Lecture 1: Intro to CNS and PNS Flashcards
what makes up the CNS?
brain and spinal cord
what makes up the PNS?
cranial nerves (arise from the brain)
spinal nerves (arise from the spine)
what is the functional unit of the nervous system?
a neuron
what is a soma
the cell body of the neuron
what is a synapse
spot on dentrites, where neurons communicate with each other
where do inputs of neurons occur
at the dendrites
where is the output of neurons
axon and axon terminal
what is a cluster of nerve cells located in the CNS called
nucleus or nuclei (plural)
what is a cluster of nerve cells located in the PNS called
ganglion or ganglia (plural)
What is the function of the myelin sheath on axons?
it provided insulation allowing the electrical signal from the cell body to rapidly reach the axon
what are cells that produce myelin in the CNS called?
Oligodendrocytes
what are cells that produce myelin in the PNS called?
Schwann Cells
what is white matter is composed of?
Myelinated axons
what is grey matter is composed of?
less myelin, mostly cell bodies
what are the two functional types of neurons in the PNS
sensory (affarent)
motor (efferent)
what are sensory (affarent) nerves?
“Affect - your feelings”
Carry nerve impulses towards CNS
what are motor (efferent)
Effect the world around you
carry nerve impulses away from the CNS
what are the 2 subdivisions of the PNS?
Somatic and viseral
what is the somatic division of the PNS?
go to and from the external environment
sensory:
1. general somatic afferents
- special somatic afferents
motor:
1. general somatic efferents
what are general somatic afferents?
pain, temperature, touch, proprioception
what are special somatic afferents?
vision, hearing, balance, smell
only found in cranial nerves 1, 2, 8
what are general somatic efferents
innervation of skeletal muscles
what is the visceral division of the PNS?
go to and from the internal environment
sensory:
1. general visceral afferent
- special visceral afferent
motor:
1. general visceral efferent
- special visceral efferent
what general visceral afferents?
pain and reflexes from organs, glands and blood vessels
mostly subconscious but can become conscious like heartburn
what are special visceral afferents?
taste
only found in cranial nerves 7, 9, 10
what are general visceral efferents?
innervation of smooth muscle (gut and arteries) and glands
controls sympathetic and parasympathetic subdivisions of nervous system
what are special visceral efferents?
innervation of skeletal muscle in pharynx
what is the large section of the brain we can view from the lateral perspective
cerebrum
think Bruh its big
what is the smaller section of the brain inferior to the larger section
cerebellum
“belly” of the brain
What are the convolutions on the cerebrum called and what separates them?
gyri separated by sulci
what are the convolutions on the cerebellum called, and what separates them?
folia separated by fissures
Name the three components of the brainstem?
Midbrain
pons
medulla
superior to inferior
What do you call the fissure that separates the two hemispheres of the brain?
Medial longitudinal fissure
What structure connects the two hemispheres of the brain?
Corpus callosum (white matter)
Name the 6 lobes of the cerebrum
Frontal, parietal, temporal, occipital, limbic, insula
What separates the frontal and parietal lobes?
Central sulcus
What separates the frontal and parietal lobes from the temporal lobe?
Lateral sulcus
Which of the 6 cerebrum lobes are defined besed on function?
Limbic and insula
What separates the parietal and occipital lobes?
parieto-occipital sulcus
where is the limbic lobe?
not visible with lateral view, only medial. next to corpus callosum and extends onto the medial surface of temporal lobe
where is the insula lobe?
Tucked under the opercula (edges) of the frontal, parietal, and temporal lopes
what are the 6 functions of the frontal lobe?
Voluntary movement
attention
short term memory tasks
motivation
Planning
Speech
What are the 2 functions of the temporal lobe?
Auditory processing
further visual processing
What are the 2 functions of the parietal lobe?
Integrates sensory stimuli
Language
What is the function of the Occipital lobe?
center for visual processing
What are the 4 functions of the limbic lobe?
Emotional regulation
learning
memory
visceral function
What are the 3 functions of the insular lobe?
taste
visceral sensation
vestibular function
What 2 main arteries supply blood to the brain?
Internal carotid (anterior)
Vertebral arteries (posterior)
the vertebral arteries join to form which artery?
Basilar artery
where does the basilar artery terminate
at the base of the circle of willis
which small arteries are along the way of the basilar artery?
pontine arteries that supply blood to the pons
which artery branches off from both of the vertebral arteries
posterior inferior cerebellar artery
which artery branches off from both sides of the basilar artery inferior to the pontine arteries
anterior inferior cerebellar artery
which artery branches off from both sides of the basilar artery anterior to the pontine arteries?
superior cerebellar artery
which arteries branch off from both sides of the posterior aspect of the circle of willis
posterior cerebral artery
what is the posterior communicating artery
forms the lateral part of the circle of willis, connects the posterior cerebral artery with the internal carotid artery
what is the internal carotid artery
artery facing the inside go of the circle of willis
what is the middle cerebral artery
artery facing outside of circle of willis
what is the anterior cerebral artery
arteries forming the anterior aspect of the circle of willis
what is the anterior communicating artery
connecting the two anterior cerebral arteries
What brain regions are supplied by the anterior cerebral artery (ACA)?
Laterally: frontal and parietal lobes
Medially: frontal, parietal and limbic lobes
What brain regions are supplied by the middle cerebral artery (MCA)?
Laterally: Frontal, parietal, temporal, opccipital, and insula
Medially: Small portion of temporal
What brain regions are supplied by the posterior cerebral artery(PCA)?
