Neuroanatomy

central nervous system

consists of the brain and spinal cord

peripheral nervous system

consists of motor neurons and sensory neurons leading to and from the spinal cord

brain

receives and processes sensory information, initiates responses, stores memories, generates thoughts and emotions

spinal cord

conducts signals to and from the brain, controls reflexes and activities

motor neurons

CNS to muscles to glands (efferent)

sensory neurons

sensory organs to CNS (afferent)

somatic nervous system

division of the peripheral nervous system that controls voluntary movements

autonomic nervous system

division of the peripheral nervous system that controls involuntary responses

sympathetic nervous system

division of the autonomic nervous system that prepares the body for emergencies - fight or fligh

parasympathetic nervous system

division of the autonomic nervous system that promotes normal functioning - rest and digest

functioning of the nervous system

1) Relay Information - sensory system, sensory neurons
2) interpret/make decisions - association system, interneurons
3) carry out some action - motor system, motor neurons

protection of the CNS

1) bone - skull and vertebral column
2) meninges - 3 layers
3) ventricular system
4) cerebrospinal fluid
5) blood-brain barrier

meninges

set of thin membranes that hold the brain and spinal cord in place and act as a protective buffer

dura mater

meninges layer - tough outer layer of fibrous tissue

arachnoid layer

meninges layer - like a spider web; thin sheet of delicate connective tissue (CSF below it)

pia mater

innermost meninge layer - moderately tough inner layer that clings to the brains surface (CSF above it)

ventricular system

responsible for circulating CSF throughout the CNS

1

lateral ventricles

2

interventricular foramen

3

third ventricle

4

cerebral aqueduct

5

fourth ventricle

6

central canal

where CSF is found

1) central canal of spinal cord
2) cerebral aqueduct of periaqueductal gray
3) ventricles (lateral, third, fourth)
4) subarachnoid space of meninges

roles of CSF

1) provides a medium through which nutrients, hormones, etc, get access to brain cells; dispose of waste products
2) protects brain and spinal cord by acting as a buffer (liquid buffer or cushion to absorb internal as well as external forces)

blood brain barrier

protection of brain from blood born substances

neuraxis

an imaginary line that is drawn through the center of the length of the CNS, from the bottom of the spinal cord to the front of the forebrain

coronal section

cut in the ventricle plane, from the crown of the head down, yielding a frontal view of the brain's internal structures

horizontal section

usually viewed looking down on the brain from above - a dorsal view

sagittal section

cut lengthwise from front to back and viewed from the side - medial view

white matter

nervous tissue of the CNS consisting of neurons and their myelin sheaths

grey matter

nervous tissue containing cell bodies as well as fibers; forms the cerebral cortex consisting of unmyelinated neurons

contralateral

on or relating to the opposite side

ipsilateral

on or relating to the same side

medial

toward the midline

lateral

away from the midline

afferent

towards point of reference (CNS)

efferent

away from point of reference (CNS)

nucleus

collection of cell bodies in the CNS

ganglion

collection of cell bodies in the PNS

tract

collection of axons running together from point A to point B in the CNS

nerve

collection of axons running together from point A to point B in the PNS

frontal lobe

lobe involved in executive functions, thinking, planning, organisation, problem-solving, emotions, behaviour control and personality

parietal lobe

lobe involved in perception, making sense of the world, arithmetic, and spelling

motor cortex

involved in movement, part of the frontal lobe

sensory cortex

involved in sensations, part of the parietal lobe

occipital lobe

lobe involved in vision

temporal lobe

lobe involved in memory, understanding, and language

3 major divisions of the brain

1) forebrain
2) midbrain
3) hindbrain

ventricles in the forebrain

1) Lateral
2) Third

subdivisions of the forebrain

1) telencephalon (lateral ventricle)
2) diencephalon (third ventricle)

ventricle in the midbrain

cerebral aqueduct

subdivision of the midbrain

mesencephalon

ventricle in the hindbrain

fourth

subdivisions of the hindbrain

1) metencephalon
2) myelencephalon

principles structures of the forebrain

1) cerebral cortex
2) basal ganglia
3) limbic system
(lateral/telencephalon)
1) thalamus
2) hypothalamus
(third/diencephalon)

principle structures of the midbrain

1) tectum
2) tegmentum
(cerebral aqueduct/mesencephalon)

principle structures of the hindbrain

1) cerebellum
2) pons
(fourth/metencephalon)
1) medulla oblongata
(myelencephalon)

gyri

hills of the cortex

sulci

grooves of the cortex

fissure

especially large, prominent sulcus

central sulcus

divides frontal/parietal lobes

lateral fissure

divides temporal love and parietal/frontal lobes

precentral gyrus

primary motor cortex

postcentral gyrus

primary somatosensory cortex

corpus callosum

large band of axons that connects corresponding part of association of the left and right hemispheres

