MSK 10 - The Axial and Brachial Plexuses Flashcards
What is a person’s axilla?
The space below the shoulder through which vessels and nerves enter and leave the upper arm; a person’s armpit.
What structures make up the boundaries of the axilla?
What does the clavipectoral fascia extend from and to? What does it encapsulate? Does it have any specializations?
What is the mnemonic to remember the arteries that branch off of the subclavian artery?
VIT C & D
Vertebral Artery
Internal Thoracic Artery
Thyrocervical Trunk
Costocervical Artery
Dorsal Scapular (if present)
Where is the axillary artery? What is it a continuation of and what does it become? How is it divided into sections?
How many branches come off of the axillary artery and where? What is an easy way to remember this?
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.
What is the acromion?
List the branches of the axillary artery and what section they arise from.
1st Part: superior thoracic artery
2nd Part: thoracoacromial & lateral thoracic arteries
3rd Part: subscapular artery and the posterior & anterior humeral circumflex arteries
What are the branches of the thoracoacromial artery? What is the mnemonic used to remember this?
PACD
Pectoral
Acromial
Clavicular
Deltoid
How can blood get to the arm if there is a blockage of the axillary artery?
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
What is the axillary sheath?
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
What spinal nerves innervate the brachial plexux?
C5-C8 & T1
What are the parts of the brachial plexus called from medial to distal? What is a good mnemonic to remember this?
Read That Damn Cadaver Book
Roots
Trunks
Divisions
Cords
(Terminal) Branches
How many roots, trunks, divisions, cords, and terminal branches are there in the brachial plexus?
5 Roots
3 Trunks
6 Divisions
3 Cords
5 Terminal Branches
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.
Draw out and label everything in the brachial plexus
What muscle(s) does the dorsal scapular nerve innervate?
Rhomboids
Levator Scapulae
What muscle(s) does the long thoracic nerve innervate?
Serratus anterior
What muscle(s) does the suprascapular nerve innervate?
Supraspinatus and infraspinatus
What muscle(s) does the sublavian nerve innervate?
The subclavius
What muscle(s) does the lateral pectoral nerve innervate?
Pectoralis major
What muscle(s) does the lower subscapular nerve innervate?
Subscapularis
Teres Major
What muscle(s) does the thoracodorsal nerve innervate?
Latissimus dorsi
What muscle(s) does the upper subscapular nerve innervate?
Subscapularis
What muscle(s) does the medial pectoral nerve innervate?
Pectoralis major and minor
Which nerves are usually affected in an upper brachial plexus injury? What types of events cause an upper brachial plexus injury?
Typically the roots and trunks of C5-C7 are injured causing issues with the musculocutaneous, axillary, and suprascapular nerves
Which nerves are usually affected in a lower brachial plexus injury? What type of events usually cause lower brachial plexus injuries?
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.
What is the memory trick for learning which types of nerves are innervated by which spinal nerves?
