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94 Cards in this Set
- Front
- Back
Denticulate ligament
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Thickening of pia and glial elements that tethers spinal cord laterally
– Forms ribben along lateral surface of the spinal cord between dorsal and ventral rootlets - attaches cord to and suspends it in dura/arachnoid tube |
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Where the two spinal cord enlargement
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cervical enlargement C4-5 - T1
lumbosacral enlargement L2-S3 |
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Conus medullaris
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Tapered end of cord
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Filum terminale
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Extension of pia and supporting cells
Anchors spinal cord to dorsum of coccyx |
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At which level does the spinal cord end
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L1-2
in children at L3 |
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Surface markings of cord
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– Anterior median fissure
– Anterior lateral sulcus – Posterior median sulcus – Posterolateral sulcus |
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What is the ventral nerve roots exit
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Anterolateral sulcus
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Where does the dorsal nerve nerve root enter
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Posterolateral sulcus
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Which portion of the cord gives rise to the spinal nerve
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Segment
- posterior and anterior roots join to form spinal nerve - 31 segments and human spinal cord giving rise to 31 pairs of spinal nerves 8C, 12T, 5L, 5S, 1C |
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Which of the longest roots and why
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Lumbosacral roots because they have to travel the furthest before they exit
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What is the difference between epidural space in the spinal cord compared to the brain
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In the spinal cord it is a true space where the dura is not fused with vertebral bodies
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Which two arteries make up the posterior blood supply of the CNS
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Vertebral arteries
Basilar artery Steer cerebral arteries |
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The vertebral arteries give rise to
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Anterior and posterior spinal arteries
Posterior inferior cerebellar artery (PICA) |
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Basilar arteries give rise to
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Anterior inferior cerebral arteries (AICA)
Pontine arteries Superior cerebellar arteries |
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Anterior blood supply is made up of
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Internal carotid arteries
Give rise to: – Anterior cerebral arteries (ACA) - Middle cerebral arteries (MCA) |
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Are anterior and posterior circulation independent?
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No, they're connected by network of arteries on cortical surface and communicating arteries on ventral surface
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Circle of Willis
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Interconnections between anterior and posterior circulations on the ventral surface
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Spinal cord and brainstem are supplied by
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vertebral-basilar system (posterior supply)
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The cortex is supplied by
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Both vertebrobasilar system and internal carotid system (post and ant circulations)
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Artery of Adamkiewicz
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Branch from segmental spinal artery
- present at ~T12 - provide major supply for lumbosacral spinal cord - a.k.a. great radicular artery |
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The vertebral arteries originate from
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Subclavian artery
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Does the posterior or superior artery supply more of the spinal cord?
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anterior
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Anterior spinal artery (ASA)
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- only 1
- branches of each vertebral artery joined to form ASA – runs in ant median fissure - 5-9 sulcal branches to each spinal cord segment - each brand supplies anterior two thirds of either right or left side [I.e. paramedian and lateral areas] |
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Posterior spinal arteries (PCA)
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- X2
- arises from vertebral arteries or PICAs – Run in posterolateral sulci – Supply posterior 1/3 of cord [Dorsomedial and dorsolateral areas] |
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Coronal arteries
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- Anterior and posterior spinal arteries give off coronal arteries that anastomosed with each other.
- Form Corona around cord. |
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Radicular arteries
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Reinforce circulation to cord
– Branches from cervical, intercostal, lumbar and sacral arteries that arise segmentally --> enter vertebral canal at intravertebral foramina --> anastamose with coronal arteries and from lower cervical area down, with anterior and posterior spinal arteries |
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Which arteries provide most supplied to upper cervical cord
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Anterior and posterior spinal arteries
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Majority of blood supply beginning with lower cervical segments comes from
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Radicular arteries
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Which artery provides most of supplies for lumbosacral spinal cord
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Artery of Adamkiewcz
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The Gray matter consists of
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– Nerve cell bodies
– Processes – neuroglia |
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The anterior horn contains
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- cell bodies of lower motor neuron
- innervate skeletal muscles |
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Lateral/intermediate horn
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- T1-L2/3 : preganglionic sympathetic cell bodies
- S2-S4 : preganglionic parasympathetic cell bodies |
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Clarks nucleus
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Located in lateral horn within lamina 7
- relay center for unconscious proprioception – Extends only to C6 |
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Rexed's laminae
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Layers that gray matter is divided into
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Major tracks and dorsal column
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Fasciculus gracialis [present at all levels]
Fasciculus cuneatus [present above T6] |
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Major tracks in lateral column
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Lateral corticospinal tract
Rubrospinal tract [from red nucleus] Spinocerebellar tracts – Dorsal spinocerebellar tract – Central spinocerebellar tract |
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Which tracks are most lateral and lateral column
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Spinocerebellar tracts
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Major tracts in anterior column
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Spinothalamic tract
Vestibulospinal tracts Reticulospinal tracts Anterior corticospinal tract |
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Lissauer's tract
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- Sensory fibers carrying pain and temperature will ascend and descend several spinal cord levels here before synapsing in the dorsal horn.
