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228 Cards in this Set

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What is the difference between general somatic efferent (GSE) and special visceral efferent (SVE) fibers?
GSE innervate muscle derived from myotomes (nuclei of III, IV, VI, XII); SVE innervate muslce derived from branchial arches (nuclei ambiguus, inferior and superior salivary, Edinger-Westphal)
What is the difference between general somatic afferent (GSA) and general visceral afferent (GVA) fibers?
GSA innervate receptors in skin, muscle, and joints; GVA innervate receptors in viscera ie. barorecpetors, pulmonary stretch, stomach and intestines
What are special visceral afferent (SVA) fibers? Where do they terminate in the brain stem?
taste bud sensation on tongue and epiglottis which terminate in the solitary nucleus
Where do all cranial nerve visceral afferents terminate in the brain stem?
all visceral afferents entering the brainstem terminate in the nucleus of the solitary tract
What are the components of the vagus nerve?
GVA of thoracic an abdominal viscera (solitary nucleus); SVA of tastebuds on epiglottis (solitary nucleus); GSA from external ear (spinal trigeminal nucleus); GVE (parasymp) to thoracic and abdominal viscera (dorsal motor nucleus of vagus and nucleus ambiguus); SVE to muscles of pharynx and larynx (nucleus ambiguus)
What are the components of the glossopharyngeal nerve?
GVA from carotid sinus, body, and eustachian tube (solitary nucleus); SVA from tastebuds on posterior 1/3 of tongue (solitary nucleus); GSA from external ear (spinal trigeminal nucleus); GVE (parasymp) to parotid gland (inferior salivatory nucleus); SVE to stylopharyngeus (nucleus ambiguus)
What are the components of the facial nerve?
GVA from nasopharynx (solitary nucleus); SVA from taste buds to anterior 2/3 of tongue (solitary nucleus); GSA from external ear (spinal trigeminal nucleus); GVE to submandibular and sublingual salivary glands (superior salivatory nucleus); SVE to muscles of facial expression (facial motor nucleus)
What are the components of the trigeminal nerve?
GSA from face (spinal trigeminal nucleus, principle trigeminal nucleus, mesencephalic trigeminal nucleus); SVE to muscles of mastication (trigeminal motor nucleus)
What is unusual about the mesencephalic trigeminal nucleus? What reflex depends on it?
Contains neurons that innervate muscle spindles in muscles of mastication; they originate from neural crest cells that later migrated into the brainstem to form the nucleus; Jaw closing reflex
What cranial nerve nuclei innervate the extraocular muscles?
the extraocular muscles are derived from myotomes are innervated by CN III, IV, VI
What small but critical fiber pathway integrates activity of the cranial nerve nuclei innervating extraocular muscles?
Medial Longitudinal fasciculus (MLF) integrates CN III, IV, VI; also carries descending reticulospinal and tectospinal projections to upper cervical cord to integrate eye and head movements
None
What is the PPRF?
paramedian pontine reticular formation; area around the abducens nucleus that coordinates horizontal eye movements via crossed connections to abducens and oculomotor
What is lateral gaze paralysis?
inability to move both eyes to the side of lesion because the lesion disrupts connections btw abducens and oculomotor nuclei (via PPRF)
What cranial nerves are involved in the pupillary light reflex?
Afferents: CN II bilaterally to pretectal area which innervates the Edinger-Westphal nucleus which projects via the oculomotor nerves to ciliary ganglion to innervate pupillary constrictor m.
What are the main elements of the auditory pathway as it ascends through the brain stem to the thalamus?
Originates in the cochlea, projects via auditory nerve to dorsal and ventral cochlear nuclei; project contralaterally (trapezoid body) and ipsilaterally to lateral lemniscus to inferior colliculus to medial geniculate
None
What happens to vestibular afferents in brain stem?
