Midterm 1 Flashcards
Vertebral arteries
brainstem and cerebellum
Internal carotid arteries
provides 80%
supplies most of telencephalon and diencephalon
What areas would be affected from the occlusion of the Anterior Cerebral Artery?
leg and hip regions
What areas would be affected from the occlusion of the Middle Cerebral Artery?
arms and facial regions
Craniorachischisis
open spinal cord and spine
CNS is abnormally open on its dorsal surface
Anencephaly
failure of the rostral end of the neural tube
to close
Spina bifida
failure of the caudal end of the neural tube
to close
Primary Brain Vesicles
bulges and kinks appear along the anterior-posterior extent of the neural tube (prosencephalon, mesencephalon, rhombencephalon)
Secondary Brain Vesicles
prosencephalon (forebrain) - telencephalon & diencephalon
mesencephalon (midbrain)
rhombencephalon (hindbrain) - metencephalon & myelencephalon
Derivatives of Secondary Vesicles
telencephalon - cerebrum
diencephalon - thalamus, hypothalamus, retina, midbrain structures
mesencephalon - midbrain
metencephalon - pons, cerebellum
myelencephalon - medulla
Holoprosencephaly
partial/complete failure of the prosencephalon to separate into the diencephalon & paired telencephalon vesicles
- caused by too little hedgehog signaling
Cyclopia
extreme case of holoprosencephaly; single brain vesicle w/ large fused single midline eye
Tangential Migration
new born neurons arise from the ganglionic eminence in ventral striatum
- migrate long distances through the developing neocortex to supply inhibitory neurons
Radial Migration
new born neurons arise at the ventricular surface and migrate upwards in a radial pattern to form cortical pyramidal neurons (excitatory)
Spinothalamic tracts pathway (orders)
1st - dorsal root ganglia
2nd - nucleus proprius
3rd - thalamus
cross - in spinal cord, prior to entering tracts
Spinocerebellar tracts pathway (orders)
only second order
1st - dorsal root ganglia
2nd - neurons in spinal cord
ipsilateral but ventral cerebellar tract undergoes double cross in spinal cord then brainstem
Corticospinal tracts pathway order
1st - motor, premotor, and supplemental motor cortices (upper motor neurons)
2nd - spinal cord (generally interneurons)
contralateral
crosses - medulla oblongata (lateral) and in spinal cord (anterior)
Brainstem tracts (involuntary) (4)
- vestibulospinal (locomotor reflex and balance)
- tectospinal (head and eye movement, direct toward sights and sound; terminates in cervical spinal cord)
- reticulospinal (postural control and locomotion)
- rubrospinal (locomotion; terminates in cervical and thoracic spinal segments - responsible for trunk and upper limbs)
Division of spinal segments
31
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
Division of Vertebrae
33
- 7 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 4 coccygeal
Foramen Magnum
the space that the spinal cord passes through to connect to the brainstem
Passing order of vertebrae & spinal segments
- first 7 cervical pass above respective vertebrae, 8th pass above first thoracic vertebra (below 7th)
- remaining nerves pass below vertebrae
- 4 coccygeal vertebrae fused; passes below first coccygeal vertebra
- sacral segments also fused
Dermatomes
areas of skin whose sensory info project via certain spinal nerves
superior and inferior articular process
help connect vertebrae to one another via facet joint
vertebral foramen
space through which the spinal cord projects
intervertebral foramen
space that spinal nerves pass through the vertebrae
intervertebral disk and facet joint
cartilaginous joints that (1) allow for minor movements of the spine and vertebrae, (2) act as ligaments to hold the vertebrae together, (3) act as shock absorbers
segmental arteries
derived from vertebral arteries
- branch off into radicular arteries that run along the dorsal and ventral nerve roots
filum terminale
extension of the pia mater that helps anchor the spinal cord to the vertebral canal
- filum terminale internum is pia mater, externum fuses with dura mater
