260
UNIT 3
Organ Systems
Lining Mucosa
Figure 14-2A.
Overview of the lip
,
H&E,
3
7.6
Lining mucosa
is a wet mucosa that covers the inside of the mouth
and is lined by nonkeratinized stratiF
ed squamous epithelium.
The labial mucosa of the
lip
is an example of lining mucosa. The
lips are soft, fl
exible, and movable; they play important roles in
food intake, speech, and as a sensory organ (e.g., kissing). Lips
can be divided into three regions: (1)
thin skin
, forming the exter-
nal surface of the lip; (2)
vermilion zone
, appearing red in color,
also called the
intermediate zone
or
mucocutaneous junction
;
and (3) the
labial mucosa (lining mucosa)
, the internal surface
of the lip. The central core of the lip contains the orbicularis oris
(skeletal) muscle, which is innervated by the facial nerve (CN
VII), and contributes to lip movement and facial expressions.
Labial
(lining)
mucosa
Fig.
14-2D
Vermilion
zone
Minor
salivary gland
Fig.
14-2C
Vermilion
zone
Skin
Fig.
14-2B
O
rb
r
b
ic
i
c
u
la
l
a
ris
r
i
s
o
ris
r
i
s
m
m
u
s
c
le
l
e
Orbicularis
oris muscle
Orbicularis
Orbicularis
oris muscle
oris muscle
Orbicularis
oris muscle
A
Sweat
Sweat
glands/ducts
glands/ducts
Sweat
glands/ducts
Sebaceous
Sebaceous
glands
glands
Sebaceous
glands
Sebaceous
Sebaceous
glands
glands
Sebaceous
glands
Sweat
Sweat
glands/ducts
glands/ducts
Sweat
glands/ducts
Hair
follicle
space
Hair
follicle
Epidermis
Dermis
Dermis
Dermis
B
Figure 14-2B.
Skin
,
lip
. H&E,
3
33; inset
3
44
An example of the
skin
on the external surface of the
lip
is shown.
It is covered by keratinized stratiF
ed squamous epithelium. The
sebaceous glands in the dermis are associated with hair follicles,
and sweat glands are present. The skin of the lip is like thin skin
elsewhere and can be divided into epidermis and dermis.
C
Ducts of sebaceous-like
Ducts of sebaceous-like
glands
glands
Ducts of sebaceous-like
glands
Fordyce granules/spots
Fordyce granules/spots
ebaceous-like glands
ebaceous-like glands
(s
(s
)
Fordyce granules/spots
ebaceous-like glands
(s
)
Parakeratinized stratified
squamous epithelium
Nonkeratinized stratified
Nonkeratinized stratified
squamous epithelium
squamous epithelium
Nonkeratinized stratified
squamous epithelium
Ducts of minor
Ducts of minor
salivary glands
salivary glands
Ducts of minor
salivary glands
Stratum
Stratum
spinosum
spinosum
Stratum
spinosum
Stratum
Stratum
basale
basale
Stratum
basale
Minor
Minor
salivary
salivary
glands
glands
Minor
salivary
glands
D
Figure 14-2C.
Vermilion zone
,
lip
. H&E,
3
33
The
vermilion zone
of the
lip
is covered by parakeratinized strati-
F ed squamous epithelium. Sebaceous-like glands (
Fordyce gran-
ules
or
spots
) may be found in the connective tissue and are not
associated with hair follicles. These glands have ducts that release
their oily product directly onto the surface of the lip. The ver-
milion zone appears red because of many blood vessels near the
surface of the thin and translucent epithelium (±ig. 14-1). This
region can become thick and forms the sucking pad in infants.
Figure 14-2D.
Labial mucosa (lining mucosa)
,
lip
. H&E,
3
33
The
labial mucosa
of the lip is an example of
lining mucosa
,
which is covered by nonkeratinized stratiF
ed squamous epithe-
lium and contains many elastic F
bers; it is very fl
exible and can
be stretched. Its submucosa layer contains many minor salivary
glands (mucous glands). The minor salivary glands in the lips are
often called
labial glands
.
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