Neuroanatomy and Sensory Pathways: Cranial Nerves, Eye, Ear, and Cortex

Which cranial nerve carries olfaction (smell)?

CN I (Olfactory)

Which cranial nerve carries vision?

CN II (Optic)

Which cranial nerves carry taste?

CN VII, CN IX, CN X

Which cranial nerve carries hearing and balance?

CN VIII (Vestibulocochlear)

Differentiate the olfactory nerve, bulb, and tract.

Olfactory nerve is outside the skull; bulb and tract are inside the skull.

Do olfactory neurons regenerate?

Yes

Does olfactory information relay through the thalamus?

No

Where does olfactory information project in the cortex?

Primary olfactory cortex (temporal lobe)

Which papillae contain taste buds?

Fungiform, foliate, circumvallate

Which papillae do NOT contain taste buds?

Filiform

Which cranial nerve carries taste from the anterior 2/3 of the tongue?

CN VII (Facial)

Which cranial nerve carries taste from the posterior 1/3 of the tongue?

CN IX (Glossopharyngeal)

What are the three tunics of the eye?

Fibrous, vascular, neural

What structures make up the fibrous tunic?

Sclera and cornea

What do the sclera and cornea have in common?

Both are part of the fibrous tunic

What is different about the cornea compared to the sclera?

Cornea is transparent and allows light entry

What structures make up the vascular tunic?

Choroid, ciliary body, iris

What are the components of the ciliary body?

Ciliary muscle and ciliary processes

What is the function of the ciliary muscle?

Changes lens shape for accommodation

What type of tissue is the iris and what is its function?

Smooth muscle; controls pupil size

How many layers of neurons are in the retina?

Three layers

What is the difference between rods and cones?

Rods: low light, black and white; Cones: color and high acuity

What are the macula lutea and fovea centralis?

Macula lutea contains the fovea; fovea is the area of highest visual acuity

What is the blind spot?

Area where the optic nerve exits the retina; no photoreceptors

Trace the route of light through the eye.

Cornea → aqueous humor → lens → vitreous humor → retina

Trace the visual pathway from retina to cortex.

Retina → optic nerve → optic chiasm → optic tract → LGN → visual cortex

Which thalamic nucleus relays vision?

Lateral geniculate nucleus (LGN)

What are the three divisions of the ear?

External, middle, inner ear

What are the three ossicles in order (external to internal)?

Malleus → incus → stapes

Are there muscles in the middle ear? What do they do?

Yes; dampen sound vibrations

Which cranial nerve innervates middle ear muscles?

CN V and CN VII

What are the three main areas of the inner ear?

Cochlea, vestibule, semicircular canals

Trace the route of sound from eardrum to basilar membrane.

Tympanic membrane → ossicles → oval window → basilar membrane → round window

Trace the auditory neural pathway.

Hair cells → spiral ganglion → cochlear nuclei → thalamus (MGN) → auditory cortex

Which thalamic nucleus relays hearing?

Medial geniculate nucleus (MGN)

What is the difference between static and dynamic equilibrium?

Static: head position; Dynamic: head movement

What sensory structure is found in semicircular canals?

Crista ampullaris

What is the cupula?

Gelatinous structure covering hair cells in semicircular canals

What sensory structures are found in the utricle and saccule?

Maculae

Trace the vestibular pathway.

Vestibular organs → vestibular ganglion → vestibular nuclei → thalamus → vestibular cortex

What modality is relayed through the lateral geniculate nucleus?

Vision

What modality is relayed through the medial geniculate nucleus?

Hearing

List the parts of the diencephalon.

Thalamus, hypothalamus, epithalamus, subthalamus

What is the thalamus and where is it located?

Major sensory relay nucleus located in the diencephalon

Which sense does NOT pass through the thalamus?

Olfaction

What are the main functions of the hypothalamus?

Homeostasis, autonomics, endocrine control

What types of information are sent to the hypothalamus?

Neural and hormonal signals from brain and body

How many layers make up the cerebral cortex?

Six layers

What is the main cell type of the cerebral cortex?

Pyramidal neurons

Is the cortex uniform throughout?

No, it varies by function

What is the functional unit of the cerebral cortex?

Cortical column

What fibers connect the right and left cerebral hemispheres?

Commissural fibers (corpus callosum)

What fibers connect the cerebrum to the brainstem and spinal cord?

Projection fibers

What fibers connect different gyri or lobes within the same hemisphere?

Association fibers

What is the main function of the amygdala?

Emotion, especially fear and threat processing

Which part of the amygdala is associated with the olfactory bulb?

Corticomedial nuclei

Which part of the amygdala is associated with the cortex?

Basolateral nuclei

What is the main function of the hippocampal formation?

Memory formation and consolidation

What are the three components of the hippocampal formation?

Hippocampus, dentate gyrus, subiculum

Name the layers of the hippocampus and dentate gyrus.

Molecular layer, granule cell layer, polymorphic layer