Gross Brain, Brainstem, and Spinal Cord Flashcards
What is the CNS vs PNS?
CNS: brain and spinal cord
PNS: spinal and cranial nerves with branches from CNS
What is the forebrain composed of?
Cerebral hemispheres and diencephalon
Where is the brainstem located?
Between the forebrain and spinal cord
What is gray matter?
Areas containing neuronal/glial cell bodies and dendrites
What are nuceli?
Collection of cell bodies w/ common function
What is the cortex?
Layers of gray matter over other parts of the CNS (cerebral and cerebellar cortices)
What is white matter?
Areas where there is a collection of axons; many covered with myelin
Other terms for white matter include fasciculus, funiculus, lemniscus, peduncle, and tract
Most tract have 2 part names. What is the 1st part? What is the 2nd part?
1st Part: location of neuronal cell bodies from which axons originate
2nd Part: site the axons terminate
What is a gyrus?
Ridge of cortical tissue
What is a sulcus?
Groove located between gyri
What is a fissure?
Particularly deep sulci
What is the purpose of gyri and sulci?
Increases the total cortical area and total number of cortical neurons
What are the 4 prominent sulci?
Central sulcus, lateral sulcus, parietooccipital sulcus, and cingulate sulcus
What is the corpus callosum?
Huge fiber bundle that joins the 2 hemispheres
What makes up the lateral surface of the frontal lobe?
Precentral gyrus and superior/middle/inferior frontal gyri
Where is the primary motor cortex found?
Precentral gyrus
Where are the premotor and supplementary motor areas located?
Remainder of precentral gyrus and portions of frontal gyri
What is Broca’s area?
Important in motor aspects of written and spoken language; usually found on the left
What is the prefrontal cortex?
Occupies rest of frontal lobe; involved with executive functions, personality, decision making, insight, and foresight
What makes up the parietal lobe?
Postcentral gyrus and superior/inferior parietal lobules
What are the functions of the parietal lobe (3)?
1) Postcentral gyrus corresponds to primary somatosensory cortex; processes tactile and proprioceptive information and sensory localization
2) Inferior parietal lobule is involved in language comprehension
3) Remainder of parietal cortex has aspects in spatial orientation and directing attention
What makes up the temporal lobe?
Superior/middle/inferior temporal gyri; inferior surface is made up of the occipitotemporal (fusiform) gyrus; also the supramarginal and angular gyri
What are the functions of the temporal lobe (4)?
1) Superior surface, continuing as a small area of the superior temporal gyrus, is the primary auditory cortex
2) Wernicke’s area, usually on the left, is important in language comprehension
3) Inferior surface is involved in higher-order processing of visual information
4) Most medial part is involved in learning and memory
What makes up the limbic structures?
Cingulate and parahippocampal gyri
What is the uncus?
Anterior end of the parahippocampal gyrus that hooks backwards on itself
Where is Wernicke’s area found?
Posterior portion of superior temoral gyrus, typically on the left
Where is the amygdala found? What is its function?
Beneath the uncus of the temporal lobe; functions in fear
What is the insula? Where is it found?
Additional area of cerebral cortex not included in the 5 lobes; lies buried in lateral sulcus
What is the circular sulcus?
Outlines the insula and marks its borders with the opercular areas of the cortex
What are the 5 lobes of the brain?
Frontal, temporal, parietal, occipital, and limbic lobes
What is the function of the occipital lobe?
Contains visual areas like the primary visual cortex and the visual association cortex (involved in higher order processing of visual information)
What structures are included in the diencephalon? What percentage of the weight of the brain does it contribute?
Thalamus, hypothalamus, epithalamus, and subthalamus; 2%, but is extremely important
What is the basal nuclei?
Group of nuclei that lies deep to the cerebral cortex in each hemisphere, specifically the caudate and lenticular nucleus (further subdivided into putamen and globus pallidus)
What is the internal capsule?
Thick sheet of fibers that separate the lenticular nuclei from the thalamus and caudate
What are arcuate fibers?
Connect cortical areas within the same sulci/gyri
What are longitudinal/association fasciculi?
Connect cortical areas within the same hemisphere
What are projection tracts?
Connect cortical areas within other body regions
About how many axons does the corpus callosum have?
Around 250 million axons
What is the anterior commisure?
Commissural fibers to/from temporal lobe (especially inferior parts)
What is the internal capsule divided into?
Anterior limb, genu, posterior limb, sublenticular limb, and retrolenticular limb
What is the midbrain?
Houses tectum; superior and inferior colliculi, paired bumps posterior to cerebral aqueduct; paired cerebral peduncles make up most of midbrain
What is the pons?
