Question

What are major sensory deficits resulting from damage along this primary sensory pathway? EXplain and give examples in your own words.

Answer 1

Introduction - The primary sensory pathway is a pathway through which all primary sensation like smell ,touch ,taste ,hear and sight travel to brain ' s different area . The primary sensory pathway also known as somatosensory pathway which is made up of three types of neuron which are located in 1) dorsal route ganglion ,2) spinal cord 3) thalamus. And the main neuron are of primary , secondary ,and tertiary neurons . One of the major pathway is dorsal column -middle lemniscus pathway .

Defects occurs due to loss of any neuron , ganglion or receptor . Major defect is formation of lesions along the pathways either in ascending pathway or motor or descending pathways .

Some major sensory defects are listed below ,

1) Vision loss == this classified as normal vision loss ,low vision loss and complete blindness . Two most significant cause of vision loss due to sensory failure are a) media opacity and b) optic nerve disease . Now media opacity occur due to presence of opacities in eye or fluid of eye which further bolcks image before it reaches to retina of eye . Optic nerve disease include optic neuritis or retrobulbar neuritis which causes distortion of afferent pathway of vision signal .

2) Somatosensory loss == it's a complexe system made of different types of receptors like thermoreceptors , mechanoreceptors , chemoreceptors and nosirecptors . Any damage to these recptors caused by paralysis makes patients unable to feel any of these primary sensation . Damage to spinal cord or any pathway causes termination of afferent and efferent signals to various area of body which further leads to loss of sensory and motor coordination of body .

3) Hearing loss == variable degree of hearing loss occur depending on exposure to harmful frequency of sound ,most common sensory loss of hearing is due to long term exposure of high frequency noise which damages machanoreceptors responsible for hearing sensation .

4) Anosmia == it's an inability to smell or lack of olfaction . Any damage to olfactory receptor neuron s leads to permanent loss of olfactory sensation , mostly seen in brain injury .

5) Ageusia == it's a loss of taste sensation , the person becomes unable to feel various taste like salty ,sweet ,sour etc. This mostly happen due to any damage of lingual nerve or glossopharyngeal nerve . Other causes include damage (severe) of taste buds .