Lecture 6: Spinal nerves and plexus Flashcards
number of spinal nerves and their associated levels
31 pairs of spinal nerves
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
describe the location of the cervical spinal nerves
the first is located between the occiput and C1 vertebrae (motor only)
2-7 are located ABOVE corresponding cervical vertebrae
C8 under C7/above T1
+1 rule = i.e. nerve under C1 vertebrae = C1 + 1 = C2 nerve
what is the endoneurium
continuous part of the pia mater
wraps a SINGLE AXON
what is the perineurium
continuous component from arachnoid mater
wraps BUNDLES OF AXONS (form a fasicle)
what is the epineurium
continuous component from dura mater wrapping BUNDLES OF FASCICLES
describe blood supply to peripheral nerves
plexus of arterioles follow the peripheral nerves
what is a neuropraxia injury
compression injury with axon intact
endoneurium is intact
good chance of recovery
what is an axonotmesis injury
tear of an axon
what is a neurotmesis injury
tear of whole fascicle/nervee
disrupted endo-, peri, or even epineurium
poor chance of recovery
describe the size of a spinal nerve
very short
soon splits to dorsal and ventral rami
what are the branches of the dorsal rami and what do they supply
medial branch = vertebral disc, facet joints, intrinsic back mm, and skin
lateral branch = intrinsic back mm mainly and skin slightly
branches of the ventral ramus as well as their further sub-branches and function
cutaneous branch
- lateral cutaneous = anterior and posterior branches
- anterior cutaneous = lateral and medial branches
muscular branch = supplies intercostals, serratus posterior, and abdominal wall mm
myotomes tested in ASIA scale
5 UE and 5 LE
major limb mm of each
dermatomes test what; how does it vary from trunk to neck/extremities
segmental distribution of nn innervation
A delta - crude touch, sharp pain
trunk area = ventral and dorsal rami of spinal nn
neck and extremities = peripheral nn from plexus fromed by VENTRAL rami
cervical plexus is formed by what rami
ventral
nerves from the cervical plexus and their roots
Lesser occipital nerve - (C2)
Greater Auricular nerve - (C2-C3)
transverse cervical nerve - (C2-C3)
Supraclavicular nerve (C3-C4)
innervation at the mandibular angle
greater auricle nerve
around the TMJ; important to know this for differential dx
where does the supraclavicular nerve (C3-C4) exit
posterior 1/3 of the SCM
area is a nerve point; common place for dry needling
if mm is strained it can compress the nerve
C1 nerve (part of cervical plexus) goes to what mm
geniohyoid and thyrohyoid mm through hypoglossal nn (CN XII)
hikes onto CN XII
roots of ansa cervicalis and the target mm
superior root = C1 (through hypoglossal n)
inferior root (C2-C3)
target mm = infrahyoid neck mm
phrenic nn roots
C3-C5
acts like CPG; doesn’t take conscious thought to breathe
what ventral rami roots supply the brachial plexus
C5-T1
superior trunk of the brachial plexus roots
C5/C6
middle trunk of brachial plexus roots
C7
inferior trunk of brachial plexus roots
C8/T1
the 1st ribs separates what
C8/T1 nerve roots
can get impinged
each trunk of the brachial plexus gives out what
anterior and posterior divisions
lateral cord is formed by
anterior divisions of the superior and middle trunk
medial cord is formed by
anterior division of the inferior trunk
posterior cord is formed by
all posterior divisions (from superior, medial, and inferior trunk)
each cord of the brachial plexus gives out what
terminal branches of nn
what nerves of the brachial plexus are directly from the nerve roots
Dorsal scapular nerve (C4 and C5)
Long thoracic nerve (C5, C6, and C7)
dorsal scapular nn supplies what mm
levator scapulae
rhomboid major and minor
long thoracic nerve supplies what mm
serratus anterior
SALT57 = serratus anterior, long thoracic, roots C5 through C7
nerves from the superior trunk of the brachial plexus
suprascapular nerve (C5 and C6)
nerve to subclavius (C5 and C6)
suprascapular nerve supplies what
supra and infraspinatus
roots of the lateral cord
C5, C6, and C7
roots of lateral pectoral nerve and mm supplied
lateral pectoral nerve technically has a bridge to the medial as well; thus nn roots are C5-T1
supplies pec major
musculocutaneous nn roots
C5-C7
mm supplied by musculocutaneous nn and roots
coracobrachialis/biceps brachii (C5/C6)
Brachialis (C5/C6) and some C7 from radial nn
skin supplied by musculocutaneous nn
lateral antebrachial nn is a branch from the musculocutaneous nerve
supplies the lateral forearm; cutaneous innervation
what are the terminal branches of the lateral cord
lateral pectoral nerve (C5-T1 b/c branch to medial pectoral nn)
musculocutaneous nerve (C5-C7)
gives branch to median nerve (C5-C7 root portion)
roots of the medial cord of the brachial plexus
C8 and T1
terminal branches of the medial cord of the brachial plexus
medial pectoral nn
medial brachial cutaneous nerve
medial antebrachial cutaneous nerve
ulnar nerve
branch to median nerve
medial pectoral nerve (C8-T1) supplies what
pec major and minor
forearm mm innervated by the ulnar nn
