brachial plexus?

Posterior Chord

3. What roots contribute to it?

C5 and C6

Question 14

Inferior Subscapular Nerve

1. What does it innervate?
2. Where does it come off of the brachial plexus?
3. What roots contribute to it?

Answer 14

1. What does it innervate?

Subscapularis Muscle and Teres Major Muscle

2. Where does it come off of the brachial plexus?

Posterior Chord

3. What roots contribute to it?

C5 and C6

Question 15

Medial Pectoral Nerve

1. What does it innervate?
2. Where does it come off of the brachial plexus?
3. What roots contribute to it?

Answer 15

1. What does it innervate?

Pectoralis Major and Minor Muscles

2. Where does it come off of the brachial plexus?

Medial Chord

3. What roots contribute to it?

C8 and T1

Question 16

Medial Brachial Cutaneous Nerve

1. What does it innervate?
2. Where does it come off of the brachial plexus?
3. What roots contribute to it?

Answer 16

1. What does it innervate?

Skin of the brachium

2. Where does it come off of the brachial plexus?

Medial Chord

3. What roots contribute to it?

Skin of Medial Arm

Question 17

Medial Antebrachium Cutaneous Nerve

1. What does it innervate?
2. Where does it come off of the brachial plexus?
3. What roots contribute to it?

Answer 17

1. What does it innervate?

Skin of medial forearm

2. Where does it come off of the brachial plexus?

Medial Chord

3. What roots contribute to it?

C8 and T1

Question 18

If there is an injury to the Anterior Rami of C5 and C6, what disease can you expect?

Answer 18

Erb-Duchenne Palsy (Waiter Tip Position)

• Adducted Arm
• Medially Rotated Arm
• Extended Elbow

Question 19

If there is an injury to lower brachial plexus or injure the ulnar nerve, what disease can you expect?

Answer 19

Klumpke Paralysis (Claw Hand)

Will affect the short muscles of the hand when the individual tries to make a fist

Question 20

What might happen if you spend an extended amount of time working with your arm above your head?

Answer 20

Compression of the Brachial Plexus

• Weakness and tingling in the arms
• Pain radiating down the arm
• Loss of sensation in the arm

Question 21

Musculocutaneous Nerve

1. What does it innervate?
2. Where does it come off of the brachial plexus?
3. What roots contribute to it?

Answer 21

1. What does it innervate?

Biceps Brachii Muscles (long and short head)

Coracobrachialis Muscle

Brachialis Muscle

2. Where does it come off of the brachial plexus?

Terminal Branch (anterior)

3. What roots contribute to it?

C5, C6, and C7

Question 22

Musculocutaneous Nerve splits off into another nerve:

What is this nerve and what does it innervate?

Answer 22

Lateral Antebrachial Cutaneous Nerve

-innervates lateral skin of the forearm

Question 23

What happens if the Musculocutaneous Nerve is injured?

Answer 23

Renders the anterior brachial muscles paralyzed and possible loss to sensation on the skin of the lateral forearm

(Quiet rare and is possible with blunt force trauma)

Question 24

Axillary Nerve

1. What does it innervate?
2. Where does it come off of the brachial plexus?
3. What roots contribute to it?

Answer 24

1. What does it innervate?

Deltoid Muscle and Teres Minor Muscle

2. Where does it come off of the brachial plexus?

Terminal Branch (posterior)

3. What roots contribute to it?

C5 and C6

Question 25

Axillary Nerve splits off into another nerve: What is this nerve and what does it innervate?

Answer 25

Superior Lateral Brachial Cutaneous Nerve ## Footnote *The name describes the position of the Deltoid, which is where the Axillary nerve innervates both Muscle and Skin.*

Question 26

What happens if the Musculocutaneous Nerve is injured?

Answer 26

Atrophy of the Deltoid Musle and loss of sensation over the superolateral arm -Inability to abduct the arm to 90 degrees (the Supraspinatus can get it up about 15 degrees)

Question 27

**Median Nerve** 1. What does it innervate? (only median nerve proper) 2. Where does it come off of the brachial plexus? 3. What roots contribute to it?

Answer 27

* 1. What does it innervate?* _Mostly forearm flexor muscles_ - Pronator Teres - Flexor Carpi Radialis - Palmaris Longus - Flexor Digitorum Superficialis * 2. Where does it come off of the brachial plexus?* Terminal Branch (anterior) *3. What roots contribute to it?* C5 - T1 (all of them)

Question 28

What are the branches off of Median Nerve and what do they innervate? * Hint: 4 branches* * P.S. Hopefully this is worst card in deck*

Answer 28

**Anterior Interosseous Nerve:** - Lateral Part of Flexor Digitorum Profundus - Flexor Pollicis Longus - Pronator Quadratus **Palmar Cutaneous Branch of the Median Nerve:** Skin of the palm (*Can feel the Palm in Carpal Tunnel)* **Recurrent Branch of Median Nerve:** - Flexor Pollicis Brevis (superificial head) - Abductor Pollicis Brevis - Opponens Pollicis **Lateral Branch of Median Nerve:** 1^st Lumbrical **Medial Branch of Median Nerve:** - 2^nd Lumbrical - Common Palmar Digital Nerves - Proper Palmar Digital Nerves

Question 29

What can damage to the median nerve cause?