Afferents from semicircular canals terminate in vestibular nuclei and give rise to vestibulospinal tracts and ascending medial longitudinal fasciculus
What is the “VOR”?
vestibuloocular reflex is coordinated by the vestibular nuclei and their projections to CN III, IV, VI via MLF to produce reflexive eye movements in relation to head movements
What two critical pathway crossings take place in the lower medulla?
Pyramidal tracts cross (corticalspinal tract); medial lemniscus (dorsal column tracts)
Where is the inferior olive? Where does it project? How does it get there?
in the upper medulla, receives afferents from many brain regions and projects to the contralateral cerebellar hemisphere via the inferior cerebellar peduncle
What is the hypothalamic-autonomic (“descending sympathetic”) tract?
tract which runs through the lateral brain stem to parasympathetic nuclei in the brainstem and sympathetic nuclei in thoracolumbar region; damage leads to ptosis bc the symp fibers innervate the tarsal muscle of the eyelid
What nucleus in the medulla is a critical element of the brain stem's respiratory center?
Solitary nucleus
What is the importance of the locus ceruleus and the raphe nuclei? At what level of the brain stem are they located?
Ceruleus: noradrenergic innervation of brain; Raphe: serotonergic innervation of brain; located in isthmus
None
What is the importance of the pontine gray? Where does it project? How does it get there?
pontine gray recieves input from the cerebral cortex and descends in the crus cerebri and projects contralaterally to the cerebellar hemisphere via the middle cerebellar peduncle
None
What happens to the fasciculus gracilis and fasciculus cuneatus in the medulla?
decussate as arcuate fibers to the medial lemniscus; gracilis is ventral to cuneatus
What happens to the dorsal and ventral spinocerebellar tracts in the brain stem?
Dorsal enters the cerebellum via the inferior cerebellar peduncle; ventral enters via the superior cerebellar peduncle
What is source of superior cerebellar peduncle?
originates from neurons of the depp cerebellar nuclei and projects to the red nucleus and ascending ventral lateral nucleus to relay cerebellar output to the primary motor cortex
What is importance of substantia nigra in midbrain?
source of ascending dopaminergic nigrostriatal pathway; degenerates in Parkinson's disease
What brain stem structure is a critical element of the orienting reflex to visual, auditory, and tactile stimuli?
tectospinal tract
None
Where does the tectospinal tract originate?
deep layers of the superior colliculus
What is an important function of the periaqueductal gray?
involved in the modulation of pain via its endorphin projections to the dorsal horn of the spinal cord
At what level of the brain stem is the red nucleus found?
midbrain tegmentum
What is the difference between the cerebral peduncle and the cerebellar peduncles?
connect to cerebrum vs. cerebellum
What is the circuitry of the baroreflex? the jaw closing reflex?
afferents via GVA from carotid sinus via CN IX to solitary nucleus, via vagus to inhibit sympathetic pressor fibers, relax vessels; to dorsal motor nucleus and nucleus ambiguus to stimulate vagal GVE to decrease ventricular contractility and HR
What is the circuitry of the jaw closing reflex?
mesencephalic trigeminal nucleus to motor trigeminal nucleus
What is the circuitry of the gag reflex?
GVEA from throat via CN IX to solitary nucleus to nucleus ambiguus, vagus SVE from nucleus ambiguus to pharyngeal and laryngeal muscles
What is the circuitry of the cough reflex?
GVA from throat via CN IX, to solitary nucleus to phrenic nucleus
What are muscle fasciculations?
grossly observable spontaneous muscle twitches that involve entire motor units; can be due to denervation or benign muscle fatigue
What are muscle fibrillations?
Not grossly observable muscle twitches caused by the anterograde degeneration of axons to individual muscle fibers, always indicate denervation
What are the three primary or basic, subcortical sensations?
