663
CHAPTER SEVENTEEN
Digestive System
Mandible
Skull
Tongue
Epiglottis
Larynx
Esophagus
Superior
constrictor
muscles
Middle
constrictor
muscles
Inferior
constrictor
muscles
3. The
laryngopharynx
(lah-ring
go-far
inks) is just
inferior to the oropharynx. It extends from the upper
border of the epiglottis downward to the lower border of
the cricoid cartilage of the larynx and is a passageway to
the esophagus.
The muscles in the walls of the pharynx form inner cir-
cular and outer longitudinal groups
(f g. 17.13)
. The circular
muscles, called
constrictor muscles,
pull the walls inward dur-
ing swallowing. The
superior constrictor muscles,
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 F bers contract most of the time, which prevents air
from entering the esophagus during breathing.
Structure of the Pharynx
The
pharynx
(far
ingks) connects the nasal and oral cavi-
ties with the larynx and esophagus (see F
g. 17.7). It can be
divided into the following parts:
1. The
nasopharynx
(na
zo-far
ingks) is superior to the
soft palate. It communicates with the nasal cavity and
provides a passageway for air during breathing. The
auditory tubes, which connect the pharynx with the
middle ears, open through the walls of the nasopharynx
(see chapter 12, p. 453).
2. The
oropharynx
(o
ro-far
ingks) is posterior to the
mouth. It is posterior to the soft palate and inferior to
the nasopharynx, projecting downward to the upper
border of the epiglottis. This portion is a passageway
for food moving downward from the mouth and for air
moving to and from the nasal cavity.
TABLE
17.4
|
The Major Salivary Glands
Gland
Location
Duct
Type of Secretion
Parotid glands
Anterior to and somewhat inferior to the ears between
the skin of the cheeks and the masseter muscles
Parotid ducts pass through the
buccinator muscles and enter the mouth
opposite the upper second molars
Clear, watery serous F
uid, rich in
salivary amylase
Submandibular glands
In the F
oor of the mouth on the inside surface of the
mandible
Ducts open inferior to the tongue near
the frenulum
Some serous F
uid with some mucus;
more viscous than parotid secretion
Sublingual glands
In the F
oor of the mouth inferior to the tongue
Many separate ducts
Primarily thick, stringy mucus
FIGURE 17.13
Muscles of the pharyngeal wall,
posterior view.
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