NEU 409 Exam 2 Flashcards
The Meninges:
The name of the three layers in order
3-layered membrane that surrounds the delicate brain (also surrounds spinal cord)
Dura Mater – outermost brain/spinal cord membrane just under skull bones
Arachnoid Mater – membrane found under dura mater, is the middle layer
Pia Mater – membrane under Arachnoid Mater and separated from it by CSF, inner/deepest layer
Blood Brain Barrier
Helps maintain stable environment for brain
Separates neurons from some blood borne substances
3 Parts:
tight junctions between capillary endothelial cells
continuous endothelial cell basement membrane
astrocytes (neuroglia) wrapped around the endothelial cell
Functions
Selective barrier
What passes by diffusion:
Small non- polar molecules (O2, CO2)
Lipid (fat) soluble substances - alcohol, steroids, nicotine, anesthetics, opioids
What passes using facilitated diffusion with “help”(transporters)
Glucose, amino acids, fatty acids
Circle of Willis feeds the brain oxygenated blood through:
CIRCLE OF WILLIS: where all arteries converge
anastomosis:
Anterior cerebral artery - Carotid arteries
Middle cerebral artery
Posterior cerebral artery - Vertebral arteries
A blockage in one area of the circle still allows blood to run other ways into the cortex (anastomosis), subjective differences.
Anterior areas are supplied by Carotid System - splits into four parts
1.Internal Carotid Artery (ICA - splits into four parts ABCD): ranges off the aorta, courses up one on each side along the lateral portions of the neck. Most important for speech as its branches supply major speech & language areas. Enters the middle of the brain and branches off into 4 branches:
A. Middle Carotid/Cerebral Artery (MCA): branches laterally & supplies most of the lateral portions (posterior part of the frontal lobe) of the cerebrum and deep structures of frontal and parietal lobes, part of medial temporal lobe, internal capsule, part of basal ganglia
B. Anterior Cerebral Artery (ACA): moves anteriorly to the frontal lobe, supplies medial portion of the cerebral hemispheres, superior portion of the frontal & parietal lobes, ant. 4/5 of corpus callosum, basal ganglia (caudate head & putamen). Left & right ACA are connected to each other by the Anterior Comm. artery (AC)
C. Anterior Choroidal : Supplies optic tract, cerebral peduncle; lateral geniculate body (part of visual pathway), and portions of internal capsule - (non cortical arteries)
D. Ophthalmic branch: supplies orbit and surrounding tissue; muscles and bulb of the eye - (non cortical arteries)
Posterior areas are supplied by BLANK
Split into three parts
Posterior areas are supplied by Vertebrobasilar system
Arise from the subclavian arteries & ascends through upper cervical vertebrae. They enter skull through Foramen Magnum and continue along ventrolateral surface of Medulla - occipital lobe
Split into three parts:
1. Posterior cerebral artery
2. Basilar artery
3. Vertebral artery
Posterior communicating artery
part of the internal carotid system connecting the two systems
Gyrus
Sulcus
Central sulcus/fissure
Lateral sulcus/fissure
Longitudinal fissure
Language center
Corpus callosum
Superior longitudinal fasciculus
Arcuate fasciculus
Gyrus (raised mountain surface bumps)
Sulcus (deep grooves or valleys)
Central sulcus/fissure = Fissure of Rolando - frontal and parietal lobe
Lateral sulcus/fissure = Sylvian Fissure - serves to separate the temporal lobe from the frontal and parietal lobes
Longitudinal fissure = connects left and right hemisphere
Language center is left hemisphere
Corpus callosum: connect the left and right cerebral hemispheres.