flexor carpi ulnaris
ulnar side 1/2 of flexor digitorium profundus
hand mm innervated by the ulnar nn
palmaris brevis
ulnar side 2 lumbricals
ulnar head of flexor pollicis brevis
interossei/adductor pollicis
hypothenar eminence mm
what are the mm of the hypothenar eminence
Abductor digiti minimi
Flexor digiti minimi
Opponens digiti minimi
cutaneous branch of the ulnar nn supplies what
dorsal and palmar sides of hand 1.5 digits
forearm mm supplied by the median nn
pronator teres
flexor carpi radialis
palmaris longus
flexor digitorum superficialis
Via anterior interosseous:
-flexor pollicis longus
-radial 1/2 flexor digitorum profundus
-pronator quadratus
anterior interosseous nerve supplies what
flexor pollicis longus
radial 1/2 flexor digitorum profundus
pronator quadratus
mm of thenar eminence
abductor pollicis brevis
flexor pollicis brevis (radial head)
opponens pollicis
hand mm supplied by median nn
thenar eminence
radial side 2 lumbricals
cutaneous branch of the median nerve supplies what
radial palmar side 3.5 fingers and dorsal DIP
roots of the posterior cord
C5-T1
terminal branches of the posterior cord
upper subscapular nn (C5-C6)
middle subscap/thoracodorsal nn (C6-C8)
lower subscapular nn (C5-C6)
axillary nn (C5-C6)
radial nn (C5-T1)
roots of upper subscap and mm it innervates
C5-C6
subscapularis
rots of the middle subscapular nn/thoracodorsal nn and mm innervated
C6-C8
latissimus dorsi
lower subscapular nerve roots and mm it innervates
C5-C6
subscapularis and teres major
axillary nn roots
C5-C6
radial nn roots
C5-T1
target mm of axillary nn
deltoid
teres minor
cutaneous branch of the axillary nn innervates what region
shoulder girdle along deltoid
arm/elbow mm innervated by radial nn
triceps
brachioradialis
anconeus
supinator
forearm mm innervated by radial nn
abductor pollicis longus
extensor pollicis brevis
extensor carpi radialis longus/brevis
extensor pollicis longus
extensor digitorum
extensor indicis
extensor digiti minimi
extensor carpi ulnaris
nn of lumbar plexus directly from the ventral rami and their corresponding roots
iliohypogastric = T12 - L1
iliolingual = L1
genitofemoral = L1-L2
anterior division of the lumbar plexus gives off what nn, what are their roots, and what do they supply
obturator nn (L2-L4) - medial thigh
lumbosacral trunk (L4-L5) - continues for sacral plexus
posterior division of the lumbar plexus supplies what
lateral and anterior thigh
posterior division of the lumbar plexus gives off what nn
lateral femoral cutaneous nn (L2-L3)
Femoral (L2-L4)
target mm of obturator nn
pectineus
obturator externus
adductors (except adductor magnus HS head)
gracilis
general functions of mm innervated by obturator nn
Hip ADD/IR
Hip ER (pectineus and obturator externus)
Knee flex
Knee IR (gracilis)
target mm of femoral nn
iliopsoas
sertorius
pectineus
quadriceps
what is special about pectineus innervation
innervated by obturator nn AND femoral
general functions of mm supplied by femoral nn
Hip flexion and ER
knee ext and IR
cutaneous branch of femoral nn supplies what
anterior thigh
medial leg to foot arch (saphenous nn)
roots of lumbosacral trunk
L4-L5
roots of sacral spinal nn
S1-S4
ventral/anterior division of the sacral plexus gives off what nn and what are their roots
tibial nn L4-S3
pudendal nn S2-S4
pelvic splanchnic nn S2-S4, parasympathetic motor
dorsal/posterior division of the sacral plexus gives off what nn and what are their roots
common fibular nn L4-S2
superior gluteal nn L4-S1
inferior gluteal nn L5-S2
roots of posterior femoral cutaneous nn
S1-S3
mm supplied by superior gluteal nn L4-S1
glut med
glut min
TFL
mm supplied by inferior gluteal nn L5-S2
glut max
thigh mm innervated by common fibular nn
biceps femoris SH
leg mm innervated by the common fibular nn
superficial
- fibularis longus/brevis
deep branch
- tibialis anterior
- extensor digitorum longus
- extensor hallucis longus
- fibularis tertius
- foot mm (ext hallucis/digitorium brevis)
general functions of mm supplied by common fibular nn
knee flexion and ER
ankle/foot
- DF
- IV
- toe EXT
- PF
- EV
cutaneous branch (superficial and deep) of the common fibular nn supplies what regions
superficial = lateral leg and dorsum of foot
deep = dorsum of food between the 1st and 2nd digit
mm innervated by the tibial nn
HS except biceps femoris SH
adductor magnus HS head
posterior leg mm??
all foot intrinsic except extensor brevis
general functions of mm supplied by the tibial nn
hip ext
knee flex, IR, ER
ankle PF, IV, ADD, toe flex
cutaneous branch of the tibial nn supplies what regions
posterior leg to lateral foot (sural nn)
sole of foot
radiculopathy vs peripheral neuropathy
radiculopathy = segmental distribution (multiple peripheral nn)
peripheral neuropathy = localized region (single or multi peripheral nn)
discs in the cervical region
C2-C7
no C1 disc
how to name nn impinged by a disc
corresponding disc is above the vertebrae (C2 disc is above C2 vertebrae)
impinged nn root number = +1
C5 disc herniation (disc above C5) would compress C6 nn root (C5+1)
