Neurological system disorders (ch 7) Flashcards
Lateral central fissure (aka_____) separates _____ lobe from _____ and _____ lobes.
Lateral central fissure (aka SYLVIAN FISSURE) separates TEMPORAL lobe from FRONTAL and PARIETAL lobes.
Longitudinal cerebral fissure separates ____________.
THE TWO HEMISPHERES.
Central sulcus separates ______ lobe from the ______ lobe
Central sulcus separates FRONTAL lobe from the PARIETAL lobe.
Frontal lobe: precentral gyrus contains….
primary motor cortex for voluntary muscle activation
Frontal lobe: prefrontal cortex controls…
emotions, judgements, higher order cognitive functions (ideations and abstraction)
Frontal lobe: premotor cortex controls…
motor aspects of speech (related to planning of movements including Broca’s area)
Parietal lobe: poscentral gyrus is…
primary sensory cortex for integration of sensation
Parietal lobe also contains…
receptive fibers conveying touch, proprioceptive, pain and temperature sensations from opposite side of body
Temporal lobe: which cortexes are here??
Primary auditory (receives/processes auditory stimuli);
associative auditory cortex (processis auditory stimuli);
Wernicke’s area (language comprehension).
Occipital lobe contains 2 cortexes…?
Primary visual cortex (recieves/processes visual stimuli);
Visual association cortex (processes visual stimuli).
Insula is located where and does what?
deep within lateral sulcus; associated with visceral functions
The limbic systems consists of what? and has what functions?
consists of limbic lobe (cingulate, parahippocampal, and subcallosal gyri), hippocampal formation, amygdaloid nucleus, hypothalamus, anterior nucleus of thalamus.
Oldest part of the brain- concerned with instincts and emotions contributing to preservation of individual. Functions include feeding, aggression, emotions, endocrine aspects of sexual response, and long-term memory formation.
What is white matter?
myelinated nerve fibers located centrally.
What are the three kinds of white matter?
- transverse fibers: interconnect the 2 hemispheres (including corpus callosum (largest), anterior commissure, and hippocampal commissure.
- projection fibers: connect cerebral hemispheres with other portions of the brain and spinal cord.
- Association fibers: connect different portions of the cerebral hemispheres (within the same hemisphere), allowing cortex to function as an integrated whole.
What/where is the basal ganglia?
Masses of gray matter deep within the cerebral hemispheres, including corpus striatum, amygdaloid nucleus, and claustrum. (Lenticular nuclei= putamen and globus pallidus).
What does basal ganglia do?
forms an associated motor system (extrapyramidal system) with other nuclei in the subthalamus and midbrain. Has numerous fiber interconnections…. caudate loop works with association cortex in motor planning; putamen loop work with sensorimotor cortex to scale/adjust movements.
What are three parts of thalamus and what do they do?
- sensory nuclei: integrate/relay sensory info from body, face, retina, coclea, and taste receptors to cerebral cortex and subcortial regions; smell is the exception.
- motor nuclei: relay motor info from cerebellum and globus pallidus to precentral motor cortex.
- other nuclei: assis in integration of visceral and somatic functions
What does subthalamus do?
involve din control of several functional pathways for sensory, motor, and reticular function.
What does hypothalamus do?
- integrates and controls functions of the autonomic nervous system and neuroendocrine system;
- maintains body homeostasis (regulates temp, eating, water balance, anterior pituitary function/sexual behavior, and emotion).
Epithalamus is made of 2 things and does what?
- Habenular nuclei: integrates olfactory, visceral, and somatic afferent pathways.
- Pineal gland: secretes hormones that influence the pituitary gland and several other organs; influences circadian rhythm.
Brainstem is made of 3 things:
midbrain, pons, and medulla oblongata
Midbrain: tegmentum contains what and does what?
- contains all ascending tracts and some descending tracts
- red nucleus receives fibers from cerebellum and is origin for rubrospinal tract (important for coordination); contains cranial nerve nuclei (oculomotor and trochlear).
Midbrain: substantia nigra
a large motor nucleus connecting with basal ganglia and cortex; is important in motor control and muscle tone.
