Week 9 General Senses and Cranial Nerves

1. Olfactory

S - smell

2. Optic

S - vision

3. oculomotor

M - moves the eye and focuse

4. Trochlear

M - moves eye

5. Trigeminal

B (both) - motor to facial expression and sensory to tear glands, saliva glands, and taste

6. Abducens

M - abduct eyeball

7. Facial

B - motor to facial expressions and sensory to tear glands, saliva glands, and taste

8. Vestibucolcochlear

S - Hearing and balance

9. Glossopharyngeal

B - pharyngeal muscles for throat, heart, intestines

10. Vagus

B - motor and sensory for throat, heart, intestines

11. Spinal Accesory

M - SCM and trapezius

12. Hypoglossal

M - tongue

General Senses

• touch, pressure, pain, stretch, etc

Special senses

• visual, hearing, smell, taste, and equilibrium

Exteroreceptors

• react to outside stimuli

Interoceptors

• react to internal stimuli

Proprioceptors

• internal skeletal or joint stimuli

Skin sensory are not evenly distributed, this is called punctuate distribution

Test: Two point test

Tactile Localization - different parts of the body have differing levels of accuracy

Test: Two marker test

Stimulus often reduce in intensity with high frequencies (Adaption)

Test: Adaptation tests

Referred pain - pain in one area is perceived in another

Test: Cold water test

External Ear Anatomy

• Auricle - the ear you know

• Lobule - earlobe

• External Acoustic Meatus - the bony hole

• Tympanic Membrane - Eardrum; it vibrates at the same time frequency of sounds to transfer them to the middle ear

Middle Ear Anatomy

• Malleus (hammer) - amplifies and transmits vibration

• Incus (anvil) - amplifies and transmits again

• Stapes (stirrups) - amplifies and transmits again

• Oval window - connection to inner ear and specifically the perilymph

• Auditory tube - it equalizes pressure (you pop this during takeoff)

Inner Ear Anatomy

• two parts: Bony Labyrinth and membranous labyrinth

• Each part has a bony and membranous part

• Cochlea (bony) and Cochlea duct (membranous)

  • Perilymph in the cochlea receives vibrations from the oval window

  • Endolymph on the cochlea duct receives vibration from the perilymph

  • Spiral Organs senses the vibrations

• Vestibule (bony) and Utricle/Saccule (membranous)

  • maintains static and linear equilibrium

• Semicircular canals (bony) and Semicircular ducts (membranous)

  • rotational equilibrium

Static/Linear Equilibrium

Maculae contain hair cells that move these small stones of otolith, which depolarize and hyper polarize depending on the position of the head

Rotational Equilibrium

The ampula contains hair cells that sense flow of endolymph in the semicircular canals. As endolymph moves the hairs on the ampula it conveys the feeling of rotation

Olfactory Sensory Neurons

Bipolar neurons that synapse in the olfactory bulb

Supporting cells

they support

Olfactory Stem Cells

They regenerate sensory neurons

Fungiform Papillae

found on most of your tongue

Foliate Papillae

V shape back of the tongue

Foliate Papillae

Side of the tongue

Sweet is activated by the _____

Presence of sugars

Sour is activated by _____

H+ ions

Salty is activated by ______

metal ions and Na+

Bitter is activated by ______

Alkaloids

Savory/umami is activated by __________

glutamate and aspartate