VPB 121: Veterinary Physiology - II (2+1)

MEDULLA OBLONGATA

• Located in the top of the spinal cord.
• Has centres that control reflectes activities such as respiration, heart rate, vaso dilation and blood pressure.
• Houses neural part ways that connect cerebral cortex and spinal cord
• The cranial nerves glosso-pharyngeal (IX), vagus (x), spinal accessory (xi) and the hypoglossal (xii) originate from the medulla.
• The nuclei gracilis‚ and cuneatus transmit the informations of the spinal cord to the somato sensory  regions  of the cerebral cortex through the thalamus.
• The nucleus gracilis and cuneatus give rise to fibres, which pass to the contralateral side and form the medial lemniscus; this medial lemniscus ascends to thalamus.
• The inferior olivary nucleus input signals to cerebellum. Within medulla there  are centres for cardiac, respiratory (inspiratory and expiratory), vasomotor, swallowing, vomiting, cough and  sneezing activities.
• Most of the tracts between the spinal cord and the higher levels of the brain pass through medulla.

• Ascending tracts: A portion of dorsal funiculus of the spinal cord terminates in accessory cuneate nucleus from which fibres project to cerebellum as external arcuate fibres. Other ascending fibre tracts of the medulla are spinothalamic, dorsal and ventral spinocerebellar, spino-olivary, spino-tectal tracts.
• Descending tracts: includes Vestibulo spinal, rubro spinal, tecto spinal tracts.