Bmk

Figure

Actinomyces bacteria (artificially colored) clinging to teeth release acids that decay tooth enamel (1,250x).

The muscles in the walls of the pharynx form inner circular and outer longitudinal groups (fig. 17.13). The circular muscles, called constrictor muscles, pull the walls inward during swallowing. The superior constrictor muscles, which are attached to bony processes of the skull and mandible, curve around the upper part of the pharynx. The middle constrictor muscles arise from projections on the hyoid bone and fan around the middle of the pharynx. The inferior constrictor muscles originate from cartilage of the larynx and pass around the lower portion of the pharyngeal cavity. Some of the lower inferior constrictor muscle fibers contract most of the time,

Figure 17.11

Locations of the major salivary glands.

Serous cells

Mucous cells Duct

Serous cells

Mucous cells

Serous cells

Mucous cells Duct

Figure 17.12

Serous cells

Mucous cells

Serous cells

Mucous cells

Duct

Serous cells

Mucous cells

Duct

Figure 17.12

Light micrographs of (a) the parotid salivary gland (75x), (b) the submandibular salivary gland (180x), and (c) the sublingual salivary gland (80x).

Shier-Butler-Lewis: Human Anatomy and Physiology, Ninth Edition

V. Absorption and Excretion

17. Digestive System

© The McGraw-Hill Companies, 2001

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