Spinal Anatomy Flashcards
Mesoderm Subgroups (4)
Paraxial (somatic and splanchnic)
Intermediate
Head
Lateral Plate
Endoderm derivatives
Organs, gut, respiratory tract
“tubular structures”
Mesoderm: Paraxial
(two parts…)
Somatic:
musculoskeletal- muscles, ligaments, tendons…
Splanchnic
smooth muscle of organs
Mesoderm: Intermediate
Urogenital system and kidneys
Mesoderm: Head
skull muscles, dentine of teeth
Mesoderm: Lateral Plate
Adrenal cortex, connective tissue, cardiovascular and lymph
Ectoderm Subgroups
“Ectoderm: nerves and skin”
Surface ectoderm
Neuroectoderm (2)
Ectoderm: Surface Ectoderm
Epidermis, anterior pituitary, lens of eye, skin, enamel, hair, nails
Ectoderm: Neuroectoderm
(Subgroups and derivatives)
Neural Tube
posterior pituitary, retina of eye, CNS, oligodendrocyte
CNS: brain and sc
- *Neural Crest**
- *Outside CNS:** sympathetic chain gangion, DRG, ANS, PNS, Schwann cells, Parafollicular cells of thyroid, adrenal medulla
Neuroectoderm:
Embryological order
notochord
↓
neural plate
↓
neural groove
↓
neural tube
↓
neural crest cell
CNS Pathologies derived from neural tube defects:
Spina Bifida Occulta
lamina failed to fuse
tuft of hair growth = “fawn’s beard”
Caused by folic acid deficiency
(“Folic acid” / “Vit B9” / “methylfolate” / “tetrahydrofolate”)
CNS Pathologies derived from neural tube defects:
Spina Bifida Vera / “Spina Bifida Manifesta”
Meningocele, myelocele, meningiomyelocele…
Meningocele: meninges protrude
Myelocele: sc protrudes because of underdeveloped meninges
Meningiomyelocele: sc and meninges protruding
CNS Pathologies derived from neural tube:
Arnold Chiari Syndrome
(two types)
Type I:
cerebellar peduncles come below foramen magnum
Type II:
Type I + meningiomyelocele
CNS Pathologies derived from neural tube:
Cleft Palate
failure of maxillary and palatine bones to fuse
neural tube defect, B9 deficiency
(Embryological stages of development)
Mesodermal Development
Sclerotome = membranous vertebral column
Myotome = muscle
- Somatic: skeletal muscle
- Splanchnic: “visceral” smooth muscle
- Epimere: dorsal, posterior mm, extensors
- Hypomere: ventral, anterior mm, flexors
Dermatome = nerves
(Embryological stages of development)
Ossification
intramembranous/intramedullary ossification
- mesenchymal tissue → bone
- clavicle / parietal bone*
*or any skull bone, all are partially intramembranous
Enchondral ossification = preformed in cartilage
- ossification for all other bones (98%)
Dorsal Primary Rami
to back mm
Ventral Primary Rami
to front mms
Exception: any back mm that is innervated by a nerve coming off brachial plexus is primary..
rhomboids → dorsal scapular n
latissimus dorsi → thoracodorsal n
(GI Embryology)
Mouth
Foregut
Midgut
Hindgut
Mouth: stomodeum
Foregut: back of throat to first 1/3 duodenum
Midgut: last <span>2</span>/3 duodenum to first <span>2</span>/3 transverse colon
Hindgut: last <span>1</span>/3 transverse colon to anus
The Gubernaculum
Males
becomes scrotal ligament aka “gubenacular testes”
Females
suspensory ligament of ovary, ovarian lig, and round lig.
