BIO 448 - Neuroanatomy

CNS

brain and spinal cord

PNS

cranial nerves and spinal nerves

outside

___ stimuli carried out by PNS sensory neurons to CNS which then travels up spinal cord to synapse on cortex neurons, which connect to other cortex neurons that send info down the motor neurons for action

neural circuits

organized ensembles of neurons

arranged in clusters, rows, or lamina

crystal violet stain

stains the basic parts of the cell (rough ER, nucleolus) which mainly leads to the cell body/cell soma being stained

neuropil

area in and around the cell bodies where most synaptic activity occurs.

Made of dense tangle of axon terminals, dendrites and glial processes

gray matter

nucleus = collection of cell bodies/cell somas in the CNS

white matter

tract = collection of axons in CNS

ganglion

collection of cell soma in PNS

nerve

collection of axons in PNS

gray matter/nuclei

concentrated in the cerebral cortex folds on the outside, closer to the surface of the brain, as well as in the thalamus/brainstem

superior

dorsal part of CNS = __ = above

caudal

posterior part of CNS = __ = behind

rostral

anterior part of CNS = __ = in front of

ventral

inferior = __ = below

sagittal cut

splitting brain along hemispheres/separating the left and right hemispheres

coronal/frontal cut

separating the front and back of the body

horizontal/axial cut

separating the superior and inferior parts of the body

cerebrum

cerebral hemisphere

diencephalon

sits underneath the cerebrum and contains thalamus

brainstem

made of 3 parts: medulla, pons, midbrain (going up from spinal cord)

cerebellum

lies over dorsal aspects of the brain stem, communicate with pons to coordinate movement and balance

hindbrain

brain stem + cerebellum

spinal cord

• receives and processes sensory information from skin and muscles

• sends commands to muscles

• houses simple reflexes

• controls locomotion

lesions in that part of the nervous system can lead to para- or quadriplegia which is an impairment of motor and sensory function

lost

anything below lesion in spinal cord is __ while anything above lesion is fine

lumbar nerves

L1 to L5

thoracic nerves

T1 to T12

cervical nerves

C1 to C8

sacral nerves

S1 to s5

H

the gray matter in the spinal cord would take the shape of the letter __ with 2 dorsal horns and 2 ventral horns connected by a line of gray matter.

autonomic nervous system

sensory spinal nerves not only communicate with the spinal cord (CNS) but also with the ___ through ganglia

neurons leave for the __ through the intermediate horn

dorsal horn/root

sensory information is always carried by sensory nerves that come in the spinal cord through the ___

ventral horn/root

motor information is always carried by motor nerves and always come OUT of the spinal cord via the ___

Options for sensory spinal neruons

• synapse on interneuron in spinal cord and bypass the brain

• synapse on motor neurons directly in ventral horn

• synapse on axons in dorsal column and go to the brain

dorsal root ganglion

sensory information from the PNS is carried by spinal nerves, go through the ___ before entering the spinal cord through the dorsal horn

brain section stained for myelin

in this situation axons appear dark (even though they form the white matter), and cell bodies appear white (even though they form the gray matter)

lumbar

part of the spinal cord where a bunch of motor neurons leave from and where a lot of sensory information from the legs comes in. Therefore, this section of spinal cord is larger.

cervical

section of the spinal cord that receives a lot of information from the arms and hand, thus has a lot of sensory neurons, and also a lot of motor neurons to direct the upper limbs. Thus, this part of the spinal cord is larger.

brainstem

medulla + pons + midbrain

neurons between pons and cerebellum coordinate movement and balance

nerves passing through this region go to cerebral cortex

function: mediates sensations and motor control of the head, neck, and face (anything above the neck), as well as all special senses like smell, taste, sight, balance etc.

diaencephalon

sitting above midbrain and contains thalamus

cranial nerves

sensory and motor info from the neck up travel through __

needed for pain and touch from the neck up, as well as special senses, and facial expressions

medulla

regulates involuntary functions such as digestion, sleep, heart rate, breathing etc.

lesion in and around this region are life threatening

Pons

control of posture and balance

pontine nuclei relays info about movement and sensation from cerebral cortex to the cerebellum