basal ganglia

-major parts include the caudate nucleus, putamen, and globus pallidus
-consits of a variety of subcortical cell groups engaged primarily in motor control, motor learning, executive functions, behaviour, and emotions
-degredation of neurons in this area causes Parkinsonsl

limbic system

involves many different brain areas and structures that all work together to play a role in out emotions and memory such as the hippocampus and amygdala

hippocampus

small organ wihich regulates emotion, associates w long term memory

amygdala

one of two almond shaped groups of nuclei located deep w/in the lobes of the brain, integrative centre for emotions, emotional behaviour, and motivation

structures of the diencephalon

thalamus + hypothalamus

thalamus

-relays info from sensory receptors to proper brain areas to be processed
-regulation of consciousness, sleep, alertness

hypothalamus

-organizes behaviour related to the survival of the speices
- controls autonomic NS and endocrine system (secretions from the anterior pituitary gland)
-posterior pituitary could be considered an extension of it

structures of the mesencephalon

tectum + tegmentum

tectum

Consists of:
-superior colliculi - located at top-role invisual system
-inferior colliculi - located below superior colliculi, role in auditory system

tegmentum

includes:
-rostal end of the reticular formation (states of consciousness like alertness and sleep)
-several nuclei controlling eye movement
-periaqueductal gray matter (primary control centre for descending pain modulation)
-red nucleus (motor coordination)
-substantia nigra (reward and movement)
-ventral tegmental area (sends dopaminergic projections to both the limbic and cortical areas)

structures of the metencephalon

cerebellum and pons

cerebellum

-receives info from the sensory systems, spinal cord, other parts of the brain and then regulates motor movements
-coordinates voluntary movements such as posture, balance, coordination, speech -- resulting in smmoth + balanced muscular activity

pons

-large bulge in the brain stem, lies between the midbrain and medulla, immediately ventral to the cerebellum
-contains a portion of the reticular formation
-contains a large nucleus that relays information from the cerebral cortex to the cerebellum
-as part of the brain stem it also impacts several automatic functions (breathing/necessary for life)s

structures of the myelencephalon

medulla oblongata

medulla oblongata

the most caudal portion of the brain stem; its lower border is the rostal end of the spinal cord
-contains numerous nuclei that act as control centers for the autonomic nervous system (vital functions are controlled -breathing, heat rate, temp - damage usually means rapid deaths

spinal cord

-long, conical structure (about as thick as an adult's little finger)
-principle function is to distribute motor fibres to the effector organs of the body (glands/muscles) and to collect somatosensory info to be passed on to the brain
-has a certain degree of autonomy from the brain; various reflexive control circuits are located there

spinal nerves

31 pairs
- 8 cervical (C1-C8)
- 12 thoracic (T1-T12)
- 5 lumbar (L1-L5)
- 5 sacral (S1-S5)
- 1 coccygeal nerve (Co1)

peripheral nervous system

cranial and spinal nervess

somatic nervous system

comprised of
-sensory neurons conveying information form the somatic receptors in head, body wall and limbs and from receptors of special senses
-motor neurons that conduct impulses from CNS to skeletal muscles

autonomic nervous system

consists of
-sensory neurons that convey information from the autonomic sensory receptors (located primarily in visceral organs) to CNS
- motor neurons that conduct impulses from CNS to smooth muscle, cardiac muscle and glands
- two main functional divisions (parasympathetic/sympathetic) most organs receive inout from both, but systems are antagonistic (produce opposite effects)

sympathetic nervous system

division of the autonomic nervous system: fight or flight response (emergency functioning)p

parasympathetic nervous system

division of the autonomic nervous system which supports activities involved w increase in body's supply or stored energy (salivation, digestion, increased blood flow to gastrointestinal system) -promotes normal functioning "rest and digest"

autonomic pathway

consists of two neurons that synapse in an autonomic ganglion
- preganglionic neuron from CNS to autonomin ganglion, postganglionic neuron from autonomic ganglion to target tissue

parasympathetic pathway

preganglionic neuron: soma is usually in the brain stem or sacral (bottom of spinal cord)
-releases acetylcholine
postganglionic neuron: soma is usually in a ganglion near the target organ
-realses NT acetylcholine or nitric oxide
activates: rest and digest
(craniosacral -> long pre-gang axon -> short post gang axon)

sympathetic pathway

preganglionic neuron: soma usually in spine
- NT acetylcholine released
post ganglionic neuron: soma in a sympathetic ganglion located next to the spinal cord
- NT released: norepinephrine
activates: fight or flight
(thoracicolumbar -> short pre gang axon -> long post gang axon)