Exteroception; Proprioception; Interoception
What are cortical or combined sensations?
several simultaneous basic sensations and their integration ie. recognition of objects by touch or weight
What is dysesthesia?
uncomfortable hypersensitivity to nonnoxious stimuli
What is paresthesia?
abnormal, spontaneous sensation of tingling or "pins and needles"
What is referred pain?
pain perceived along a dermatome having sensory afferents from the same dorsal root level as the diseased internal organ
What is mononeuropathy?
decreased or lost sensation in the territory of one peripheral nerve
What is polyneuropathy?
decreased or lost sensation in several peripheral nerves, creates a "stocking and glove" pattern deficit
What is a intramedullary lesion?
a lesion within the spinal cord which often produce a suspended or vestlike sensory loss and sacral sparing
What is an extramedullary lesion?
a lesion which compresses the spinal cord from the outside, leads to initial sensory loss in sacral segments and progresses up to a level
What does impairment of cortical sensations indicate?
dysfunction of the contralateral parietal lobe or its connections, if primary, subcortical sensations are relatively intact
What is stereognosis?
tactile recognition of common objects with eyes closed; deficit is astereognosis
What is graphesthesia?
identification of numbers traced on the palm with eyes closed; deficit is agraphesthesia
What is double simultaneous stimulation and what does it test?
Perception of two tactile stimuli applied simultaneously to bilateral parts of the body with patients eyes closed; tests the integrity of the parietal lobe, if there is a lesion the contralateral stimulus with not be perceived
What does two-point discrimination test?
While conveyed by the posterior columns, it tests a cortical sensation
What is the body landmark that tests the C5 dermatome?
lateral shoulder
What is the body landmark that tests the C6 dermatome?
thumb
What is the body landmark that tests the C7 dermatome?
index and middle finger
What is the body landmark that tests the C8, T1 dermatome?
ring, little fingers
What is the body landmark that tests the T4 dermatome?
nipples
What is the body landmark that tests the T10 dermatome?
umbilicus
What is the body landmark that tests the L3,L4 dermatome?
anterior thigh
What is the body landmark that tests the L5 dermatome?
dorsal foot
What is the body landmark that tests the S1 dermatome?
lateral foot, sole
What nerve roots does the biceps muscle reflex test?
C5,C6
What nerve roots does the triceps muscle reflex test?
C7, C8
What nerve roots does the brachioradialis muscle reflex test?
C5,C6
What nerve roots does the finger flexors muscle reflex test?
C8, T1
What nerve roots does the quadriceps muscle reflex test?
L2, L3, L4
What nerve roots does the achilles muscle reflex test?
S1, S2
What is the Jendrassik maneuver?
the contraction of muscles distant from the tested reflex, creates increased gamma activity which sortens intrafusal fibers and lengthens the spindle
What is hyperreflexia associated with?
an upper motor neuron releasing a lower motor neuron from supraspinal inhibition; ie UMN lesion
What is hyporeflexia associated with?
possibly a normal finding in healthy elderly; abnormally could be a lower motor neuron lesion affecting the efferent arc of the MSR or a dorsal root afferent lesion affecting the afferent arc of the MSR.
What are superficial reflexes?
elicited by tactile stimuli to skin or mucous membrane, or shining a light into pupil
What is a consensual reflex and whay type of reflexes exhibit this characteristic?
is a bilateral response to a unilateral stimulus; Cranial nerve mediated reflexes
What is Hoffman's sign?
rapid flexion of fingers after flicking the distal phalanx of middle finger down; this abnormal reflex indicates an upper motor neuron lesion
What is the babinski sign and what does it indicate?
Slow dorsiflexion of the great toe and fanning of other toes in response to stroking the lateral side of the foot; normally present in infants until 1 or 2 years of age
What nerves convey the afferent and efferent pathways of the Pupillary reflex?
Afferent: shine light into eye (CN II); Efferent: pupils constrict (CN III)
What nerves convey the afferent and efferent pathways of the corneal reflex?
Afferent: touch cornea (CN V); Efferent: eyes blink (CN VII)
What nerves convey the afferent and efferent pathways of the palpebral reflex?
