ANAT2004 Neuroanatomy Week 7: Special Senses and Pathways - Flashcards

50 QA-style flashcards covering hearing, balance, vision, olfaction, and taste based on lecture notes.

Which special sense uses olfactory receptor neurons instead of a non-neural receptor compared to the others?

Olfaction (sense of smell)

The first cranial nerve involved in olfaction?

CN I (olfactory nerve)

The organ in the cochlea that contains hair cells and transduces sound vibrations into neural signals?

Organ of Corti

Name the four orders of neurons in the auditory pathway from CN VIII to the auditory cortex.

1) Dorsal/ventral cochlear nuclei; 2) Lateral lemniscus to inferior colliculus; 3) Medial geniculate nucleus; 4) Primary auditory cortex in the superior temporal gyrus.

What are the three auditory ossicles?

Malleus, incus, and stapes.

Which middle-ear muscle dampens the movement of the stapes?

Stapedius muscle (CN VII).

Which cranial nerve innervates the tensor tympani?

CN V (mandibular division).

What structural features of the middle ear increase the transmission of sound energy to the inner ear?

Lever action of the ossicles and a tympanic membrane area about 15 times larger than the oval window, increasing force per unit area.

What is the boundary between the middle ear and inner ear?

Oval window

What are the two windows of the cochlea?

Oval window and round window

Which nerve carries the auditory and vestibular information from the inner ear to the brain?

Cranial nerve VIII (vestibulocochlear).

What structure inside the semicircular canal detects angular motion?

Crista ampullaris

What detects gravity and linear acceleration in the vestibular system?

The otolithic membrane with statoconia (otoliths) in the utricle and saccule.

What is the vestibulo-ocular reflex?

A reflex that stabilizes gaze during head movement by producing compensatory eye movements.

Through which pathway do vestibular signals reach the extraocular muscles for the VOR?

Vestibular nuclei to CN III, IV, VI via the medial longitudinal fasciculus (MLF).

Which cranial nerves convey taste from the tongue?

CN VII (anterior 2/3 via chorda tympani), CN IX (posterior 1/3), CN X (epiglottis and other areas).

Where is the primary gustatory cortex located?

Insular cortex (gustatory area).

Name the three tunics of the eyeball.

Fibrous tunic, vascular tunic (uvea), and retina.

What photoreceptors are found in the retina?

Rods and cones.

Which structure controls pupil size?

Iris (dilation via sympathetic, constriction via parasympathetic).

Which nerve provides parasympathetic innervation to the sphincter pupillae and ciliary muscle?

CN III (oculomotor nerve).

What is the function of the ciliary body?

Contains the ciliary muscle and processes; changes lens shape via zonules (accommodation).

What attaches the lens to the ciliary body?

Zonules (suspensory ligaments).

What is contained in the photoreceptor outer segment?

Discs with photopigments; site of phototransduction in rods and cones.

First-order neurons of the auditory pathway run in which nerve?

CN VIII (vestibulocochlear).

Which thalamic nucleus relays auditory information to the cortex?

Medial geniculate nucleus (MGN).

Which retinal region provides the highest visual acuity?

Fovea centralis (within the macula lutea).

Trace the basic visual pathway from the retina to the primary visual cortex.

Retina → optic nerve → optic chiasm → optic tract → lateral geniculate nucleus → optic radiations → primary visual cortex (occipital lobe).

What crossing occurs at the optic chiasm?

Nasal retinal fibers cross to the contralateral side; temporal fibers stay on the same side.

What structure follows the optic chiasm in the visual pathway?

Optic tract

What fibers relay information from the LGN to the visual cortex?

Optic radiations (geniculocalcarine fibers).

Which papillae contain taste buds?

Vallate (circumvallate), fungiform, and foliate papillae.

Which papillae lack taste buds?

Filiform papillae.

What are the three epithelial cell types in a taste bud?

Supporting cells, gustatory receptor cells, and basal cells.

Which cranial nerves carry taste from the tongue?

CN VII (facial) via chorda tympani for anterior 2/3; CN IX for posterior 1/3; CN X for epiglottis and other areas.

Which nucleus receives gustatory information from CN VII, IX, and X?

Solitary nucleus (gustatory nucleus) in the medulla.

What structure covers the crista ampullaris?

Cupula.

What is the function of the cupula?

Gelatinous mass that bends hair cells in response to endolymph movement, signaling angular acceleration.

Name the two otolith organs of the vestibular apparatus.

Utricle and saccule.

Which cortex region is involved in the conscious perception of body orientation (vestibular sense)?

Parieto-insular vestibular cortex (PIVC).

Which tracts transmit vestibular information to the spinal cord for posture?

Vestibulospinal tracts.

Which thalamic nucleus receives vestibular input before cortical processing?

Ventral posterior nucleus of the thalamus.

Which eye structure provides the majority of refractive power?

Cornea (about two-thirds of refractive power).

What is the vascular tunic of the eye called?

The uvea (iris, ciliary body, choroid).

What is the function of the iris?

Regulates pupil size to control the amount of light entering the eye.

Which nerve supplies the levator palpebrae superioris for eyelid elevation?

CN III (oculomotor).

Which glands produce the oily layer of the tear film?

Meibomian (tarsal) glands.

Which enzyme in tears provides antimicrobial action?

Lysozyme.

Which nerve innervates the orbicularis oculi (blinking)?

CN VII (facial nerve).

What is the function of the lacrimal glands?

Produce tears that lubricate the eye and contain antimicrobial components.

Which tissue forms the white of the eye and is the tough protective outer layer?

Sclera (part of the fibrous tunic).

What is the term for the vascular layer of the eye that contains the iris, ciliary body, and choroid?

The uvea (vascular tunic).

What is the role of the cornea in refraction?

