homunculus, dermatomes and myotomes Flashcards
what do multipolar neurons do
- they have a motor function
- one directional
- gave many inputs into the cell body
what do pseudo-unipolar neurons do
- they have a sensory function
- have one input (signal enters the cell body and then leaves next to it
what do bipolar neurones do
- they are associated with special senses
- have 2 clear axons
what is grey matter
packed cell bodies or the ganglia
what is white matter
the myelin sheath
what are the structural parts of the central nervous system
- brain - cerebral hemisphere, cerebellum and brainstem
- spinal cord
- cranial nerves - I (olfactory) and II (optic)
what are the structural parts of the peripheral nervous system
- cranial nerves (minus I & II)
- spinal nerves (31 pairings)
what are the parts of the spinal cord
- afferent (access in)
- dorsal root
- dorsal horn (at the back)
- ventral horn (at the front)
- ventral root
- efferent (exit)
where does the motor tract pass through
it leaves through the ventral root (descending pathway)
what does the sensory tract pas through
it enters in through the dorsal root (ascending pathway)
what dose the spinothilamic sense
temperature (looks like a banana)
what dose the dorsal column sense
- gracile - sensation (from ground to the brain)
- cuneate - touch and proprioception
what is the function of the cortical spinal tract
the motor tract that sends signals from the brain through the rest of the body
what is the function of the anterior cortical spinal tract
it sends signals to the core body
what are the main parts of the brainstem (top to bottom)
- CNII
- pituitary stalk
- mamillary bodies
- crus cerebri
- basilar groove
- olives
- pyramidal decussation
what are the internal landmarks of the brain (basal ganglia)
- caudate nucleus
- lentiform nucleus: putamen, globus pallidus
- subthalamic nucleus
- substantia nigra
- corona radiate
- internal capsule
- thalamus
what is the function of the white matter in the brain
it allows the axons of both motor and sensory neurones to reach other parts of the nervous system
what is the function of the internal capsule
it provides a common route for both sensory and motor information and connects the cerebral hemisphere to the brainstem
what are the 3 parts of the internal capsule
- anterior limb
- Genu
- posterior limb
anterior limb features
- from the frontal lobe to the pons
- thalamus to the frontal lobe
genu features
- cranial nerves
- corticospinal tract
posterior limb features
- sensory tracts
what are the different lobes of the brain
- frontal
- parietal
- occipital
- temporal
- insula
what is processed in the frontal lobe
decision making and movement
what is processed in the parietal lobe
sensory
what is processed in the occipital lobe
vision
what is processed in the temporal lobe
hearing, memory, emotion, sense of smell
what is processed in the insula
taste and pain process
what is at the pre-central gyrus
its the primary motor cortex
what is at the post central gyrus
its the primary somatosensory cortex
what is the homunculus
it is one gyrus of the brain that has nerves for all sections of the body but primarily is the main area for nerve process of the mouth lips and hands
how does the slow pain pathway work
- it is the medial pathway
- carried by the anterior spinothalamic tract (or the palaeospinothalamic tract)
- causes a burning, aching and throbbing pain
how does the fast pain pathway work
- it is the lateral pathway
- carried by the lateral spinothalamic tract
- can be called neospinothalamic
- causes a sharp, acute, prickling pain
what is the function of the cerebellum
- involved with muscle coordination
- influences muscle tone and posture
- maintenance of balance
what are the anatomical parts and location of the cerebellum
- anterior lobe
- posterior lobe
- flocculonodular lobe
- separated into two hemispheres by the vermis
- in the posterior cranial fossa
explain the spinocerebellar tract
- sensory information from muscles and joints which travels to the anterior lobe of the cerebellum
- involved in coordination and balance
- it compares what you thought you were going to do with what is actually happening to you limbs from proprioceptive feedback
where does the posterior spinocerebellar tract enter from
via the inferior cerebellar peduncle
where does the anterior spinocerebellar tract enter from
via the superior cerebellar peduncle
explain the rubrospinal tract
- the red nucleus (collection of cell bodies) in the midbrain that communicate with the cerebellum and spinal cord
- it helps the corticospinal tract by specifically exciting flexor muscles
- posture of comatose patients
what is decorticate
when there is a lesion above the red nucleus (hands crossed into a c shape)
what is decerebrate
damage caused between the red nucleus and inferior olivary nucleus (extends hands)
what is the arterial supply of the brain
- anterior cerebral artery
- middle cerebral artery
- posterior cerebral artery
where does the anterior cerebral artery supply
the medial surface
where does the middle cerebral artery supply
the lateral surface and internal capsule
where does the posterior cerebral artery supply
the posterior of the brain
corticospinal process
- processes movement
1. upper motor neuron - lateral tract = limbs
- anterior tract = axial
2. lower motor neuron
where is the decussation in the lateral tract
at the pyramids brainstem
where is the decussation in the anterior tract
at the exit level of the spinal cord via the ventral white commissure
what does the spinothalamic process
- temperature
- pain
- pressure
- crude touch
spinothalamic route
- dorsal root ganglion
- dorsal horn of the spinal cord
- decussation at same level of entry - thalamus
what does the dorsal column process
- fine touch
- proprioception
- vibration
dorsal column route
- dorsal route ganglion
- cuneate nucleus (above T6) OR gracile nucleus (below T6)
- decussation in brainstem at mid medulla - thalamus
what are dermatomes
patches of skin the rely on certain nerve supplies
what are myotomes
group of spinal nerve roots that collectively innervate a group of muscles
what happens in a upper limb motor neuron lesion
- affect the CNS
- large areas are affected
- hyper-reflexia (increased stretch reflex)
- hypertonia (increased tone of muscle
what happens in a lower limb motor neuron lesion
- affects the PNS
- small area affected
- decreased stretch reflex
- decreased tone of muscle
- loss of muscle mass
