🧭 Sense of positioning → Proprioception
🧭 Proprioception is the body’s internal sense of position and movement without visual input.
🧭 Relies on muscle spindles, Golgi tendon organs, and joint mechanoreceptors sending signals to the CNS.
🧭 Integrated by the cerebellum to coordinate balance, posture, and smooth movement.
🧭 Impairment (e.g., peripheral neuropathy, B12 deficiency) leads to ataxia and falls; bedside tests include joint-position sense and Romberg.
👃 Sense of smelling → Olfactory
👃 Mediated by Cranial Nerve I (olfactory); receptors in the olfactory epithelium detect volatile chemicals.
👃 Signals project to the olfactory bulb and limbic system, linking smell with memory and emotion.
👃 Loss of smell (anosmia) follows URIs, head trauma, sinonasal disease, or neurodegeneration.
👃 Test with familiar, non-irritating odors (coffee/vanilla); avoid irritants like ammonia.
👂 Sense of hearing → Auditory
👂 Sound waves → tympanic membrane → ossicles → cochlea; transduced by the organ of Corti to CN VIII.
👂 Patterns of loss: conductive (e.g., cerumen, otitis) vs sensorineural (presbycusis, ototoxic drugs).
👂 Screening includes whisper test, Rinne/Weber, and audiometry for thresholds/frequencies.
👂 Prevention: hearing protection for ≥85 dB environments; review ototoxic medications.
👅 Sense of tasting → Gustatory
👅 Detects sweet, salty, sour, bitter, umami via taste buds; carried by CN VII, IX, X.
👅 Saliva dissolves tastants; olfaction strongly augments perceived flavor.
👅 Aging and polypharmacy cause hypogeusia; common culprits: ACE inhibitors, metformin, anticholinergics.
👅 Nursing: optimize oral hygiene, hydration, use herbs/acid/umami (not excess salt); consider zinc assessment.
👀 Sense of seeing → Sight (Vision)
👀 Light focuses on retina; rods (dim light) and cones (color/acuity) send signals via CN II.
👀 Eye movements/pupil control via CN III, IV, VI; assess Snellen, visual fields, PERRLA, EOMs.
👀 Common changes: presbyopia, cataracts, glaucoma, age-related macular degeneration (AMD).
👀 Support with bright, non-glare lighting, high-contrast cues, fall-prevention strategies, and timely ophthalmology referral.