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Flashcards in Brainstem Tracts Flashcards Lower Deck (69)
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What is the Nucleus Gracilis?

The nucleus gracilis is the termination of the dorsal columns (vibration, well-localized touch/pressure) from the lower limbs (the fascicullus gracilis). It is the origin of the medial lemniscus.


What is the Fasciculus Gracilis?

The fasciculus gracilis is a tract (part of the dorsal columns) that contains the central process of large-diameter primary sensory nerve fibers conveying vibration sense, well-localized touch and conscious proprioception from the legs.


What is the Fasciculus Cuneatus?

The fasciculus cuneatus is a tract (part of the dorsal columns) that contains the central process of large-diameter primary sensory nerve fibers conveying vibration sense, well-localized touch and conscious proprioception from the arms.


What is the Nucleus Cuneatus?

The nucleus cuneatus is the termination of first order sensory fibers conveying well-localized touch, vibration & conscious proprioception from arms (the fascicullus cuneatus). It is the origin for many of the internal arcuate fibers that comprise the medial lemniscus.


What is the Spinal Tract of the Trigeminal?

The spinal tract of the trigeminal nerve contains first order trigeminal sensory fibers conveying pain and temperature from the ipsilateral side of the face. This tract descends the brain stem to the lower medulla and upper spinal cord.


What is the Spinal Nucleus of the Trigeminal?

The spinal nucleus of the trigeminal receives pain and temperature information from the ipsilateral side of the face via the spinal tract of V. It relays information via the ventral trigeminothalamic tract to the contralateral VPM of thalamus.


What is the Lateral Corticospinal Tract?

The lateral corticospinal tract arises in the precentral (motor) cortex and consists of nerve fibers (upper motor neurons) involved in control of skilled movements, particularly of the distal limbs.


What is the Central Gray Matter?

The central gray extends through the brainstem and is invloved in autonomic reflexes and pain control mechanisms.


What is the Central Canal?

The central canal is the remnant of the neural tube, connects the third ventricle to the 4th ventricle & contains CSF. It passes through the midbrain.


What is the Pyramidal Decussation?

The pyramidal decussation is the location that nerve fibers in the medullary pyramid cross to enter the lateral corticospinal tract. It can be seen n the ventral surface of the brain at the spinomedullary junction.


What is the Medial Longitudinal Fasciculus?

The MLF contains ascending fibers from the vestibular nuclei and eye movement areas (i.e., PPRF) and descending fibers from the superior colliculus (tectospinal), vestibular nuclei (medial vestibulospinal) and reticular formation (pontine reticulospinal) to the cervical spinal cord.


What is the Medullary Pyramid?

The medullary pyramids are ridges located on either side of the midline on the ventral side of the medulla, containing fibers of the corticospinal tract.


What is the Ventral Horn?

The ventral horn contains the motor neurons for upper cervical nerves.


What are the Medullary Reticulospinal and the Lateral Vestibulospinal Tracts?

The medullary reticulospinal & Lateral vestibulospinal tracts descend the spinal cord in the area between the ventral funiculus and lateral funiculus. These tracts go to all spinal levels and are involved in regulating muscle tone. The lateral vestibulospinal tract particularly activates extensor motor neurons.


What are the Spinal Accessory Motor Neurons?

This is the location of the neurons (lower motor neurons) of the spinal accessory nerve to the trapezius and sternocleidomastoid muscles.


What is the Ventral Spinocerebellar Tract?

The anterior (ventral) spinocerebellar tract arises in the intermediate gray matter of the spinal cord, crosses in the anterior white commissure of the spinal cord, ascends in the ventral part of the lateral funiculus and joins with the superior cerebellar peduncle where it re-crosses.


What is the Spinothalamic Tract?

The spinothalamic tract contains the nerve fibers arising in the substantia gelatinosa that convey pain and temperature sensation from the contralateral side of the body. It will terminate in the thalamic VPL.


What is the Rubrospinal Tract?

The rubrospinal tracts consist of nerve fibers arising in the red nucleus, crossing in the ventral tegmental decussation and descending to all levels of the spinal cord. They primarily control proximal flexor muscles of the limbs.


What is the Dorsal Spinocerebellar Tract?

The posterior (dorsal) spinocerebellar tract is a tract conveying muscle stretch and tension information from the lower portion of the body. It begins in neurons of the nucleus dorsalis (of Clarke) and projects through the inferior cerebellar peduncle to the cerebellum. It ends somatotopically in the spinocerebellum.


What is the Reticular Formation?

The reticular formation is a large area of (phylogenetically) ancient brain that represents and integrating center for behavioral and autonomic responses. It regulate muscle tone, contains centers for respiration and cardiovascular control and many neurons that participate in routine activities such as gait, regulation of muscle tone and patterning of complex reflexes (such as cough, sneeze, vomiting, etc)


What is the Nucleus Ambiguus?

The nucleus ambiguus is a difficult to define nucleus that contains the motor neurons to muscles of the pharynx, larynx and palate and that are contained in the CNIX, CNX and the cranial part of CNXI (which, in humans, travel in CNX).


What are the Internal Arcuate Fibers?

Internal arcuate fibers are decussating second order sensory fibers arising from neurons in the dorsal column nuclei (nucleus cuneatus and gracilis). These fibers will terminate in the VPL of the thalamus and convey well-localized touch, vibration and joint position sense.


What is the Hypoglossal Nucleus?

The hypoglossal nucleus contains motor neurons for the hypoglossal nerve.


What is the Dorsal Motor Nucleus of the Vagus Nerve?

The dorsal motor nucleus of the vagus nerve contains parasympathetic motor neurons for the vagus and glossopharyngeal nerves. It is rostrally continuous with the salivatory nuclei, which sends fibers into CNIX and CNVII.


What is the External (Lateral) Cuneate Nucleus?

The external (lateral) cuneate nucleus consists of a group of neurons that receive proprioceptive (muscle stretch and tension) information from the upper limb and give rise to a tract (cuneocerebellar tr.) that courses through the ipsilateral restiform body to the spinocerebellum.


What is the Inferior Olivary Nucleus?

The inferior olivary nucleus is the origin for all cerebellar climbing fibers. This is a relay that receives input from all areas of the motor system (from cortex to spinal cord) and relays this to the cerebellum. Heavily involved in coordination of voluntray movements.


What is the Arcuate Nucleus?

The arcuate nucleus is a collection of cells in the pyramid that relay nerve fibers to the cerebellum.


What is the Solitary Nucleus?

The solitary nucleus (nucleus tractus solitarius) is the nucleus of termination of visceral afferent fibers (baroreceptor, chemoreceptor, etc.) in CNX and CNIX. Rostrally, it is continuous with the gustatory nuclei (termination of taste from CNVII and CNIX). It surrounds the solitary tract.


What is the Solitary Tract?

The solitary tract (tractus solitarius) contains visceral afferent fibers (baroreceptor, chemoreceptor, taste etc.) in CNVII, CNX and CNIX on their way to the solitary nucleus.


What is the Inferior Cerebellar Peduncle?

The inferior cerebellar peduncle (restiform body) is a bundle of fibers connecting the medulla to the cerebellum, through which olivocerebellar, vestibulocerebellar and almost all spinocerebellar fibers enter the cerebellum. Some projections from the fastigeal nucleus of the cerebellum reach the brainstem through this peduncle.