NeuroAnatomy
1. General Organization
1. General Organization
a.
31 pairs of spinal nerves & 12 CN
i.
C1-C7 exit on top on vertebrae, rest is below
1.
C8 goes over T1 vertebrae
2.
Blood supply, Meninges & spinal fluid
a. 2 main arteries:
Internal carotid - supplies front area
1.
obstruction causes CONTRALATERAL weakness & loss of sensation
2.
divisions:
a.
ACA- midline area -- LEGS
b.
MCA- lateral level of cerebrum -- ARM
c.
PCA- lower level of cerebrum -- HEAD
ii.
Vertebral artery – changes its name to basilar
at the pons & then divides to PCA
1.
Obstruction affects visual area of cerebrum,
brain stem & cerebellum
b.
Circle of willis:
CN III- exits btwn the posterior cerebral a.
& sup. cerebellar Aneurysm of either causes CN III palsy – down
& out eye
ii.
Located within the PIA
c.
PAD
i.
From brain à
skull = Pia, Arachnoid, Dura
d.
Sinuses:
i.
Superior sagittal sinus- spinal fluid drainage
ii.
Cavernous sinus- venous blood drains from the
eye, entry source into brain of orbital & facial infections
1.
Carotid a. & all nerves entering orbit go
through sinus
iii.
Transverse sinus- runs by ear, can be involved
in inner ear infections
e.
CSF:
i.
Secreted by chroid plexus
ii.
Flows from the 2 lateral ventriclesà2 interventricular
foramina à 3rd
ventà
aqueduct of sylviusà
4th ventricleà
outside brain via Middle foramena of Magendie, or Lateral foramena of Luschkaà subarachnoid space
iii.
Obstruction anywhere will head to dilation of
lateral vents = hydrocephalus
iv.
Hemorrages:
1.
Subarachnoid- rupture of aneurysm
2.
Subdural- tearing of bridging veins
3.
Epidural – blood collects btwn dura & bone,
tears middle meningeal a.
3.
Spinal cord
a.
Central= gray matter (neuronal cell bodies &
synapses), peripheral= white matter (ascending & descending pathways)
b.
SPINOTHALAMIC:
enters spinal cord, crosses over to opposite half of cord, ascends to thalamis
on OPPOSITE side, then moves on to cerebral cortex
i.
LESION= loss
of pain & temp. CONTRALATERAL, BELOW level of lesion
c.
DORSAL
COLUMN: initially on same side of spinal cord, crosses over @ junc btwn
spinal cord & brain stem
i.
Synapses
before cross over- n.cuneatus (upper level), n. gracilis (lower level)
ii.
LESION= decrease
in conscious proprioception & sterognosis (vibration) IPSILATERAL, BELOW
level of lesion
d.
SPINOCEREBELLAR:
remains ipsilateral. Enters cerebellum via sup. & inf. peduncles
e.
**CEREBELLAR LESIONS TEND TO PRODUCE IPSILATERAL DEFECTS.
CEREBRAL CONTRALATERAL DEFECTS**
f.
CORTICOSPINAL
TRACT (MOTOR): extends from motor area of cerebral cortex down to brain
stem, crossing over at medial lemniscus
i.
Synapse in the anterior horn – above synapse=
UMN, below = LMN
ii.
UMN- spastic paralysis, no muscle atropy, no
fasiculations & fibrillation, hyperreflexia, Babinski reflex present
iii.
LMN- opposite
4.
Brain stem
a.
Location: diencephalon- 1,2; midbrain- 3,4; pons- 5,6,7,8; medulla- 9,10,11,12
b.
CN parasym: 3,7,9, 10
c.
Rostral Midbrain:
d.
Pons:
e.
Rostral medulla:
f.
nucleus Solitarius-
located in medulla (somatic Sensory-
lateral)
i.
include taste (7,9 & 10), sensory from
carotid (9), sensory return along vagus (10)
g.
Nucleus aMbiguous-
located in medulla (somatic Motor-
medial)
i.
Involved in swallowing (9&10) & speech
(10)
h.
CCR: vertigo,
with difficulty in taste, swallowing or speech.
i.
Brain
stem lesion. Nucleus solitaries
& ambiguous lie near vestibular nuclei
i.
CCR: lesion
ABOVE level of nucleus of CN 7 (pons)- area of face BELOW eye paralyzed
j.
CCR: lesion
severed nucleus of CN 7- bell’s palsy
i.
“crocodile
tears”= cry when eating instead of salivating. Regenerating fibers are effd
up
5.
Visual system:
a.
CCR: pt
with severe blow to back of head = bilateral
central scotomas
i. center of the retina projects to occipital lobe
b.
Optic reflexes:
i.
Pupillary light reflex = shine light in 1 eye
both pupils constrict (consensual reflex)
c.
Accommodation
i.
Stimulate the smooth muscle of the ciliary body
in the eye to contract, enabling the lens to change its shape
ii.
CN 3: constricts pupil to focus
iii.
CCR:
syphilitic pupil (Argyll-robertson)- constricts during accommodation, but not
to light
1.
Lesion
lies in pretectal area of superior colliculus
d.
Conjugate gaze:
i.
Damage to the motor areas of the cerebral cortex
produce contralateral paralysis of extremities & ABILITY OF EYE TO LOOK
TOWARD
CONTRALATERAL ENVIORN
CONTRALATERAL ENVIORN
1.
Broadmans area 8
ii.
MEDIAL
LONGITUDINAL FASCICULUS – seen in MS. Eye can’t look medially
iii.
CCR: Lesion close to SUP. COLLICULAR LEVEL
(convergence & vert gaze circuit in MB next to sup. colliculus)
1.
parinaud’s
syndrome: pupillary constriction & paralysis of vert gaze
2.
pineal
gland tumor
6.
ANS & Hypothalamus:
a
7.
Cerebellum, basal ganglia, & thalamus
a.
Cerebellar dysfunction – awkwardness of
intentional movements
i.
Sways with or without eyes closed
b.
Basal ganglia disorder- meaningless
unintentional movement occurring unexpectedly
8.
Cerebral cortex
a.
CN10- kuh kuh kuh (soft palate), CN12- la la la (tongue), CN 7-
mi mi mi (lips)
b.
Cerebral cortical regions:
i. Area 4 (primary motor area): lesion = flaccid
paralysis, spasticity & deep tendon reflex increases if area 6 is involved
ii. Area 8 (frontal eye field): lesion= probs moving
eye to opp side
iii. Area of frontal cortex: complex behavioral
activities. Lesion changes judgment
iv.
Lesion to dominant cortex = aphasia, lesion to
non-dominant cortex= visual & auditory
v.
Area 44,45 (brocas): Lesion to dominant cortex =
aphasia, lesion to non-dominant cortex= visual & auditory
vi.
Area 3,1,2 (primary somesthetic area): lesion
CONTRA impairment of touch, pressure & proprioception.
vii.
Area 41, 42 (auditory)
viii.
Area 22 (wernickes)
ix.
Area 39 (angular): lesion in DOMINANT hemisphere
= alexia & agrapha (cant read & write)
x.
Area 17,18, 19: total destruction causes
blindness in CONTRA visual field,
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