Nervous System Part 3: Cerebral Cortex Flashcards
Glistening white material on either side of the thalamus/lateral ventricles.
-Contains myelinated axons coming down out of the Motor regions of the brain.
-Also has fibers that travel up to the Thalamus
-Takes sensory info to cerebral cortex and motor info down from cerebral cortex
Internal Capsule
Separates the Right Hemisphere from the Left Hemisphere of the Brain
Median Longitudinal Fissure
Primary Motor Center.
Located between the Precentral Sulcus and the Central Sulcus.
-Originates most corticospinal tract motor fibers (brain fibers -> cross over at inf. Medulla -> project to end of spinal cord)
-Primarily responsible for Voluntary, Fine digital movement (mostly distal movement - hands/wrists)
Precentral Gyrus
Primary receiving area for (Somesthetic) General Sensation. Located behind the Central Sulcus.
-Relay fibers carrying general sensation project here first.
-Follows Homunculus Pattern
Postcentral Gyrus
Area 312
Postcentral Gyrus
Area 4
Precentral Gyrus
Deep in Median Longitudinal Fissure: Foot, Hip
Around curve: trunk, arm, HAND
Then, FACE, tongue, and Larynx
Motor Homunculus
An area just rostral to the Precentral Gyrus
-Responsible for movement of large proximal muscles.
-Follows homuncular pattern (view picture of Homunculus)
Premotor Cortex
Portion of premotor cortex that allows you to carry out single tasks by memory.
Ex: putting on a coat. Do it naturally.
-Facilitator of motor planning (plan out ahead of time what you’re going to do)
-Guided more by memory than by visual cues
Supplementary Motor Area
Area rostral to the Premotor Cortex/Supplementary Motor Area.
-Portion of the Cerebral Cortex that controls Voluntary extra-occular movement
-Eyes will move together at the same speed in the same direction.
Frontal Eye Field
Rostral to the Frontal Eye Field.
-The executive portion of the brain.
-Measurement of personality, problem solving, emotions/control, reasoning, decision making, memory, and anything unique about a person.
-Tells the rest of the brain what to do.
Prefrontal Area
-Pars Orbitalis: sits right over the orbit
-Pars Triangularis: triangular gyrus with apex pointed down and back
-Pars Opercularis: pothole looking, sits nearest to Precentral Gyrus
Inferior Frontal Gyrus
Pars Triangularis + Pars Opercularis.
-Drives motor speech
-Expressive aphasia: can’t talk
-Dominant on the left side in most people
“Broken Speech”
Broca’s Area
Median Longitudinal Fissure: Toes, feet
Around the curve: hip, neck, arm, wrist, hand (big, but not as big as motor)
Lateral Side: LIPS, face, teeth, jaw, tongue, pharynx
Sensory Homunuculus
Pain and Temperature
Tactile Senses:
-Fine touch (can you tell what you are touching) and pressure
-Stereognosis (can you pick up an object and be able to tell the shape of it without looking)
-2 Point discrimination (can you differentiate between 2 close points)
-Kinesthetic sense (conscious proprioception - can you tell where limbs are at all times)
-Vibration (can you feel vibration when a tuning fork is placed against bone)
General Sensation (Somesthesis)
Lateral Group of Thalamic Nuclei contains 2 Components:
-VPL (Ventral Posterolateral Nucleus)
-VPM (Ventral Posteromedial Nucleus)
Thalamus (General Sensory Nuclei)
Involved with general sensation fibers coming in from the body (trunk, extremities) that project to the relay nucleus of the thalamus.
VPL (Ventral Posterolateral Nucleus)
Involved with general sensation fibers coming off of the face and projecting to relay nucleus of the thalamus
VPM (Ventral Posteromedial Nucleus)
Dorsal to the Postcentral Gyrus
-Contains the General Sensory ASSOCIATION Areas
-Superior Lobule
-Inferior Lobule
-Precuneus
-Interparietal sulcus (separates superior from inferior).
Helps you make decisions and process different types of sensations that come into the brain that are being relayed up via the relay nuclei of the thalamus.
