ch21 short version
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CHAPTER 21Special Senses
Principles of
Human Anatomy 12th Edition
Gerard J. Tortora
&Mark T. Nielsen
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Olfaction: Sense of Smell
Olfactory epithelium
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The Olfactory Pathway
Olfactory (I) nerves Olfactory bulbs
Olfactory tract
Olfactory sensations are the only sensationsthat do what?
The axons of the olfactory tract project to the
primary olfactory area; located at the inferiorand medial surface of the temporal lobe
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Olfactory Pathway
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Gustation
Five primary tastes
Sour
Sweet
Bitter
Salty
Umami
All other tastes are combinations of these five
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Anatomy of Gustatory Receptors The receptors for taste are located in the taste buds,
and the number of taste buds declines with age
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Taste Buds
Taste buds are found in elevations on the
tongue called papillae
Three types of papillae contain taste buds
Circumvallate (vallate)
Fungiform papillae
Foliate papillae
Filiform papillae Clinical connection: taste aversion
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The Gustatory Pathway
Three cranial nerves contain axons ofsensory neurons from taste buds
Facial (VII)
Glossopharyngeal (IX) Vagus (X)
From taste buds, impulses propagate along
these cranial nerves to the gustatory nucleus
in the medulla oblongata
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Accessory Structures of the Eye:
Eyelids
Eyelids, or palpebrae
Levator palpebrae superioris muscle
Palpebral fissure Lateral commissure, and the medial
commissure
Lacrimal caruncle
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Vision: Accessory Structures of the Eye
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Visual Pathway
in the Brain
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Visual Pathway
in the Brain
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Hearing and Equilibrium
Anatomy of the ear The ear is divided into three main regions
External ear
Middle ear Internal ear
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The External Ear
The external ear consists of several
structures
Auricle (pinna)
External auditory canal Tympanic membrane
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Anatomy of the Ear
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The Middle Ear
The middle ear is a small, air-filled cavity inthe temporal bone that is lined by epithelium
Auditory ossicles
Three ossicles: malleus, incus and stapes The head of the malleus articulates with the
incus
The incus articulates with the stapes and thefootplate of the stapes fits into the oval
window (fenestra vestibuli)
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Internal Ear (Labyrinth) Structurally, there are two main divisions - the
outer bony labyrinth that encloses an innermembranous labyrinth
Three main areas Semicircular ducts
Vestibule
Cochlea - receptors for hearing
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Internal Ear
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Internal Ear
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Auditory Pathway
Spiral ganglia
medulla
Decusssion
Midbrain
Pons
Thalamus
cortex
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