Lec. 14 Flashcards
What are the two main divisions of the human nervous system?
the CNS and PNS
What two structures compose the CNS?
The brain and spinal cord
What are the two divisions of the PNS?
Sensory and Motor divisons
What are the two types of fibers of the sensory division?
The somatic and visceral fibers.
In which direction do sensory division fibers run?
From receptors to the CNS.
What are the two types of motor nerve fibers and what are their effectors?
Motor somatic fibers are voluntary and signals are sent from the CNS to muscle fibers. Autonomic motor fibers are involuntary and run from the CNS to cardiac muscle, smooth muscle, and glands.
What is a ganglion?
A collection of neuron cell bodies in the PNS.
Describe the process of integration in the nervous system.
It is the nervous system processing/interpreting sensory input and deciding on a course of action.
What characteristic of the brain is important to intelligence/knowledge/etc?
The complexity of wiring is more important than the size of the brain.
What are the two types of matter in the brain? What differentiates them?
Grey matter consists of short, non-myelinated neurons and cell bodies and white matter consists of mostly myelinated axons.
What are the three large subdivisions of the brain not including the hemispheres?
The diencephalon, brain stem, and cerebellum.
What are the subdivisions of the brain stem in order of most superior to most inferior?
The midbrain, pons, and medulla oblongata.
What is the basic pattern of grey and white matter in the CNS?
It is grey matter surrounded by white matter.
What does a cross section of the brain stem look like in terms of grey and white matter?
There is still grey matter surrounded by white matter, but there is more grey matter scattered within the white matter.
What is the definition of cortex and where are they found?
A cortex is an outer layer of grey matter, and ca be found on the cerebral hemispheres and the cerebellum.
What do rostral and caudal mean?
Rostral is towards the front of the brain, and caudal is towards the back.
What is the brain ventricle?
It is a space that is continuous with other cavities and the spinal cord that is filled with CSF and surrounded by ependymal cells.
How many brain ventricles are there?
4 Brain ventricles
What are the names of the ventricles?
There are two lateral ventricles, a third ventricle, and a fourth ventricle.
What do the two lateral ventricles look like?
Horns.
What separates the two lateral ventricles?
A double membrane called the septum pellucidum.
What links the lateral ventricles with the third ventricle?
The intraventricular foramen.
Around what big structure is the 4th ventricle found?
The pons
What structure links the 3rd and 4th ventricles?
The cerebral aqueduct.
What are the 3 protrusions of the 4th ventricle called? What do they do?
The 2 lateral apertures and the medial aperture connect the ventricles to the subarachnoid space around the brain.
What is a gyrus?
It is a ridge of the brain.
What is the difference between a sulcus and a fissure?
A fissure is a larger furrow dividing the brain into lobes. A sulcus is a groove in the cortex.
What separates the two brain hemispheres?
The longitudinal fissure.
What separates the frontal and parietal lobes, and what is found on either side of it?
The lateral sulcus separates the two lobes, and the precentral and postcentral gyrus are on the front and back of it.
What separates the cerebellum and occipital lobes?
The transverse cerebral fissure.
What separates the parietal lobe and occipital lobe?
The parieto-occipital sulcus.
How much brain mass do the hemispheres make up?
Roughly 83 percent.
What are the five lobes?
The frontal, parietal, temporal, occipital lobes; and the insula.
What sulcus is found on the insula?
The insular central sulcus.
What are some functions of conscious behavior (found in the cerebral cortex)?
Perception, communication, memory, understanding, initiating voluntary movement.
What is the cerebral cortex composed of? How thick is it?
Cell bodies, dendrites, and unmyelinated axons. It is 2-4mm thick.
What are Brodmann Areas?
It is a system of organizing the brain according to thickness/histology developed in the 1900s by Korbinan Brodmann.
What are the three functional areas of the cerebral cortex?
The motor, sensory, and association divisions.
What does it mean when we describe the cerebral cortex as contralateral?