Primary and Secondary Vesicles
“Tell Di Mes Met Mye”
Prosencephalon
- Telencephalon
- Diencephalon
Mesencephalon
- Mesencephalon
Rhombencephalon
- Metencephalon
- Myelencephalon
Telencephalon
Derived from Prosencephalon
Cortices, basal ganglion, cingular gyrus
CN I (Olfactory n)
Lateral Ventricle
Diencephalon
Derived from Prosencephalon
thalamus (hypo-, epi-, sub-)
*epithalamus = pineal gland
CN II (Optic n)
3rd ventricle
Mesencephalon
remains mesencephalon
midbrain
CN III (oculomotor) CN IV (trochlear) *\*only CN off posterior portion of brainstem, and contralateral*
Aqueduct of Sylvius AKA Cerebral Aqueduct
Metencephalon
From Rhombencephalon
Pons and cerebellum
CNs 5-8
(V: trigeminal, VI: abducens, VII: facial, VIII: vestibulocochlear)
roof of 4th ventricle
Myelencephalon
From Rhombencephalon
medulla oblongata
CNs 9-12
(IX: glossopharyngeal, X: vagus, XI: accessory, XII: hypoglossal)
floor of 4th ventricle
*fold of tissue at floor of 4th vent: “obex”
just below 4th ventricle: cisterna magna/”cerebellomedullary cisterm”
(Neurology)
Dendrites vs Axons
Dendrites: impulse towards cell body
Axon: impulse away from body
*impulse originates at axon hillock
Overview
receptor (dendrite) → peripheral nerve → spinal cord → brainstem → cerebellum
(or) ↓
thalamus → parietal lobe → Wernicke’s area (POT) → limbic system → motor response
*Only senseation that bypasses thalamus is smell. Cerebellum receives information after impulses pass thru brainstem and also from cortex
(Action Potential)
Resting Membrane Potential
muscle vs neuron
Resting Membrane Potential: (-) inside, (+) outside
large molecules create (-) inside, sodium creates (+) outside
Muscle = (-85-90mv)
Neuron = (-65-70mv)
(Action Potential)
Receptors
Allow Na+ leak into cell, twoards depolarization of nerve for AP
Depolarization = Na+ rushing in
Dorsal Column Receptors
Pacinian
insignificant vibration
A-beta fibers
Dorsal Column Receptors
Ruffini
joint position sense
A-beta fibers
Dorsal Column Receptors
Meissner’s/Merkel’s
accurate touch
A-Beta fibers
Spinothalamic Tracts
Free Naked endings
pain, temperature, crude touch
unmyelinated C fibers
AP Threshold
controlled by
Ca++
Subnormal Period
“Hyperpolarized”
“relative refractory period”
more negative, harder to fire
Na/K Pump
kicks in after subnormal/hyperpolarized period
helps reach equilibrium/resting
pumps 3 Na+ OUT
2 K+ IN
Medulla and Pons
Respiratory and cardiac center
autonomics
CN 5-12
Midbrain
reflexes to light and sound
proximal flexor relay
CN 3&4
Thalamus
relay station
sensory fibers
Pulvinar region = integration of sensory information
VPM of Thalamus
sensory from face
VPL of Thalamus
sensory from arms and legs
Lateral geniculate of Thalamus
sensory from eyes
Medial Geniculate of Thalamus
sensory from ears
Cerebrum
Intellect and association
Parietal Lobe
localization
“somesthetic cortex”
Post-central gyrus
Brodman 1,2,3
problem solving
Occipital Lobe
Vision
Brodman’s 17
Superior Temporal Lobe
Hearing
Inferior Temporal Lobe
Long term memory
(hippocampal cells)
damage to hippocampus = anterograde amnesia
smell
(parahippocampal cells)
Uncal area
“Uncus is the skunkest”
Wernicke’s Area
junction of P/O/T lobes
sensory matching, interpretation
(does this make sense? if not, fire sympathetics)
Destroyed by B1/Thiamine
d/t alcoholism = Wernicke Korsakoff Syndrome
d/t diet = Beri Beri
sensory aphasia: can’t understand language
word blindness in angular gyrus
Frontal Lobe
Voluntary Motor
precentral gyrus
brodman 4, 4s, 6
corticospinal tracts
corticobulbar/pyramidal tracts = personality
motor aphasia = broca’s speech, left inferior frontal lobe
blood supply from middle cerebral artery
Limbic System
associated w amygdala
pleasure or pain?
do I need to remember this?
