Anatomy 337 Exam #3, Brain-UW Madison

Telenchephalon

cerebral hemispheres

Diencephalon

thalamus, hypothalamus, epithalamus

Mesencephalon

the midbrain; a region of the brain that surrounds the cerebral aqueduct; includes the tectum and the tegmentum

Metencephalon

pons and cerebellum

Myelencephalon

medulla oblongata

gray matter

cell bodies, dendrites, unmyelinated axons

gray matter cortex

covers the surface of the brain and forms discrete internal clusters called cerebral nuclei

White matter

myelinated axons, towards the middle

Cerebral cortex

-awareness, knowledge, memory, perception, information processing, and thinking

Motor areas

control voluntary movement

sensory areas

conscious awareness of sensation

multimodal association areas

integration and interpretation of sensory and motor information

cytoarchitecture

The arrangement of neuronal cell bodies in various parts of the brain (ie. cerebral cortex has 6 layers, each layer has different function)

Brodmann's Areas

regions of cortex defined by the relative distribution of cell types across cortical layers (cytoarchitecture), location varies from person-to-person

Cerebral hemispheres

-mirror images, different function

-connected by white matter pathways (corpus callosum, anterior commissure, and posterior commissure)

Median longitudinal fissure

separates left and right hemispheres

Corpus callosum

the large band of neural fibers connecting the two brain hemispheres and carrying messages between them, white matter

Anterior commissure

connects medial temporal lobes

Posterior commissure

white matter

Corpus callosum and TBI

-rotational injuries are usually worse

-almost always damaged in TBI/repetitive trauma

Parietal Lobe

general sensory functions, tactile sensation, proprioception, taste, language, spatial orientation, directing attention

-primary somatosensory cortex, somatosensory association cortex (where DCL pathway ends)

Central sulcus

separates frontal and parietal lobes

Lateral sulcus

Separates temporal lobe from parietal and frontal lobes

parieto-occipital sulcus

separates parietal and occipital lobes

Primary somatosensory cortex

receives general somatic sensory information from touch, pressure, pain, and temperature receptors; located within the postcentral gyrus

Somatosensory association cortex

-posterior to primary somatosensory cortex

-integrates and interprets sensory information

Prefrontal cortex

Dorsolateral, orbitofrontal, anterior cingulate

Dorsolateral Prefrontal Cortex

-organization and planning

-managing behavior

-high-level decision making

-multitasking

-working memory

Orbitofrontal Cortex

modulating emotions, inhibition, adaptive learning, rewards, and emotion

Anterior Cingulate Cortex

-Motivational behavior

-Reward-based learning: error detection, outcome monitoring

-Pain processing

Phineas Gage

-understanding of the localization of brain function

-prefrontal cortex is not vital to being alive

Primary motor cortex

-voluntary motor activity

-beginning of corticospinal tract

-innervation similar to sensory homunculus

sensory homunculus

Demonstrates that the area of the cortex dedicated to the sensations of various body parts is proportional to how sensitive that part of the body is.

Motor homunculus

broad areas of primary motor cortex devoted to controlling movements of different body regions

Prefrontal/supplementary motor cortices

-process motor information

-plans and coordinates learned, skilled motor activity

-"making the plan"

Broca's area

-left side of brain

-controls muscles of speech

Broca's aphasia

can understand spoken language, but can't speak it

Temporal Lobe

-hearing and smell

-medial associated with limbic system (memory, learning, aggression, emotion)

Wernicke's area

-recognizing and comprehending written and spoken language

-left side

-overlaps the parietal and temporal lobes

Hippocampus

-medial temporal lobe

-essential in learning, storing memories, and forming long-term memory

Patient HM

Fell off his bike in the 1950's which caused him to have seizures. As a solution, doctors took out his medial temporal lobe which led to him not being able to form any new memories

Amygdala

-anterior to hippocampus (medial temporal lobe)

-associations between sensory input and emotions

-sort and code memories based on emotions

-fear

Insula

-primary gustatory cortex (taste)

-"old area", primal, not entirely sure function

Limbic system structure

form ring around diencephalon

Limbic system

-establishes and processes emotional states and behavioral drives

-affects memories (formation, storage, retrieval) through integration, emotional states, physical sensations

-links consciousness, intellectual cortex with unconscious ANS functions

cerebral nuclei (basal ganglia)

-control of posture and voluntary motor movements

-adjust rhythm/pattern (+ learned movement)

-muscle tone

-process, integrate, and relay info from cortex to thalamus

Cerebral nuclei structure

-paired gray matter nuclei deep within the white matter

-caudate nucleus

-putamen

-globus pallidus

Hypothalamus

-controls release of regulatory hormones from anterior pituitary gland

-specific hormones from posterior pituitary gland

-controls adrenal medulla

Pituitary gland

-inferior to hypothalamus

-attached to hypothalamus by infundibulum

-anterior: adenohypophysis

-posterior: neurohypophysis

Adenohypophysis (anterior pituitary)

controlled by releasing and inhibiting hormones via the hypothalamus, travels through hypothalamohypophyeal tract

-uses a portal system

Neurohypophysis (posterior pituitary)

neural connection between the hypothalamus and the posterior pituitary (axons make the hypothalmohypophyseal tract

-does not make the hormones, the hypothalamus does (stores and releases hormone when needed)

Cerebellum

-voluntary motor activity (precision, timing, error-correction)

-muscle tone and posture

-eye blink, visceromotor, vestibuloocular reflex

-higher cognitive functions

-emotional processing

-ipsilateral

Midbrain

Tectum and reticular formation

Tectum

-midbrain

-contains 2 pairs of sensory nuclei call corpora quadrigemina

-visual reflexes: superior colliculi

-auditory reflexes: inferior colliculi

Reticular Formation

arousal and consciousness

cerebral peduncles (midbrain)

-primarily motor axons

-corticospinal tract

substantia nigra (midbrain)

-neurons secrete dopamine

-voluntary movements through connections to basal ganglia

red nucleus (midbrain)

involuntary motor control, maintaining muscle tone and limb position

Substantia Nigra and Parkinson's

Pons

-contains corticospinal tract fibers

-somatosensation (DCML pathway)

-process and relay cerebellar commands

-origin of four cranial nerves

-sleep regulation, breathing, hearing, balance

Pons breathing

-autonomic nuclei in the pontine respiratory center

-regulate activity of respiratory rhythmicity center of the medulla oblongata

Pons Hearing

superior olivary nuclei receive auditory input and help localize sound

Pons Balance

nuclei that relay info from the cerebellum

Medulla Oblongata

-connects brain and spinal cord

-white matter tracts through it

-origin of 5 cranial nerves

-sensory nuclei from DCML

-motor: pyramids

Cardiovascular Center

-medulla

-autonomic nuclei, adjust HR, strength of contraction, vasoconstriction/dilation

Medullary Respiratory Center

sets the pace of breathing

Other Medullary Nuclei

coughing, sneezing, salivation, swallowing, gagging, and vomiting

Subdural Hematoma

-rapid acceleration or deceleration of head

-tearing of a cerebral vein as it pierces the arachnoid mater

-typically slower

Epidural Hematoma

-can occur with skull fracture

-damages the meningeal artery

-often fatal