Neuro: development, brain and spinal cord Flashcards
3 embryonic layers present around 3wks gestation
- endoderm
- ectoderm
- mesoderm
ectoderm becomes what?
–> neural plate –> neural tube (@ 3-4 wks gestation) –> CNS
mesoderm becomes what?
–> notochord –> then adds vertebral column
…and signals the activation of ectoderm development
how does closure occur in the neural tube?
what about neural crests?
starts in the middle and goes in either direction
(important clinically)
neural crests migrate away and become the progenitors of neurons and supporting cells of PNS
meningocele and spina bifida
meningocele: protrusion of meninges though gap in the spine
spina bifida: incomplete closure of vertebral column
what segments of the neural tube become the brain?
10 most rostral
what part of the spinal cord is white and what part is grey? butterfly and surrounding?
butterfly: grey
surrounding: white
where is the grey matter in the spinal cord located?
5 locations
- dorsal root ganglion
- dorsal horn cell columns
- sympathetic chain ganglia
- parasympathetic chain ganglia
- ventral horn cell columns
how are the dermatomes organized on the arms and legs?
in longitudinal stripes- “6 shooters, 7, 8” corresponds to CN that innervate that area (same with the legs/feet)
what does the sympathetic chain ganglia include?
pre and para vertebral ganglia
what does the parasympathetic chain ganglia include?
the head and the enteric plexus
how do afferent and efferent go into the spinal cord?
afferent are sensory and enter dorsal horn
efferent are coming out of the ventral horn going to muscle and glands
what are the 4 different afferents that enter the dorsal horn?
2 somatic and 2 ANS
- SSA: special somatic afferent: joint/tendon perception. reflexes for posture and movement (your elbow tells you that its at 90 degrees)
- GSA: general somatic afferent: innerv. skin and somatic structures (temp, pain, pressure)
- SVA: special visceral afferent: gut-related receptors, taste buds and olfactory- ( joy of eating)
- GVA: general visceral afferent: GI, GU, heart and great vessels (vital reflex circuits + sensation, bladder pressure + stomach fullness)
what 3 efferents enter the ventral horn?
- GVE: general visceral efferent - ANS preganglionic (PNS and SNS)
- SVE/PE: special visceral or pharyngeal (muscles for chewing +facial expression, pharynx, larynx and muscles to move the head
- GSE: general somatic efferent: motor output of skeletal muscle - LMNs - lower motor neurons. (“final common pathway” of neurons)
upper motor neurons (UPNs) go where?
part of CNS: start in motor cortex of brain and go to spine and are about VOLUNTARY control
(spinoreticular and spinothalamic tracts)
which layer of longitudinal tract is present at birth and which is not?
1st and 2nd are present at birth
3rd (neo) is not- present at 2 yo..fine motor skills
what are the 3 longitudinal tracts?
- inner: reticular formation and RAS (brainstem). VITAL reflexes (breathing, cardiovascular function, swallowing and vomit)
- middle layer (paleo): sensation and motor function. primitive functions- present at birth.
- spinoreticulo and spinothalamic tracts - outer layer (neo): fine motor skills, not present till 2 yo
collateral communication pathways
inner and middle longitudinal tracts have collateral branches to BYPASS damage
- none in outer layer - can’t get fine motor skills back
3 parts of the brain where RAS is
- medulla: which does vital reflexes (breathing, cardiovascular, reflex)
- pons: breathing and balance
- midbrain: eye movement, auditory and vision
where does all sensory info flow through in the brain?
thalamus
what does the hypothalamus do?
homeostasis control
what are the 4 dural venous sinuses
superior, inferior, cavernous, transverse
cavernous vs transeverse dural sinus…where would infection to brain come from?
cavernous: eye and face
transverse: ear
classify the spaces: subarachnoid, subdural, epidural
subarachnoid: CSF
subdural: venous (low pressure)
epidural: arterial (high pressure)
3 artery areas of brain
- anterior (internal carotid)
- middle (internal carotid)
- posterior (vertebral)
* circle of willis- where all three connect
where do veins drain into from brain?
sinuses then into the interjugular vein
4 ventricles of brain- to drain CSF
right and left, 3rd and 4th
how does the CSF of the brain drain?
secretes from choroid plexus: right and left ventricle –> 3rd –> 4th –> subarachnoids space –> cisterna in spinal canal OR superior sagittal sinus
(reabs by arachnoid villi)
