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

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).

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).

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

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”.

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!

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

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)

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

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

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

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.

CV-1 CV-5 CV-6 CV-7 TV-1 Add an X or multiplication sign .

CV-1 CV-5 CV-6 CV-7 TV-1 Add a forward slash

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

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

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

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

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

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

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

CV-1 CV-5 CV-6 CV-7 TV-1 OK—here come the branches

CV-1 CV-5 CV-6 CV-7 TV-1 Now we add the 16 branches---first dorsal scapular from c4 root.

CV-1 CV-5 CV-6 CV-7 TV-1 Nerve to subclavius and--------

CV-1 CV-5 CV-6 CV-7 TV-1 Suprascapular nerve from upper trunk.—large nerve travelling thru suprascapular notch and innervating suprspinatus and infraspinatus muscles.

CV-1 CV-5 CV-6 CV-7 TV-1 Then lateral pectoral from lateral cord.

CV-1 CV-5 CV-6 CV-7 TV-1 Upper--

CV-1 CV-5 CV-6 CV-7 TV-1 Middle----

CV-1 CV-5 CV-6 CV-7 TV-1 And lower subscapular nerves from posterior cord.—note middle subscapular is commonly called thoracodorsal nerve.

CV-1 CV-5 CV-6 CV-7 TV-1 Medial pectoral

CV-1 CV-5 CV-6 CV-7 TV-1 Medial brachial cutaneous

CV-1 CV-5 CV-6 CV-7 TV-1 And medial antebrachial cutaneous from medial cord—Jack Cook puts ketchup on hotdogs.

CV-1 CV-5 CV-6 CV-7 TV-1 and another from the roots--

CV-1 CV-5 CV-6 CV-7 TV-1 C4,5,6

CV-1 CV-5 CV-6 CV-7 TV-1 From the roots c4,5,6-----------------the long thoracic nerve

CV-1 CV-5 CV-6 CV-7 TV-1 The long thoracic nerve.

CV-1 CV-5 CV-6 CV-7 TV-1 Then the median nerve and the MARMU branches are complete—musculocutaneous, axillary, radial, median, and ulnar.

CV-1 CV-5 CV-6 CV-7 TV-1 DONE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

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

Lateral head Medial head MARMU Mus DS Sup LP CV-1 CV-5 Subc AX CV-6 M LS 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

Repeticio est mater studiorum Repetition is the mother of learning

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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

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.

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

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

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

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)

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

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

Answers: C D E A