Cerebellum

coordination of movement

receive sensory input from spinal cord, motor info from cerebral cortex, and balance input from vestibular organs in inner ears

Midbrain

coordinate eye movement

sits above the pons

important link between cerebellum and cerebral hemispheres

contains the substantia nigra (linked to Parkinson’s disease)

diencephalon

contains the thalamus, which receive and sort ALL sensory information, before transferring them to the cortex

contains hypothalamus, which regulates autonomic and endocrine functions, circadian rhythm, and motivational system

thalamus

receive and sort ALL sensory information, before transferring them to the cortex

hypothalamus

connected to pituitary gland, in charge of homeostasis and hormone release

regulates autonomic and endocrine functions, circadian rhythm, and motivational system

cerebral cortex

made of the 2 cerebral hemispheres

frontal lobe, parietal lobe, temporal lobe, occipital lobe

responsible for cognitive abilities like language, perception, consciousness, learning, memory, planning and theoretical thought

frontal lobe

planning of actions and control of movement of skeletal muscles

parietal lobe

sense of touch and position and pain

occipital lobe

responsible for vision and sensory information coming from the eyeball

temporal lobe

hearing

hippocampus

memory of facts, events, places, faces etc.

gyrus

ridge/fold in the cortex

sulcus

groove, furrow, trench in the cortex

central sulcus

divide between frontal and parietal lobes

precentral gyrus

where the motor cortex is located

postcentral gyrus

where sensory cortex islocated

longitudinal fissure

separation between the left and right hemispheres of the cerebral cortex

meninges

3 protective layers surrounding and protecting the brain which extend down the brainstem and spinal cords

• dura matter

• arachnoid matter

• pia matter

dura matter

hard mother

thick and tough outermost layer

mostly made out of collagen

basically glued to the skull

arachnoid matter

spider-like processes which extend from this layer to the pia matter

lining right underneath the dura matter

creates cavity where CSF is flowing

pia matter

tender mother

delicate layer of cells that envelopes vessels and apposes to the outer surface of brain

single layer of cell right on top of the cortex

superior sagittal sinus

CSF is draining through granules into the cavity situated between the hemisphere, cavity which is called __ and is connected to superior vena cava

below

the BBB is situated __ the pia matter around capillaries

cerebrospinal fluid

aka CSF

produced by modified vascular structures called choroid plexus

flows through cerebral ventricles that are interconnected by fluid filled space mostly in the core of the forebrain and brainstem

choroid plexus

specialized vascular structure producing CSF in the brain

lateral ventricles

largest of the ventricles

lies within cerebrum

aka 1st & 2nd venticles

C-shaped`

3rd ventricle

midline space between the right and left diencephalon

4th ventricle

large space lying between pons/medulla and the cerebellum

central canal

fluid filled canal in spinal cord

CSF pathway

CSF flows through lateral ventricles, which are connected to 3rd ventricle, which is connected to the 4th ventricle near the cerebellum and that ventricle is continuous with the central canal in spinal cord

1. CSF made in choroid plexus

2. flows into the ventricles

3. flows into arachnoid space through holes called apertures

4. passed into arachnoid villi along dorsal midline

5. returned to venous circulation via superior sagittal sinus cavity (make up blood serum)

500

choroid plexus makes about __mL of CSF per day while the normal volume of CSF in ventricles and subarachnoid space is about 150 mL so the entire CSF volume is turned over multiple times a day

hydrocephalus

condition where the flow of CSF is obstructed, leading to increased pressure on the brain, causing compression which leads to brain damage due to excess CSF volume in ventricles

studies to figure out functions of nervous systems

• lesions studies

• neural tracing studies

• electrophysiological recordings

lesions studies

can correlate gross damage to brain structures with functional deficits

ex: stroke in hippocampus leads to memory loss

neural tracing studies

anterograde tracing = from source to terminus

retrograde tracing = from terminus to source

used to map the connections between neurons in one structure (ex: eye) and their targets ini the brain

• injection of fluorescent molecule picked up at nerve terminals at site of injection and retrogradely transported

• tracers reveal new axon pathways (anterograde) usually transsynaptic tracer like modified rabies virus

electrophysiological recordings

use microelectrodes to record activity of neurons

give insight into the type of stimulus that a particular neuron is tuned to