Midbrain: superior colliculus
important relay station for visual and visual reflexes; inferior colliculus is important relay station for hearing and auditory reflexes.
Pons! Where and what?
- Connects medulla oblongata to the midbrain, allowing passage if important ascending and descending tracts.
- acts as bridge to cerebellum
- midline raphe nuclei project widely and are improtant for modulating pain and controlling arousal
- tegmentum contains cranial nerve nuclei of abducens, trigeminal, facial, vestibulocochlear.
Medulla oblongata! where and what?
- connects spinal cord with pons; contains relay nuclei of dorsal columns; fibers cross to give rise to medial lemniscus.
- inferior cerebellar peduncle relays dorsal spinocerebellar tract to cerebellum.
- corticospinal tracts decussate in pyramids.
- medial longitudinal fasciculus arises from vestibular nuclei and extends throughout brain stem and upper cervical spinal cord; important for control of head mvmts and gaze stabilization.
- cranial nerve nuclei: hypoglossal, dorsal nucleus of vagus, and vestibulocochlear
- contains centers for vital functions: cardiac, respiratory, and vasomotor centers.
Cerebellum is located where?
behind dorsal pons and medulla in posterior fossa.
3 parts of the cerebellum and what they do:
- archicerebellum (flocculonodular lobe) connects with vestibular system and is concerned with equilibrium and regulation of muscle tone.
- paleocerebellum (anterior lobes and vermis) recieves input from proprioceptive pathways and is concerned with modifying muscle tone and synergistic actions of muscles; imprtant in maintenance of posture and voluntary mvmt control.
- Neocerebellum (middle lobes) receives input from cortiopontocerebellar tracts and olivocerebellar fibers; is concerned with smooth coordination of voluntary mvmts; ensures accurate force, direction, and degree of mvmt.
Segments of the spinal cord:
8 cervical 12 thoracic 5 lumbar 5 sacral and a few coccygeal segments
Dorsal column/medial lemniscus tract
convey sensations of proprioception, vibration, and tactile discrimination.
- divided into fasciculus cuneatus (UE tracts, laterally located) and fasciculus gracilis (LE tracts, medially located)
- neurons ascend to medulla where fibers cross (lemniscal decussation) to form medial lemniscus, ascend to thalamus and then to somatosensory cortex
Spinothalamic tracts:
convey sensations of pain and temperature and crude touch; tracts ascend 1 or 2 ipsilateral spinal cord segments, synapse and cross in spinal cord to opposite side and ascend in ventrolateral spinothalamic system.
Spinocerebellar tracts:
convey proprioception info from muscle spindles, Golgi tendon organs, touch, and pressure receptors to cerebellum for control of voluntary movements; dorsal spinocerebellar tract ascends to ipsilateral inferior cerebellar peduncle.
Spinoreticular tracts:
convey deep and chronic pain to reticular formation of brain stem via diffuse, polysynaptic pathways
Corticospinal tracts:
- descending; important for voluntary motor control
- arise from primary motor cortex, descend in brain stem, cross in medulla, via lateral cortiospinal tract to ventral gray matter; 10% of fibers do not cross and travel in anterior cortiospinal tract to cervical and upper thoracic segments.
Vestibulospinal tracts:
- descending; important for control of muscle tone, antigravity muscles, and postural reflexes.
- arise from vestibular nucleus and descend to spinal cord in lateral and medial vestibulospinal tracts.
Rubrospinal tract:
- descending; assists in motor function
- arises in contralateral red nucleus and descends n lateral white columns to spinal gray.
Reticulospinal system:
- descending; modifies transmission of sensation, especially pain; influences gamma motor neurons and spinal reflexes.
- arises in the reticular formation of the brain stem and descends in both ventral and lateral columns, terminates both on dorsal gray and ventral gray.
Tectospinal tract:
- descending; assists in head turning responses in response to visual stimuli.
- arises from superior colliculus and descends to ventral gray.
What does the autonomic nervous system do?
innervations of involuntary structures (smooth muscle, heart, glands; helps maintain homeostasis).
What are the 2 divisions of autonomic nervous system and what do they do?