- Associated with spinothalamic tract. |
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Substantia gelatinosa
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lamina 2 of the gray matter, first processing for pain and temperature
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Anterior White commissure
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Pain and temperature fibers cross
Anterior corticospinal tract fibers cross |
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Six sulci of the spinal cord
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– Posterior median sulcus
– Posterolateral sulcus X 2 - Anterolateral sulcus X2 - anterior median fissure |
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Where is the entry point of the dorsal root
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Posterolateral sulcus
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Where is the exit point for the ventral root
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Anterolateral sulcus
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Which is larger the anterior median sulcus or the anterior median fissure
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Anterior median fissure is much larger
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Anterior corticospinal tract
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- Motor to ipsi- and contra- lateral ventral horn
- Mostly axial musculature |
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Spinothalamic tract
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Pain and temperature from contralateral side of the body
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Lateral corticospinal tract
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Motor to ipsilateral ventral horn
- mostly limb musculature |
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Spinocerebellar tract
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Proprioception from limbs to the cerebellum
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Fasciculus cuneatus
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Sensory [fine touch, proprioception] from ipsilateral upper limb
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Fasciculus Gracialis
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Sensory [find touch, proprioception] from ipsilateral lower limb
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Summary: which tracks are ipsilateral
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– Lateral corticospinal tract
– Anterior corticospinal tract – Fasciculus gracialis and cuneatus |
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Summary: which tracks are contralateral
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– Spinothalamic tract
– Anterior corticospinal tract |
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Somatotopic arrangement of fibers
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– Head [cervical region] fibers are always closest to the Gray matter
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What is the primary neurons synapse in the spinothalamic tract
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Primary Axons enter the spinal cord from the spinal ganglion, travel up or down 1 to 2 segments in the Lissauer's track and synapse in the posterior horn
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Which structures do the secondary neuron's of the spinothalamic tract pass
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Travels in the anterior lateral system:
– Caudal Medulla – Rostral Medulla [between the inferior olivary nucleus and the nucleus of the spinothalamic tract of the trigeminal nerve] - through pons and midbrain lateral to the medial lemniscas |
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What is the spinothalamic tract terminate
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In the VPL of the thalamus
– From the thalamus fiber project through the internal capsule and Corona radiata to terminate in the primary somatosensory cortex [postcentral gyrus] |
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What are the three Antero lateral pathways
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– Spinothalamic
– Spinalreticular – Spinal mesencephalic |
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Where do the primary axons of the dorsal columns synapse
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Axons enter the spinal cord from the spinal ganglion and passed directly to ipsilateral dorsal column and synapse
– Caudal fibers [below T6] enter FG [medial] – Rostral Fidlers [above T6] enter FC to ascend |
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Where do the secondary neuron of the dorsal columns travel
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Primary neurons terminate in NG and NC
- secondary neuron's cross the midline of internal arcuate fibers [Forming the medial lemniscus] - they travel medial lemniscus adjacent to the midline thru the roster medulla - through the caudal ponds, the media lemniscus flattens horizontal |
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Where does the media lemniscus terminate
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In the VPL of the thalamus
– From the thalamus fiber project through the internal capsule and Corona radiata to terminate in the primary somatosensory cortex [postcentral gyrus] <-- same as SpT tract |
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Where do the primary neurons of the corticospinal tract originate
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Primary motor cortex
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What is the path of the primary neurons of the lateral corticospinal tract
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- descending fibers from corona radiata converge to passes the posterior limb of the internal capsule
- fibers then descend through the middle 3/5 of the crus cerebri in the anterior part of the midbrain - fibers a broken up into many bundles in the pons - fibers descend as the pyramids in the anterior part of the medulla - |
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Where does crossover of the corticospinal fibers occur
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At the junction of the Meduna in the spinal cord, most of fibers cross the midline in the deposition of the planets.
