Neuro Tract Mini Study Guide PDF

Neuro Tract Mini Guide Dan Cutter Dorsal Column Medial Lemniscus Function: 2pt Touch, Vibration, Joint Position DCML is somatotopically arranged…This means that axons for the cervical spine are most medial and sacral axons are most lateral in spinal cord Sample Question: Patient presents with los...

Neuro Tract Mini Guide Dan Cutter Dorsal Column Medial Lemniscus Function: 2pt Touch, Vibration, Joint Position DCML is somatotopically arranged…This means that axons for the cervical spine are most medial and sacral axons are most lateral in spinal cord Sample Question: Patient presents with loss of 2pt touch, vibration, and Jt position on their right side. What side of what tract is malfunctioning? Left DCML if at level of Medulla or above, Right DCML if in Spinal cord. Crossing Point: Internal Arcuate Fibers Steps: 1. Cell bodies are located in the DRG. The axons will enter through the medial division. The axons will carry up the spinal cord either within the Fasiculus Gracilis (T6 and below) or the Fasciculus Cuneatus (T5 and above) 2. These axons will synapse on the cell bodies located in the cuneate or gracile nucleus and immediately cross over. 3. These axons will continue to the thalamus and synapse in the Ventral Sample Q: What Tract crosses in the Dorsal Medulla/ tegmentum Posterior Lateral nucleus of thalamus. of caudal medulla 4. Axons will then carry info to the by way of the internal cortex (post-central gyrus) A: DCML (think where the cuneate/gracile nuclei are) Neospinalthalamic Tract: Lateral part of A-L System Function: Sharp well localized pain and Temp. Part of ALS Crossing Point: Ventral White Commisure Steps: 1. Cell bodies are in the DRG. These will then enter the spinal cord via Lissauer’s Tract, axons may then ascend or descend 1-2 cord levels. These will then synapse in Lamina 1 (substantiated gelatinosa) or Lamina 5. 2. The 2nd order cell bodies will immediately cross and ascend the spinal cord to the Thalamus and synapse in the Ventral Posterior Lateral Nucleus. Q: How does the Neospinalthalamic tract enter the spinal cord? A: Via Lissauer’s Tract. 3. The 3rd order neurons will then ascend from the thalamus to the cortex. Bonus info: Neospinalthalamic tract is Somatotopically arranged. This is the “Newest” (Neo) and can be thought of as the most precise pain. These are like the new shiny car and will be FASTER traveling on the Alpha delta fiber types. Q: Patient stubs their toe, at first they have severe pain, their toe then goes a bit numb Function: Dull and Achy Pain and then it suddenly starts to ache. What tract accounts for Crossing point: Ventral White Comisure this 2nd pain? Steps: 1. Cell bodies are in the DRG. Axons will enter the spinal cord via Lissauer’s tract and Synapse in Answer: Paleospinalthalamic Tract lamina 7 and 8 Paleospinalthalamic Tract: Part of ALS Step 2. Secondary cell bodies in Lamina 7 and 8 will immediately cross at ventral white commissure and will ascend the spinal cord. As these axons ascend towards the thalamus, small fibers will branch off and synapse in the reticular formation. The main axons will synapse in the inter thalamic nuclei. NO SOMATOTOPIC ORGANIZATION Step 3: Cell bodies in inter thalamic nuclei will ascend to the cortex and spread out wide in the cortex including the motivational and emotional areas of pain Paleo means ancient (think cave man diet) So this tract is made of the slower axons C fiber axons, and the achy part of pain. Spinomesencephalic Tract Function: Reflexes for Visual, Auditory, and Cutaneous stimuli. Also will play a factor in pain modulation. Cross: at ventral white Commisure SpinalReticular Tract: b(Periaqueductal grey for pain managment) Superior Colliculus for visual reflexes Function: Sensation involving Consciousness and alertness in relation to dull or achy pain. This arouses the cortex to stay awake. (You get hurt and your body wants you to wake up and stay awake right? Whether it be to fight back, run away, or deal with the injury. Pain doesn’t make you sleepy) Crossing Point: Ventral White Commisure Steps: 1. Cell bodies in DRG and will synapse in lamina 1 or 2. 2. Cell bodies in lamina 1 or 2 will cross and ascend the spinal cord, passing through the raphe nuclei, and will synapse in the periaqueductal grey area or in the superior colliculus. I/L to medulla: M stands for Morning. Only need 1 to wake up in the morning Steps: 1. 1st Order are inside of the DRG, axons and will enter spinal cord via Lissauer’s Tract and synapse in Lamina 7 and 8. C/L to Potine and medulla. PM. If someone crosses me 2. Cell bodies in lamina 7 and 8 will when I’m tired in the PM I either cross or ascend ipsilaterally. I/L will wake up! fibers will go to the medullary reticular Part of ALS formation, C/L will go to Pontine and Part of ARAS Medullary reticular formation. Finally will Ascending reticular continue to intrathalamic nuclei, and activating system spread wide through the cortex. Dorsalspinocerebellar tract: Function: Unconscious Proprioception from trunk and lower extremity. DOES NOT CROSS Steps: 1. Starts in the DRG if between C8 and L3 will synapse on Clarke’s Nucleus in lamina 7. If below L3, will ascend via Fasciculus Gracilis and synapse on Clarke’s nucleus. 2. Following synapsing on Clarke’s Nucleus, 2nd order cell bodies will enter via inferior cerebellar peduncle into the Cerebellum. Q. What Tract has cell bodies located in Clarke’s nucleus? A. Dorsalspinocerebellar tract. l Ventralspinocerebellar tract Function: Unconcious Proprioception from trunk and lower extremity (may modulate descending tracts) Crossing point: 1st Ventral White Commisure 2nd: White matter of cerebellum. Steps: 1. Cell bodies in the DRG, axons enter the ventral horn to lamina 7 (NOT CLARKE’S NUCLEUS) and will synapse. 