Basal Ganglia
inhibits thalamus
Disfunction: trivial information elicits motor response
= Parkinson’s
(stops motor response)
Basal Ganglia
Caudate Nucleus
secretes GABA
defective caudate
= Huntington’s Chorea
Basal Ganglia
Striatum
putamen + caudate
separated by internal capsule
Basal Ganglia
Lentiform Nucleus
globus pallidus + putamen
Hypothalamus
hunger
thirst
temperature regulation
sex
rage
fear
Cerebellum
balance
equilibrium
involuntary coordination
unconscious proprioception
Blood-Brain Barrier
astrocytes + tight capillary beds
stores glucose/glycogen
Microglia
macrophages
Ependymal Cells
line ventricles, produce CSF
CSF made in choroid plexus in lateral ventricles
resorbed in arachnoid granulations of superior sagittal sinus
Oligodendrocytes
myelin in CNS
demyelination = MS
derived from neural tube because within CNS
Schwann Cells
myelinate PNS
demyelinization = post-infectious polyradiculopathy
“Guillan-Barre”
ascending paralysis, post vaccine, post infection
Meissner’s & Auerbach’s Plexuses
allows peristalsis
from neural crest cells
absense = no peristalsis
congenital megacolon/Hirschprung’s Disease
Renshaw Cells
inhibit alpha motor neuron
(-) feedback
Alpha waves
quiet, meditative
disappear in sleep
Beta waves
intense mental activity
REM sleep
Delta waves
deep sleep or coma
ARAS = Ascending REticular Activating System
= wakes up the cortex
flying delta puts you to sleep/coma
Theta waves
normal in children, abnormal in adults
2nd/3rd stage of sleep, non-REM
Association fibers of cerebrum
connect same hemisphere
from frontal to temporal, etc.
Commissural fibers of cerebrum
connect L to R
corpus callosum
Projection fibers of cerebrum
connect up and down both directions
brainstem/sc
pass through internal capsule
Central chemoreceptors
found in brainstem (medullary neurons)
most sensitive to HIGH CO2
dilate cerebral blood vessels
Peripheral chemoreceptors
found in carotid and aortic bodies
most sensitive to LOW OXYGEN
dilate cerebral blood vessels
Vertebral arteries enter spine at
C6 transverse foramen
feed into Circle of Willis
enter skull at foramen magnum
PICA
Posterior Inferior Cerebellar Artery
off Vertebral Arteries
Damage to PICA = Wallenberg Syndrome
ipsilateral loss of pain and temperature to face
contralateral loss of pain and temperature to body
Anterior Spinal Artery
from both vertebral arteries
blood to anterior 2/3 of spinal cord
Posterior Spinal Arteries
off radicular arteries
blood to posterior 1/3 of spinal cord
Carotids
Right Carotid off R brachiocephalic
Left Carotid off Aorta
both bifurcate at C3/4 into
Internal Carotid and External Carotid
manterior and middle cerebral aa // maxillary to middle meningeal a
Straight Sinus
Great Cerebral Vein of Galen drains into Straight Sinus
“Great is Straight”
Straight Sinus found in tentorium cerebelli
Superior Sagittal Sinus
Superior Cerebral Vein drains into Superior Sagittal Sinus
“Superior is Superior”
Superior Sagittal Sinus found in falx cerebri
contains arachnoid granulations for resorbing CSF
Falx Cerebri attachments
Anterior attachment: crista galli of ethmoid
Posterior attachment: tentorium cerebelli
Confluence of Sinuses
torculus herophilus
on inner portion of occipital bone
Damage to sinuses
subdural hematoma
Emissary veins
drain scalp into superior sagittal sinus
Damage to middle meningeal a
epidural hemorrhage
epidural hematoma
Damage to venous system
