Ch.12 Flashcards
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Cerebrum
- largest part of the brain
- Majority of brain mass (83%)
- Superficial gray matter - cerebral cortex
- deeper white matter: tracts
- deepest gray matter are the cerebral nuclei
Cerebellum
- cauliflower shape
- Two hemispheres connected by vermis
- white matter on cerebellum forms the arbor vitae
– Sits in posterior cranial fossa
– Each hemisphere has anterior, posterior and flocculonodular region
– It receives input from the motor cortex, sensory receptors, proprioceptors (stretch), and brain stem
– Functions to coordinate skeletal muscle movement, maintains posture and balance
Diencephalon
thalamus, hypothalamus, epithalamus
Brain stem
- continuous with the spinal cord
- Consists of medulla, pons, and midbrain
Brain Anatomy
deep gray matter (neuron cell bodies) –> white matter (myelinated fiber tracts) –> superficial gray matter
Ventricles
- Fluid (CSF) fills these spaces in brain, all connected to each other and to central canal of spinal cord
1. Lateral ventricles - Pockets into the cerebral hemispheres
2. Third ventricle - Narrow canal through the diencephalons
3. Fourth ventricle - Canal under brain stem
Cerebral Spinal Fluid
- Colorless liquid: circulates through the subarachnoid space of the brain, spinal cord, ventricles , central canal of cord
- Function: cushion brain and cord, provide buoyancy, circulates nutrients for optimal neuron functioning and eliminates waste products
- Made by ependymal cells of choroid plexus located in each ventricles.
- returned to circulatory system (dural sinuses) by the arachoid villi
The Blood-Brain Barrier
- Endothelial cells have tight junctions, thick basement membranes - form a seal so only selected substances enter the brain
- Barrier is ineffective against fats, fatty acids, oxygen, carbon dioxide. Nicotine, alcohol, and anesthetics affect the brain as they are fat soluble
Cortex
- Responsible for higher thinking
- Has Sensory, Motor, and Multimodal Association areas
- Within these areas there is regional dedication
Primary motor (somatic) cortex
Motor
- Allows conscious control of precise, skilled, voluntary movements
- Large pyramidal neurons form pyramidal tracts (corticospinal)
Premotor cortex
Motor
Controls learned, repetitious, or patterned motor skills ex musical instrument
Broca’s area
Motor
- Speech area that directs muscles of the tongue
- Usually only on left side.
Frontal Eye Field
Motor
Controls voluntary eye movement
Primary somatosensory cortex
Sensory
Receives info from skin and skeletal muscles; exhibits spatial discrimination
Somatosensory association cortex
Sensory
- comprehensive understanding of stimulus
- Determines size, texture, and relationship
- Ex: recognition of contents of pocket
Visual areas
Sensory
Receives visual information from retinas & interprets (color, form, movement)
Auditory areas
Sensory
Receives information related to pitch, rhythm, and loudness
Olfactory cortex
Sensory
Conscious awareness of odors
involved in smell
Gustatory cortex
Sensory
involved in taste
Visceral sensory area
Sensory
- conscious perception visceral sensation
- Ex: full bladder, upset stomach
Vestibular cortex
involved in balance and equilibrium
Prefrontal cortex
- Involved with intellect, cognition, recall, personality, judgment, reasoning, persistence, and conscience
- associated with Limbic system
Language area
Wernicke’s area, Broca’s area, Lateral prefrontal cortex ,Lateral & ventral temporal lobe
General interpretation area
integrates multiple stimuli for understanding
Visceral association area
perception of visceral sensations
White matter of cerebrum
Deep to the cortex, made of
myelinated axons connecting
different areas
Commissures
White matter of cerebrum
- Tracts that connect corresponding areas between the two hemispheres
- Largest is corpus callosum (superior to lateral ventricles)
Association fibers
White matter of cerebrum
Tracts connecting areas within the same hemisphere