Parietal Lobe
Composed of the Supramarginal Gyrus and the Angular Gyrus
Inferior Parietal Lobule
Provides sensory tactile feedback to guide motor tasks.
-Carrying out a motor task requires sensory input to project into the motor system to tell it what to do.
-Provides texture discrimination input for motor tasks involving sensory feedback.
-Also has Speech comprehension area (Wernicke’s Area).
Supramarginal Gyrus
Processes and integrates speech to understand what someone is telling you
-Supramarginal Gyrus
Wernicke’s Area
Dyspraxia (Ideational or Ideamotor). Problem with interface between sensory and motor. Cannot process the tactile information, so can’t carry out the activity.
Receptive Aphasia (can talk ok, but can’t put words together = word salad)
Disorders of the Supramarginal Gyrus
A form of dyspraxia where you know what you’re supposed to do with an object, but you can’t do whatever it is.
Ex: you have a shirt, but you can’t remember how to put it on properly
Ideamotor
A form of dyspraxia where you do not know what you’re supposed to do or how you’re supposed to do it.
Ideational
Lesions in this area make it so that you cannot form a sequence of movements from memory to accomplish tasks.
-Motor output issue
-Ex: Cannot remember how to put on a coat
Supplementary Motor Area Dysfunction
Area for Reading Association. Allows you to read accurately.
Angular Gyrus
-Dyslexia: unable to read properly
-Agraphia: unable to write out a communication
-Acalculia: unable to do simple math problems (3+2)
-Finger agnosia: hold up a finger, can’t tell which finger it is (Ex: Index finger)
-Left-right disorientation: can’t tell R from L.
Could be due to trauma in area, molecular, genetic, etc.
Angular Gyrus Dysfunction
Sulcus that can only be seen on medial view and separates Parietal lobe from Occipital Lobe.
Parieto-occipital Sulcus
Marks the determination between the Occipital Lobe and the Temporal Lobe.
Pre-occipital Notch
Separates Gyrus Cuneus from the Lingual Gyrus.
-Only visible on medial side
Calcarine Sulcus
2 Main Medial Gyri:
-Gyrus Cuneus: visual feel of objects in the lower portion of the visual field
-Lingual Gyrus: visual feel of objects in the upper portion of visual field
Occipital Lobe
-Loops around Calcarine Sulcus
-Incoming information from the visual field is routed to the Thalamus via the Optic Nerve. Relay nuclei originate new fibers that go to the Occipital Lobe.
-Lesion = Cortical Blindness
Primary Visual Area
The parts of the Occipital lobe not looping around the Calcarine sulcus. Allow us to identify what we are seeing.
Lesion = can see an object, but can’t identify what it is.
Visual Association Cortex
Receives information from the Lateral Geniculate Nuclei (Thalamic Visual Relay Nuclei) via the Optic Nerve. Lateral Geniculate Nuclei originate new fibers that project back to the Occipital Lobe, specifically to the Primary Visual Cortex (area surrounding Calcarine Sulcus).
-Lesion = Cortical Blindness
Primary Visual Cortex
Gyrus cuneus to Calcarine sulcus, and then sulcus to Lingual Gyrus (skips looping part of Primary Visual Cortex).
Responsible for Integration and interpretation of visual information.
Problems = Visual Agnosia
Median Occipital Cortex (Visual Association Area)
Composed of the Superior, Lateral, and Inferior Occipital Gyri
Lateral Occipital Cortex
Composed of the Superior, Middle, and Inferior temporal gyri, as well as the Superior and Inferior Temporal Sulci
Also has Anterior Transverse Temporal Gyri (Heschel’s Convolutions).
Temporal Lobe
Primary Auditory Area. When sound comes into the nervous system, it projects from the thalamic auditory relay nuclei (Medial Geniculate Nuclei) to here, and then to the Auditory Association Area.
-Carried by Vestibulocochlear Nerve (CN VIII)
Anterior Transverse Temporal Gyri (Heschel’s Convolutions)
Speech Association Area.
-Inferior portion of the Supramarginal gyrus right where it blends into the Superior Temporal Gyrus
-Dominant on the left side of the brain
-Language comprehension: Understanding spoken word.