Lumbar Cistern (definition)
region from conus medullaris to end of dural sac
dorsal roots
sensory axons that enter the spinal cord
dorsal root ganglia
contains cell bodies of sensory neurons
ventral root
motor axons that leave the spinal cord
spinal nerve
contains both motor and sensory axons leaving and entering the spinal cord
ventral ramus
contain motor and sensory axons innervating the ventral portion of the body (spinal segment)
dorsal ramus
contain motor and sensory axons innervating dorsal portion of the body (spinal segment)
sympathetic ganglia
contain afferent and efferent nerve cell bodies responsible for the sympathetic nervous system
Reasons for Spinal cord enlargements
- quantity of white mater decreases from rostral to caudal segments
- gray mater is largest in the cervical and lumbar segments
dorsal horn
contains mainly interneuron cell bodies for sensory integration and pathways
ventral horn
contains the cell bodies of motor neurons which drive muscle activity and interneurons
Lissauer’s tract
ascending and descending small fibers that generally terminate in the SG
- fibers convey pain, temperature, and light tough
substantia gelatinosa
collection of cells that receive direct input from the dorsal roots
nucleus proprius
similar function to the SG but more ventral and medial in position
Central Pattern Generator
collection of interneurons in the spinal cord that are responsible for driving rhythm of locomotion and pattern of motor neuron activity
Cutaneous receptors
- touch, pain, temp., itch
- encapsulated > meissner corpuscles, pacinian corpuscles, ruffini endings
- nonencapsulated > root hair plexus, merkel cells, free nerve endings
Proprioceptive (muscle) receptors
- encapsulated
- muscle spindles and golgi tendon organ
encapsulated
Root Hair Plexus
touch
wrap around hair to detect movement
Merkel Cells
- touch
connect to nerve endings of skin
Free Nerve Endings
touch, pain, temp., itch
Meissner Corpuscles
detects fine touch and pressure
Pacinian Corpuscles
deeper sensory receptors for vibration and deep pressure
Ruffini Endings
detects skin stretch, pressure, joint movement, temp.
Muscle Spindles
- wraps around intrafusal muscle fibers
- muscle stretch and velocity
Golgi Tendon Organs
muscle tension
Sensory Fiber Entry Zones
small > join and form Lissauer’s tract
large > enter medial to Lissauer’s tract
cerebrospinal fluid
- 70% produced in choroid plexus, 30% secreted by parenchyma in brain
- filtrates blood as it passes through choroid plexus
- low protein content
- clear, colorless, sterile
- presence of white blood cells indicates bacteria meningitis or viral encephalitis
Ventricles (functions)
- brain and spinal cord float in CSF > reduces tension bw CNS and connecting nerves and blood vessels
- provides cushion that dampens the effect of trauma
- acts as a vehicle to remove metabolites from CNS
- stabilizes ionic composition of CNS
Acquired Hydrocephalus
develops after birth as a result of neurological conditions such as head trauma, brain tumor, cyst, intraventricular hemorrhage or infection of CNS
congenital hydrocephalus
present at birth, caused by complex interaction of genetic and environmental factors during fetal development
4 Main Functional Types of Cranial Nerves
- somatic sensory > senses from the face
- visceral sensory > taste
- visceral motor > pupil constriction, salivation, cardiac, digestion, airway, lacrimation
- somatic motor > lower motor neurons
Cranial Nerve Rules
- The nuclei of CNs with pure motor function are located along the midline
- Axons exit on the ventral side of the brain stem (except CN IV)
- CN nuclei are ipsilateral to their targets (except CN IV)
- If it has autonomic function it will be parasympathetic
Cranial Nerves
1/I - olfactory bulb
2/II - optic nerve
3/III - oculomotor nerve
4/IV - trochlear
5/V - trigeminal
6/VI - abducens
7/II - facial
8/VIII - vestibulochochlear
9/IX - glossopharyngeal
10/X - vagus
11/XI - spinal accessory
12/XII - hypoglossal