- Sympathetic (thoracolumbar)- fight or flight, emergency, raises heart rate and BP, contstricts peripheral BVs and redistributes blood; inhibits peristalsis.
- Parasympathetic (craniosacral)- conserves and restores homeostasis; slows heart rate and reduces BP, increases peristalsis and glandular activity.
What are the autonomic plexuses (name them)?
cardiac, pulmonary, celiac (solar), hypogastric, pelvic
What are the 3 meninges of the brain (and name them)?
3 membranes that envelop the brain!
- Dura mater (outer, tough, fibrous membrane attached to inner surface of cranium)
- arachnoid (delicate, vascular membrane)
- 5… then subarachnoid space (formed by arachnoid and pia mater, contains CSF and cisterns, major arteries).
- Pia mater (thin, vascular membrane that covers the brain surface; forms tela choroidea of ventricles.)
Ventricles of brain- there are 4!
Filled with CSF and communicate with each other and with spinal cord canal….
- Lateral ventricles: large, irregularly shaped, with anterior posterior and inferior horns; communicates with third ventricle through foramen on Monro.
- Third ventricle: located posterior and deep b/w the two thalami; cerebral aqueduct communicates third with fourth ventricle.
- Fourth ventricle: pyramid-shaped cavity located in pons and medulla
What does cerebrospinal fluid do?
provides mechanical support (cushions brain), controls brain excitability by regulating ionic composition, aids in exchange of nutrients and waste products.
- produced in chorioid plexuses in ventricles.
- normal pressure 70-180 mm/H2O.
- total volume: 125-150 cc.
What is the blood-brain barrier
the selective restriction of blood borne substances from entering the CNS; associated with capillary enothelial cells.
Blood supply to the brain: brain is 2% of body weight with a circulation of 18% of total blood volume. Just a fun fact
:)
What is the carotid system of blood supply?
internal carotid arteries arise off of common carotids and branch to form anterior and middle cerebral arteries;
supplies a large area of brain and many deep structures.
What is the vertebrobasilar system of blood supply?
vertebral arteries arise off of subclavian arteries and unite to form the basilar artery; this vessel bifurcates into two posterior cerebral arteries;
supplies the brain stem, cerebellum, occipital lobe, and parts of thalamus.
What is the Circle of Willis?
formed by anterior communicating artery connecting the two anterior cerebral arteries and the posterior communicating artery connecting each posterior and middle cerebral artery!
What are ganglia?
compact groups of peripheral nerve cell bodies (nuclei)
Projection neurons carry impulses to….
other parts of the CNS
Interneurons are…
short relay neurons
Axon bundles are called…
tracts or fasciculi (in spinal cord, collections of tracts are called columns, or funiculi)
What are neuroglia?
support cells that do not transmit signals; important for myelin and neuron production; maintenance of K+ levels and re-uptake of neurotransmitters following neural transmission at synapses.
Resting membrane potential is ____ on outside and ____ on inside
positive on outside and negative on inside.
What is action potential?
increased permeability of Na+ and influx into cell with outflow of K+ results in polarity changes and depolarization; generation of an action potential is all-or-none!!!
Just know this: Conduction velocity is proportional to axon diameter; the largest myelinated fibers conduct the fastest.
:)
The small gaps in myelination are called…
nodes of Ranvier
what is saltatory conduction
when the action potential jumps from one node of Ranvier) to the next.
Nerve fiber types: “A” fibers characteristics and types?
large, myelinated, fast conducting
- Alpha (proprioception, somatic motor
- Beta (touch, pressure)
- Gamma (motor to muscle spindles
- Delta (pain, temp, touch)
Nerve fiber types: B fibers characteristics?
small, myelinated, conduct less rapidly; preganglionic autonomic.
Nerve fiber types: C fibers characteristics and types?
smallest, unmyelinated, slowest conducting.
- dorsal root (pain, reflex responses)
- sympathetic (post-ganglionic sympathies)
Lower Motor Neurons: structures, and symptoms of a lesion
Structures: cell bodies in the anterior horn of spinal cord, spinal nerves, and cranial nerve fibers that travel to target muscles.
Symptoms of lesion: flaccidity, decreased or absent deep tendon reflexes, atrophy.