Afferent: touch eyelid, lash (CN V); Efferent: eyes blink (CN VII)
What nerves convey the afferent and efferent pathways of the Gag reflex?
Afferent: touch pharynx (CN IX,X); Efferent: gag (CN X)
What is Monoparesis?
partial weakness of one limb
What is monoplegia?
total paralysis of one limb
What is a segmental motor weakness?
weakness of muscles innervated by one or several adjacent nerve roots
What is hemiparesis or hemiplegia?
partial weakness or paralysis of upper and lower limbs on one side of the body; can be caused by an UMN lesion on the ipsilateral spinal cord or contralateral brain or brainstem
What is muscle tone?
the resistance in a limb moved passively by an examiner
What are the clinical signs of an Upper motor neuron lesion?
diffuse weakness; slight atrophy; severe weakness relative to minimal atrophy; no fasciculations; increased muscle tone (except spinal shock); increased muscle stretch reflex (except in spinal shock); possible clonus; presence of Babinski sign (except in spinal shock)
What are the clinical signs of a Lower motor neuron lesion?
focal weakness; focused, severe atrophy; some strength preserved despite atrophy; possibe fasciculations; decreased muscle tone; decreased muscle stretch reflex; no clonus; no Babinski
What is spasticity?
increased muscle tone, unequal between agonist and antagonist muscles, especially in antigravity muscles
What is rigidity?
increase muscle tone, equal between agonist and antagonist muscles; caused by a lesion in the extrapyramidal system
What is radicular pain and its cause?
lightning, stabbing, shooting pain in the distribution of a dorsal root. Indicates dorsal root inflammation or compression by extramedullary lesion
What is the cause of diffuse, steady pain?
intramedullary lesion or from nearby structures including vertebrae to involve the spinal cord
What is Transverse myelopathy?
"partial or complete lesion traversing one spinal cord level
What are the signs and symptoms of transverse myelopathy?
LMN signs and level of sensory loss located at level of lesion; UMN signs below lesion; spinal shock can occur immediately after time of trauma
What are the causes of transverse myelopathy?
Caused by trauma; inflamation from infections (viral); demyelination (MS); autoimmune disorders; tumor
What is Brown-Sequard Syndrome?
spinal cord hemisection; lesion or severance of one half of the spinal cord
What are the signs and symptoms of Brown-Sequard syndrome?
contralateral deficit of pain and temperature (spinothalamic); ipsilateral weakness (corticospinal); ipsilateral deficit to vibration and position sense (posterior columns)
What is the etiology of Brown-Sequard syndrome?
tumor; trauma; herniated disc, infection, or inflammation
What is a Syringomyelia?
a cavity or syrinx within the central gray matter which may progressively expand in any direction
What are the signs and symptoms of a Syringomyelia?
initially a vestlike pain and temp sensory loss due to the decussating spinothalamic tracts; subsequently loss of LMN at the level of the lesion if anterior horn cells are lost and development of paraparesis if the corticospinal tract is involved
What are the causes of syringomyelia?
tumor, resorption of traumatic hematoma; abnormal CSF dynamics due to congenital defect
What results from the occulusion of the anterior spinal artery?
loss of the blood supply to the anterior 2/3 of the spinal cord; resulting in hyperreflexic spastic paraparesis and loss of pain and temp below the lesion leve; vibration and position sense are preserved (bc posterior columns are preserved)
What is the cause of an occlusion of the anterior spinal artery?
artherosclerotic aortic disease or aortic surgery
What is subacute combined degeneration (posterolateral sclerosis)?
degeneration of posterior and lateral columns, beginning in the thoracic cord
What are the signs and symptoms of subacute combined degeneration?
bilateral loss of position sense and vibration in legs and UMN signs
What is the cause of subacute combined degeneration?
vitamin B12 deficiency
What is amyotrophic lateral sclerosis (ALS)?
progressive degeneration of the lateral corticospinal tract and loss of anterior horn cells at multiple spinal levels and brainstem; motor neurons in the brain and brainstem degenerate
What are the signs and symptoms of amytrophic lateral sclerosis (ALS)?