Lesion = Receptive Aphasia (word salad)
Wernicke’s Area
A fiber pathway that allows for transmission between Broca’s and Wernicke’s Area.
-Allows for very fast communication (high speed axonal pathway)
-Also connects speech receptor areas to Broca’s and Pre-motor Areas.
Lesion = Conduction Aphasia
Arcuate Fasciculus
Comprehending speech and speaking is ok, but connection between the two areas is knocked out.
-Cannot repeat speech back to you.
Conduction Aphasia
Loss of both Broca’s and Wernicke’s Areas. Cannot understand speech or form it at all.
Global Aphasia
Rostral Portion of the Temporal lobe at the Uncus and the Rostral Parahippocampus.
-Only sensory system not routed through the Thalamus
-Also called the Piriform Cortex
Primary Olfactory Area
Incoming olfactory information goes directly here (skips Thalamus)
-Has Association Areas around it (Entorhinal/Transentorhinal Area) and Paraolfactory area
-Helps identify what you smell
Piriform Cortex
Olfactory Fibers pierce Cribriform Plate -> Olfactory Bulb -> Olfactory Tract -> Olfactory Triangle -> Medial or Lateral Striae
Olfactory Tract
Contains fibers that go into the Anterior Commissure and project into the Olfactory Area on the other side of the brain
-Also helps connect smell to Limbic System
Medial Striae
Contains fibers that go to the Primary Olfactory Cortex (Uncus)
Lateral Striae
Fibers project directly here (skipping Thalamus)
-Uncus of Parahippocampus
-Entorhinal/Transentorhinal Areas
These help you understand what exactly you’re smelling.
Primary Olfactory Receiving Area
-Hippocampus with Fornix
-Parahippocampus
-Mammillary Bodies
-Anterior Thalamic Nucleus (Association nucleus)
-Gyrus Cinguli
-Amygdala (cluster of cells in rostral aspect of temporal lobe)
Limbic Lobe Components
-Emotional Control/regulation
-Memory: transfers ST to LT memory
-Spatial Navigation: allows you to navigate from place to place
Hippocampus
-No control over emotions (unexpected crying/laughing)
-Have no recent memory. Unable to make ST memory go into LT memory.
-Go somewhere (like grocery store) but can’t figure out how to get home
Lesion in Hippocampus
A thin membrane running from the Corpus Callosum to the Fornix. Offers supportive functions.
Septum Pellucidum
Receive fibers from the Fornix and initiate new fibers that ascend to the Thalamus (Anterior Nucleus of the Thalamus)
Mammillary Bodies
Receives fibers from the Hippocampus and projects them into the Mammillary Bodies
Fornix
Originates new fibers that travel to the Gyrus Cinguli
Anterior Nucleus of the Thalamus
Exchanges functions with the Association Cortical Area.
Functions:
-Connects sensory input to emotions
-Emotional responses to pain
-Regulation of aggressive behavior
-Communication
-Maternal Bonding
-Language expression
-Decision making
Does all this via interconnections to/from the Cerebral Cortex
Gyrus Cinguli
Cluster of cells found in the Rostral tip of the Temporal Loe.
-Provide a direct connection between the prefrontal cortex, allowing for the exchange of information (both are involved with memory)
Amygdala
A basal ganglia associated with the Limbic System.
-Emotional Fear (walking in a dark place and hear footsteps)
-Emotional Memory (PTSD)
-Long term memory consolidation (Stores memories as a block for future use)
Amygdala
Projects to and connects with the:
-Hippocampus
-Entorhinal Area (area around the Piriform cortex)
-Thalamus
-Septum (medial portion of prefrontal cortex)
-Prefrontal cortex
-Hypothalamus
-Brainstem (to create actions/effects of emotional responses)
Has to coordinate with all of these to form a typical sympathetic response.
Amygdala
Divided into two parts:
-Larger Anterior Insula
-Smaller Posterior Insula
Lies deep within Lateral Fissure
Insular Lobe
-Controls compassion and empathy
-Motor control (hand-eye coordination)
-Self-awareness
-Taste
Insular Lobe
