Gross Brain, Brainstem and Spinal Cord Flashcards
Gray matter
Areas containing neuronal/glial cell bodies and dendrites
White matter
Areas where there is a collection of axons, many covered with myelin
Fasciculus, funiculus, lemniscus, peduncle and tract are all terms for white matter
Frontal lobe areas
Precentral gyrus, and superior, middle and inferior frontal gyri make up the lateral surface of frontal lobe
Precentral gyrus houses what and what is their function
Primary motor cortex
Premotor and supplementary motor areas occupy the remainder of the precentral gyrus and portions of frontal gyri
- planning and initiating voluntary movements
Brocas area location/brief description of function
Opercular and triangular parts of inferior frontal gyrus (only in one hemisphere, usually left)
-important in motor aspects of written/spoken language
Prefrontal cortex location and brief description of function
Occupies the rest of frontal lobe
-Involved with executive functions, personality, decision making, insight and foresight
Parietal lobe areas/functions
Postcentral gyrus- corresponds to primary somatosensory cortex; contrals w/processing of tactile and proprioceptive information, sensory localization
Inferior parietal lobule (one hemisphere, usually left)- involved in language comprehension
Remainder of parietal cortex has aspects in spatial orientation and directing attention
Homonculus
A somatotopic map reflecting where somatosensory information enters the brain
Temporal lobe areas/functions
Superior, middle and inferior temporal gyri
Inferior surface is made up of broad occipitotemporal (fusiform) gyrus
Superior surface, continuing as a small area of the superior gyrus, is the primary auditory cortex
Wernicke’s area is located on the posterior portion of the superior temporal gyrus (one hemisphere, usually left) is important in comprehension of language
Inferior surface is involved in higher-order processing of visual information
Most medial part is involved in learning and memory
Also includes supramarginal & angular gyri
Limbic structures
Mostly composed of the cingulate and parahippocampal gyri
Anterior end of parahippocampal gyrus hooks back on itself forming a medial bump, the uncus
Folded into the temporal lobe at the hippocampal sulcus is the hippocampus
Amygdala lies beneath the uncus of the temporal lobe
Limbic lobe is important in emotional responses, drive related behavior and memory
Insula
Additional area of cerebral cortex not included in the five lobes
Lies buried in lateral sulcus
Concealed by portions of frontal, parietal and temporal lobes
Can be seen by prying opening lateral sulcus or by removing opercula of frontal, parietal or temporal lobes
Circular sulcus outlines the insula and marks its borders with the opercular areas of cortex
Occipital lobe areas/functions
Lateral surface contains lateral occipital gyri
Cuneus, a wedge shaped area b/w parietooccipital and calcarine sulci
Primary visual cortex is contained in the walls of the calcarine sulcus
Remainder of lobe is the visual association cortex which is involved in higher order processing of visual information
Diencephalon
Accounts for only 2% of brain mass but is very important
Includes hypothalamus, epithalamus and subthalamus
Inferior surface of hypothalamus is visible on an intact brain, including the infundibular stalk- two rounded protuberances, mamillary bodies are also visable
Basal nuclei
Group of nuclei that lie deep to the cerebral cortex in each hemisphere
Caudate & lenticular nucleus (subdivided into putamen and globus pallidus)
Lenticular nuclei are physically separated from the thalamus and caudate by a thick sheet of fibers, the internal capsule
Internal capsule contains most of the fibers interconnecting the cerebral cortex & thalamus, basal nuclei and brainstem
Arcuate fibers
Connect cortical areas within the same sulci/gyri
Longitudinal/association fasciculi
Connect cortical areas within the same hemisphere
Projection tracts
Connect cortical areas within other body regions
Corpus callosum
Interconnects the two cerebral hemispheres, contains somewhere around 250 million axons
Anterior commissure
Commissural fibers to/from temporal lobe (especially inferior parts)
Brainstem role/areas
Plays major role in cranial nerve function, conveys info to/from forebrain
Midbrain
Pons
Medulla
Midbrain
Houses the tectum (latin for roof) of the midbrain
Superior and inferior colliculi, paired bumps posterior to cerebral aqueduct
Paired cerebral peduncles make up most of midbrain
Pons
Protruding basal pons & pontine tegmentum forms part of floor of 4th ventricle