Laterally: Posterior/inferior occipital and temporal lobes
Medially: Occipital, temporla, limbic lobes
Name the 4 regions of the spinal cord
Cervical
Thoracic
Lumbar
Sacral
The spinal cord ends at the level of what vertebrae?
L1/L2
What is the end of the spinal cord called?
Conus Medullaris
What is the collection or roots below the conus medullaris called
cauda equina
in the spinal cord, is white or gray matter central?
gray matter is central surrounded by white matter
Name the the three column divisions of the white matter in the spinal cord
anterior, lateral, posterior
The gray matter in the spinal cord is divided into three what?
Horns (anterior, lateral, posterior)
What sensory information passes through the Posterior Horn?
Somatic sensory information (general somatic afferents [GSA])
The anterior horn is associated with the:
Somatic motor pathway (general somatic efferents [GSE])
The lateral horn is associated with the:
sympathetic portion of the autonomic nervous system (General Visceral
Efferents [GVE])
only found at T1-L1/L2
Name the 2 categories of sensory receptors
Discriminative/fine touch mechanoreceptors
Crude touch/pain/temp free nerve endings
Which specialized sensory receptors in muscles and joints are responsible for
proprioception, and what do each of them do?
Muscle spindles: detect muscle length
Golgi tendon organs: detect muscle tension
Processes project from the sensory receptors to primary neurons located where?
in the posterior (dorsal) root ganglia
what are posterior (dorsal) root ganglia
collections of neurons associated with each posterior (dorsal) spinal cord root
contains neurons that receive input from individual sensory receptors
what is the structure of the neurons of the DRG
pseudounipolar
They have just a single process that makes contact with the cell body. But the single process is split, with one portion carrying signals to the cell and the other portion carrying signals away from the cell.
what are Posterior (dorsal) roots
they travel from the DRG to the spinal cord, but depending on the sensory modality, can go either to white matter (to travel up the spinal cord) or gray matter (posterior horn).
what are the 3 pathways different sensory modalities take within the CNS
posterior column/medial lemniscus pathway
(discriminative touch and conscious proprioception)
spinothalamic pathway (crude touch/pain/temperature)
spinocerebellar pathways (unconscious proprioception
what is the starting point of the Posterior column/medial lemniscus pathway
touch receptors and proprioceptors in skin, muscle and joints
where are the somata (cell bodies) of the primary sensory neurons associated with the receptors in the posterior column/medial lemniscus pathway
posterior (dorsal) root ganglia.
where do the axons from the primary neurons join white matter for the posterior column/medial lemniscus pathway
in the posterior columns of the spinal cord
those from the lower body go into the fasciculus gracilis (more medial)
those from upper body into the fasciculus cuneatus (more lateral)
which levels of the spinal cord is the fasciculus gracilis evident at
every level of the spinal cord
which levels of the spinal cord is the fasciculus cuneatus evident at
at T6 and above
what do the axons do once they reach the Fasciculus gracilis and the fasciculus cuneatus in the posterior column/medial lemniscus pathway
they ascend up the spinal cord to the medulla (lowest part of brainstem) where they synpapse with second order neurons in the nucleus gracilis and nucleus cuneatus
what do the axons from the second order neurons do in the nucleus gracilis and cuneatus in the posterior column/medial lemniscus pathway?
they cross and enter the medial lemniscus on the opposite side of the medulla, then ascend all the way through the brainstem until reaching the thalamus
what do the axons do when they reach the thalamus in the posterior column/medial lemniscus pathway?
they synapse on the third order neurons in the ventral posterolateral nucleus
what do the axons do in the ventral posterolateral nucleus in the posterior column/medial lemniscus pathway
they project to the post- central gyrus (parietal lobe, just posterior to the central sulcus), the location of the primary somatosensory area.
all sensory information except for which kind travels through the thalamus before it reaches the cerebrum
smell
what is the starting point of the spinothalamic pathway
crude, pain and temperature
where are the primary sensory neurons for the spinothalamic pathway located
in the DRG
where do the axons from the primary neurons project in the spinothalamic pathway
into Lissauer’s tract before entering the dorsal horn (grey matter) and contacting the dendrites of other neurons in the substantia gelatinosa or the nucleus proprius (deeper)
(different from white matter in posterior column pathway)
where do the second order neurons on the spinothalamic pathway go after they entered the substantia gelatinosa or the nucleus proprius
cross from one side of the cord in the anterior white commissure (white matter) and enter the spinothalamic tract (STT) on the opposite side.
where do the second order neurons on the spinothalamic pathway go after they enter the spoinothalamic tract on the opposite side
ascend through the spinal cord white matter (anterior, lateral columns) and then through the brainstem, reaching the VPL nucleus of the thalamus where they synapse (onto 3rd order neurons).
where do 3rd order neurons in the spinothalamic pathway project
to the primary somatosensory cortex
how is he primary somatosensory cortex organized
in a somatopic fashion, creating a “homunculus” of body regions.
An MRI of a 49-year old women shows a tumor located immediately superior to the corpus callosum. The lesion is most likely located in which lobe?
limbic
Which of the following statement concerning the spinothalamic tract are INCORRECT?
It decussates in the anterioir (ventral) white commissure
Its cells of origin are in the posterior (dorsal) horn of the spinal cord
It projects to the ventral posteralolateral (VPL) nucleus of the thalamus
It mediates pain and temperature sensation
Its cells of origin are in the posterior (dorsal) horn of the spinal cord
An MRI of a 49-year-old individual shows a tumour located in the occipital lobe of the brain. This lesion would most likely cause what impairments?
Visual impairments
The large gyrus immediately anterior to the central sulcus plays a large role in:
Motor Control