2. Cell bodies in lamina 7 will crossing ascend. These will enter into the SUPERIOR Cerebellar peduncle, and will then cross in the cerebellar white matter. Thus they will terminate on the same side they started. Q. Which of the tracts will enter through the superior cerebellar peduncle? A: Ventralspinocerebellar tract Q. Does the ventralspinocerebellar tract end I/L or C/L A. I/L these cross twice and R. Ventralspinocerebellar tract will end in the R part of cerebellum. Cuneorspinocerebellar tract: Function: Unconscious Proprioception from the upper extremity DOES NOT CROSS Steps: 1. Cell bodies in the DRG, axon will ascend via the Fasciculus Cuneatus up the spinal cord and synapse in the lateral/accessory cuneate nucleus. 2. Cell bodies in lateral/accessory cuneate nucleus will ascend and enter through the inferior cerebellar peduncle. Will then synapse in cerebellar cortex. Q. What tracts enter via the inferior cerebellar peduncle? A. Dorsalspinocerebellar and cuneospinocerebellar. t Spino-olivary Tract Function: Unconscious proprioception that will end in the cerebellum. Will be majorly involved in motor learning and corrections during movements. Crossing point: Crosses in ventral white commissure. Olivocerebellar will recross in tegmentum of the medulla. Steps: 1. Cell bodies are in the DRG. Will enter the spinal cord and will synapse in the spinal gray matter. 2. 2ndary cell bodies will then cross in the ventral white commissure and will ascend to the inferior olivary nucleus. THIS IS THE END OF THE TRACT A second tract now begins called Olivocerebellar that will cross and carry the information from the inferior olivary nucleus to the the cerebellum. Corticospinal Tract Function: Voluntary Skeletal movement Crosses at pyramidal Decussation Lesion before crossing (above medulla) C/L loss Lesion below decussation =I/L loss. Be familiar with signs of upper motor neuron lesion Ex. Clonus, babinski, hyperreflecia. Steps: from cortex, through corona radiata, internal capsule, crus cerebri, basal pons then 85 to 90% will cross at the pyramidal decussation (lateral corticospinal) 10-15% will remain uncrossed (Ventral CST) Following this will descend the spinal cord and exit to stimulate muscle. Upper motor neuron fibers will stimulate the interneurons that inhibit motor neurons. This is why lesion we see hyperreflexia! 1 Corticobulbar Tract Function Voluntary Skeletal Muscle to the face Corticobulbar will descend in the same way as the corticospinal tract and will then synapse on different nuclei that will allow for voluntary movement of muscles in the head/ neck. Be familiar with facial lesion pathology and the loss on only the lower portion of one side as a possible giveaway for a corticobulbar lesion. Pontinereticulospinal tract Medial part Medullaryreticulospinal tract: Lateral Part Function: Function: Stimulates Flexors and will inhibit extensors Facilitates axial and limb extensors and inhibits flexors influences movements of trunk and responding to stimuli These will descend from the medullary reticular formation and will terminate in the ventral white commissure. These will descend B/L these will primarily excite cervical and back muscles. Will descend from the pontine reticular formation and will terminate in the ventral horn. Will only descend I/L Both of these tracts will control and coordinate automatic movements that are related to posture and locomotion by modulating activity. ex. stabilize proximal its during distal movement. Lateral Vestibulospinal Tract Receives input from the cerebellum and from the ear. Will Descend uncrossed from the lateral vestibular nucleus to ventral horn Effects Antigravity Muscles (extensors) Help to maintain balance and staying upright. We can see this in all levels of spine. Special ones to think about are the suboccipital triangle muscles, as well as the erector spinae, Quads, glutes, and soleus. l Medial Vestibulospinal Tract Function : Maintain head position in response to vestibular nuclei (Tracking) This is also known as our Descending MLF. This tract will descend B/L and will terminate in both sides of the ventral horn. Since this tract is primarily used for tracking it will only be affecting/ found in the cervical and upper thoracic areas I like to think of this pair of tracts as being the baseball/ softball tract A player is in the outfield and there is a pop fly coming towards him. The player is going to be watching the ball with his eyes and follow the ball as he runs towards where it is going to land. While he is running he isn’t think about moving his head to follow it, his head is making slight adjustments as he moves in space to track ( this is all medial Vestibular tract). While running he must maintain his upright position to not fall flat on his face, and if he trips at all he must activate his extensors such as quads, glutes, erector spinae to catch himself from falling (lateral vestibulospinal tract) Rubrospinal Tract Function: Facilitates Flexor motor neurons and inhibits extensor motor neurons Starts from stimulation from cortex and cerebellum to the red nucleus This will cross at the ventral tegmental decussation. This tracts will descend down the cord and end in the upper cervical cord This will descend C/L 1 Helpful hint: I always remember this tract’s function by thinking of working out When someone does Bicep Curls (activates the flexor muscles of the arms) they are going to get RED in the face. Rubrospinal is coming from the Red nucleus! Tectospinal: Function: Reflexive head movements in response to visual or auditory stimuli. Will also be involved in head movements for tracking a stimuli. These will descend from the superior colliculus and cross in the DORSAL TEGMENTAL DECUSSATION These fibers will descend C/L and will synapse in the upper cervical areas. This tract will also be associated with the Medial Longitudinal Fasciculus the big difference is that it will be coming down from the superior colliculus, will be crossing in the dorsal tegmental decussation and will be associated with Reflexes! I like to call this one the “Scare Tract” While sitting at your desk studying, you see someone with an axe out of the corner of your eye, you get startled and turn your head and eyes to this person. (then if you tract this person as you run away that is medial Vestibular Tract).