University:
Kentucky State University
Course:
BIO 301 | Human Anatomy
Academic year:

2019
Views:

118

Pages:

14
Author:

SataTalluctft9

Posterior White Column-Medial Lemniscal Pathway • Modality: Discriminative Touch Sensation (include Vibration) and Conscious Proprioception Receptor: Most receptors except free nerve endings Ist Neuron: Dorsal Root Ganglion 2nd Neuron: Dorsal Column Nuclei (Nucleus Gracilis and Cuneatus) ---Internal Arcuate Fiber Lemniscal Decussation ---Medial Lemniscus 3rd Neuron: Thalamus (VPL) Internal Capsule ----- Corona Radiata Termination: Primary Somesthetic Area (S I) • • • • • Posterior White Column-Medial Lemniscal Pathway Discriminative touch, vibratory sense, and conscious muscle-joint sense •Posterior Column tract consists of: •Fasciculus gracilis •Transmits information coming from areas inferior to T6 •Fasciculus cuneatus •Transmits information coming from areas superior to T6 Posterior Columns Midbrain Nucleus gracilis nucleus cuneatus Medial lemniscus Medulla oblongata Fasciculus cuneatus fasciculus gracilis Fine-touch, vibration, pressure, and proprioception sensations from right side of body 46 Primary Somatosensory (SI) Cortex Axons from third-order thalamic neurons terminate in the primary somatosensory (SI)cortex subdivided into four distinct areas; from anterior to posterior, these are Brodmann areas 3a, 3b, 1, and 2 Area 3a: muscle spindle afferents (mainly) Area 2: Golgi tendon organs, and joint afferents (mainly). Areas 3b and 1: They receive cutaneous afferents from receptors such as Meissner corpuscles and Merkel cells). also receive input from cutaneous receptors that transmit pain and temperature Lateral inhibition The receptor at the site of most intense stimulation is activated to the greatest extent. Surrounding receptors are also stimulated but to a lesser degree The most intensely activated receptor pathway halts transmission of impulses in the less intensely stimulated pathways through lateral inhibition This process facilitates the localization of the site of stimulation 49 lateral spinothalamic tract • • • • • • Modality: pain and temperature Receptors: free nerve endings 1st Neuron: Dorsal root ganglia Ventral 2nd Neuron: the posterior gray nuclei in column (substantia gelatinosa) thalamus The axons of 2nd order neurons cross obliquely to the opposite side in the anterior gray and white commissures , ascending in the contralateral white column as the lateral spinothalamic tract 3rd Neuron: Thalamus (VPL) Lateral spinothalamic Internal Capsule ----- Corona tract Radiata Termination: Primary Somesthetic Area (S I) and Widespread Cortical Region Pain and temperature Midbrain sensations from right side of body Rexed laminae • • • • • • Lamina 1 relay information related to pain and temperature Lamina 2: relay information related to pain and temperature (pain modulation) Lamina 3 and 4: nucleus proprius; these laminae have many interneurons Lamina 5: relay information related to pain and temperature Lamina 6: presents only at the cervical and lumbar enlargements and receives proprioception Lamina 7: Intermedio-lateral nucleus, contains preganglionic fibers of sympathetic (T1 -L2). Intermedio-medial nucleus ,all over the spinal cord, receive visceral pain. Dorsal nucleus of Clark’s presents at (C8 – L2 or T1L4) , relay center for unconscious proprioception lateral spinothalamic tract • • Lamina 1+ 5: the spinothalamic tract ascend which transmit pain, temperature and touch. (A delta fibers) Lamina 1+ 2: the spinothalamic tract ascend (C fibers). Posterolateral tract of Lissauer • located between the posterior white column and the lateral white column Other Terminations of the Lateral Spinothalamic Tract • Reticular formation: (majority of the slow pain fibers) individual becomes aware of the pain • Cingulate gyrus: interpretation of the emotional aspect of pain • Insular gyrus: concerned with the interpretation of pain stimuli from the internal organs of the body and brings about an autonomic response thalamus reticular formation

Posterior White Column

of 14

Description

Free up your schedule!

Take 5 seconds to unlock