The Brain Flashcards
Human Brain size
- weight
- 2 directional terms
-Weight; 1.35-1.4kg
Directional terms: Rostral (toward nose)
-Caudal (toward tail)
4 major regions of human brain
- Cerebrum
- Diencephalon
- Brainstem (midbrain, pons, medulla oblongata)
- Cerebellum
Organisation of Neural Tissue areas in brain (2)
- Gray Matter
- houses motor neuron & interneuron cell bodies, dendrites, telodendria, unmyelinated axons
- forms cortex which overs surface of most of adult brain
- forms discrete internal clusters called cerebral nuclei
- White matter:
- made up of myelinated axons
- lies deep to gray matter of the cortex
Support & Protection of brain
- 4 roles of Cranial meninges
- 3 layers
- Cranial Meninges are CT layers that;
- separate soft tissue of brain from bones of cranium
- enclose & protect blood vessels that supply brain
- contain & circulate cerebrospinal fluid
- form some of veins that drain blood from brain
Layers; dura mater, arachnoid mater, pia mater
Cranial meninges; layers (3)
- Dura Mater
- External tough dense irregular CT
- 2 layers of fibrous layers which separate to form large blood fills spaces (DURAL VENOUS SINUSES - is where deoxygenated blood leaves) connects to jugular vein to drain blood from the head - Arachnoid Mater
- spider web structure - collagen & elastic fibres
- subarachnoid space between AM and PM
- potential space between AM & DM = subdural space where subdural hematomas form - Pia Mater
- innermost cranial meningeal layer
- Thin areolar tissue, highly vascularised and adheres to the brain
- directly in contact w/ brain -> follows grooves
Brain Ventricles
-Ventricles = cavities or expansions w/in brain that are continuous w/ one another & central canal of spinal cord
-all contain cerebral spinal fluid
Are 4 ventricles;
-2 lateral ventricles, one in each hemispheres of cerebrum (separated by thin septum pellucidum)
-third ventricle in diencephalon
-fourth ventricle b/w pons and cerebellum
Cranial Dural Septa
-Dural mater creates divisions w/in brain -> creates different divisions
Cerebrospinal Fluid
- what it is
- 3 functions
-is a clear, colourless liquid that circulates in the ventricles & subarachnoid space
FUNCTIONS
-Buoyancy: takes 95% of brain’s weight (brain floats in CSF)
-Protection: provides liquid cushion from sudden movements
-Environmental stability: transports nutrients & removes waste from brain (involved in homeostatic properties)
Blood-Brain Barrier
- what it does
- cells that contribute to BBB
- 3 locations where it is missing or reduced & why
-strictly regulates what substances can enter the interstitial fluids of brain
-Capillary endothelial cells and astrocyte perivascular feet contribute to BBB
Missing or reduced in 3 locations;
-Choroid plexus
-Hypothalamus
-pineal gland
- Choroid plexus - must be permeable to produce CSF
- other 2 = produce hormones that must have ready access to bloodstream
Cerebrum
-what it does
- is location of conscious thought processes & origin of intellectual functions
- large no. of neurons that needed for complex analytical & integrative functions
- left & right hemispheres
- largest part of brain
Cerebrum
- what formed from
- outer layer & internal layer (what matter)
- cerebral nuclei
- gyri and sulci and fissures
- Formed from telencephalon
- outer layer = cerebral cortex & is gray matter
- internal layer = white matter
- cerebral nuclei = deep to white matter are discrete regions of gray matter
- surface of cerebrum folds into elevated ridges called gyri (contours of brain)
- Adjacent gyri separated by shallow sulci or deeper grooves called fissures
Cerebral Hemispheres
- how many & how separated
- Corpus callosum
- cerebrum composed of 2 halves (left & right cerebral hemispheres)
- divided by a longitudinal fissure along midsaggital plane
- hemispheres separated from each other except at few locations where bundles of axons called tracts form white matter regions that allow comm. b/w them
- Corpus Callosum: largest tract & main tract that connects the two hemispheres
Lobes of Cerebrum (5 distinct lobes)
- Frontal lobe: concentration, communication & personality
- Parietal lobe: sensor, texture and shape
- Temporal lobe: hearing and smell
- Occipital lobe: processing visual information and visual memories
