1. A Quickee Brachial Plexus Intro
Or: Overcoming Perplexing Plexus Problems
By Dr. Michael Dauzvardis
2019/2020

2. OBJECTIVES: Be able to draw the brachial plexus in your sleep.
Learn to identify the roots, trunks, divisions, cords, and individual branches by using the interactive images.
Link the various major terminal branches with their specific origins and spinal root components (MARMU).
Equate the various major plexus related traumas with their specific site of injury (focus on upper and lower trunk injuries plus long thoracic nerve trauma).

3. What is the Brachial Plexus??
ANSWER: A spaghetti- like network of nerves that lives in the armpit (axilla) and controls movement and sensation in the upper extremity (arm and hand).

4. Axilla: Space of the Armpit
A. Boundaries:
1. Superiorly by the clavicle, the scapula, and the 1st rib
2. Inferiorly by the skin at the lower borders of the pectoralis major and the teres major/latissimus dorsi
3. Anteriorly by pectoral muscles
4. Posteriorly by the subscapularis
5. Medially by the serratus anterior
6. Laterally by the humerus
B. Contents
1. Brachial plexus
2. Axillary fat and fascia
3. Axillary vessels and branches
4. Axillary lymph nodes

5. The brachial plexus resides mainly in the neck and axilla
The brachial plexus resides mainly in the neck and axilla. Its parts are defined by the axillary artery. Always look for the “M”.

7. Robert Taylor drinks cold beer
Robert Taylor drinks cold beer.—The BP comes from roots c5, c6, c7, c8 and t1. the various root contributions come together –twist—turn separate—etc—to make up the terminal branches.—YIKES!

8. Let’s draw the damn thing::::
Start with 4 boxes representing vertebrae c5-t1

9. CV-1
CV-5
CV-6
CV-7
TV-1
These are vertebrae—label them cervical vertebra 5-6, (CV-5 etc.) and thoracic vertebra 1 (TV-1)

10. CV-1
CV-5
CV-6
CV-7
TV-1
Draw a lazy “Y” with the open end originating above and below vertebra c5

11. CV-1
CV-5
CV-6
CV-7
TV-1
Draw another lazy Y originating above and below vertebra t1

12. CV-1
CV-5
CV-6
CV-7
TV-1
Then a third “reversed lazy Y” slipping between vertebra c6 and7

13. CV-1
CV-5
CV-6
CV-7
TV-1
Add a “sideways” M.---or W if your last name Wang, Wasilewski, Webb, Werner, Weyenberg , Whiston, Wiechhaus, Williams, or Winfrey.

14. CV-1
CV-5
CV-6
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TV-1
Add an X or multiplication sign .

15. CV-1
CV-5
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TV-1
Add a forward slash

16. C5 C6 C7 C8 T1 ROOTS CV-1 CV-5 CV-6 CV-7 TV-1
Now you have the main body of the plexus. Note the parts—first : roots (actually ventral rami of spinal nerves C5—T1)
ROOTS

17. CV-1
CV-5
CV-6
CV-7
TV-1
Then trunks—(upper, middle, and lower)
TRUNKS

18. CV-1 CV-5 CV-6 CV-7 TV-1 DIVISIONS
Then divisions (note; 3 short anterior divisions are colored black, and 3 short posterior divisions are green). Hard to identify in the cadaver.
DIVISIONS

19. CV-1
CV-5
CV-6
CV-7
TV-1
Then cords
CORDS

20. LATERAL POSTERIOR MEDIAL CORDS CV-1 CV-5 CV-6 AXILLARY A. CV-7 TV-1
Cords are named by their relationship to the axillary artery lateral , posterior, and medial—remember; thumb is lateral (radial side). Is Roman out of bed yet?
DAUZVARDIS ‘13
CORDS

21. BRANCHES CV-1 CV-5 CV-6 CV-7 TV-1
Branches are the terminal named nerves to skin or muscle. (some do come off the roots and cords as we shall see)
BRANCHES

22. REAL TEACHERS DRINK COLD BEER
CV-1
CV-5
CV-6
CV-7
TV-1
DAUZVARDIS ‘13
Easy mnemonic for major parts.---actually would apply to drawing made from left to right. Caution; this is not a palindrome or zinc finger.
BRANCHES
CORDS
DIVISIONS
TRUNKS
ROOTS
REAL TEACHERS DRINK COLD BEER

23. CV-1
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TV-1
OK—here come the branches

24. CV-1
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TV-1
Now we add the 16 branches---first dorsal scapular from c4 root.

25. CV-1
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TV-1
Nerve to subclavius and

26. CV-1
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TV-1
Suprascapular nerve from upper trunk.—large nerve travelling thru suprascapular notch and innervating suprspinatus and infraspinatus muscles.

27. CV-1
CV-5
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TV-1
Then lateral pectoral from lateral cord.

28. CV-1
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TV-1
Upper--

29. CV-1
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TV-1
Middle----

30. CV-1
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TV-1
And lower subscapular nerves from posterior cord.—note middle subscapular is commonly called thoracodorsal nerve.