It means that each hemisphere handles sensory/motor functions of the opposite side of the body.
What word describes the idea that the two hemispheres are not equal in function?
Laterlaization
Do functional areas of cortexes act alone?
No, all conscious behavior includes the entire cortex.
Where are the motor areas of the brain located?
The posterior part of the frontal lobes.
What are the 4 motor areas?
The primary motor cortex, premotor cortex, Broca’s area, and the frontal eye field.
Where is the primary motor cortex located?
In the precentral gyrus.
What large neuron cells allow the primary motor cortex to control skeletal muscles?
Pyramidal cells.
What does somatotopy in the primary motor cortex describe?
The body is represented spatially in the primary motor cortex.
Is motor innervation in the primary motor cortex ipsilateral or contralateral?
Contralateral
What is a stroke?
Damage to one hemisphere of the primary motor cortex loses voluntary movement on that side.
Where is the premotor cortex found?
Anterior to the primary motor cortex.
What is the role of the premotor cortex? (4)
- It plans by selecting/sequencing basic motor movements.
- It can coordinate several muscle groups.
- It is referred to as “muscle memory”.
- It can control voluntary actions that depend on sensory feedback.
What is Broca’s Area? Where is it found?
It is anterior/inferior to the premotor cortex, and it was originally described as a motor speech area, but has been found to be active when preparing to speak.
What motor area is responsible for the voluntary movement of the eyes?
The frontal eye field.
What are the 8 sensory areas of the cerebral cortex?
- Primary somatosensory cortex
- Somatosensory association cortex
- Visual Areas
- Auditory Areas
- Vestibular/Equilibrium Cortex
- Olfactory Cortex
- Gustatory Cortex
- Visual Sensory area
Where is the PSC located and where does it receive information from? Define spatial discrimination.
The primary somatosensory cortex is located on the postcentral gyrus and receives information from somatic sensory receptors, as well as proprioceptors. Spatial discrimination is the PSCs ability to locate sensations on the body.
What sensory area of the cerebral cortex is located posteriorly to the PSC and is responsible for the integration of somatic input? What kind of information is this part of the brain responsible for?
The somatosensory association cortex is responsible for inputs such as temperature and pressure, and can interpret characteristics such as size and texture based off prior experience.
What are the two visual areas? Where are they located?
The Primary Visual Cortex (PVC) and visual association area are located on the posterior tip of the occipital lobe. The visual association area surrounds the PVC.
What does the PVC handle? What about the visual association area?
The Primary Visual cortex deals with receiving visual information, and the visual association area relates it to previous knowledge.
What are the two auditory areas in the sensory division of the cortex? Where are they located?
The Primary auditory cortex is located in the temporal lobe and the auditory association area is slightly anterior to the primary auditory cortex.
What is the vestibular cortex responsible for? Where is it found and what lobes does it involve?
It is responsible for balance, and involves part of the Insula and parietal cortex. It is not visible on the surface of the brain.
On what face of the temporal lobe is the Uncus located?
The uncus is the medial aspect of the temporal lobes.
What is the uncus part of?
It is part of the olfactory cortex.
What tissues surround the olfactory cortex?
Limbic system tissues.
What cortex is responsible for taste? Where is it located?
The gustatory cortex is located on the insula.
What functions does the visceral sensory area have? Where is it located?
The visceral sensory area is posterior to the gustatory cortex on the insula, and is responsible for visceral organ senses eg. feeling nauseous or needing to urinate.
What are multimodal association areas? How many are there? What are they?
Multimodal association areas receive inputs from, and send outputs to multiple areas. There are three of them, the anterior association area, the posterior association area, and the limbic association area.
What is the flow of information like towards a multimodal association area?
Sensory receptors send information to primary sensory cortexes, which send the information to the sensory association cortexes, and that information gets sent to multimodal association areas.
What functions does the anterior association area have? (3) What is another name for it?
The prefrontal cortex is responsible for thinking/intellect, abstract ideas/planning/judgement, and is involved in mood and regulation of the limbic system.
