Special Senses Labs

Anatomy & Physiology 34B Lab
Exercises 24, 25 & 26 – Special Senses: Eye, Ear, Olfaction & Taste
I. Lab Objectives
A. Dissect a cow’s eye
B. Identify the structures of the eye, and conduct visual physiology activities
C. Identify the structures of the ear, and conduct hearing and equilibrium activities
D. Conduct activities related to senses of taste and smell
Lab 24 - Vision
I. Activities 1 & 2: Eye structures - identify on models (and eye slides, where applicable).
A. Fibrous tunic – sclera, cornea, scleral venous sinus (canal of Schlemm)
B. Vascular tunic – choroid, ciliary body with ciliary processes and ciliary muscle, iris, pupil,
lens, suspensory ligaments (ciliary zonules), ora serrata, central artery and vein.
C. Sensory tunic – retina (neural and pigmented layers), fovea centralis, macula lutea, optic
disc, optic nerve. Microscopic structures: photoreceptors, bipolar cells, ganglionic cells.
D. Chambers – posterior cavity, anterior cavity divided into anterior and posterior chambers
E. Lacrimal apparatus – lacrimal gland, lacrimal puncta, lacrimal sac, nasolacrimal duct
F. Extrinsic eye muscles – lateral, medial, inferior, and superior rectus muscles, as well as the
superior and inferior oblique muscles.
II. Cow Eye Dissection –follow the lab manual directions to dissect a cow’s eye. Identify the
following structures of the eye:
A. Fibrous tunic structures – sclera, cornea, conjunctiva
B. Vascular tunic structures – choroid, ciliary body, iris, pupil, lens
C. Sensory tunic structures – retina, optic disc, optic nerve
D. Chambers – posterior cavity with vitreous humor, anterior cavity with anterior and
posterior chambers containing aqueous humor.
E. Extrinsic muscle (remnants)
III. Activity 3: Microscopic Anatomy of the Retina – Examine an eye slide under the
microscope and identify the retina’s pigmented layer and nuclei of rods and cones, bipolar
cells, and ganglionic cells in the neural layer.
IV. Activities 4-12: Eye Physiology – work with a partner and follow lab manual directions to
perform these activities.
Homework – Answer the Review Sheet questions at the end of Lab 24.
Lab 25: Hearing and Equilibrium
I. Activity 1: Ear structures to identify on ear models (and cochlear slide, where applicable)
A. Outer ear – pinna (auricle), external auditory (acoustic) canal, tympanic membrane
B. Middle ear – malleus (hammer), incus (anvil), stapes (stirrup), Eustachian tube (aka
pharyngotympanic or auditory tube), tympanic cavity
C. Inner ear (bony and membranous labyrinth)
1. Semicircular canals – lateral, posterior, and superior, ampullae, and semicircular ducts
2. Vestibule - contains the utricle and saccule, oval (vestibular) window; vestibular nerve
emerges from the vestibule
3. Cochlea – round (cochlear) window, vestibular duct (scala vestibuli), cochlear duct
(scala media), tympanic duct (scala tympani), cochlear nerve, organ of Corti with hair
cells, basilar membrane, tectorial membrane, and vestibular membrane
4. Vestibulocochlear nerve (CN VIII).
II. Activity 2: Otoscopic ear exam – work with a partner and follow the lab manual instructions
to examine their ear with an otoscope.
III. Activity 3: Cochlear structures – examine a cochlea under the microscope and identify the
scala vestibuli, vestibular membrane, scala tympani, basilar membrane, cochlear duct,
tectorial membrane, receptor hair cells, cochlear nerve fibers.
IV. Activities 4, 5, and 7: Conduct lab tests of hearing and equilibrium.
V. Activity 6: Cristae ampullaris structures – examine this slide under the microscope and
identify the cupula, receptor hair cells, and vestibular nerve fibers
Homework – Answer the Review Sheet questions at the end of Lab 25.
Lab 26: Olfaction and Taste
I. Activity 1: Olfactory epithelium - examine the lab manual illustrations and compare to
microscope slide, if available.
II. Activity 2: Taste buds – look at your tongue in a mirror and locate the circumvallate, foliate,
and fungiform papilla. Next, view the lab manual diagrams of taste bud structures, and
compare to a microscope slide, if available.
III. Activities 3-6: Taste & Olfactory Physiology - perform these taste and smell investigations
with a partner.
Homework – Answer the Review Sheet questions at the end of Lab 26.