Interneurons in SC
Interneurons in the brain
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Brain and Cranial Nerves
• a few brain directions• brain anatomy• cranial meninges• ventricles and flow of CSF• dural sinuses and venous flow• head injuries• Brainstem anatomy & function• cerebellar anatomy & function• cerebrum – anatomy & function
• lobes• sensory & motor cortex• limbic system• Blood flow• brain damage• cranial nerves (II, XII, V)
rostral caudal
cerebrum
cerebellumdiencephalon
Brain stem
dorsal
ventral
Anatomical directions and parts of the brain
Posterior = dorsalAnterior = ventral
Corpus callosum
Thalamus Hypothalamus
Diencephalon
Brainstem
Midbrain
Pons
Medulla oblongata
Cerebral cortex
rostral
caudal
cortex
diencephalon
S = skinC = connective tissue **A = aponeurosisL = loose connective tissueP = periosteum
Dura mater• periosteal layer• meningeal layer• sinus (venous blood)
ArachnoidSubarachnoid space (CSF)Arachnoid villusPia mater
anastomosis
Meningitis = viral, bacterial, fungal infection of blood and CSF Viral >> bacterial but bacterial is a medical emergencySymptoms: fever, headache, nausea, vomiting, light sensitivity….People living in close quarters (ie dorms) should get vaccination
Lateralventricles
Central canal
Fourthventricle
Thirdventricle
Cerebral aqueduct Lateral
ventricle
ThirdventricleCerebralaqueduct
Lateralaperture
Fourthventricle
Medianaperture
Ventricles are filled with CSF
Choroid plexus• Ependymal cells• choroid plexus (capillary bed)
Lateral ventricle
Third ventricle
Fourth ventricle
Cerebral aqueduct
1
23
4
56
7
8
Subarachnoid space
Central canal of spinal cord
Arachnoid granulation
“dirty” CSF is resorbed into the venous blood at the sinusesthrough the arachnoid villi
Dural sinuses drain into the:• jugular veins•Vertebral plexus, cavernous sinus, pterygopalatine plexus• scalp infection• occlusion of sinuses• cancer metastasis
Head injuries
Epidural hematoma• arterial bleeding• blow to head• concussion• drowsiness & coma
Subarachnoid hematoma• usually arterial• 70% due to aneurysm• rest are due to trauma• headache, stiff neck & loss of consciousness• blood in CSF
Subdural hematoma• usually venous at cerebral vein – sinus junction• creates space at dural- arachnoid junction• blow to head that jerks the brain (elderly)• trauma often forgotten
Foramen magnum
Loss of consciousnessSeizuresHeadachesDisorientationNausea and/or vomitingWeaknessSlurred speechPersonality changes
Brain stem = diencephalon, midbrain, pons, medulla oblongata
Medulla: controls respiration, heart rate and blood pressure!
Anterior view Dorsolateral view
thalamus
Pons
colliculi
Cerebral peduncle
Medullaoblongata
Brainstem anatomy and function
Thalamus: relay stationfor sensory input to the cortex
Hypothalamus: controls ANS & endocrine system
Diencephalon
T
T
Cerebellar function• coordinates joint movements• coordinates eye – motor movements• aids in planning, learning & storing motor movements• maintains muscle tone and posture• adjusts muscle performance during movement• damage to cerebellum
pons
ALPL
pons
Middle cerebellar peduncle
Damage to cerebellum
• clumsy, awkward gait• difficulty initiating movement• over or undershoot target• problems with coordination• Purkinje cells and alcohol
Fissure > sulcus
• Frontal lobe – cognition and “higher” mental processes, motor• Parietal lobe – receiving & interpreting general sensory & taste• Occipital lobe – visual information• Temporal lobe – hearing, smell, learning, memory, emotions• Insula – taste, hearing, visceral sensory info
Central sulcus
Lateral sulcus
Longitudinal fissure
Visual association area
Primary visual area
Primary somatosensory areaPostcentral gyrus
Somatosensory associationarea
Motor associationarea
Primary motor areaPrecentral gyrus
Broca area: planning speechgenerates motor program for speech Wernicke area: recognition of spoken &
written language
Cuneate fasciculusCorticospinal tract
Primary Sensory & Motor
Areas
Precentral GyrusPrimary motor
Postcentral GyrusPrimary somatosensory
Fig. 15.19(TE Art)rostral
Postcentralgyrus
Frontallobe
Centralsulcus
Primary somatosensory area
Sensory homunculus: body part inproportion to cortical area
Fig. 15.20(TE Art)rostral
Precentral gyrus
Centralsulcus
Vocalizatioin
Primary Motor Area
Motor homunculus: body part inproportion to cortical area
Basal ganglia• help in planning and executing movement• degeneration of BG with Parkinson disease
Prefrontal cortex
Abstract thought, judgement, foresight, responsibilitySense of socially responsible behavior, motivation
Limbic SystemHippocampus, amygdala, tracts, cingulate gyrus, thalamus, hypothalamus, forebrain
• Emotional brain• visceral responses to sensory input• Short term memories into long term memories
thalamus
hypothalamus
hippocampus
amygdala
forebrain
Cingulate gyrus
taste
smell
Prefrontalcortex
hearing
vision
touch
Alzheimer’s
Anterior cerebral
Middle cerebral
Posterior cerebral
vertebral
Internal carotid
Blood supply to the brain - Circle of Willis
Arteriole anastamosis
basilar
Brain damage
How? Where?• head trauma• CVA or stroke• cancer• disease• cardiac arrest• alcohol poisoning • drugs
Coma: profound state of unconsciousness (usually eyes closed, no sleep/wake cycles)alive but unable to respond to environment (some reflexive activity)can be irreversible depending, maybe still be breathing on ownhave electrical activitycan lead to PVS
Persistent Vegetative State: severe brain damage – coma – no detectable awarenessunconscious, unresponsive, unaware (can have arousal & sleep/wake cycles)exhibit some “spontaneous” behaviors (may open & close eyes, grind teeth..)usually irreversible
Brain death: complete & irreversible cessation of brain activityno electrical activity – no CN reflexesincludes cortex & brainstemdefinition has changed (anencephaly)
Terry Shiavo
Cranial nerves
Peripheral nerves that leave at the base of the brain (instead of the spinal cord)Carry sensory & motor information to head, neck and visceraThere are 12 pair of cranial nerves I-XII (each has a name and number)Can use cranial nerves to test brain function
Cranial Nerve II – Optic NerveAn example of a purely sensory cranial nerve
CN II – receives sensory information from the retina relays info to occipital lobe
Cranial Nerve XII – Hypoglossal NerveAn example of a purely motor cranial nerve
CN XII – motor information to tongue muscles responsible for swallowing, speech, chewing
Cranial Nerve V – Trigeminal NerveAn example of a mixed cranial nerve
CN V – carries sensory information from face, teeth, gums, tongue cornea, sinuses, dura mater, test using the corneal blink reflex
CN V – motor to muscles of mastication and tensor tympani
Cranial nerves
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