Brachial Plexus

Question 1

Answer 1

Cranial to caudal: C5, C6, T2, T3

Question 2

Answer 2

Dark purple: T2 lateral cutaneous branch

Light purple: Axillary nerve

Grey: T3 lateral cutaneous branch

Question 3

Answer 3

Light blue: C5 ventral cutaneous branch

Turquoise: Brachiocephalic nerve (C6)

Question 4

Answer 4

Orange: Musculocutaneous (C6, 7, 8)

Yellow: Ulnar nerve (C8, T1, 2)

Green: Radial nerve (C7, 8, T1, 2)

Question 5

Autonomous zone palmar surface of the paw

Answer 5

Overlap of cutaneous zones of median (C8, T1) and ulnar (C7, 8, T1)

Question 6

What segment makes up the brachiocephalic nerve?

What is the autonomous innervation of this nerve?

Answer 6

Brachiocephalic nerve = C6 (7)

Autonomous zone: craniolateral shoulder

Question 7

Suprascapular and subscapular nerve:

• spinal cord segments
• muscles
• actions

Answer 7

Suprascapular C6, 7

• Supraspinatus - extends the shoulder, advances the limb
• Infraspinatus - lateral rotation and abduction of the proximal humerus

Subscapular C6, 7

• Subscapularis - shoulder flexion

Question 8

Musculocutaneous and Axillary nerves:

• spinal cord segments
• muscles
• actions

Answer 8

Musculocutaneous (C6, 7, 8)

• biceps brachii - extends the shoulder, flexes elbow
• Brachialis - flexes elbow
• coracobrachialis - extends/adducts shoulder

Axillary (C6, 7, 8)

• Deltoid - flex shoulder
• Teres major, minor - “
• subscapularis - “

Question 9

Radial nerve

• Spinal cord segments
• Muscles
• Actions

Answer 9

Radial nerve (C7, 8, T1, 2)

• Triceps - extends the elbow
• Extensor carpi radialis - extends carpus and digits
• Ulnaris lateralis - abducts/laterally rotates the carpus
• Common and lateral digital extensors - extends digits II-V (common) and III - V (lateral)
• Overall - extends elbow, carpus, digits

Question 10

Median nerve

• spinal cord segments
• muscles
• actions

Answer 10

Median nerve (C8, T1)

• Flexor carpi radialis - flexes carpus
• Superficial digital flexor - flexes digits II - V
• Deep digital flexor - flexes carpus and digits
• Overall: Flexes carpus and digits

Question 11

Ulnar nerve

• spinal cord segments
• muscles
• actions

Answer 11

Ulnar nerve (C8, T1, 2)

• Flexor carpi ulnaris - flexes carpus and digits
• deep digital flexor - “ “ “

Question 12

Muscles of the lateral scapula (4)

Muscles of the medial scapula (2)

Innervation?

Answer 12

Lateral scapula - innervated by suprascapular and axillary nerves

1. Supraspinatus
2. Infraspinatus
3. Deltoid
4. Teres minor

Medial scapula - innervated by subscapular and axillary nerves

1. Subscapularis
2. Teres major

Question 13

Cranial brachial muscles (3)

Caudal brachial muscles (1)

Innervation?

Answer 13

Cranial brachial muscles - musculocutaneous nerve

1. Biceps brachii
2. Brachialis
3. Coracobrachialis

Caudal brachial muscles - radial nerve

1. Triceps

Question 14

Craniolateral antebrachial muscles (4)

Caudolateral antebrachial muscles (4)

Answer 14

Craiolateral antebrachial muscles - innervated by radial nerve

• Extensor carpi radialis
• Ulnaris lateralis
• Common digital extensor
• Lateral digital extensor

Caudolateral antebrachial muscles - innervated by ulnar nerve and median nerve

• Flexor carpi radialis
• Superficial digital flexor
• Deep digital flexor
• Flexor carpi ulnaris