What is known about the maturation of the prefrontal cortex?
It matures slowly and is dependent on social feedback.
What part of the posterior association area is responsible for written and spoken language?
Wernicke’s Area
What is a potential outcome of damage to the posterior association area?
Contralateral neglect. People will not recognize half of their bodies.
What are two functions of the posterior association area?
It links the senses to understand situations (has lots of memory of sensation), and deals with recognition of faces/patterns.
What does the limbic system do?
It provides emotional impact of learned experiences.
Which hemisphere is cerebral dominance associated with?
The hemisphere that is dominant for language, which is the left side 90 percent of the time.
What thought processes are linked to the cerebrally dominant hemisphere?
Language, logic, math
What thought processes are linked to the not cerebrally dominant hemisphere?
Artistic thoughts, imagination, music, spatial skills.
What can we say about cerebral dominance and dominant hand usage?
Generally, left-dominant brains are right-handed people, and right dominant brains are left handed people/ambidexterious.
Within cerebral white matter, what are the three types of fibres?
Commissural fibers, association fibers, and projection fibers.
What do commissural fibers connect? What is the most commonly known place they can be found?
They connect corresponding areas between the two hemispheres. An example of them is the corpus callosum.
What do association fibers connect?
Two areas within a hemisphere.
Where do projection fibers run? What is their orientation?
They run to or from the cortex and the rest of the nervous system. They run vertically.
What are the three components of the basal nuclei?
The caudate nucleus (anterior), the putamen (lateral), and the Globus pallidus (medial).
What does the basal nuclei look like?
A bit like a sleeping lizard
Where does the basal nucleus get its information?
It gets input from the entire cerebral cortex as well as other subcortical nuclei and one another.
What do the basal nuclei do?
They monitor movement and deal with starting, stopping, monitoring intensity. They also inhibit unnecessary actions, and is associated with filtering emotions as well.
What are two disorders related to the basal nuclei?
Parkinson’s disease and Huntingtons.
Describe the mechanics of Parkinson’s Disease.
The substantia Nigra dopamine-releasing neurons in the midbrain degenerates, causing the basal nuclei to become more active. This leads to a persistent tremor at rest, and muscle rigidity.
Describe the mechanics of Huntington’s disease.
Huntingtin is a protein that accumulates in the brain and destroys the basal nuclei. As the caudate nucleus breaks down, connections to the frontal lobe are broken and the individual can no longer control thoughts or emotions.
What three structures make up the diencephalon, and what brain structure does it surround?
The thalamus, hypothalamus, and epithalamus make up the diencephalon, which envelops the third ventricle.
What is the composition of the thalamus?
It is two masses of grey matter held together by a commissure called the Interthalamic Adhesion
What is the phrase used to describe the main function of the Thalamus?
It is the sensory gateway to the cerebral cortex.
What does the Thalamus do?
It sorts and edits sensory information, and directs it to the right part of the cerebral cortex. It also has a crude awareness of pleasant and unpleasant feelings. It has input pertaining to emotions and viscera from the hypothalamus, and mediates sensation learning, and memory.
What are the 7 roles of the hypothalamus?
- Autonomic control center (homeostasis of BP, HR etc.)
- Center for emotional response and behavior
- Body temperature and regulation
- Regulation of Food intake
- Regulation of Water
- Regulation of sleep cycles
- Control of the endocrine system
What three nuclei within the hypothalamus do we need to know? What are their functions?
The suprachiasmatic nucleus is the most anterior and regulates sleep-awake cycles, the supraoptic nucleus is superior to that produces ADH (antidiuretic hormone), and the paraventricular nucleus is the most superior nucleus and produces oxytocin.
What is the most dorsal section of the diencephalon called?
The epithalamus.
What part of the brain is responsible for the secretion of melatonin? Where is it located?
The pineal gland is located at the dorsal border of the epithalamus.
What is the name of the structure in the epithalamus that makes cerebrospinal fluid?
The choroid plexus.