subdural hemorrage
7-14 days to show
slow bleed
Beri aneurysm
(Circle of Willis)
subarachnoid hemorrhage
worst headache of life
full intensity, immediately
Flocculonodular lobe of cerebellum
midline
balance of spine
Cerebellar Nuclei
Fastigial
spine
Cerebellar Nuclei
Globus
proximal joints
glenohumeral
Cerebellar Nuclei
Emboliform
middle joints
elbow
globus + emboliform = interpose nuclei
Cerebellar Nuclei
Dentate
distal joints
digits
motor output
Interpose Nuclei
globus + emboliform
MSC
type 1a fibers
stretch
GTO
type 1b fibers
tension
Tectum of Midbrain
superior and inferior colliculi
- *superior** = light
- *inferior** = sound
reflex to light and sound = tectospinal tract
Corpora quadrigemina = the 4 colliculi
Tegmentum of Midbrain
CN 3 and 4*
CN4 comes off posterior portion
center of mesencephalon
Cerebral peduncles
“Basis Pedunculi”
contains corticospinal tracts
red nucleus = origin of rubrospinal tract
substantia nigra = dopamine for thalamus
Parkinsons if damaged
CN I: Olfactory
Origin
Foramina/bone
Action
frontal lobe
cribiform plate of ethmoid
smell
CN II: Optic
Origin
Foramina/bone
Action
thalamus
optic foramen of sphenoid
S: vision
R: afferent pupillary light reflex
CN III: Oculomotor
Origin
Foramina/bone
Action
midbrain
superior orbital fissure of sphenoid
M: “All else 3” (SO4, LR6, all else 3)
R: pupillary constriction
P: efferent pupillary light reflex
CN IV: Trochlear
Origin
Foramen/bone
Action
midbrain
superior orbital fissure/sphenoid
M: superior oblique
CN V1: Opthalmic/Trigeminal
Origin
Foramen/bone
Action
pons
superior orbital fissure of sphenoid
S: corner of canthus to bald spot
R: afferent corneal, afferent oculocardiac
“Oval Man, Rotate Max, Spin the Middle”
CN V2: Maxillary
pons
foramen rotundum of sphenoid
S:corner of canthus to corner of mouth
“Oval Man, Rotate Max, Spin the Middle”
CN V3: Mandibular/Trigeminal
pons
foramen ovale of sphenoid
S: corner of mouth to chin, general sensation to tongue
M: mm of mastication and tensor tympani
R: jaw jerk (afferrent and efferent)
CN VI: Abducens
pons
superior orbital fissure of sphenoid
M: lateral rectus
CN VII: Facial
pons
internal auditory meatus to stylomastoid foramen
of temporal bone
pierces parotid
S: “chordae tympani” from middle ear to anterior 2/3 of tongue for taste
M: facial mm and stapedius
R: efferent corneal
P: lacrimation, salivation
CN VIII: Vestibulocochlear
pons
internal auditory meatus, temporal bone
S: Balance (vestibulo)
Hearing (cochlear)
CN IX: Glossopharyngeal
medulla
jugular foramen, temporal/occipital
S: posterior 1/3 tongue - taste. middle ear
M: stylopharyngeus
R: carotid afferent, gag afferent
P: salivation (parotid glands)
CN X: Vagus
medulla
jugular foramen, temporal/occipital
S: tympanic membrane
M: palate, pharynx, larynx
R:carotid, gag, and oculocardiac efferent
P: palate to 1st 2/3 transverse colon
CN XII: Spinal Accessory
medulla
jugular foramen, temporal/occipital
M: SCM (w/CN2,3) - cont’l rotation, ipsi’l lat. flexion
traps (w/CN3,4) - forms slope of neck
O: acromion + clavicle I= sup nuchal line
CN XII: Hypoglossal
medulla
hypoglossal foramen, occiput
M: intrinsic mm of tongue
Temporalis
O: Temporal fossa
I: coronoid of mandible
closes jaw
Masseter
O: Zygomatic
I: external angle of jaw
closes jaw
Internal/medial pterygoid
O: medial pterygoid process
I: internal angle of jaw
closes jaw
External/lateral pterygoid
O: lateral pterygoid process
