Brain Description. Brain weighs 3 to 3.5 poundsMajor portions -- brainstem, cerebrum, and cerebellumcerebrum is 83% of brain volume___________________ contains 50% of the neurons. Brain. Longitudinal fissure separates 2 cerebral hemispheres.. Meninges. Dura materouter periosteal layerinner meningeal layerdural venous sinusesdural septafalx cerebri, falx cerebelli and tentorium cerebellidural hemorrhages Arachnoid materPia mater .
An Image/Link below is provided (as is) to download presentation
Download Policy: Content on the Website is provided to you AS IS for your information and personal use only and may not be sold or licensed nor shared on other sites. SlideServe reserves the right to change this policy at anytime.
While downloading, If for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Brain Meninges, ventricles, cerebrospinal fluid & blood supply Hindbrain and midbrain Forebrain Limbic system Brain Description Brain weighs 3 to 3.5 pounds Major portions -- brainstem, cerebrum, and cerebellum cerebrum is 83% of brain volume ___________________ contains 50% of the neurons Brain
Longitudinal fissure separates 2 cerebral hemispheres.
Meninges Dura mater outer periosteal layer inner meningeal layer dural venous sinuses dural septa falx cerebri, falx cerebelli and tentorium cerebelli dural hemorrhages Arachnoid mater Pia mater Ventricles and Cerebrospinal Fluid Internal chambers within the CNS lateral ventricles third ventricle cerebral aqueduct fourth ventricle central canal of spinal cord Lined with ependymal cells and contains ______ Cerebrospinal Fluid Clear liquid fills ventricles and canals & bathes its external surface ________________________ Brain produces & absorbs about 500 ml/day filtration of blood through choroid plexus has more Na+ & Cl- but less K+,Ca+2, and proteins than plasma Functions (3) Buoyancy, protection, and chemical stability Escapes from 4th ventricle to subarachnoid space Drains from _________________________ into venous sinus Flow of Cerebrospinal Fluid Blood-Brain and Blood-CSF Barriers BBB - endothelium & perivascular astrocyte feet permeable to lipid-soluble materials (alcohol, O2, CO2, caffeine, nicotine and anesthetics) administer drugs through nasal sprays Circumventricular organs – breeches in the system Hypothalamus, Post. pituitary, Pineal, & Choroid plexus monitoring of glucose, pH, osmolarity & others may allow route for HIV virus to invade the brain Blood-CSF barrier - choroid plexus is ependymal cells joined by _________________________ Medulla Oblongata 3 cm long Ascending & descending tracts CN nuclei (VIII, IX, X, XI, XII) Nuclei for somatic and visceral sensory; somatic cerebellar relay Cardiac, vasomotor, & respiratory centers Reflex centers for coughing, sneezing, gagging, swallowing, vomiting, salivation, sweating, and movements of the tongue and head Pons Bulge in the brainstem, rostral to the medulla Ascending sensory tracts Descending motor tracts Pathways in & out of cerebellum - peduncles Nuclei concerned with sleep, hearing, balance, taste, eye movements, facial expression, facial sensation, respiration, swallowing, bladder control & posture cranial nerves V, VI, VII, and VIII Cerebellum Connected to brainstem by cerebellar peduncles White matter _____________________ Folia? Sits atop the 4th ventricle Output from Cerebellum Smoothes muscle contractions, maintains muscle tone & posture, coordinates motions of different joints, aids in learning motor skills & coordinates eye movements Midbrain ____________________ Mes. aqueduct CN III and IV Cerebral peduncles hold corticospinal tract Tegmentum connects to cerebellum & helps control fine movements through red nucleus Substantia nigra sends inhibitory signals to basal nuclei & thalamus Superior & Inferior Colliculus Tectum (4 nuclei) called corpora quadrigemina superior colliculus inferior colliculus Reticular Formation Clusters of gray matter scattered throughout pons, midbrain & medulla Regulate balance & posture relaying information from eyes & ears to cerebellum gaze centers allow you to track moving object Includes cardiac & vasomotor centers Analgesic pathways Regulates sleep, conscious attention, fatigue Thalamus Oval mass of gray matter in center of ________________ Receives nearly all sensory information on its way to cerebral cortex integrate & directs information to appropriate areas Interconnected to limbic system so involved in emotional & memory functions Hypothalamus Walls & floor of 3rd ventricle Functions hormone secretion & pituitary autonomic NS control thermoregulation food & water intake sleep & circadian rhythms memory (mammillary bodies) emotional behavior Epithalamus (Pineal Gland)
In fish, amphibians, and reptiles monitors day and season length
Endocrine function in mammals, secreting melatonin
Seasonal sexual cycles
Humans - circadian
Cerebrum -- Gross Anatomy Cerebral cortex is 3mm layer of gray matter with extensive folds to increase surface area ---- divided into lobes Functions of Cerebrum Lobes Frontal contains voluntary motor functions and areas for planning, mood, smell and social judgement Parietal contains areas for sensory reception & integration of sensory information Occipital is visual center of brain Temporal contains areas for hearing, smell, learning, memory, emotional behavior Association Areas
Association areas interpret information
Somesthetic association area limb position, location of touch or pain, and shape, weight & texture of an object Visual association area identify the things we see Auditory association area remember the name of music or identify a person by voice Motor association area Tracts of Cerebral White Matter Basal Nuclei Masses of gray matter deep to cerebral cortex Receive input from substantia nigra & motor cortex & send signals back to these regions Involved in motor control & inhibition of tremors LimbicSystem Loop of cortical structures surrounding deep brain amygdala, hippocampus, fornix & cingulate gyrus Amydala important in ________________ and ____________________________ in memory Somesthetic Sensation
Somatosensory area is postcentral gyrus
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.
Ditto for Motor Homunculus
Motor Control Intention to contract a muscle begins in motor association (premotor) area of frontal lobes Precentral gyrus (primary motor area) processes that order by sending signals to the spinal cord upper motor neurons to contralateral muscles Motor homunculus is proportional to number of muscle motor units in a region