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Flashcards in the central nervous system Deck (30):
1

what is the skull / vertebrae

- outermost protective layer
- spinal cord runs down vertebral canal

2

what is the meninges

- cover entire CNS, connective tissue (membranes)
- dura mater: tough, fibrous, connective, external, two layers, periosteal (attaches to periosteum of skull), meningeal (true external covering of brain), fused but in some spaces sinuses occur (space, collect venous blood from brain)
- arachnoid: loose meshwork of fibres, contains BV
- pia mater: delicate, contains BV, directly attached to surface of brain

3

what is cerebrospinal fluid

- occupies space in middle layer of meninges brain cavities, brain ventricles and centre of spinal cord
- watery, clear, some cells, glucose, proteins (less than plasma), urea, lactic acid, ions, WBC's, salt, constant V
- support (brain floats in it), protection (shock absorber, cushioning), transport nutrients / wastes (nourish brain, carry signals, removes waste)
- formed by blood, circulates CNS and re-enters blood

4

what is the blood brain barrier (BBB)

- continuous endothelium (attached via tight junctions) of capillary walls
- maintain stable environment of brain, selective barrier, separates neurons from some blood borne substances
- no large molecules of toxic substances, protective mechanism to protect the brain from toxins or parasites
- pharmacology is developing treatments that can cross BBB

5

what are the ventricles of the brain

- 4 ventricles
- connected to one another and to central canal of spinal cord, lined by ependymal cells, contain CSF
- 1-2: c-shaped, in cerebral hemispheres, anterior / inferior horns, septum pellucidum (double membrane)
- 3: in the diencephalon
- 4: in the hind brain

6

what are the functional regions of the brain

- cerebral hemispheres
- diencephalon
- brain stem
- cerebellum

7

describe the structure of the cerebral hemispheres

- cerebrum: largest division, cerebrum (gray), white mater (myelinated), basal ganglia (grey, deep), 2 hemispheres, 5 lobes
- gyri: elevated ridges (pre / post central gyrus)
- sulci: small grooves, divide gyra, central sulcus divides frontal and parietal lobes
- fissure: deep grooves, divide large regions / lobes, transverse (occipital / cerebellum), longitudinal (left / right hemisphere), lateral / sylvian (temporal / parietal + frontal)

8

name the lobes of the brain

- frontal, parietal, occipital, insula (deep, under temporal)

9

what is the cerebral cortex

- gray mater outside, cell bodies, dendrites, glia and BV, convolutions = big SA
- conscious mind, aware of ourselves, communication, memory, understanding
- motor (impulses to muscles voluntary movement)
- association (interpret / integrate info, intellectual / emotional responses)
- sensory (receive / process impulses, conscious awareness of sensation)
- contralateral

10

what is the fontal lobe

- primary motor cortex (pre-central gyrus), conscious control of precise, skilled voluntary movement
- motor homunculi upside down caricatures, motor innervation, precise motor control (face, tongue, hands) = disproportionately large area in brain
- pre motor cortex: anterior, learned, repetitious / patterned motor skills
- contralateral

11

what is the parietal lobe

- primary somatosensory cortex (post central gyrus), sensory info from skin, skeletal, joints, capable of spatial discrimination (without sight)
- damage = could not recognise objects without looking at them

12

what is the occipital lobe

- processing, integrating, interpretation of vision and visual stimuli
- primary visual cortex: input from retina via optic nerve, does not give meaning (role of cerebellum)
- visual association area: use past visual experiences to interpret stimuli

13

what is the temporal lobe

- hearing, language comprehension, memory, information retrieval
- primary auditory cortex: interprets pitch, loudness, location
- auditory association area: perception of sound stimulus, whether a scream, thunder, music etc (uses memories)
- wernickes area: top back of temporal, language comprehension, give meaning to what we read / what people say
- damage: hear with no meaning

14

what is an ischemic stroke

- blood circulation blocked, brain tissue dies
- blockage of cerebral artery by blood clot (thrombotic)
- blockage of BV, clot moves and eventually causes blockage to brain (embolic)
- hemiplegia, sensory / speed deficits, paralysis loss of balance, vertigo, vision loss, speech impairment
- treat with drugs, stent (remove clot) if quickly administered (4.5 hours after)

15

what is the diencephalon

- least developed part of brain, eldest region
- thalamus: gateway to cerebral cortex (sensory info), sorts, edits, relays info, mediates sensation, motor actives, cortical arousal, learning, memory, pleasant / unpleasant stimuli
- hypothalamus: anterior, autonomic control, emotional / limbic response, regulation
- epithalamus: posterior, pineal gland (melatonin = sleep)

