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Saint Louis University Baguio City Pain, Numbness and Other Sensory Modalities Group 6 Andres, Xyrose Bangloy, Michael Batino, Laurence Kristoffer Hullon, Timothy James Artienda, Aubrey Bolislis, Mellicent Chan, Jacqeline Reginaldo, Venus Sicat, Sheena Marie Pain Receptors ‡ Meissner s Corpuscle ‡ Dendrites enclosed in CT in dermal papillae of hairless skin ‡ Discriminative touch & vibration-- rapidly adapting ‡ Generate impulses mainly at onset of a touch ‡ Hair Root Plexus ‡ y Free ner
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  Saint Louis UniversityBaguio City           Pain, Numbness and Other Sensory Modalities                Group 6Andres, XyroseBangloy, MichaelBatino, Laurence KristofferHullon, Timothy JamesArtienda, AubreyBolislis, MellicentChan, JacqelineReginaldo, VenusSicat, Sheena Marie        Pain Receptors   ‡   Meissners Corpuscle ‡   D endrites enclosed in CT in dermal papillae of hairless skin ‡   D iscriminative touch & vibration-- rapidly adapting ‡   Generate impulses mainly at onset of a touch   ‡   H air Root Plexus   y   F ree nerve endings found around follicles, detects movement of hair ‡   Merkels Disc ‡   F lattened dendrites touching cells of stratum basale ‡   Used in discriminative touch (25% of receptors in hands)      y   Ruffinis Corpuscle ‡   F ound deep in dermis of skin ‡   D etect heavy touch, continuous touch, & pressure     ‡   Pacinian Corpuscle o   O nion-like connective tissue capsule enclosing a dendrite o   F ound in subcutaneous tissues & certain viscera o   Sensations of pressure or high-frequency vibration    Spinal Trigeminal Tract  The spinal trigeminal tract involves Cranial Nerves V, VII, IX, X as primary neuron for thetract. The cell body of the receptive fiber is considered a psudounipolar type. These cell bodiesare localized in a ganglion, the trigeminal ganglion for CN V located in proximity to the pons; theGeniculate ganglion for CN VII, and the Superior ganglion for CN IX and X located near themedulla. Cranial nerves V, VII, IX, and X serve the cutaneous receptors of the face, the oral cavity,and the dorsum of the head except for the area served by the cervical nerves. In addition tocutaneous structures, the trigeminal nerve also innervates deep tissues, including thetemporomandibular joint, the meninges, and the peridontium. The primary sensory fibers of   these nerves have their cell bodies in the trigeminal ganglion, the geniculate ganglion of cranialnerve VII, and the superior ganglia of cranial nerves IX and X.The central processes of small and large trigeminal ganglion cells are part of the trigeminal sensory root, which attaches to the pons. The bifurcating small-diameter axonscourse posteromedially into the pontinetegmentum, sending an ascending branch to the principal sensory nucleus. The descending branch of these fibers joins with numerous otherunbranched small-diameter fibers to form a prominent fiber bundle in the posterolateralbrainstem, the spinal trigeminal tract  . Through the caudal pons and the rostral medulla, thistract is internal to the restiform body. However, in the lower medulla caudal to the obex, itforms a superficial landmark lateral to the cuneate tubercle, known as the trigeminal tubercle(tuberculumcinereum). This landmark served as a useful reference point for surgeons, whodiscovered that sectioning the spinal tract of the trigeminal nerve at this level (tractotomy)  provides substantial relief from facial pain on the operated side.In addition to the large contributions from the trigeminal nerve, small numbers of fibersconveying general somatic afferent information from the ear on cranial nerves VII, IX, and Xalso enter the spinal trigeminal tract and terminate in the spinal nucleus. The primary afferentneurons associated with cranial nerves VII, IX, and X have cell bodies in their respective ganglia,enter the medulla, and take a position adjacent to those of the mandibular division in the spinaltrigeminal tract.The peripheral distribution of the branches of the trigeminal nerve (V 1 , V 2 , and V 3 )delineates the facial dermatomes. Unlike the spinal segmental dermatomes, which partiallyoverlap, the boundaries between adjacent facial dermatomes are sharply defined. Thissegregation of trigeminal branches is maintained by their central processes in the spinaltrigeminal tract. An unfortunate clinical condition that illustrates the divisional pattern of thetrigeminal system is herpes zoster, or shingles. Patients with shingles have a characteristic rashthat outlines the affected dermatome or spinal cord segment; the ophthalmic or maxillarydivision is usually affected, and the rash is unilateralInjury to trigeminal nerve fibers produces a paresthesia restricted to specific regions of theface. The pain of  tic douloureux (trigeminal neuralgia) produces episodic paroxysmal painusually restricted to the peripheral distribution of the maxillary or mandibular division on oneside.The spinal trigeminal nucleus, located medial to the spinal tract, is the site of terminationfor fibers of the spinal trigeminal tract. O n the basis of cytoarchitecture, this nucleus is dividedinto a pars caudalis, a pars interpolaris, and a pars oralis. The caudal subnucleus (parscaudalis) extends from C2 or C3 rostrally to the level of the obex. This part of the spinal nucleus

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Nov 21, 2017
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