Superior longitudinal fasciculus (anterior to posterior areas connected)
Arcuate fasciculus (frontal temporal connections; connect Broca’s and Wernicke’s area)
Lobes of the Brain:
Frontal lobe
Parietal lobe
Occipital lobe
Temporal lobe
Frontal lobe - reasoning, planning, motor movement
Parietal lobe - sensory perception, & interpretation
Occipital lobe - vision - posterior artery
Temporal lobe - memory, receptive language
Language posterior superior temporal lobe
Frontal Lobe: Prefrontal Cortex
Occupies BA 9, 10, 11, 46, 47
Executive control, personality, decision making, and social behavior (Phineas Gage)
19th century case of Phineas Gage and his prefrontal cortex damage taught much about the functioning of this area - working on railroad and had a nail through head and his whole personality changed completely but not major affected areas
Functionally involved with cognition (executive control), personality, decision making, and social behavior
Frontal Lobe: Broca’s area - left hemisphere
Occupies BA 44 and 45
BA 45: Interpretation of language (syntax) and planning/programming of verbal responses
BA 44: Coordination of speech organs for language production
Paul Broca, through observations of Tan, one of first to associate BA 44, 45 with speech production
Impairment to this area may lead to Broca’s aphasia (language production impaired)
Frontal Lobe: Premotor Cortex
Occupies BA 6
Involved in selecting and planning of motor movements including speech
Close relationship to BA 44
Supplementary motor area (SMA) located at top of BA 6 and involved in sequencing and “turning on” motor plans
Frontal Lobe: Primary Motor Cortex
Occupies BA 4
Sends motor plans developed in BA 6 to the muscles for them to act (e.g., speech muscles)
BA 4 has been mapped to form a homunculus or “little man”
Upper motor neurons
Voluntary movement
Parietal Lobe: Primary Sensory Cortex
Occupies BA 1, 2, and 3
Processes somatosensory information
Processes somatosensory information such as:
Vibration
Proprioception
Touch
Astereognosis
Homunculus present
Parietal Lobe: Angular Gyrus
Occupies BA 39
Involved in reading and math abilities
Damage can lead to alexia and acalculia
May also be involved in understanding metaphors and our sense of embodiment
Damage can lead to outer body experiences (OBEs)
Damage can lead to Gerstmann syndrome—agraphia, alexia, finger agnosia (unable to ID fingers), right/left disorientation
Parietal Lobe: Supramarginal Gyrus
Occupies BA 40
Involved in phonological system; stores auditory representations of phonemes (auditory images)
Closely related to the angular gyrus (BA 39)
Helps us sound out words
Damage can result in phonological dyslexia, difficulty reading new and nonwords
Occipital Lobe: Visual Cortices
Occupies BA 17, 18, and 19
Where information from eyes is received and processed
Two streams of vision:
Dorsal stream the where of vision - analyzes motion and spatial relationships - (18, 19, 7, and 39?)
Ventral stream the what of vision - analyzes forms, colors, and faces - (18, 19, and 37)
Temporal Lobe: Primary Auditory Cortex
Occupies BA 41 and 42 a.k.a., Heschl’s gyrus
Receives auditory information from the ears via CN VIII
Sylivan fissure front and back
Occupies BA 41 and 42 (42 is the secondary auditory cortex, but 41/42 usually discussed as a unit called the primary auditory cortex)
a.k.a., Heschl’s gyrus
Initial cortical region that receives auditory information from the ears via CN VIII8 and the auditory pathway
Processes sound intensity and frequency
Organized by tones (topographically arranged)
Primary Auditory Cortex: Topographic Organization
Temporal Lobe: Wernicke’s Area
Occupies BA 22
Meaning of auditory information
Named after Karl Wernicke
Involved in attaching meaning to auditory information
Damage can result in Wernicke’s aphasia, characterized by verbal jargon and a lack of understanding others’ speech
Artery attacked is middle cerebral artery
What’s happening to you - don’t understand language - don’t understand what someone is saying
Speech production and compression (old model)
Conduction aphasia
Brocas is movements - can understand
Parts of diencephalon: left hemisphere - Diencephalon consists of 4 parts:
Located
Brain stem
thalamus, epithalamus, subthalamus, hypothalamus
Located superior to the brainstem (specifically to the medulla) and inferiorly to the cortex (telencephalon)
Brain stem: midbrain, pons, medulla
Midbrain = most superior portion
Pons = middle portion
Medulla = lowest portion
Thalamus:
Thalamus: Left and right sides of thalamus connected at medial nucleus
A relay station
Sits above brainstem
“Gateway” to cerebral cortex
Functions:
Relays sensory information (except smell)
Perception of pain, temperature, & touch
Helps to maintain cortical arousal, attention, & sleep/wake cycle
Indirectly involved in motor function through fibers into basal ganglia
Routes sensory information to the cortex (except olfaction/smell)
Hypothalamus
A regulator for the body
Pituitary gland
Functions:
Autonomic nervous system control
Metabolism
Water balance
Sleep/wake mechanism
Body temperature
Food intake regulation
Secondary sex characteristics
Connects nervous system to endocrine (hormone) system via the pituitary gland
Controls metabolism, food intake, body temperature, emotion
Important role in maintaining homeostasis in the body (even keel)
Epithalamus
Connects limbic system to:
Forebrain and Other parts of brain
Parts:
Pineal gland – produces melatonin (regulates sleep/wake)
Habenula- olfactory reflexes (trigger hunger/salivation, gag)
Stria medullaris- connects habenula with limbic system
Pineal gland calcification
Associated with decreased melatonin production
Sleep disorders–association not clear
Associated with some degenerative diseases (like Alzheimer’s)
Melatonin may serve as a neuroprotectant
Mechanism not well understood, but possibly similar to bone formation
Possibly related to age BUT, not everyone shows calcification
Subthalamus
Lies below the thalamus
Connects basal ganglia to motor cortex,
thus more related to basal ganglia than thalamus
Damage can result in hemiballism
Involved in selection of actions and impulse control