– Cross fibers going to form the lateral corticospinal tract – Uncrossed fibers descend as the anterior corticospinal tract |
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What percentage of fibers cross over and what percentage of fibers descend in the anterior corticospinal tract
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– 85-90% of fibers crossover
- 10-15% descend in anterior corticospinal tract |
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Where does the lateral corticospinal tract terminate
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On the lower motor neurons in the ant horn of the spinal cord
- anterior corticospinal tract fibers cross the midline at the level where they terminate on the LMN |
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Corona radiata becomes the internal capsule when
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… It reaches striatum [caudate + putamen]
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Which cranial nerves are part of the parasympathetic nervous system
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3, 7, 9, 10
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Pain and temperature sensation from the bladder is carried by
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Somatic afferents
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Sensory fibers supplying the mucus and fundus of the bladder
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- travel with sympathetic
– reach spinal cord at T 12/L1 --> via spinothalamic tract to CNS |
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Sensory from neck of the bladder
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– travel with parasympathetic's
– Reach spinal cord at S2/3/4 --> via spinothalamic tract to CNS |
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Fullness of bladder
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– Carried by visceral afferents (PSNS)
– bladder wall mechanoreceptors --> sarcral parasympathetic's 2/3/4 |
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Voiding
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– Parasympathetic visceral motor
– Ditchers or muscle innervated by parasympathetic's from as 2/3/4 in the spinal cord --> hypogastric plexus --> synapse in vesical plexus --> detrusor muscle |
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Internal urethral sphincter
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– Sympathetic visceromotor
- t11 – L2 - lumbar splanchnic nerves --> inferior mesenteric ganglion --> internal urethral spincter |
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External urethral sphincter
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– Somatic motor, pudendal nerve
- S2/3/4 with pudendal nerve - conscious and voluntary |
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Onuf nucleus
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Origin of the pudendal nerve
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Micturition centers in cortex
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superior frontal gyrus
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Micturition centers in pons
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Pontine micturition center
Pontine storage center Periaqueductal gray |
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What needs to be inhibited or excited for voiding to occur
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– Inhibition of sympathetics (T12 L1) (to relax int sphincter)
- inhibit Onuf ( to relax ext sphincter) - excitation of parasympathetic S2/3/4 (to contract detrusor) |
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Why did infants have poor bladder control
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- their sacral reflex causes reflex contraction of the detrusor
- no control of external sphincter |
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Sacral reflex pathway
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– Stretch receptors and bladder wall are activated
– Stretch receptor output is transmitted via afferet fibers of the pelvic nerve to the sacral cord – Parasympathetic nerves bodies activated – ACH released by parasympathetic cause contraction of the detrusor muscle - in infants there is no control over the external center - in adults the ext sphincter is under somatic control thru the pudendal nerve |
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Voiding in adults
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– Under central control
– bladder feels full --> info is relayed to the cortex and PAG - if socially susceptible to avoid, the Pontine micturition center is activated for both the cortex and the PAG - excitation of parasympathetic as 2/3/4 --> contraction of detrusor muscle - simultaneous inhibition of T12, L1 and internal sphincter relaxes – inhibition of onuf (S2/3/4) --> somatic control of external sphincter is inhibited --> relaxation of ext sphincter |
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Overflow Incontinence
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a form of urinary incontinence, characterized by the involuntary release of urine from an overly full urinary bladder, often in the absence of any urge to urinate. This condition occurs in people who have a blockage of the bladder outlet (benign prostatic hyperplasia, prostate cancer, or narrowing of the urethra), or when the muscle that expels urine from the bladder is too weak to empty the bladder normally.
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Reflex Bladder
Overflow bladder Spastic bladder Small volume bladder |
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BROWN SEQUARD SYNDROME:
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loss of pain & temperature on contralateral side of body
loss of discriminative touch, vibration & proprioception on ipsilateral side of body UMN lesion on ipsilateral side of body LMN for C8 myotome |
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The spinal tap where's the needle extracting fluid from
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Subarachnoid space [CSF extraction]
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Spinal tap: at which level is a needle inserted
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L3 – L4
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Spinal tap: how is it performed in a newborn or a two-year-old
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At L4 or below
- posterior superior iliac spine [as L4 landmark] |
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What is an epidural? How does it result in pain control?
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The form of local anesthetic
- blocks fast Na channels (washes over spinal nerves) |
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Epidural: at which level do you insert the catheter? Which space is a needle inserted into?
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- Insertion at L3-L4
– Epidural space [outside sack] |
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Spastic paralysis of the leg and Babinski signs are both indicators of
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Upper motor neuron lesion
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Loss of discriminative touch, vibration and joint position sense from approximately the level of the nipples down on the left side only. Where is the lesion?
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Dorsal column
– Nipples located at approximately T4 – At T4 fibres uncrossed --> Cross at medulla |
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Lots of pain and temperature sensation from the mid abdomen downward on the right side. Where is the lesion?
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Spinothalamic tract
– Cross at spinal quite level – At approximately T10 |
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What consequence will a severe lesion at the level of T8 have on bladder function?
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Lesion above T11 lose conscious control of bladder
– retain ANS reflex |