initially asymmetrical and later general LMN signs (atrophy, fasciculations, weakness) without sensory loss; UMN signs (spastic paraparesis, hyperreflexia, babinski sign)
What are the signs and symptoms of Tabes dorsalis?
initially radicular, lightning pain from dorsal root involvement; secondary paresthesia and loss of vibration and position sense from degeneration of dorsal columns, absent reflexes but intact strength
What is the cause of Tabes dorsalis?
neurosyphilis
What are the 4 secondary or cortical sensations?
stereognosis; graphesthesia; double simultaneous stimulation; two-point discrimination
What is clonus and its significance?
the rhythmical oscillatory muscle contractions sustained by stretching an abnormally hyperreflexic tendon; signifies and UMN corticospinal tract lesion
Why is the babinski sign present in infants?
The corticospinal tract and other supraspinal tracts are not fully myelinated
What is spinal shock?
in an acute severe spinal cord injury there are generally LMN signs present, the expected UMN signs take days to weeks to develop
What structures make up the brainstem?
medulla, pons, midbrain
What cranial nerves arise from the brainstem?
CN III - CN XII
What are the functional components of CN III oculomotor?
GSE & GVE
What are the functional components of CN IV trochlear?
GSE
What are the functional components of CN V, trigeminal ?
SVE & GSA
What are the functional components of CN VI, abducens ?
GSE
What are the functional components of CN VII, Facial ?
SVE, GVE, GSA, GVA, SVA
What are the functional components of CN VIII, vestibulocochlear?
SSA
What are the functional components of CN IX, glossopharyngeal?
SVE, GVE, GSA, GVA, SVA
What are the functional components of CN X, vagus?
SVE, GVE, GSA, GVA, SVA
What are the functional components of CN XI, Accessory?
GSE, SVE
What are the functional components of CN XII, hypoglossal
GSE
What is the Alar plate?
embryologically the dorsal aspect of the spinal cord and lateral aspect of the brainstem which develops into sensory nuclei; corresponds to GVA, SVA, GSA, SSA
What is the Basal plate?
embryologically the ventral aspect of the spinal cord and medial aspect of the brainstem which develops into motor nuclei; corresponds to GVE, GSE, SVE
What is the sulcus limitans?
the longitudinal groove between the alar and basal plates
What are the four levels of the medulla?
Pyramidal decussation; Medial lemniscal decussation; Vagus/Hypoglossal Nerve level; Glossopharyngeal level
What are the two main crainial nerve nuclei at the level of the pyramidal decussation in the medulla?
accessory nucleus (GSE fibers); spinal trigeminal nucleus (GSA fibers from CN V, VII, IX, X)
Within the medial lemniscal tract, do the fibers from nucleus gracilis or cuneatus lie more ventrally?
gracilis
How does the dorsal spinocerebellar tract enter the cerebellum?
via the inferior cerebellar peduncle
How do the cuneocerebellar fibers enter the cerebellum?
via the infereior cerebellar peduncle
What is the solitary nucleus?
nucleus of the dorsal medulla which is critical part of the medullary respiratory center and controls breathing by linking the vagal afferent input to the phrenic motor nucleus output to the diaphragm
What does the inferior cerebellar peduncle convey into the cerebellum?
dorsal spinocerebellar, cuneocerebellar, and olivocerebellar fibers
What is the tegmental pons?
the dorsal portion of the pons which is the rostral continuation of the medulla
What does the Paramedian Pontine reticular formation (PPRF) control?
conjugate horizontal eye movements by activating ipsilateral lateral rectus motor neurons in the abducens nucleus and contralateral medial rectus motor neurons in the oculomotor nucleus via the medial longitudinal fasciculus
What is the basilar pons?
the ventral portion of the pons which consists of the pontine gray which receives inputs from the cerebral cortex and projects into the contralateral cerebellum via the middle cerebellar peduncle
What does the middle cerebellar peduncle convey?
