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Chapter 20

The Special Senses

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Chapter 20 The Special Senses

Introduction to Special Senses

Humans have five special senses—vision, smell, taste, hearing, and equilibrium. All these senses have anatomically distinct receptors to detect …

Accessory Structures of the Eye

The accessory structures of the eyes protect and support the eye but are not directly involved in vision. Eyebrows, …

Anatomy of the Eyeball

The eyeball is a hollow fluid-filled structure composed of three layers—the fibrous, vascular, and inner layers. The superficial fibrous layer has …

Focusing of Light in the Eye

In a normal human eye, as light rays enter, they bend at the cornea, and the lens, to form an inverted image on the retina. The extent to which rays …

Photoreceptors and Visual Pathways

The retina contains two major types of photoreceptors— rods and cones. Their inner segment, which contains most cell organelles, is situated in the …

Olfactory Receptors: Location and Structure

The olfactory organ is situated on the roof of the nasal cavity. It covers the superior nasal concha on each side of the nasal septum. It consists of the …

Physiology of Smell and Olfactory Pathway

The olfactory organs are responsible for the olfaction or sense of smell. The process of olfaction begins as olfactory cilia capture the odorant …

Taste Buds and Receptors

Taste buds—the sensory organs of the taste—are oval-shaped structures consisting of two major types of epithelial cells. Gustatory epithelial …

The Physiology of Taste

Taste physiology begins when the tastants — the chemicals that stimulate gustatory receptor cells — dissolve in saliva, diffuse through the …

Anatomy of the Ear

The human ear has three important regions— external, middle, and internal. The external ear consists of the cartilaginous auricle and the auditory …

Auditory Pathway

Auditory pathways constitute the complex neural circuits responsible for transmitting and interpreting auditory information from the peripheral auditory …

Equilibrium and Balance

The body position and balance are detected by specialized organs in the inner ear. These include the utricle and saccule of the vestibule and the …

Olfactory Assays for Mouse Models of Neurodegenerative Disease

In many neurodegenerative diseases and particularly in Parkinson’s disease, deficits in olfaction are reported to occur early in the disease process …

Morphological and Functional Evaluation of Ribbon Synapses at Specific Frequency Regions of the Mouse Cochlea

Cochlear inner hair cells (IHCs) transmit acoustic signals to spiral ganglion neurons (SGNs) through ribbon synapses. Several experimental studies have …

Microdissection of the Rodent Eye

The ocular micro-dissection of the rodent eye involves the segmentation of the enucleated eyeball with the attached nictitating membrane, or third eyelid, …