55: Brachial Plexus Flashcards
Randy Travis Drinks Cold Beer
Roots Trunks Divisions Cords Branches
roots of plexus
C5-T1
upper trunk
C5 + C6
middle trunk
C7
lower trunk
C8 + T1
clinical importance of anterior and posterior divisions
correlate directly to innervation of anterior (flexor) and posterior (extensor) compartments
posterior cord
all 3 posterior divisions united
lateral cord
anterior division of upper and middle trunk (C5-7)
medial cord
anterior division of lower trunk
the cords are named for their relationship to the …
axillary a.
medial cord is medial to it
lateral cord is lateral to it
posterior cord is posterior to it
terminal branches of posterior cord
axillary n. and radial n.
median n.
medial and lateral cords both send a contribution
terminal branch of lateral cord
musculocutaneous n.
terminal branch of medial cord
ulnar n.
dorsal scapular n.
from C5 root
long thoracic n.
from C5-7 roots
upper trunk (roots)
C5-6
suprascapular n.
from upper trunk
n. to subclavius
from upper trunk
branches off of the divisions
NONE
lateral cord (roots)
C5-7
lateral pectoral n.
off of the lateral cord (C5-7)
posterior cord (roots)
C5-8
upper subscapular n.
from posterior cord (C5-6)
thoracodorsal n. (aka middle subscapular)
from posterior cord (C6-8)
lower subscapular n.
from posterior cord (C5-6)
medial cord (roots)
C8- T1
medial pectoral n.
from medial cord (C8-T1)
medial brachial cutaneous n.
from medial cord (C8-T1)
medial antebrachial cutaneous n.
from medial cord (C8-T1)
axillary n.
one of two terminal branches of posterior cord
C5-C6
radial n.
one of two terminal branches of posterior cord
C5-C8
musculocutaneous n.
one of two terminal branches of lateral cord
C5-C7
median n.
a terminal branch of lateral and medial cord
C6- T1
“center of M”
median n.
ulnar n.
one of two terminal branches of the medial cord
C8-T1
superior lateral cutaneous n. of the arm
off of axillary n.
inferior lateral brachial cutaneous n.
off of radial n. (C5-6)
posterior brachial cutaneous n.
off of radial n. (C5-C8)
posterior antebrachial cutaneous n.
off of radial n. (C5-8)
superficial branch of radial n (C6-8) —>
lateral dorsum and lateral thenar area of hand
lateral antebrachial cutaneous n.
C6-7
branch off of musculocutaneous n.
cutaneous branch of median n. (C6-8) –>
palmar surface of lateral three digits and fingertips, lateral palm
dorsal branch of ulnar n. (C8-T1) —>
palmar and dorsal surface of medial hand and medial two digits
sensory and motor deficits that follow a dermatomal and myotomal pattern are generally due to injuries…
to the roots or trunks of the brachial plexus as a result of trauma to the neck
deficits that follow the distribution of peripheral nn are generally due to injuries of the….
terminal branches of the brachial plexus as a result of trauma to the upper limb
myotomes invade upper limb in a …
proximal to distal sequence
abduction of the shoulder
C5
flexion of elbow
C5
extension of wrist
C6
flexion of wrist, extension of fingers
C7
extension of elbow
C7-C8
why is C7 a critical injury location?
functional C7 necessary to get in/out wheelchair
flexion of fingers
C8
abduction/adduction of fingers
T1
biceps reflex
C5
brachioradialis reflexx
C6
triceps reflex
C7
dermatomes invade the upper limb in a…
preaxial-postaxial sequence
preaxial = lateral postaxial = medial
shoulder
C5
tip of thumb
C6
where do you do dermatome testing for C7?
too variable to test
tip of 5th digit
C8
medial forearm at cubital region
T1
lateral aspect of deltoid
tests cutaneous nerves off of axillary n.
lateral forearm
tests cutaneous nerves off of musculocutaneous n.
dorsum of webbing between thumb and index finger
tests cutaneous nerves off of radial n.
tip of index finger
tests cutaneous nerves off of median n.
medial tip of fifth digit
tests cutaneous nerves off of ulnar n.
erb-duchenne palsy is a lesion of which roots?
C5-C6 (upper plexus injury)
paralysis of abductors and lateral rotators of shoulder
loss of suprascapular and axillary n. associated with erb-duchenne palsy
paralysis of elbow flexors and forearm supinators
loss of musculocutaneous n. associated with erb-duchenne palsy
“waiter’s tip”
erb-duchenne palsy
loss and wasting of deltoid muscle, arm hangs at side.
internal rotation of arm
pronation at forearm (loss of biceps)
sensory loss at shoulder and lateral arm and forearm (c5-6 dermatomes)
“stap hangers syndrome”
klumpke paralysis
lesion associated with klumpke paralysis
C8-T1 roots (lower plexus injury)
impacts lower trunk, loss of ulnar nerve and weakness in median n.
“claw hand”
klumpke paralysis
loss and weakness of ulnar forearm flexors, pronators and all intrinsic hand muscles
muscle wasting, especially flexor carpi ulnaris, ulnar half of flexor digitorum profundus and all intrinsic hand muscles
why is the hand in full claw positon?
function of long flexors innervated by the median n., tonus of extensors, and loss of lumbricals which result in flexion at the IP joints but extension at the MCP joint
what sensory loss is associated with klumpke paralysis?
loss to medial forearm and hand (c8-t1 dermatomes)
Horner syndrome (can be with klumpke paralysis)
disruption of the rami communicantes from T1 to the sympathetic chain
miosis (pupil constriction due to unopposed parasymp)
ptosis (loss of superior tarsal m.)
anhydrosis
thoracic outlet syndrome
constriction of narrow area between first rib, clavicle and scalene muscles through which neurovasculature to upper limb passes
C8 and T1 are most involved
pain, numbness, muscle weakness, edema, muscle fatigue and cold skin