pontocerebellar projections from the pontine gray which is ultimately from the cerebral cortex
Where do the two secondary trigeminal pathways project?
to the ventral posteromedial nucleus (VPM) of the thalmus, which projects to the somatosensory cortex of the postcentral gyrus
What is the isthmus?
the junction of the pons and midbrain
What does the superior cerebellar peduncle convey?
ventral spinocerebellar tract and others
What is the locus ceruleus?
located within the isthmus btw the pons and midbrain, has widespread noradrenergic projections that function in arousal to novel stimuli and in sleep; affected by some antidepressants
What is the raphe nuclei?
located centrally within the isthmus btw the pons and midbrain, has widespread serotonergic projections
What information is carried within the lateral lemniscus and where does it terminate?
is a relay station in the auditory pathway and terminates in the inferior colliculus which then projects rostrally to the medial geniculate nucleus to the primary auditory cortex of the temporal lobe
What type of fibers and information is sent from the Edinger-Westphal nucleus?
GVE fibers provide preganglionic parasympathetic innervation to ciliary ganglion to innervate the ciliary muscles (accommodation for near vision) and pupillary sphincter (light refex)
What information is controlled by the interstitial nucleus of Cajal?
efferents project to the oculomotor nuclei to control vertical eye movements; analogous to the PPRF
What is the function of the superior colliculus?
is the origin of the tectospinal tract which is the reflex center for orientation of eyes and head in response to visual, auditory, and somatic stimuli; also projects to the brainstem reticular formation and the pathways controlling conjugate eye movements; traverses to lateral geniculate
What is the red nucleus?
a prominent nucleus in the middle of the midbrain tegementum, is a major termination for the superior cerebellar peduncle; magnocellular division gives rise to crossed descending rubrospinal tract; parvocellular division gives rise to central tegmental tract
What is substantia nigra?
black-pigmented nucleus of the midbrain with ascending dopaminergic projections to the caudate nucleus and basal ganglia; Site of degeneration in Parkinson's Disease
What does the nucleus ambiguus innervate?
muscles derived from the 3rd and 4th branchial arches
What does the facial motor nucleus innervate?
muscles derived from the 2nd branchial arch
What does the trigeminal motor nucleus innervate?
muscles derived from the 1st branchial arch
What is the area postrema?
one of the brain's circumventricular organs in the dorsal medulla, has a leaky BBB and is exposed to the 4th ventricle, has a chemoreceptive trigger zone which is sensitive to emetics and disturbances in CSF composition and sends projections to the vomiting center of the solitary nucleus.
What is unique about the facial nucleus control of the the upper 1/3 vs. lower 2/3 of the face?
Upper 1/3: bilateral cortical innervation via corticobulblar fibers while Lower 2/3: contralateral cortical corticobulbar innervation
What is vertigo?
dizziness, and sometimes nausea, vomiting, and pallor caused by labyrinthine irritation
What is Meniere's disease?
recurrent vertigo with tinnitus (ringing) and deafness caused by complex pathology leading to degeneration of vestibular and cochlear hair cells
What are semicircular canals?
three interconnected tubes positioned approximately at right angles to one another in three planes of space
Where are the vestibular hair cells located within the vestibular system?
cristae ampullares of the semicircular canals, maculae of the utricle and saccule
What are vestibular hair cells?
sensitive mechanoreceptors which have specialized microvilli (stereocilia) and a single long kinocilium
What occurs within the semicircular canals to sense rotary movement?
changes in acceleration change the movement of the endolymph of the membranous labyrinth which cause deflections of the hair cell cilia because of inertia.