Answer 29

Hand of Benediction

Question 30

**Ulnar Nerve** 1. What does it innervate? (only ulnar nerve proper) 2. Where does it come off of the brachial plexus? 3. What roots contribute to it? 4. What are its two main branches?

Answer 30

*1. What does it innervate? (only ulnar nerve proper)* Flexor Carpi Ulnaris Muscle Flexor Digitorum Profundus (medial half) *2. Where does it come off of the brachial plexus?* Terminal branch (anterior) *3. What roots contribute to it?* C8 and T1 *4. What are its two main branches?* Deep Ulnar Nerve and Superficial Ulnar Nerve

Question 31

What artery does Ulnar Nerve run with?

Answer 31

Superior Ulnar Collateral Artery

Question 32

What does Deep Ulnar Nerve innervate? *Hint: A lot*

Answer 32

1. Flexor Pollicis Brevis Muscle (deep head) 2. Adductor Pollicis Muscle 3. 3^rd and 4^th Lumbricals 4. Dorsal and Palmar Interossei Muscles 5. Adductor Digiti Minimi Muscle 6. Flexor Digiti Minimi Muscle 7. Opponens Digiti Minimi Muscle

Question 33

What nerves does the Superficial Ulnar Nerve give rise to?

Answer 33

1. Common Palmar Digital Nerves 2. Proper Palmar Digital Nerves

Question 34

Ulnar Nerve splits off into two cutaneous nerves: What are these nerve and what does they innervate?

Answer 34

**1. Dorsal Cutaneous Branch of Ulnar Nerve:** Skin on the dorsal side of the _hand_ **2. Palmar Cutaneous Branch of Ulnar Nerve:** Skin on _palm_

Question 35

What can be the result of damage to the Ulnar Nerve?

Answer 35

1. Claw Hand (same as lower plexus injury) 2. Handlebar Neuropathy (pulling at Guyon canal) - pressure on medial side of the hand

Question 36

Where can Ulnar Nerve Damage Occur?

Answer 36

Posterior to the Medial Humeral Epicondyle (funny bone area) Between the Ulnar and Humeral Heads of the Flexor Carpi Ulnaris *(we didn't learn about these heads)* The Wrist The Hand

Question 37

**Radial Nerve** 1. What does it innervate? (only ulnar nerve proper) 2. Where does it come off of the brachial plexus? 3. What roots contribute to it? 4. What are its two main branches? (that innervates muscles)

Answer 37

* 1. What does it innervate? (only ulnar nerve proper)* - Triceps Brachii Muscle (all heads) - Anconeus Muscle - Brachioradialis Muscle - Extensor Carpi Radialis Longus Muscle * 2. Where does it come off of the brachial plexus?* Terminal Branch (posterior) *3. What roots contribute to it?* C5-T1 (all of them) *4. What are its two main branches? (that innervates muscles)* Deep and Superficial Radial Nerves

Question 38

What does the Superficial Radial Nerve innervate and branch off into?

Answer 38

**Mostly cutaneous sensation** in lateral half of dorsum of hand 1. _Dorsal Digital Nerves:_ goes to bases of proximal phalanges 2. _Digital Branches of Dorsal Digital Nerves:_ Dorsal aspect of thumb and proximal aspect of second, third, and lateral half of fourth digit

Question 39

What muscles do the Deep Radial Nerve innervate? What happens after it inervates these muscle?

Answer 39

1. Extensor Carpi Radialis Brevis Muscle 2. Supinator Muscle Deep Radial Nerve changes its name to **Posterior Interosseous Nerve**

Question 40

What does the Posterior Interosseous Nerve innervate?

Answer 40

1. Extensor Digitorum Muscle 2. Extensor Digitorum Minimi Muscle 3. Extensor Carpi Ulnaris Muscle 4. Extensor Indicis Muscle 5. Abductor Pollicis Longus Muscle 6. Extensor Pollicis Longus Muscle 7. Extensor Pollicis Brevis Muscle

Question 41

Radial Nerve splits off into two cutaneous nerves: What are these nerve and what does they innervate?

Answer 41

**Posterior Brachial Cutaneous Nerve:** posterior arm **Posterior Antebrachial Cutaneous Nerve:** posterior forearm

Question 42

What can happen if radial nerve is damaged?

Answer 42

Wrist Drop - Impairment of elbow extension - Impairment of thumb abduction and extension

Question 43

The Radial Nerve innervates most of the lateral part of the dorsal hand, but what nerve innervates the most distal, dorsal part of the 2nd, 3rd, and 4th digit?

Answer 43

The Proper Palmar Digital Nerves **of the Median Nerve** ## Footnote *The Median Nerve wraps over the fingertips and gets the dorsal tips of Digits 2, 3, and 4,*

Question 44

Where does the Intercostobrachial Nerve come from? What does it do?

Answer 44

A Thoracic Spinal Nerve Provides Sensory Innervation to the most medial part of the posterior brachium.