MSK 10 - The Axial and Brachial Plexuses

Question 1

What is a person’s axilla?

Answer 1

The space below the shoulder through which vessels and nerves enter and leave the upper arm; a person’s armpit.

Question 2

What structures make up the boundaries of the axilla?

Answer 2

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Question 5

What does the clavipectoral fascia extend from and to? What does it encapsulate? Does it have any specializations?

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Question 8

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Question 10

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Question 12

What is the mnemonic to remember the arteries that branch off of the subclavian artery?

Answer 12

VIT C & D

Vertebral Artery

Internal Thoracic Artery

Thyrocervical Trunk

Costocervical Artery

Dorsal Scapular (if present)

Question 13

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Question 14

Where is the axillary artery? What is it a continuation of and what does it become? How is it divided into sections?

Answer 14

Question 15

How many branches come off of the axillary artery and where? What is an easy way to remember this?

Answer 15

The 1st part of the axiallary artery (the part medial to the pectoralis minor) has 1 branch. The 2nd part (the part deep to the pectoralis minor) has two branches. The 3rd part (the part lateral to the pectoralis minor) has 3 branches.

Question 16

What is the acromion?

Answer 16

Question 17

List the branches of the axillary artery and what section they arise from.

Answer 17

1st Part: superior thoracic artery

2nd Part: thoracoacromial & lateral thoracic arteries

3rd Part: subscapular artery and the posterior & anterior humeral circumflex arteries

Question 18

What are the branches of the thoracoacromial artery? What is the mnemonic used to remember this?

Answer 18

PACD

Pectoral

Acromial

Clavicular

Deltoid

Question 19

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Question 21

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Question 23

How can blood get to the arm if there is a blockage of the axillary artery?

Answer 23

The suprascapular artery anastomoses with the circumflex scapular artery which anastomoses with the subscapular artery which anastomoses with the distal end of the axillary artery

Question 24

What is the axillary sheath?

Answer 24

A fibrous sheath that encloses the axillary artery and the axillary vein and the three cords of the brachial plexus to form the neurovascular bundle

Question 25

What spinal nerves innervate the brachial plexux?

Answer 25

C5-C8 & T1

Question 26

What are the parts of the brachial plexus called from medial to distal? What is a good mnemonic to remember this?

Answer 26

Read That Damn Cadaver Book Roots Trunks Divisions Cords (Terminal) Branches

Question 27

How many roots, trunks, divisions, cords, and terminal branches are there in the brachial plexus?

Answer 27

5 Roots 3 Trunks 6 Divisions 3 Cords 5 Terminal Branches

Question 28

Draw out the brachial plexus (without the small branches). Show which sections correspond to roots, trunks, divisions, cords, and terminal branches. Label which spinal nerves innervate which root.

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Question 33

Draw out and label everything in the brachial plexus

Answer 33

Question 34

What muscle(s) does the dorsal scapular nerve innervate?

Answer 34

Rhomboids Levator Scapulae

Question 35

What muscle(s) does the long thoracic nerve innervate?

Answer 35

Serratus anterior

Question 36

What muscle(s) does the suprascapular nerve innervate?

Answer 36

Supraspinatus and infraspinatus

Question 37

What muscle(s) does the sublavian nerve innervate?

Answer 37

The subclavius

Question 38

What muscle(s) does the lateral pectoral nerve innervate?

Answer 38

Pectoralis major

Question 39

What muscle(s) does the lower subscapular nerve innervate?

Answer 39

Subscapularis Teres Major

Question 40

What muscle(s) does the thoracodorsal nerve innervate?

Answer 40

Latissimus dorsi

Question 41

What muscle(s) does the upper subscapular nerve innervate?

Answer 41

Subscapularis

Question 42

What muscle(s) does the medial pectoral nerve innervate?

Answer 42

Pectoralis major and minor

Question 43

Which nerves are usually affected in an upper brachial plexus injury? What types of events cause an upper brachial plexus injury?

Answer 43

Typically the roots and trunks of C5-C7 are injured causing issues with the musculocutaneous, axillary, and suprascapular nerves

Question 44

Which nerves are usually affected in a lower brachial plexus injury? What type of events usually cause lower brachial plexus injuries?

Answer 44

Lower brachial plexus injuries usually result in damage to the C8 & T1 roots and trunks which will affect the function of the ulnar and part of the median nerve.

Question 45

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Question 47

What is the memory trick for learning which types of nerves are innervated by which spinal nerves?

Answer 47