What does the Macula Utriculus sense?
linear acceleration or deceleration in the horizontal plane
What surrounds the hair cells of the utricle and saccule?
gelatinous otolithic membrane with small crystals of calcium carbonate (otoliths) to provide mass to be sensed by the cilia
What does the Macula Sacculus sense?
verticle movement
Where is the vestibular ganglion and its projections?
internal auditory meatus; peripherally the bipolar neurons extend on the hair cells of the cristae and maculae, centrally enters brainstem via CN VIII at pontomedullary junction to vestibular nuclei
Where are the 4 vestibular nuclei?
floor of the fourth ventricle and extends from the obex to the abducens nucleus
What is the function of the cerebellar flocculonodular lobe?
participation in the control of tracking or smooth pursuit eye movements
What information does the cerebellar vermis via the fastigal provide the vestibular nuclei?
information concerning the status of skeletal muscle and spinal cord activity necessary for responses to vestibular sensory inputs
What are the two spinal cord projections of the vestibular system?
lateral vestibulospinal tract ipsilateral to extensor motor neurons at all levels; medial vestibulospinal tract (via MLF) ipsilateral to cervical spinal cord to innervate neck muscles
What are the three brainstem connections of the vestibular nuclei?
to the reticular formation; vestibular commisural connections; Ascending medio longitudinal fasciculus (MLF)
What is the function of vestibular commissural connection of the vestibular nuclei?
coordination of the right and left vestibular inputs
What is the function of the ascending medial longitudinal fasciculus (MLF)?
coordinates conjugate eye movements with head movements
What is contained within the bony labyrinth?
perilymph (similar to extracellular fluid)
What is contained within the membranous labyrinth?
endolymph (similar to intracellular fluid)
Does movement toward or away from the kinocilium result in depolarization of the hair cell and an increase in firing rate?
towards
What is the longitudinal fissure?
the fissure that separates the two hemispheres
What is the transverse fissure?
separates the hemispheres from the brain stem and cerebellum
What is the lateral Sylvian fissure?
separates the temporal lobe below from the frontal and parietal lobes above
What is the central Rolandic sulcus?
forms the posterior boundary of the frontal lobe deliniating it from the parietal lobe
What is the uncus?
a bulge in the medial border of the temporal lobe ventrolateral to the mammillary bodies
What is the crus cerebri?
large bundles of fibers running on the ventral surface of the midbrain
What cranial nerve courses just medial to the uncus and could be compressed if the uncus herniated?
CN III - oculomotor
What is the coccygeal ligament?
filum terminale externa, filum terminale interna invested by dura as it penetrates the dura of the lumbar cistern
What is the blood supply of the spinal cord?
anterior (2/3) and posterior (1/3) spinal arteries from the vertebral arteries; radicular arteries from segmental vessels;
What structures are penetrated by a lumbar puncture?
supraspinous ligament, interspinous ligament, ligamentum flava, dura mater, arachnoid mater, enter lumbar cistern
What are the two layers of the dura mater and what do they create?
periosteal (lines cranium), meningeal layer; form venous sinuses at certain sites
What are leptomeninges?
the pia mater and arachnoid mater together
What is the tentorial notch?
opening in the tentorium cerebelli through which the midbrain passes
What is the origin of the middle meningeal artery and what does it produce if it is severed?
Maxillary artery to supply the dura; epidural hemorrhage
Where do the venous sinuses of the cranium drain?
Internal jugular vein
What cranial nerve emerges from the interpeduncular fossa?
CN III - oculomotor nerve
Where does the optic tract project to in the brain?
lateral geniculate body
What cranial nerve is the only one to leave the brain stem dorsally?
CN IV - trochlear
Where does CN IV emerge from the brain stem?
immediately caudal to the inferior colliculi after crossing the midline in the anterior medullary velum
Where does CN V emerge from the brain stem?
ventrolateral aspect of the pons 1/2 way between the rostral and caudal borders of the middle cerebellar peduncle
What cranial nerves course through the cavernous sinus?