I: disc of TMJ and condyle of mandible
opens/depresses jaw
protrudes jaw
Greatest input into parasympathetics
nucleus solitarius (CN 7,9,10) for taste
Fovea centralis
most acute vision
has cones: bright light and colors
Rods
periphery
dim light, night vision
glaucoma affects rods first
Optic nerve decussates at
optic chiasm
nasal tracts also decussate at optic chiasm
carry temporal fields of vision
damage: bitemporal hemianopia
Upper Motor Neuron lesion
no inhibition
clonus because constant firing
spasticity because increased firing
= increased muscle tone
hyperreflexia from tight mm spindle
Lower Motor Neuron lesion
fasciculations = muscle dying, spontaneously firing
hypotonia: lose 1b and 1a afferents for tone
hyporeflexia: decrease tone on spindles
True Ribs
Ribs 1-7
False Ribs
ribs 8-10
Floating ribs
Ribs 11-12
Direction of articular facets
Cervical = AIL
Thoracic = AIM
Lumbar = AIL
Anterior boundary of IVF
disc, body, rib head
cervicals include uncinates
thoracics include rib heads
Posterior boundary of IVF
articular facets = articular pillars
Z joints
Superior/Inferior boundaries of IVF
pedicle or ‘vertebral notch’
Landmarks
Hyoid bone
C3
Landmarks
Carotid artery bifurcation
C3, C4
Landmarks
Carotid tubercle
C6 transverse process
Landmarks
Episternal Notch
T2
Landmarks
Dermatome of Xyphoid process
T7
(vertebral level T10)
Landmarks
Dermatome of umbilicus
T10
(vertebral level L3)
Landmarks
Transpyloric Line
L1
Landmarks
Transtubercular Line
L5
2 neck mm with cranial nerve and cervical innervation
Trapezius = CN XI, cervical 3,4
SCM = CN XI, cervical 2,3
Muscles that elevate first four ribs during inspiration
Serratus Posterior Superior
Innervation T1-T4 thoracic/costal nn
Muscles that depress last four ribs during exhalation
Serratus Posterior Inferior
innervation T9-T12 thoracic/costal nn
Anterior scalene
inserts on scalene tubercle of first rib
located between subclavian vein and subclavian artery
Digastric
anterior belly: CN5
posterior belly: CN7
derived from 1st, 2nd branchial arches
form two sides of submandibular triangle
Galea aponeurotica
forehead fascia
Levator palpebrae superioris
oculomotor III
Levator scapulae
transverse processes of C1-C4
Longus capitis
flex the head and neck
Longus Colli
anterior tubercles and anterior surfaces of bodies of C1-T3
deep neck flexor
masseter
powerful m of mastication
mentalis
skin of the chin
middle scalene
upper surface of first rib
orbicularis oculi
closes the eyelids
CN VII facial
orbicularis oris
purses the lips
kissing muscle
palatoglossus
vagus nerve X
palatopharyngeus
vagus nerve x
posterior scalene
lateral surface of second rib
longest of scalene muscles
risorius
active in expressions of mirth
sphincter pupillae
constricts the pupil
parasympathetic fibers of oculomotor CN III
splenius
splenius means bandage
named for broad, flat shape
stapedius
derivative of second pharyngeal arch
starts second bracheal arch
first muscle fired in a sprinter
styloglossus
retracts and elevates tongue
hypoglossal nerve XII
extrinsic muscle of the tongue
tensor veli palatini
opens auditory tube
L5 Vertebra
wedge-shaped
large anteriorly, small posteriorly
fused to sacrum = sacralization
if L6 = lumbarization
smallest spinous of all lumbars
Typical ribs
Ribs 3-9
Atypical ribs and vertebrae
ribs 1 and 2
thoracics 10, 11, and 12
R1: short and flat
R2: surface for posterior scalene/serratus ant.
