7/31/2019 Neuro - 8-3-09 Somatosensory

1/3

Neuro 8-3-09 Somatosensory/Ascending systems and special systemsPicture in the book!

Fasiculus cuneatus Fasiculus gracilis Posterior spinocerebellar tract Lateral corticospinal tract Bulboreticulospinal tract

Rubrospinal tract Anterior spinocerebellar tract - receptors Lateral spinothalamic tract more medial than posteroior and anterior spinothalamic tract Anterior reticulospinal tract Medial reticulospinal tract Anterior spinothalamic tract Anterior corticospinal tract

German sounding receptors (Messiner)more superficial then the Italian receptors (pacinian)Face is your benchmark when you are tested for pain. Go on the face and ask if dull or sharp, usually sharp thencompare to other areas of the body. Go to the more distal ends of the extremities such as the big toe or dorsum of thethumb. If the pain on the ends are the same then no problem. Pain is a subjective phenomenon.To get the sensory level. Start from the area with no sensation to the area with sensation. To go from area of lowerchest to the area of the upper chest. Tuning fork best on the toe in the lower extremities.

Spino cerebellar enter from spinal chord to the cerebellum. The 3 functions of the cerebellum are for unconsciousprorprioceptor

1. Spinocerebellum enter the vermis truncal ataxia if compromised

Review Rexted Lamine. Dorsal horn has XVII is where the intermedial lateral chord in the ventral horn.Posterior spinocerebellar spans from C8 to L2 neurons go into the tract and ascend into the restiform body and inferiorcerebellar presynaptic to the vermis.Anterior spinocerebellar has the cuneatus in the medulla into the superior peduncle into the vermis as well.Posterior Column-Medial Lemniscal system Look for the tract in the book goes into the VPL of the thalamus and does 2point discrimination

Dorsal column pathways

Anterolateral system goes to dorsal horn and crosses to opposite side at the level of the spinal chord for the lateralspinothalamic tract. Anterior commissure has rexed lamina X. For light touch. Has a catch: for pain and temperaturemostly ascend 1-2 levels before join the dorsal horn unlike other sensations that go directly to the dorsal horn. Areas

that caps the dorsal horn is the leshower zone that makes the ascending of the levels for pain and temp. The clinicalsignificance causes higher sensation on the right site. The second catch is Topographic localization within the dorsalcolumns and the spinothalamic tract. A lamination for the pathways, the most medial is the fasciculus gracilis. Thecortico spinal tract if there is a cervical lesion then patients has paraparesis

Spinocerebellar pathways Both for unconscious proprioception. Difference in the posterior receptors in muscle,tendon, and trunk that enters the cerebellum via the restiform body. The anterior is different because it only uses the

7/31/2019 Neuro - 8-3-09 Somatosensory

2/3

golgi tendon organ and goes through the cuneus cerebellar tract. If a lesion then truncal ataxia. Receptors in the musclespindles change as reguard to the muscle, the stretch receptors with the flower spray ends. The golgi receptors are inthe tendon area.

Nociceptive (pain fiver typesAcute painC fiber burning pain unmylinated

Classical muscle receptors.Muscle spindles ascend to the proprioceptors

Descending noncieptive inhibitory

Ascending input. Ascending pathway.

Pain is not as simple as an ascending pathway because there are decending modulatory pathways that are opioidreceptors.

Dermatomes t4 is the most popular. There is no C1 dorsal root ganglion.

Stretch receptors. The visceral fibers use the same glanglion and enter about the same ganglion- refererred and visceralpain.Prinicipal dermatimes for referred painC3-c4 diaphram.

AbnormalitiesBrown

Dystal symmetric polyneuropathy usually with diabetes, distal segments of the axons degrade causing stocking andglove abnormalities.

Usualy dx tests:- Emg-ncv- Somatosensory evoked potentials*- Nerve biopsy- Skin biopsy

*Pitfall: may not reflect entire nerve fiber population as these tests may be sensitive for large diameter nervefibers only.

Epidermal nerve fibers

Noncicepitive vs neuropathic pain statesPain from a stimulus from outside of the systemProportional to the stimulation of the receptorsAcute serves as a protective

Signs and symptoms of neuropathic pain

7/31/2019 Neuro - 8-3-09 Somatosensory

3/3

DysesthesiasParathesiasSpontaneous pain

Spimulis evoved allodyna

Trigeminal nerve of the face there are 5 lines that delineate them.

Primary, secondary, and tertiary trigeminal afferents.Trigeminal neuralgiaLateral medullary syndrome swallowing difficulty.Special sense start with taste in ant 2/3 of tounge facial nerve called the tympany nerve through the gustatory nucleusof the facial nerve. Goes to the 9 th cranial nerve

Primary gustatory cortex.

Smell/olfaction the cribiform plate in the ant skull the olfactory fibers pierce the cribiform then goes to the olfactorytract and nerves to the bulb to the tract that divides into the medial and lateral stria lateral is for the bad smells.

Meningoma compressive tumor in the area if the olfactory track so loose smell and have behavioral disturbances. Somany olfactory tests for parkinsons because first sense to disappear when the disease occurs

Visial optic nerve the temporal fibers go ipsilateral to the lateral geniculate to the 17, 18, 19 th area of the cerebralcortex. Temporal fibers for nasal vision?Superior quadratic lobe a lesion of the ?

Vestibular cochlear nerve has many pathways which some enter the spinal ganglion from the dorsal coclear nucleusgoes to ascend or to the ventral nucleus to go into the inferior colliculus then to the temporal lobe. Some fibers enteripsilaterally or some ascend. Only time loss of hearing if a lesion outside of the spinal chord such as a ganglion.

Vestibular disturbancesVertigo: Illusory disturbance of motion.Nystagmus: Oscillatory eye movementsDisequilibrium: postural imbalance

Dolls head phenomenon. Brain stem is intact.