Medulla
Rostral open portion containing part of 4th ventricle
Caudal closed portion, continuous with SC
Cerebellum
Functions in sensory information processing & influences motor neurons
Cerebellar damage results in abnormalities of equilibrium, postural control, and coordination of voluntary movements
Surface is made up of transverse ridges- folia
Prominent fissure divide it into lobes and lobules
White matter in the medullary center, composed of afferent and/or efferent fibers
Spinal cord
Anterior vs posterior horns
Posterior rootlets enter SC via posterolateral sulcus, a shallow longitudinal groove
Anterior rootlets leave SC via anterolateral sulcus
Posterior and anterior rootlets–> spinal nerves
Posterior horn
Substantia gelatinosa- region of gray matter that caps the posterior horn
Body- interneurons and projection neurons that transmit somatic and visceral sensory information
Lissauer’s tract- white matter located b/w substantia gelatinosa and surface of SC
Clarks nucleus (posterior thoracic nucleus)
Cells located on the medial surface of the base of the posterior horn
Has a prominent role in sensory processing and typically treated as part of posterior horn
Anterior horn
Cell bodies of lower MNs supplying skeletal muscles
Cells provide CNS control over body movements (voluntary or involuntary)
Influenced by different pathways to modulate movements
Intermediate gray matter
Collection of various projection neurons, sensory interneurons and interneurons
Preganglionic sympathetic neurons, in the intermediolateral cell column, form the lateral horn (axons leave via ventral roots)
Sacral parasympathetic nucleus spans S2-S4 but does not form a distinct lateral horn
Lamina I
Marginal zone- is a thin layer of gray matter covering the substantia gelatinosa
Lamina II
Is the substantia gelatinosa
Lamina III-VI
Are the body of the posterior horn
Lamina VII
Corresponds to the intermediate gray matter (including Clarke’s nucleus) but also includes extensions into anterior horn
Lamina VIII
Comprises some of the interneuron zones of the anterior horn
Lamina IX
Consists of the clusters of motor neurons embedded in the anterior horn
Lamina X
Is the zone of gray matter surrounding the central canal
Marginal zone
All levels
Lamina I
Some spinothalamic tract cells
Substantia gelatinosa
All levels
Lamina II
Modulate transmission of pain and temperature info
Body of posterior horn
All levels
Lamina III-VI
Sensory processing
Clarke’s nucleus
T1-L2
Lamina VII
Posterior spinocerebellar tract cells
Intermediolateral column
T1-L3
Lamina VII
Preganglionic sympathetic neurons
Sacral promontory nucleus
S2-S4
Lamina VII
Preganglionic parasympathetic neurons–> pelvic viscera
Accessory nucleus
Medulla-C5
Lamina IX
Motor neurons–>sternocleidomastoid and trapezius
Phrenic nucleus
C3-C5
Lamina IX
Motor neurons–>diaphragm
Primary afferents and lower motor neurons
Convey info to/from the CNS
Primary afferents terminate in the CNS on second order neurons (with a few exceptions, sensory primary afferents are ipsilateral)
Lower motor neurons convey info from CNS to skeletal muscle
Second order neurons
Relay a signal from primary afferents in the periphery to a target in the CNS
Can cross the midline of the body
Third order neurons
Relay the message to final target in a specific cortical area(s)
Cortex decides on given output
Ascending tracts
Posterior columns- convey ipsilateral proprioceptive, tactile and vibratory information from the body (not face)
Spinocerebellar tracts- information relays to cerebellum, thalamus and motor cortex to influence efficiency of motor activity
Anterolateral system- relays pain, temperature and nondiscriminative touch from body (not face)
Descending tracts
Corticospinal tract- controls voluntary, fine movements of the musculature
Vestibulospinal tract- influence motor neurons innervating primarily axial and neck musculature
Rubrospinal fibers- excite flexor motor neurons and inhibit extensor motor neurons
Retrolenticular limb of internal capsule fed by what artery
Anterior choroidal arteries
Posterior limb of internal capsule fed by what artery
Anterior choroidal arteries
Anterior limb of internal capsule has what tracts
Frontopontine
Anterior thalamic radiations
Frontal eye field
Genu of internal capsule has what tracts
Corticonuclear
Posterior limb of internal capsule has what tracts
Corticorubral, cor. reticular, cor. nigral, cor. subthalamic Superior thalamic radiations Corticospinal Parietopontine Pallidothalamic
Retrorenticular limb of internal capsule has what tracts
Optic radiations
Corticotectal
Corticorubral
Corticotegmental