T10: full facet and superior demifacet
T11,T12 body: single full facet, floating ribs
Branchial Arches
1st: “Mandibular”
CN V
Trochlear
Mandible, malleus, incus
all mm of mastication
tensor tympani
tensor veli palatini
anterior belly of digastric
“from jaw to stapes”
general sensation to anterior 2/3 of tongue
Branchial Arches
2nd: “Hyoid”
stapes, styloid process, cornu of hyoid
CN VII Facial
mm of facial expression
stylohyoid
stapedius
posterior belly of digastric
taste anterior 2/3 of tongue
Branchial Arches
3rd: “Thymus”
CN IX
body of hyoid
greater cornu
stylopharyngeus
thymus gland
taste and general sensation to posterior 1/3 of tongue
Branchial Arches
4th-6th: “Thyroid and Cricoid”
CN X, Vagus
laryngeal cartilage
cricothyroid
levator veli palatine
mm of larynx
recurrent laryngeal nerve, part of “5th” arch
Ectoderm
nn and skin
Folic Acid
B9
Methylfolate
Tetrahydrofolate
deficiency: neural tube defects, spina bifida occulta
“Hypovitaminosis B”
cleft palate
Spina Bifida Vera (“true”)
Spina Bifida Manifesta
meningocele, meningomyelocele, myelocele
Nucleus Pulposis collagen
type II
Annulus fibrosis collagen
Type I
what organ is found in foregut and midgut
duodenum
what organ is found in midgut and hindgut
transverse colon
DRG cell type
unipolar
Striking golgi tendon
stretch muscle spindles
myototic reflex = monosynaptic
Medial branch of dorsal primary rami
facet joint innervation
T1-T7 skin on back
Lateral branch of dorsal primary rami
innervation to T8-glutes
Back mm with nerve supply from brachial plexus
ventral primary ramus
rhomboids: dorsal scapular n
latissimus dorsi: thoracodorsal n
Voluntary motor tracts
lateral corticospinal
reticulospinal
rubrospinal
UMN
runs from cerebral cortex down to anterior horn, does not include alpha motor neuron (AKA”ventral/ant horn cell”)
LMN
anterior horn to muscle
Final common pathway
lower motor neuron
alpha motor neuron
Endplate potential
alpha motor neuron innervates muscle
Pineal gland on level with
3rd ventricle
CN4
only one off posterior portion of brainstem
and contralateral side
Obex
at floor of 4th ventricle
just below 4th ventricle - cisterna magna
“cerebellomedullary cistern”
Bellies of digastric
Anterior: V
Posterior: VII
stylopharyngeous
CN IX
derived from 3rd br. arch
Myesthenia Gravis
thymus
Free naked nerve endings
sensitive to chemical pain/ nociception, temperature
lateral spinothalamic
crude touch
ventral spinothalamic
A delta fibers
extreme pain
fast pain
pressure pain
Unmyelinated C fibers
chemical pain
slow pain
Depolarization
ascending limb of spike potential
drive to Na+ equilibrium point
Repolarization
descending limb of spike potential
drive to K+ equilibrium point
Na+ movement
in direction of concentration gradient
in direction of electrochemical gradient
K+ movement
in direction of concentration gradient
against electrochemical gradient
Divergence
when one cell fires onto many
Convergence
when many cells fire onto one
“spatial summation”
Temporal summation
one or more cells fire over time
Inhibitory Post-Synaptic Potential
chloride ion
Cardioinhibitory Center
vagus → heart
slows down heart
Cardioacceleratory center
sympathetics → heart
increase HR
Reflexes to light
superior colliculi
Reflexes to sound
inferior colliculi
Corpra quadrigemini
2 superior + 2 inferior colliculi
tectum of midbrain
Cspine (tectospinal tract)
turns head in response to light or sound
CN 3 or 4
Somesthetic Cortex
post-central gyrus
Calcarine fissure
Calcarine sulcus
vision
brodmans area 17
Corticospinal & corticobulbar tracts
“pyramidal tracts”
start at giant cells of Betz (pyramid shaped)
Any motor tract NOT
Corticospinal or corticobulbar
extrapyramidal tracts
Broca’s blood supply
middle cerebral artery
mc for stroke
Most common tumor of ventricles
ependymoma
MS
distal mm weakness
S.I.N.