CN III, IV, VI, and V
Where does CN VI emerge from the brain stem?
near midline within the pontomedullary sulcus
Where does CN VII emerge from the brain stem?
at the caudal border of the pons lateral to the sixth nerve and rostral to the flocculus
Where does CN VIII emerge from the brainstem?
immediately lateral to the facial along the lateral border of the pons
Where do CN IX and X emerge from the brainstem?
at the cerebellopontine angle and immediately posterior to the inferior olive
Where does CN XII emerge from the brainstem?
anteromedial sulcus between the pyramid and the olive on the ventral aspect of the medulla
Which cranial nerves have an autonomic component?
CN III, VII, IX, X
What is the massa intermedia?
midline structure where the thalami may fuse across the 3rd ventricle
What makes up the diencephalon?
Thalamus and hypothalamus
What is the medial geniculate body?
a thalamic relay for the auditory pathway which projects to the auditory cortex in the temporal lobe
What is the lateral geniculate?
a thalamic relay of visual information to the occipital lobe of the cortex
What does the embryologic metencephalon develop into?
pons and cerebellum
What is another name for the middle cerebellar peduncle and what fibers does it carry?
Brachium Pontis; comprised of pontocerebellar fibers from the basilar pons
What is another name for the superior cerebellar peduncle and what fibers does it carry?
Brachium conjunctivum; cerebellar efferents coursing rostrally towards the midbrain near the midline
What is another name for the inferior cerebellar peduncle and what fibers does it carry?
restiform body; contains both cerebellar efferents and afferents
What does the embryologic myelencephalon develop into?
medulla
What direction does the superior oblique muscle move the eye?
down and in (adducted)
What direction does the inferior oblique muscle move the eye?
up and in (adducted)
What is doll's eyes and what does it test?
reflex compensatory eye movements seen by moving the head from side to side in a comatose patient; indicates intact brainstem and contributes to the diagnosis of brain death
What is the orienting or startle response?
the turning of eyes and head and raising of arms to an unexpected visual or auditory stimulus; mediated by tectospinal and tectoreticular projections
How would a lesion of the frontal eye field present?
the inability to look contralaterally to the site of the lesion
What is the frontal eye field?
a location in the middle frontal gyrus which is the center for voluntary eye saccades; influences ocular nuclei via projections to the superior colliculus and PPRF
What are saccades?
voluntary, rapid ballistic eye movements made to turn eye toward objects in periphery of visual field; controlled by contralateral cerebral cortex or superior colliculus
What is vergence?
reflex convergence or divergence of the eyes to focus on objects moving toward or away
What region of the brain controls tracking or smooth pursuit movements of the eyes?
ipsilateral occipital eye fields
What is nystagmus?
oscillating eye movements, often with a slow and fast component, the direction of the nystagmus is the direction of the fast component
What is often the cause of nystagmus?
vestibular disorders due to destructive or irrigating lesions
What would be the symptoms of a unilateral abducens nerve lesion?
at rest the affected eye deviates medially; voluntary gaze to the side of the lesion results in diplopia because the affected eye cannot move laterally
What would be the symptoms of a unilateral abducens nucleus lesion?
lateral gaze paralysis, inability to move both eyes to the side of lesion because the lesion disrupts connections btw the abducens and oculomotor nucleus
What would be the symptoms of a lesion of the PPRF?
disruption of saccadic eye movements in horizontal plane
What would be the symptoms of a lesion of the frontal eye fields?
inablity to move eyes voluntarily away from the side of lesion
What would be the symptoms of a lesion of the MLF rostral to the abducens nucleus?
unilaterally: inability to move affected eye medially, horizontal nystagmus results; bilaterally: dissociated horizontal eye movements with attempted gaze to either side (reptilian stare)
What are the two possible causes of ptosis?
lesion of CN III (levator palpebrae superioris m.) or Horner's syndrome (sympathetic of tarsal m. of Muller)
What nerve and muscle control the closing of the eyes?
CN VII; orbicularis oculi m.
What is the innervation of the lacrimal gland?
salivatory nucleus of CN VII to geniculate ganglion to pterygopalatine ganglion to lacrimal glands