16

describe the hypothalamus in detail

- autonomic control centre: regulates visceral functions, BP, rate / force of HB, digestive tract motility, breathing rate / depth
- emotional response: ANS, perception of pleasure, fear, rage, biological rhythm and drives
- regulates: body temp (sweating / shivering), food intake (sugar / glucose / AA), water balance (osmotic pressure, thirst, kidneys)
- controls: release of hormones from anterior pituitary gland (directly attached)
- produces: ADH (reabsorption of water) and O (oxytocin, contraction of uterus, breastfeeding)

17

what is the brainstem made up of

- midbrain
- pons
- medulla oblongata

18

what is the mid brain

- between diencephalon and pons, posterior, cerebral aqueduct (connects 3-4 ventricles)
- nuclei controls CN3-4 (external muscles of eye)
- colliculi (superior visual and inferior hearing reflexes)
- substantia nigra (dark = melatonin, dopamine, damage = Parkinson's)
- red nuclei: high capillaries and iron cells, involuntary movement

19

what is the pons

- bridge
- connect higher brain centre and spinal cord

20

what is the medulla oblongata

- contains choroid plexus (produces CSF) of 4th ventricle
- just above spinal cord medulla, junction fibres cross over (decussation of pyramids = contralateral control of body)
- cranial nerves: 8 (equilibrium), 10 (parasympathetic) and 12 (tongue movement)
- autonomic reflex centre
- cardiovascular centre: activity of heart, contraction
- respiratory centre: breathing process, damage = death

21

what is the cerebellum

- word association and puzzle solving - coordination of fine contractions of muscles (smooth movements)
- maintenance of posture and balance (receives from inner ear, unconsciously)
- cerebellar ataxia (lack of coordination, clumsy speech, movement of limbs, gait), caused by (bleeding, ischemic stroke, multiple sclerosis, cancer, alcoholism)

22

describe communication within the cerebral white mater

- contains axons, communicating tracts that connect gray matter, 3 arrangements
- projection tracts: extend vertically, cerebral cortex to spinal cord
- commissural tracts: cross cerebral hemispheres, extend horizontally
- association tracts: connect different regions within same hemisphere

23

what are corticospinal tracts

- rapid, direct mechanism for controlling skeletal muscles
1. originate in pre central gyrus (frontal lobe)
2. pyramidal neuron = UMN form corticospinal tract (CCST)
4. exit spinal cord via anterior root
5. 10% axons dont decussate at medulla (anterior)
6. 90% axons decussate and form CST tract (lateral)
7. synapse at anterior grey horn of spinal cord, form LMN
8. reach skeletal muscles

24

what is the dorsal column medial lemniscal pathway

- detect discriminative touch and body position
- sensory nerve endings in skin relay sensory neurons
- cuneatus: afferent impulses, upper limbs / trunk, neck
- gracilis: impulses from lower limbs, inferior body trunk
- pass through thalamus, relayed to ventro postero lateral nucleus
- reach dorsal root ganglion and fibres run in dorsal column (posterior funiculi)

25

what is the spinal cord

- begins at foramen magnum ends at conus medullaris
- two way communication to and from brain
- spinal reflex centres
- protection = vertebral column / meninges
- cervical, thoracic, lumbar, sacral, coccygeal
- cervical and lumbar enlargements = supplies upper / lower limbs

26

describe the cross section of the spinal cord

- anterior median fissure and posterior median sulcus
- gray: inner, surrounds central canal, butterfly, cell bodies, 3 horns (posterior dorsal, anterior ventral and lateral = only in T and L regions),
- white: 3 columns (funiculi), dorsal (posterior), ventral (anterior) and lateral (lateral) = divided into sensory / motor tracts

27

what are 2 examples of spinal cord trauma (paralysis)

- flaccid: ventral root / horn damage, impulses do not reach muscles, no voluntary / involuntary, smaller muscles (atrophy)
- spastic: damage to UMN of primary motor cortex, spinal neurons in tact, no voluntary movement, spinal reflexes occur, shorter muscles

28

what is SCI

- spinal cord injury (acute / chronic)
- ASIA guidelines = motor control vs sensory assessment
- little hope in terms of treatment

29

what is poliomyelitis

- infection of polio virus, contact with faeces / contaminated water, worldwide epidemic
- destroys ventral horn motor neurons, no connection between spinal cord and muscles (flaccid paralysis)
- incubation period = 5-35 days

30

what is ALS

- amyotrophic lateral sclerosis
- 3-8 per 100000, risk increase with age (56-63)
- asymmetric, destroys ventral horn and pyramidal tract, limb weakness = greater in upper extremities
- glutamate excitotoxicity produced in CNS increase in conc. = kill neurons
- free radical toxicity or mitochondrial dysfunction