Projection fibers
White matter of cerebrum
Tracts entering and leaving the cerebrum from other regions
Deep Gray Matter of the Cerebrum
- Basal nuclei (Basal Ganglia – cell bodies – gray matter)
- Consists of many nuclei, receive input from many areas and perform diverse functions
- Huntington’s Disease results in massive degeneration of these nuclei which then progresses to cortex
Diencephalon
- Intermediate to the brain stem and cerebrum
- Forms core of forebrain; all gray matter
- Hypothalamus, thalamus, epithalamus
Thalamus
Diencephalon
- Gateway to the cerebral cortex
- Sensory relay station where sensory signals can be edited, sorted, & routed; motor & cognitive function
Hypothalamus
Diencephalon
- Attached to Pituitary gland
- Main visceral control center for homeostasis in the body
- Autonomic Regulatory Center, Emotional Response, Regulation of Body Temperature, Regulation of Food Intake, Regulation of Water Balance and Thirst, Regulation of Sleep/Wake Cycles, Hormonal Control, heart rate, blood pressure
Epithalamus
Diencephalon
- Releases melatonin from pineal gland; regulates sleep/wake cycle and food/water intake, emotional response to odors
Brain Stem
- Three parts: medulla, pons, midbrain
- Responsible for low level activities, reflexes and automated responses
- Controls automatic behaviors necessary for survival
– Connects cerebrum to spinal cord
Midbrain
Brain Stem
- Contains reflex centers that move eyes and head
- maintains posture, auditory reflex center
Pons
Brain Stem
- Relays nerve impulses to and from medulla oblongata & cerebrum
- helps regulate breathing rate and depth
Medulla Oblongata
Brain Stem
- Conducts impulses between brain and spinal cord
- contains cardiac, vasomotor, respiratory control centers; nonvital reflex control centers
Substancia nigra
Midbrain
- nucleus for unconscious muscle activity
- dopamine releasing neurons die here during Parkinson’s Disease
Pons
- has fiber tracts sensory and motor to cerebellum
- has nuclei associated with breathing
Medulla Oblongata
- homeostasis centers for heart rate, vessel diameter, and respiration
- reflex centers for vomiting, hiccupping, coughing, sneezing
Concussion
Brain Trauma
blow to the head with temporary symptoms (dizzy, nausea, blurry vision)
Contusion
Brain Trauma
results from serious concussion that bruises brain and causes some permanent damage
Stroke
Brain Trauma
brain blood flow has been blocked and tissue dies
Spinal cord
Functions:
- Pathway to/from brain
- Coordinate spinal cord reflexes
Structure:
- 16”-18” long
- 3/4” diameter
- Associated with 31 pair of spinal nerve
- Gray matter in core, white matter is outside
Subarachnoid space
Meninges of spinal cord
- contains cerebrospinal fluid
Subdural space
Meninges of spinal cord
contains
interstitial fluid
Pia mater
Meninges of spinal cord
transparent, thin connective tissue
Arachnoid mater
Meninges of spinal cord
loose connective tissue
Dura mater
Meninges of spinal cord
dense irregular connective tissue, continuous with inner layer of brain dura mater
Epidural space
Filled with fat and blood vessels
Gray Matter
Spinal cord
- unmyelinated axons + cell bodies of multipolar neurons
- Form the horns & Gray commissure
Dorsal Horn
Gray Matter
contains cell bodies of interneurons
Ventral Horn
Gray Matter
contains cell bodies of motor neurons
Lateral Horn
Gray Matter
- Located only in upper lumbar/thoracic and sacral regions
- House cell bodies of autonomic (sympathetic division) motor neurons
White Matter
Spinal cord
- Contains myelinated axons
- Arranged in roots + columns
Dorsal root
White Matter
contains axons entering the CNS
Dorsal Root Ganglion
White Matter
Contains cell bodies to
Sensory neurons
Ventral root
White Matter
contains axons exiting the CNS
Columns (funiculi)
White Matter
- named by origin and destination
- all are paired (left/right)
- columns contain tracts with similar destinations/functions
- most all cross over in the cord
