214
UNIT TWO
6.
Vomer bone.
The thin, fl
at vomer (vo
mer) bone is
located along the midline within the nasal cavity.
Posteriorly, it joins the perpendicular plate of the
ethmoid bone, and together they form the nasal septum
(f
gs. 7.27
and
7.28)
.
7.
Inferior nasal conchae.
The inferior nasal conchae
(kong
ke) are fragile, scroll-shaped bones attached to
the lateral walls of the nasal cavity. They are the largest
of the conchae and are below the superior and middle
nasal conchae of the ethmoid bone (see F
gs. 7.17 and
7.23). Like the ethmoidal conchae, the inferior conchae
support mucous membranes in the nasal cavity.
8.
Mandible.
The mandible (man
dı˘-b’l), or lower
jawbone, is a horizontal, horseshoe-shaped body with
a fl at
ramus
projecting upward at each end. The rami
are divided into a posterior
mandibular condyle
and an
anterior
coronoid
(kor
o-noid)
process
(f g. 7.29)
. The
mandibular condyles articulate with the mandibular
fossae of the temporal bones, whereas the coronoid
processes provide attachments for muscles used in
chewing. Other large chewing muscles are inserted on
the lateral surfaces of the rami. A curved bar of bone on
the superior border of the mandible, the
alveolar border,
contains the hollow sockets (dental alveoli) that bear
the lower teeth.
On the medial side of the mandible, near the
center of each ramus, is a
mandibular foramen.
This opening admits blood vessels and a nerve,
which supply the roots of the lower teeth. Dentists
inject anesthetic into the tissues near this foramen
to temporarily block nerve impulse conduction and
desensitize teeth on that side of the jaw. Branches
of the blood vessels and the nerve emerge from the
3.
Zygomatic bones.
The zygomatic (zi
go-mat
ik) bones
are responsible for the prominences of the cheeks below
and to the sides of the eyes. These bones also help form
the lateral walls and the fl
oors of the orbits. Each bone
has a
temporal process,
which extends posteriorly to join
the zygomatic process of a temporal bone (see F
g. 7.19).
4.
Lacrimal bones.
A lacrimal (lak
rı˘-mal) bone is a thin,
scalelike structure located in the medial wall of each orbit
between the ethmoid bone and the maxilla (see F g. 7.19).
A groove in its anterior portion leads from the orbit to
the nasal cavity, providing a pathway for a channel that
carries tears from the eye to the nasal cavity.
5.
Nasal bones.
The nasal (na
zal) bones are long, thin,
and nearly rectangular (see F
g. 7.17). They lie side by
side and are fused at the midline, where they form the
bridge of the nose. These bones are attachments for the
cartilaginous tissues that form the shape of the nose.
Frontal sinus
Ethmoidal sinuses
Sphenoidal sinus
Maxillary sinus
FIGURE 7.25
Locations of the paranasal sinuses.
Coronal section
Horizontal portion
Perpendicular
portion
FIGURE 7.26
The horizontal portions of the palatine bones form the
posterior section of the hard palate, and the perpendicular portions
help form the lateral walls of the nasal cavity.
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