31. CV-1
CV-5
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TV-1
Medial pectoral

32. CV-1
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TV-1
Medial brachial cutaneous

33. CV-1
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TV-1
And medial antebrachial cutaneous from medial cord—Jack Cook puts ketchup on hotdogs.

34. CV-1
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TV-1
and another from the roots--

35. CV-1
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C4,5,6

36. CV-1
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TV-1
From the roots c4,5, the long thoracic nerve

37. CV-1
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TV-1
The long thoracic nerve.

38. CV-1
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TV-1
Then the median nerve and the MARMU branches are complete—musculocutaneous, axillary, radial, median, and ulnar.

39. CV-1
CV-5
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TV-1
DONE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

40. Mus DS Sup LP CV-1 CV-5 Subc AX CV-6 M CV-7 R LS MS US LT TV-1 MAC MP
MBC MP
All terminal branches labelled—see key on later slide. U

41. Lateral head Medial head MARMU Mus DS Sup LP CV-1 CV-5 Subc AX CV-6 MLS MS US
Medial
head LT
TV-1
MAC
MBC MP
Note median nerve has a lateral head from the lateral cord , and a medial head from the medial cord
DAUZVARDIS ‘13 U
MARMU

42. Repeticio est mater studiorum
Repetition is the mother of learning

44. CV-1
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45. CV-1
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46. CV-1
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47. CV-1
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48. CV-1
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49. CV-1
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50. CV-1
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51. CV-1
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52. CV-1
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53. CV-1
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54. CV-1
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55. CV-1
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56. CV-1
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57. CV-1
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58. CV-1
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59. CV-1
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60. CV-1
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61. CV-1
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62. CV-1
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63. CV-1
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TV-1

64. CV-1
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65. CV-1
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TV-1

66. MARMU Mus DS Sup LP CV-1 CV-5 Subc AX CV-6 M CV-7 R LS MS US LT TV-1
MAC
MBC MP
DAUZVARDIS ‘13 U
MARMU

67. Nerve Abbreviation Key
DS----dorsal scapular
LT-----long thoracic
Sup---suprascapular
Subc--nerve to subclavius
LP-----lateral pectoral
Mus--musculocutaneous
US----upper subscapular
MS---middle subscapular(thoracodorsal)
LS-----lower subscapular
AX----axillary
R------radial
M-----medial
U------ulnar
MP------medial pectoral
MBC----medial brachial cutaneous
MAC----medial antebrachial cutaneous
McClane was spotted at Jewel with 11 items in his grocery cart in the 10 item express lane.

68. Muscles innervated by a specific nerve
Dorsal scapular---levator scapulae, rhomboids
Long thoracic------serratus anterior
Suprascapular-----supraspinatus, infraspinatus
Nerve to subclavius----subclavius
Lateral pectoral----1/2 pectoralis major
Medial pectoral----1/2 pectoralis major, pectoralis minor
Musculocutaneous---biceps, brachialis, coracobrachialis
Upper subscapular---1/2 of subscapularis
Thoracodorsal latissimus dorsi
Lower subscapular-----teres major, 1/2 of subscapularis
Axillary teres minor, deltoid

69. Muscles innervated by the radial nerve
Extensor pollicis longus
Extensor indicis
Abductor pollicis longus
Triceps
Anconeus
Brachioradialis
Extensor carpi radialis longus
Extensor carpi radialis brevis
Supinator
Extensor digitorum
Extensor digiti minimi
Extensor carpi ulnaris
Extensor pollicis brevis

70. Muscles innervated by the median nerve
Pronator teres
Flexor carpi radialis
Palmaris longus
Flexor digitorum superficialis
Pronator quadratus
Flexor pollicis longus
½ flexor digitorum profundus
Abductor pollicis brevis
Flexor pollicis brevis
Opponens pollicis
Lumbricals 1&2

71. Muscles innervated by the ulnar nerve
Flexor carpi ulnaris
½ flexor digitorum profundus
Palmaris brevis
Abductor digiti minimi
Flexor digiti minimi
Opponens digiti minimi
Lumbricals 3&4
Dorsal and palmar interossei
Adductor pollicis
Flexor pollicis brevis (deep head)

72. Q1—brachial plexus
The cords of the brachial plexus are named for their relationship to which artery?
A .Carotid
B. Aorta
C. Axillary
D. Brachial
E. Ulnar
Q2—brachial plexus
Which of the following nerves originates from the roots of the brachial plexus?
Radial
Median
Lateral pectoral
Long thoracic
suprascapular

73. Q3—brachial plexus
DJ gets his pants cuff caught in his bike chain. Upon attempting to remove his skinny jeans from the sprocket entanglement, he amputates his little finger. Which nerve is probably relaying the pain to his brain?
Median
Radial
Nerve to subclavius
Long thoracic
Ulnar
While looking at his reflection in a store window, Caylon trips, falls into an open manhole and fractures his humerus. He has trouble extending his wrist. Which nerve was compromised?
Medial pectoral
Lower subscapular.
Q4—brachial plexus

74. Answers: C D E A