Axilla and Brachial Plexus Flashcards
Define the boundaries of the axilla
Anterior: pectoralis major and minor muscles
Posterior: latissimus dorsi, teres major, long head of triceps and subscapularis
Medial: lateral thoracic wall and serratus anterior
Lateral: intertubercular groove of the humerus
List the contents of the axilla
- Axillary artery and the brachial plexus of nerves
- Axillary vein and lymphatics
- lymph nodes and the lymphatics from the upper extremity, the breast, and even the upper abdominal wall
- Fat
What encases the axillary artery and vein and the brachial plexus?
axillary sheath
Where is the apex of the axilla?
near the clavicle and first rib
What is the floor of the axilla?
axillary skin fold
Brachial Plexus:
- What spinal cord levels?
- What does it innervate?
- Mnemonic for segments?
- C-5 to T-1
- ALL THE INNERVATION to the upper extremity (Small exception is the intercostobrachial sensory nerve from T-2)
- “Read That Damn Cadaver Book” = roots, trunks, divisions, cords, and branches
Name the 5 major nerve branches of the brachial
plexus and their cords:
- musculocutaneous: lateral cord
- median: lateral and medial cords
- radial: posterior cord
- axillary: posterior cord
- ulnar: medial cord
Name all branches of lateral cord
- lateral pectoral nerve to the pectoralis MAJOR muscle
- musculocutaneous nerve
- LATERAL ROOT of the median nerve
Name all the branches of the Medial Cord
- medial pectoral nerve to both pectoral muscles
- medial brachial cutaneous nerve
- medial antebrachial cutaneous nerve
- ulnar nerve
- MEDIAL ROOT of the median nerve
Name all the branches of the posterior cord
- upper subscapular nerve
- thoracodorsal nerve
- lower subscapular nerve
- radial nerve
- axillary nerve
Describe the location of different parts of the brachial plexus relative to the scalene
muscles, the first rib, and the axillary artery
- Brachial plexus passes between the anterior and middle scalenes.
- Brachial plexus is superior to the first rib; cords of the brachial plexus are at or inferior to the clavicle
- The cords of the brachial plexus (lateral, posterior and medial) are named by their anatomical relation to the axillary artery
Which nerves leave the brachial plexus proximal to the divisions AND what do they innervate?
- long thoracic nerve (to the serratus anterior)
2, dorsal scapular nerve (to the rhomboids and some of the levator scapulae) - the suprascapular nerve (to supraspinatus and infraspinatus muscles)
- the nerve to the subclavius muscle (not important)
What does the axillary nerve innervate?
deltoid and teres minor muscles
Name the arteries BEFORE and AFTER the axillary artery and at what locations the change occurs
subclavian artery becomes axillary artery at the lateral border of the first rib
axilla artery becomes the brachial artery at the inferior border of the teres major muscle
What are the locations of the three parts of the axillary artery and what branches come off of each?
First branch is proximal to the pectoralis minor: superior thoracic (not important)
Second branch is posterior to pectoralis minor: thoracoacromial and the lateral thoracic
Third branch is distal to pectoralis minor: subscapular and the anterior and posterior circumflex
humeral
Axillary vein:
- merger of what two veins
- where does it end
- anatomical position to axillary artery (what if abducted)?
- brachial and basilic veins
- becomes subclavian vein at the lateral border of the 1st rib
- lies anteromedial to the axillary artery in anatomic position and anteroinferior if the arm is abducted
cephalic vein
- where is it located?
- What does it empty into?
- major subcutaneous vein of the lateral upper extremity
- empties into the axillary vein slightly lateral to the 1st rib, above the pectoralis minor
What is the function of the lymphatic system?
Multiple one-way valves in these vessels permit flow only toward the central venous system
Lymph nodes serve to filter the fluid and are sites of immunologic activity
Where does the lymph fluid travel to and where does it drain?
Most of the lymph fluid travels to the thoracic duct, which in turn drains into the left subclavian vein
Define terms:
Lymphangitis
Lymphadenitis
Lymphadenopathy
Lymphedema
Chlye
Lymphangitis = inflammation of lymph vessels Lymphade**_n**_itis = inflammation of lymph _**n_**odes
Lymphadenopathy = lymph node swelling or enlargement whether or not inflamed…often a result of cancer metastases
Lymphedema = Accumulation of lymph in interstitial spaces
Chlye = lymphatic fluid from the intestines involved in fat digestion and often
appears milky
Which nerve travels on the lateral surface of the serratus anterior muscle (i.e. medial wall of the axilla)?
long thoracic