Protruding basal pons and pontine tegmentum forms part of the floor of 4th ventricle
What is the medulla?
Rostral open portion contains part of 4th ventricle; caudal closed portion is continuous with the spinal cord
What is the function of the cerebellum? What does damage cause? What is the surface made up of?
Functions in sensory information processing and influences motor neurons; damage results in abnormalities of equilibrium, postural control, and coordination of voluntary movements; made up of transverse ridges called folia
What is the medullary center in the cerebellum composed of?
Afferent and/or efferent fibers
Posterior rootlets enter the SC via what?
Posterolateral sulcus (shallow longitudinal groove)
Anterior rootlets leave the SC via what?
Anterolateral sulcus (poorly defined)
What makes up a posterior horn?
Substantia gelatinosa, body, and Lissauer’s tract
What is the substantia gelatinosa?
Region of gray matter that caps the posterior horn
What is the body of the posterior horn?
Interneurons and projection neurons that transmit somatic and visceral sensory information
What is Lissauer’s Tract?
White matter located between substantia gelatinosa and surface of SC
What is Clark’s Nucleus (posterior thoracic nucleus)?
Cells located on medial surface of the base of the posterior horn (T1-L2); has a prominent role in sensory processing and typically treated as part of posterior horn
Describe the anterior horn
Cell bodies of lower MNs supplying skeletal muscle; cells provide CNS control over body movements (voluntary/involuntary); influenced by different pathways to modulate movements
What is intermediate gray matter?
Collection of various projection neurons, sensory interneurons, and interneurons
What forms the lateral horn?
Preganglionic sympathetic neurons (T1-L3) in the intermediolateral cell column; axons leave via ventral roots
Where is the sacral parasympathetic nucleus located?
Spans S2-4 but does NOT form a distinct lateral horn
What are the ascending tracts?
Posterior columns, spinocerebellar tracts, and anterolateral system
What are the descending tracts?
Corticospinal tract, vestibulospinal tract, rubrospinal fibers
What do the posterior columns do?
Convey ipsilateral proprioceptive, tactile, and vibratory information from the body, but NOT THE FACE
What do the spinocerebellar tracts do?
Information relays to cerebellum, thalamus, and motor cortex to influence efficiency of motor activity
What does the anterolateral system do?
Relays pain, temperature, and nondiscriminative touch from the body, but NOT THE FACE
What do the corticospinal tracts do?
Controls voluntary, fine movements of the musculature
What do the vestibulospinal tracts do?
Influence motor neurons innervating primarily axial and neck musculature
What do rubrospinal fibers do?
Excite flexor motor neurons and inhibit extensor motor neurons
What is lamina I (marginal zone)?
Thin layer of gray matter covering the substantia gelatinosa
What is lamina II?
Substantia gelatinosa
What are lamina III through VI?
Body of the posterior horn
What is lamina VII?
Corresponds to the intermediate gray matter (including Clarke’s nucleus), but also includes extensions into anterior horn
What is lamina VIII?
Comprises some of the interneuron zones of the anterior horn
What is lamina IX?
Consists of the clusters of motor neurons embedded in the anterior horn
What is lamina X?
Zone of gray matter surrounding the central canal
What nucleus is found in lamina I? What vertebral levels does lamina I correspond to? What is the function of lamina I?
Nucleus: marginal zone
Vertebral Levels: all
Function: some spinothalamic tract cells
What nucleus is found in lamina II? What vertebral levels does lamina II correspond to? What is the function of lamina II?
Nucleus: substantia gelatinosa
Vertebral Levels: all
Function: modulate transmission of pain and temperature information
What nucleus is found in lamina III through VI? What vertebral levels does lamina III through VI correspond to? What is the function of lamina III through VI?
Nucleus: body of posterior horn
Vertebral Levels: all
Function: sensory processing
What nucleus is found in lamina VII? What vertebral levels does lamina VII correspond to? What is the function of lamina VII?
Nucleus: Clarke’s nucleus, intermediolateral nucleus, and sacral parasympathetic nucleus
Vertebral Levels: T1-L2, T1-L3, and S2-4
Function: posterior spinocerebellar tract cells, preganglionic sympathetic neurons, and preganglionic parasympathetic neurons to pelvic viscera
What nucleus is found in lamina IX? What vertebral levels does lamina IX correspond to? What is the function of lamina IX?
Nucleus: accessory nucleus and phrenic nucleus
Vertebral Levels: medulla-C5, C3-5
Function: motor neurons to the sternocleidomastoid and trapezius and motor neurons to the diaphragm