- *S**lowed speech
- *I**ntention tremor
- *N**ystagmus
Meissner’s
mucosal
failure of neural crest to migrate
Hirschprung’s Disease
congenital megacolon
Wallenberg Syndrome
damage to PICA
Basilar artery
begins at foramen magnum,
ends as posterior cerebral artery
Artery of Adam Kiewitcz
large radicular artery
supplies lumbar and sacral portions of spinal cord
Synarthrosis
Immovable
Fibrous
Synostosis = skull sutures
Gomphosis = teeth
Amphiarthrosis
Slightly movable
cartilagenous
synchondrosis = epiphyseal plates, hyaline cartilage
symphysis = IVD, pubic symph, fibrocartilage
syndesmosis = tib/fib, interosseous membrane
Diarthrosis
Freely Movable
Synovial
Uniaxial
- *hinge/ginglymus =** phalanges
- *pivot/trochoid** = rotatory, C1/C2
Biaxial
- *ovoid** = MCP, TMJ, knee (modified)
- *saddle/sellar =** sternoclavicular jts
Triaxial
- *gliding/planar** = facets, intercarpal/intertarsal
- *ball and socket =** shoulder, hip
*SI jts are atypical diarthrodial
Schindylesis
perpendicular articulation of ethmoid and vomer
C3 C4 C5
keeps the human alive
phrenic → diaphragm
C5 C6 C7
long thoracic n → serratus anterior
“SA/LT”
damage = scapular winging
Femoral Nerve
off posterior divisions of L2 L3 L4
(even though its in front)
Obturator Nerve
off anterior divisions of L2 L3 L4
Cords of brachial plexus
named for relationship to axillary artery
Brachial Plexus
Lateral Cord
musculocutaneous n → biceps, coracobrachialis, brachialis
Brachial Plexus
Medial Cord
ulnar nerve → all adductors
Brachial Plexus
Posterior Cord
axillary n → deltoid, teres minor
subscapularis → (lower) to t. major
radial n → all extensors of forearm, wrist, hand, supinator mm, branches to fingers (posterior interosseous nerve)
median → pronators, all flexors of wrist and hand
(branches to anterior interosseous)
Flexor digitorum profundus
dual innervation
“dual innervation is profound”
medial and ulnar nn
Axillary n
sensory
shoulder → elbow
musculocutaneous n
sensation
lateral elbow → wrist
“lateral antebrachiocutaneous”
Medial cord
medial senseation elbow → wrist
“medial antebrachialcutaneous”
Superficial branch of radial n
all posterior structures from shoulder down
fracture of surgical neck of humerus
axillary n damage
fracture to mid-shaft of humerus
radial nerve damage
Subclavian artery
to first rib
@ R1, becomes axillary artery
@ t major, becomes brachial artery
Lumbosacral Plexus
(runs L4-S2/S3)
gluteal nerves
@L5-S1: superior gluteal → g med & min
@S1-S2: inferior gluteal → g max
Sciatic Nerve
comes out of back as common peroneal and tibial, down back of leg
tibial branch of sciatic
→ hamstrings
EXCEPT: short head of bic. femoris = common peroneal
con’t back of leg to plantarflexors
gastroc, soleus, plantaris
ends in foot as medial and lateral plantar nerves
short head of biceps femoris
common peroneal
fracture at head or neck of fibula
damage to common peroneal
(wraps around, splits into deep/superficial)
Deep peroneal nerve
anterior tibialis
peroneous tertious
= dorsiflexion
Superficial Peroneal
peroneous longus and brevis
= eversion
Sensory to posterior thigh
posterior femoral cutaneous