Upper Motor Neurons: structures, and symptoms of a lesion
Structures: any nerve cell body or nerve fiber in the spinal cord (except the anterior horn cells), all superior structures (gray and white matter affecting motor function and descending nerve tracts), cranial nerve nuclei.
Symptoms of lesion: increased depp tendon reflexes, spasticity, clonus, emergence of primitive reflexes including Babinski sign, exaggerated cutaneous reflexes, autonomic dysreflexia, flaccidity may occur at the level of lesion.
What is a myotome?
the skeletal muscles innervated by motor axons in a given spinal root.
A motor unit consists of…
the alpha motoneuron and the muscle fibers it innervates
The spinal cord ends at the level of ____. Below that, nerve roots descend vertically to form the ________.
L1; cauda equina.
Ventral (anterior) root of spinal cord contains…
efferent (motor) fibers to voluntary muscles, and to viscera, glands and smooth muscles.
Dorals (posterior) root of spinal cord contains…
afferent (sensory) fibers from sensory receptors from skin, joints, and msucles; each dorsal root possesses a dorsal root ganglion; there is no dorsal root for C1.
Dermatome is…
a specific segmental skin area innervated by sensory spinal axons.
What are spinal level reflexes?
involuntary responses to stimuli; basic, specific and predictable; dependent upon intact neural pathway (reflex arc).
Stretch (myotatic) reflex: stimulus, reflex arc, and function
- stimulus: muscle stretch
- reflex arc: afferent 1a fiber from muscle spindle to alpha motoneuron projecting back to muscle of origin (monosynaptic)
- functions to maintain muscle tone, support agonist muscle contraction, and provide feedback about muscle length.
- clinically, sensitivity of the stretch reflex and intactness of spinal cord segment are tested by applying stretch to the deep tendons (DTR)
- reciprocal innervation: describes the responses a stretch stimulus can have on agonist, antagonist, as well as synergistic muscles.
Inverse stretch (myotatic) reflex: stimulus, reflex arc, and funciton
- stimulus: muscle contraction
- reflex arc: afferent 1b fiber from Golgi tendon organ via inhibitory interneuron to muscle of origin (polysynaptic)
- functions to provide against inhibition, diminution of force of agonist contraction.
Gamma reflex loop: _____ reflex forms part of this loop. Allows what? How does it happen?
STRETCH reflex forms part of this loops.
Allows muscle tension to come under control of descending pathways.
Descending pathways excite gamma motor neurons, causing contraction of the muscle spindle, and in turn increased stretch sensitivity and increased rate of firing from spindle afferents; impulses are then conveyed to alpha motor neurons.
Flexor (withdrawal) reflex: stimulus, reflex arc, function.
- stimulus: cutaneous sensory stimuli
- reflex arc: cutaneous receptors via interneurons to largely flexor muscles; multi-segmental response involving groups of muscles (polysynaptic).
- functions as a protective withdrawal mechanism to remove body part form harmful stimuli.
Crossed extension reflex: stimulus, reflex arc, function
- stimulus: noxious stimuli and reciprocal action of antagonists ; flexors of one side are excited causing extensors on same side to be inhibited; opposite responses occur in opposite limb.
- reflex arc: cutaneous and muscle receptors diverging to many spinal cord motor neurons on same and opposite side (polysynaptic).
- function: coordinates reciprocal limb activities such as gait.
CVA: ischemic vs hemorrhagic
ischemic= clot hemorrhagic= bleed
Cerebral insufficiency
due to transient disturbances of blood flow (like TIA- brief interruption of blood supply). TIA symptoms don’t last as long as stroke (usually only hour to 24 hours).
Cerebral infarction
due to either embolism or thrombosis of the intra or extracranial arteries.
thrombus vs embolus
thrombus: mass of clotted platelets and other parts of blood;
embolus: when a piece of the thrombus moves and then gets stuck somewhere else.
Cerebral hemorrhage
bleed secondary to hypertension or aneurysm
Cerebral arteriovenous malformation (AVM)
abnormal, tangled collections of dilated blood vessels that result from congenitally malformed vascular structures