Provides about 2/3 of the eye's refractive power.

What is the optic disc?

The point where the optic nerve exits the retina; it is the blind spot with no photoreceptors.

Which nerve carries parasympathetic innervation to the lacrimal glands via the pterygopalatine ganglion?

Greater petrosal nerve (branch of CN VII).

Which layer contains photoreceptors and conducts neural signals in the retina?

Neural layer (inner retina) containing photoreceptors (rods and cones) and bipolar/ganglion cells.

Which layer of the retina contains melanin and supports photoreceptors in pigment production?

Pigmented (outer) layer of the retina.

What are the two main compartments of the anterior eye where aqueous humor circulates?

Anterior chamber and posterior chamber.

Which nerve innervates the levator palpebrae superioris and controls eyelid opening?

CN III (oculomotor).

Which cranial nerve controls pupillary constriction via the sphincter pupillae?

CN III (oculomotor) with parasympathetic input.

Which cranial nerve carries taste sensations from the anterior two-thirds of the tongue?

CN VII (facial) via the chorda tympani.

Where is the primary olfactory cortex located?

Temporal lobe (olfactory cortex/entorhinal cortex).

What is the direct route of olfactory signals from receptor to cortex?

Olfactory receptor neurons → olfactory bulb → olfactory tract → ipsilateral primary olfactory cortex.

What unique feature characterizes the olfactory pathway compared with other senses?

It does not pass through the thalamus or brainstem before cortex.

What can cause anosmia?

Colds, allergies, sinus infections, polyps, trauma, neurodegenerative diseases (e.g., Alzheimer’s, Parkinson’s).

Which nerve is associated with taste from the epiglottis?

CN X (vagus).

What is the main function of the macula in the utricle and saccule?

Detects linear acceleration and head position relative to gravity (otolithic function).

What is the major output pathway for balance and posture beyond the cortex?

The vestibulospinal tracts projecting to the spinal cord.

What is the thalamic nucleus for auditory input?

Medial geniculate nucleus.

Which structure receives input for balance and posture from the vestibular system to influence neck movements?

Vestibulocollic reflex pathway (via vestibular nuclei).

Which nerve is the vestibular component of CN VIII primarily associated with?

Vestibular nerve (branch of the vestibulocochlear nerve).

Which nerve provides motor innervation to the stapedius muscle and which nerve innervates the tensor tympani?

Stapedius: CN VII; Tensor tympani: CN V (mandibular division).

What is the role of the organ of Corti’s outer hair cells?

Amplify basilar membrane movement and modulate sensitivity of inner hair cells.

What permits accommodation of the lens during near vision?

Contraction of the ciliary muscle loosens zonules, rounding the lens.

What happens to the lens when the ciliary muscle relaxes?

Zonules tighten and the lens becomes flatter (less refractive power).

What are the two main layers of the retina called?

Pigmented (outer) layer and neural (inner) layer.

What is the function of the fovea?

Region of highest visual acuity with dense cone packing.

Which part of the ear is responsible for detecting the location of a sound in the horizontal plane?

The superior olivary complex (in the pons) contributes to sound localization.

What structure transmits tears from the lacrimal gland across the eye surface?

Lacrimal fluid (tears) spreads across the ocular surface; tears drain via the lacrimal puncta and canaliculi.

Which gland contributes to the tear film’s oily layer to reduce evaporation?

Meibomian (tarsal) glands.

What is the role of Bowman's glands and Goblet cells?

Mucus production to keep the conjunctiva and ocular surface moist.

What is conjunctiva and where is it located?

A mucous membrane lining the inner surface of the eyelids (palpebral conjunctiva) and covering the sclera (bulbar conjunctiva).

Which nerve supplies the orbicularis oculi for closing the eyelids?

CN VII (facial nerve).

Which structure contains the posterior boundary of the tympanic membrane and helps separate the middle ear from the cranial cavity?

The tegmen tympani (top boundary) and aditus to the mastoid antrum; the provided notes mention boundaries of the middle ear with parts like the tegmental wall.

Which nerve supplies taste to the anterior two-thirds of the tongue via the chorda tympani?

CN VII (facial) via chorda tympani.

What does the tympanic membrane do in hearing?

It vibrates in response to sound and transmits energy to the ossicles.

Where do the hair cells in the cochlea project their stereocilia?

They project into the endolymph fluid and bend in response to basilar membrane motion.

What is the primary visual cortex located?

Occipital lobe.

Which structure carries the first visual information from the retina to the brain?

Optic nerve (CN II).

Which structure acts as the boundary where the optic nerve exits the retina?

Optic disc (blind spot).

Which cranial nerve is involved in pupillary constriction and lens accommodation?

CN III (oculomotor).

What is the function of the choroid?

Nutrient supply to the outer retina and light absorption to reduce scattering.

Which neural pathway carries somatosensory information to the postcentral gyrus?

Not directly in this set; refers to primary somatosensory pathway (broad context).

What is the role of the medio-lateral organization in the thalamus for sensory processing?

Different nuclei relay different sensory modalities (e.g., MG for audition, LG for vision, VP for somatosensory/b vestibular).

What common cause can produce a temporary loss of smell related to viral infection?

Colds or COVID-19 (temporary olfactory dysfunction).

Which organ detects vertical motion and gravity in the vestibular system?

Saccule (and utricle for horizontal).

Which structure contains the spiral ganglion that houses sensory neuron cell bodies for the cochlear nerve?

Spiral organ/ganglion within the modiolus.

Which structure of the eye is transparent and contributes most to light refraction?

Cornea.

What is the primary role of the optic chiasm?

Crossing of nasal retinal fibers to the contralateral side, ensuring visual field information stays organized.

Which layer of the retina contains photoreceptors and transduces light?

Neural (inner) retinal layer containing rods and cones.