Sensory to lateral thigh
lateral femoral cutaneous n
L2/L3
damage = myralgia paresthetica
Sensory from anterior thigh
femoral
Sensory from medial thigh
obturator
Sensory from posterolateral leg
sural nerve from sciatic
sensory from anteromedial leg
saphenous from femoral
Sensory from webbing between toes
superficial peroneal
EXCEPT between 1st and 2nd
= deep peroneal
L5
flexes toes
S1
extends toes
Cervical enlargement
C5, C6
central canal expansion
loss of sensation C5 C6 = syringomyelia
Alpha Motor Neuron
controlled by cortex
extrafusal fibers
movement and strength
Gamma motor neuron
cerebellum (unconscious)
and vestibular nuclei
intrafusal = tone
Cortex
aware
cerebellum
unaware
Annulospiral/Flowerspray
primary: annulospiral
secondary: flowerspray
MSC
Muscle Spindle Cells
unconcsious
stretch
1a fibers fired
slightly faster
GTO
Golgi Tendon Organ
unconscious
tension
1b fibers fired
MSC/GTO → posterior horn → cerebellum
spinocerebellar pathways
MSC/GTO → posterior horn → cerebellum
spinolivary tract → inferior olive of medulla → cerebellum
via climbing fibers
Climbing fibers
Mossy fibers
excitatory
Purkinje fibers
inhibitory
found in cerebellum
Fastigial nuclei
spine
any stimulus to cortex
→ to cerebellum
anything to cerebellum
→ to cortex
Tract of Lissauer
pain and nociception
Dorsal Nucleus of Clarke
cerebellum
(C8-L2)
IML
Inter-medio-lateral
located in lateral horn from T1-L2
lamina 7
bar of H
primary neuron for sympathetics
(“visceral efferents”)
= motor to viscera
Red Nucleus
rubrospinal origin
Substantia Nigra
dopamine production
Adrenergic receptors
norepinephrine/epinephrine
sweat glands
Ach, muscarinic
(only in ANS)
for “sudomotor” activity
visceral efferents
myelinated when leaving lateral horn
Preganglionic Sympathetics
“white rami communicantes”
size B
most synapse at pre chain ganglion
Postganglionic Sympathetics
“gray rami communicantes”
C fibers
synapse at adrenal medulla
*Pheochromocytoma
All splanchnics
sympathetic
*EXCEPT: S2-S4 pelvic splanchnic
= parasympathetics
pudendal nn
keep urine off the floor, keeps mr. happy off the floor
Greater splanchnic
T5-T9
Lesser splanchnic
T10-T11
Least splanchnic
T12
Inferior splanchnic
L1
Cervical Parasympathetics
CN 3,7,9,10
CN7 from second br. arch
Olfactory bulb of CN1
mitral cells
Exiting superior orbital fissure
CN 3,4,6,V1
Exit internal auditory meatus
CN 7 and 8
CN7 to stylomastoid foramen
to middle ear
“cauda tympani”
pierces parotid
taste sensation
*acoustic neuroma
Child with middle ear infection most likely to lose
taste sensation
Child with mumps (parotitis) most likely to lose
taste sensation
Exiting jugular foramen
CN 9,10,11
Corneal reflex
CN5 sensory
CN7 motor
Parotid gland
produces only serous fluid, no mucous
Stenson’s duct, opens opposite 2nd molar
SCM
CN11, spinal accessory
ipsilateral lateral flexor
contralateral rotator
torticollis = wry neck
pain and temperature from face
trigeminothalamic tract
VPM
(from body = VPL)
mm of mastication
“TIME”
Temporalis
Internal Pterygoid
Masseter
External Pterygoid
only mm of mastication that <strong>opens/depresses</strong> jaw