Axilla and Brachial Plexus Flashcards
boundaries of axilla
ant: pec major and minor
post: lat dorsi, teres minor, subscapularis
med: serratus anterior
lat: intertubercular sulcus of humerus
base: skin and fascia of armpit
what is the dermatome innervation of the axilla?
T2
contents of the axilla
fat and CT, axillary v and lymphatics (outside sheath), cutaneous nn, axillary sheath (axiallary a and brachial plexus)
what are the three layers contributing to thick axillary fascia?
axillary, pectoral, and skin
5 lymphatic areas of axialla
- pectoral
- subscapular
- humeral
- central
- apical
what do the pectoral lymph nodes drain?
ant thoracic wall and most of breast
what do the subscapular lymph nodes drain?
post thoracic wall and scapular region
what do the humeral lymph nodes drain?
UL except for portion along cephalic v
what do the central lymph nodes drain?
from pectoral, subscapular, and humeral, to apical
what do the apical lymph nodes drain?
all lymph nodes and proximal cephalic v nodes
axillary sheath location and contents
located down medial aspect of arm
contents: axillary a, nn, vv. lymphatics
pt 1-2 of axillary a
lateral border of 1st rib
pt 2-3 of axillary a
inf border of pec minor
brs from pt 1 of axillary a
superior thoracic a
brs from pt 2 of axillary a
- thoracoacromial a
2. lateral thoracic a
brs from pt 3 of axillary a
- subscapular a
- anterior circumflex humeral a
- posterior circulflex humeral a
nerve composition of brachial plexus
ventral rami C5-T1
what does the brachial plexus innervate?
nn for all UL mm except trapezius mm
structure of brachial plexus
rami (5): emerge in upper neck trunks (3): form in lower neck divisions (6): split off behind clavicle cords (3): form in axillary region branches (5): split off in upper arm
trunks of brachial plexus
- upper (C5-C6)
- middle (C7)
- lower (C8-T1)
each divides into anterior and posterior divisions
cords of brachial plexus
- lateral: ant from upper and middle tr (C5-C7)
- posterior: all post (C5-T1)
- medial: ant from lower (C8-T1)
branches of brachial plexus
- musculocutaneous n: from lat cord (C5-C7)
- medial n: from lat and med cords (C5-T1)
- axillary n: from post cord (C5-C6)
- radial n: from post cord (C5-T1)
- ulnar: from med cord (C8-T1)
musculocutaneous n
passes through coracobrachialis m
enters biceps and brachialis mm
innervates coracobrachialis, biceps, 1/2 brachialis
median n
passes medial to arm mm
“major n” of ant forearm
innervates most of anterior forearm, 3 thenar mm
ulnar n
runs behind medial epicondyle
major n of hand
innervates most of hand, FCU m, ulnar FDP m
axillary n
circles behind humerus in quadrangular space
innervates deltoid and teres minor m
radial n
passes posterior to humerus in radial groove and in triangular interval
major n of posterior arm and forearm
innervates all mm in both regions and 1/2 brachialis mm
upper plexus nn
- dorsal scapular n: C5, rhomboid and levator scapulae
- long thoracic n: C5-C7, serratus ant m
- suprascapular n: C5-C6, supra/infra spinatus
pectoral nn
- lateral pec n: C5-C7, pec major m
2. medial pec n: C8-T1, pec minor and major
lower plexus nn
- upper subscapular: C5-C6, subscapularis
- thoracodorsal: C6-C8, lat dorsi
- lower subscapularis: C5-C6. subscapularis and teres major
additional nn
- n to subclavius: C5-C6, subclavius m
- medial br of cut n: C8-T1, sensory to med arm
- med antibrachial cut n: C8-T1, sensory to med arm
