Anatomy: Brachial Plexus

Question 1

The brachial plexus is intimate with ______ artery

Which section of the brachial plexus are named in relationship to the artery mentioned above?

Answer 1

The brachial plexus is intimate with the axillary artery

The cords are names in relationship to the artery (RTDCB)

Cords are lateral, medial, and posterior

Question 2

What are the components of the brachial plexus from medial to lateral?

Answer 2

Robert Taylor Drinks Cold Beer

Roots, trunks, divisions (X), cords, branches

Question 3

Explain the roots of the brachial plexus

Which two nerves come off the roots of the brachial plexus

Answer 3

The Roots:

C5-C8 and T1

Nerves that come off the Roots of the Brachial Plexus

• Dorsal Subscapular Nerve
• Long Thoracic Nerve (C5-C7)

Question 4

Where does the dorsal subscapular nerve originate?

Where does the Long Thoracic Nerve originate from?

Answer 4

The dorsal subscapular nerve comes from the posterior aspect of the C5 root

Long Thoracic Nerve: roots C5, C6, C7

Question 5

Explain the trunks of the brachial plexus

Make sure to explain any nerves that come off of them

Answer 5

Trunk of brachial plexus: There are upper, middle, and lower trunks

Upper trunk: formed by union of C5 and C6

• only trunk to have branches
• suprascapular nerve: innervates supra and infraspinatus muscles
• nerve of subclavious

Middle Trunk: continuation of C7

Lower Trunk: Formed by union of C8 and T1

Question 6

Where does the supraclavicular nerve branch from?

Where does the nerve of subclavious branch from?

Answer 6

Both the supraclavicular nerve and the nerve of subclavious branch off of the upper trunk.

Question 7

Describe the cords of the brachial plexus?

What nerves stem from the chords?

Answer 7

Lateral Chord: LP

Posterior Chord: LS, MS, PS, and axillary and radial nerves

Medial Chord: MAC, MBC, MP

Question 8

Describe an injury to the “upper trunk”

Also known as ______ Palsy

How does it happen?

Signs and symptoms

Answer 8

Upper trunk injury: Erb’s Palsy

(damage to C5, C6)

Birth injury during breech delivery or violent displacement of the head from the shoulder (like a motorcycle accident or a fall from horse)

Produces waiter’s tip hand

Question 9

Injury to the lower trunk:

Also known as _______ palsy

Caused by?

Signs?

Answer 9

Injury to the lower trunk:

Also known as Klumpke’s palsy

Caused by difficult breech delivery where the arm was forcefully abducted, or by an injury where the arm was forcefully abducted

Signs: claw hand

Question 10

What is the pneumonic to remember the root contributions to MARMU?

Answer 10

Three muskateers (Musculocutanoues: C5, C6, C7)

assasinated (C5, C6)

five rats (C5, C6, C7, C8 T1)

five mice (C5, C6, C7, C8, T1)

two unicorns (C8, T1)

Question 11

Root contributions to musculocutaneous nerve

Answer 11

“Three muskateers”

C5, C6, C7

Question 12

Root contributions to axillary nerve

Answer 12

“Assasinated”

C5, C6

Question 13

Root contributions to radial nerve

Answer 13

Five rats

C5, C6, C7. C8, T1

Question 14

Root contributions to medial nerve

Answer 14

Five mice

C5, C6, C7, C8, T1

Question 15

Root contributions to ulnar nerve

Answer 15

Two unicorns

C8, T1

Question 16

Draw the brachial plexus

Answer 16

Question 17

The cords of the brachial plexus are named for their relationship with which artery?

Answer 17

The axillary artery

Question 18

Which nerves originate from the roots of the brachial plexus?

Answer 18

Dorsalsubscapular

Long thoracic

Question 19

DJ gets his pants stuck in bike and amputates his finger. Which nerve is probably relaying this pain to his brain?

Answer 19

Ulnar nerve for fingers

Question 20

Which nerve is important for the wrist?

Answer 20

Radial is important for wrist

Ulnar is important for hand