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Spinal Tracts
Sensory and Motor components associated with ascending and descending pathways
Question | Answer |
---|---|
Ascending Tracts | Sensory pathways providing the cerebral cortex and brainstem with information from throughout the body. Dorsal Columns (medial lemniscal), Anterolateral Columns (Spinothalamic, half of the Spinocerebellar tracts and the Spinoreticular tracts) |
Dorsal Columns | Carry proprioception, vibration, and tactile discrimination information. Fibers cross over in the Medulla. Dorsal portion of Spinocerebellar tract also conveys proprioception from muscle spindles. |
Anterolateral: Anterior | Anterior Spinothalamic carries crude touch and crosses over at the level of the spine. Anterior portion of Spinocerebellar tract conveys proprioception from muscle spindles. Spinoreticular tracts are polysynaptic tracts also in lateral pathways. |
Anterolateral: Lateral | Lateral Spinothalamic tract carries pain and temperature.. Spinoreticular tracts are polysynaptic tracts dispersing through the reticular formation to spread pain and emotional arousal. Reticular formation at the level of the pons/medulla. |
Descending Tracts | Motor pathways containing: Corticospinal, Vestibulospinal, Rubrospinal, Reticulospinal and Tectospinal tracts. |
Corticospinal Tract | Lateral and Anterior. Carries voluntary motor control and crosses over in the medulla. |
Vestibulospinal Tract | Lateral (and medial) aides voluntary movement through muscle tone and postural reflexes. |
Rubrospinal Tract | Not a cortical tract, but one that terminates at the red nucleus housed in the midbrain. Assists in motor function and produces the decorticate posture in response to painful stimuli: ext of lower extremities and flex of upper extremities. |
Reticulospinal Tract | Not a cortical tract, but one that terminates in the recticular formation between the pons and medulla. Influences motor neurons and spinal reflexes. Also produces the decerebrate posture in response to pain: Ext of LE and Ext of UE (wrist flex) |
TectoSpinal Tract | head turning response to visual stimuli |
Types of Nerve fibers | Alpha, Beta, Gamma, Delta (1, 2 ,3 for conduction speed) |
Senses carried by Alpha | Proprioception (Primarily Dorsal pathways) & somatic motor (anterior and lateral) |
Senses carried by Beta | Touch (crude and discrimination = anterior and dorsal pathways & pressure (anterior?) |
Senses carried by Gamma | Motor to muscle spindles |
Senses carried by Delta | pain/temperature/touch (mainly anterior) |