- Insula: memory and taste
Frontal lobe (Cerebrum)
- location
- boundaries
- precentral gyrus
- what involved in
- Located deep to frontal bone
- ends posteriorly at central sulcus - inferior border marked by lateral sulcus
- Precentral gyrus is mass of nervous tissue in frontal lobe immediately anterior to central sulcus
- involved w/ voluntary motor function, conc., verbal comm, decision making, planning & personality
Parietal Lobe (Cerebrum)
- Where it is
- boundaries
- what involved with
- Forms superoposterior part of each hemisphere (underlies parietal bone)
- Terminates anteriorly at central sulcus, laterally at lateral sulcus & posteriorly at parietao-occipital sulcus
- postcentral gyrus is mass of nervous tissue in parietal lobe immediately posterior to central sulcus
*involved w/ general sensory functions
Temporal lobe (Cerebrum)
- where located
- what involved in
- Located inferior to lateral sulcus underlying temporal bone
- Involved w/ hearing and smell
Occipital lobe (Cerebrum)
- where located
- what it does
- Located in posterior region of each hemisphere underlying occipital bone
- Processes incoming visual information
- Stores visual memories
Insula (Cerebrum)
- where located
- what involved in
- located deep to lateral sulcus
- involved in memory & interpretation of taste
Functional areas of cerebrum (3 areas)
-what they do
- Motor areas: control voluntary motor functions
- Sensory areas: provide conscious awareness of sensation
- Association areas: integrate and store information
Motor Areas (3)
- Primary Motor Cortex (somatic motor area)
- controls voluntary skeletal muscle activity; located within precentral gyrus (anterior to central sulcus) - Motor speech area (Broca’s area)
- controls muscular movements necessary for vocalization - Frontal eye field
- controls and regulates eye movements and binocular vision
Diencephalon - 3 components
-what they do
-Components include;
Epithalamus: pineal gland involved in circadian rhythms
Thalamus: filters background info before relaying it to cerebrum
Hypothalamus: controls ANS & endocrine system; regulates body temp, emotional behaviour, food intake, water intake & sleep
Functions of Hypothalamus (7)
- Master control of ANS
- Master control of endocrine system
- Regulation of body temp
- Control of emotional behaviour
- control of food intake
- control of water intake
- regulation of sleep-wake (circardian) rhythms
Brainstem
-what it does
- connects forebrain & cerebellum to spinal cord
- is bidirectional passageway for all tracts extending between cerebrum & spinal cord
- Contains many autonomic centers and refex centers
- houses nuclei of many of cranial nerves
Brainstem: 3 regions
- Mesencephaon: mid brain
- Pons: Sensory & motor tracts connect brain to spinal cord
- Medulla Oblongata: vital autonomic nuclei for regulating functions relating to;
- cardiac centre (heart rate)
- vasomotor centre (blood pressure)
- respiratory centre (respiratory rate)
- others (coughing, sneezing, swallowing, gagging)
Cerebellum
-folia
- 2nd largest part of brain
- has complex, highly convoluted surface covered by layer of cerebellar cortex w/ folds called folia
- left and right cerebellar hemispheres
- each hemisphere = 2 lobes (anterior & posterior - separated by primary fissure)
Cerebellum - 3 regions
- An outer gray matter layer of cortex
- Internal region of white matter, called arbor vitae
- Cerebellar nuclei in deepest layer
Cerebellar Functions - 3
- Coordinates and fine-tunes skeletal muscle movements and ensures that skeletal muscle contraction follows correct pattern leading to smooth, coordinated movement
- stores memories of previously learned movement patterns
- receives proprioceptive info from muscles and joints - uses this info to regulate body’s position
Limbic system
- structure
- what it affects
- structures of limbic system form a ring around diencephalon
- composed of multiple cerebral and diencephalic structures that collectively process and experience emotions
- affects memory formation through integration of past memories of physical sensations w/ emotional states
Cranial nerves
- 12 pairs
- numbered w/ roman numerals by their position (beginning w/ most anteriorly placed nerve)
- names generally related to function
