ORAL
CAVITY
©
2005 zillmusom
I. SUBMANDIBULAR
REGION ‑ area between mandible and hyoid bone - REVIEW MUSCLES
IN SUBMANDIBULAR REGION - Digastric,
Mylohyoid and Geniohyoid.
II.
TONGUE ‑ mobile muscular organ involved in speech, swallowing and
taste; attached to hyoid, mandible and skull by muscles.
A. Superficial Structures (Atlas
Fig. 7.52A, 7.55)
1. Sulcus terminalis –
V-shaped groove dividing anterior 2/3 and posterior 1/3 of tongue.
2. Foramen caecum ‑
pit in middle of sulcus terminalis; marks site of invagination of thyroid
diverticulum.
3. Lingual frenulum ‑
midline fold extending from floor of mouth to tongue on inferior surface; has
swelling at floor of mouth called sublingual papilla.
4. Fimbriated folds
(Plica fimbriata) ‑ small folds lateral to lingual frenulum; mark
location of lingual veins.
5. Sublingual folds
(Plicae sublingualis) - overlie sublingual salivary glands and have openings
for ducts of glands.
B. Muscles of Tongue ‑ all
innervated by hypoglossal nerve (XII).
1. Extrinsic muscles (Atlas Figs.
page 667, 7.54)
|
MUSCLE |
ORIGIN |
INSERTION |
ACTION |
NERVE |
|
Genioglossus |
Mandible - genial tubercle on inner
side |
Tongue - up to dorsal surface |
Protrudes Tongue |
XII |
|
Hyoglossus |
Hyoid bone - greater and lesser horns |
Lateral side of Tongue |
Depresses Tongue |
XII |
|
Styloglossus |
Temporal bone - styloid process |
Lateral side of Tongue |
Draws Tongue superiorly and
posteriorly |
XII |
2. Intrinsic muscles ‑ have no
bony attachment; change shape of tongue. (Atlas Fig. page 667)
|
MUSCLE |
FIBER ORIENTATION |
ACTION |
NERVE |
|
Longitudinal muscle |
Anterior-posterior |
Shorten Tongue |
XII |
|
Transverse muscle |
Horizontal |
Narrow Tongue |
XII |
|
Vertical muscle |
Superior-inferior |
Flatten and Broaden Tongue |
XII |
C. Innervation (Atlas Fig. 7.52B)
1. General sensation (touch, pain, etc.) ‑ GSA to anterior
2/3 of tongue via Lingual nerve (V3); GVA to posterior 1/3 of tongue and
area anterior to epiglottis - Glossopharyngeal nerve (IX) to posterior 1/3
of tongue, Vagus (X) nerve to area anterior to epiglottis.
2. Taste = SVA ‑ Chorda tympani
(VII) to anterior 2/3 of tongue, Glossopharyngeal (IX) to taste buds of
posterior 1/3 of tongue, Vagus (X) to taste buds anterior to epiglottis.
3. Motor = GSE – All muscles of tongue
are innervated by Hypoglossal nerve (XII) on that side.
Note: In paralysis of XII
on one side, protruded tongue deviates toward the side of the lesion due to
unopposed action of the Genioglossus muscle.
D. Lymphatic drainage ‑ tip of tongue drains to
submental lymph nodes; remainder of anterior two thirds drains to submandibular and deep cervical lymph
nodes; posterior third drains to deep cervical lymph nodes.
Note: lymph vessels cross
over midline of tongue; lesion on one side may spread to opposite side via
crossing lymphatics.
III. STRUCTURES OF
SUBMANDIBULAR REGION: NERVES, ARTERIES AND SALIVARY GLANDS
A. Nerves
1. Lingual nerve ‑
arises from posterior division of mandibular division (V3) of trigeminal nerve;
courses medial to ramus of mandible; joined by chorda tympani (see below);
enters floor of mouth medial to root of third mandibular molar tooth; courses
upward on lateral surface of hyoglossus muscle to terminate in dorsum of
tongue; provides general sensation (GSA) to anterior two thirds of tongue.
(Atlas Fig. 7.47B, 7.55B, page 810)
Note:
Lingual nerve is joined by chorda tympani in infratemporal fossa; chorda
tympani arises from facial nerve in facial canal; passes through tympanic
cavity medial to malleus; passes out of tympanic cavity into infratemporal
fossa by petrotympanic fissure; chorda tympani carries taste fibers (SVA) to
anterior two thirds of tongue and parasympathetic preganglionic fibers (GVE) to
submandibular ganglion; submandibular ganglion is suspended from lingual nerve
superior to submandibular salivary gland.
2. Glossopharyngeal
nerve ‑ comes out of jugular foramen; passes lateral to and around
stylopharyngeus muscle; courses between borders of superior and middle
constrictor muscles to terminate in posterior tongue; provides general
sensation (GVA) and taste (SVA) to posterior one third of tongue.(Atlas Figs.
pages 816-817)
3. Hypoglossal nerve ‑
comes out via hypoglossal canal; passes between internal jugular vein and
carotid arteries; courses on surface of hyoglossus muscle; enters tongue;
supplies motor innervation (GSE) to all muscles of tongue. (Atlas Fig. page 821)
B. Arteries
1. Lingual artery ‑
arises from external carotid just below tip of greater horn of hyoid; courses
anteriorly forming upward loop then passes deep to posterior margin of
hyoglossus; turns upward to supply tongue; branches: a) Dorsal lingual branches
to dorsum of tongue; b) Sublingual artery to sublingual salivary gland. (Atlas
Figs. 8.13, 8.14)
2. Facial artery ‑
arises from external carotid superior to lingual artery; first passes medial to
mandible, then courses on face; branches to structures medial to mandible: a)
Ascending Palatine artery to palate; b) Tonsillar artery to Palatine tonsil; c)
Glandular arteries to submandibular salivary gland; d) Submental artery to region
of chin. (Atlas Figs. 8.11, 8.32)
C. Salivary Glands ‑ both
innervated by chorda tympani; see above. (Atlas Figs. 7.45, 8.12)
1. Submandibular glands
a. Location ‑
C shaped gland wraps around posterior border of mylohyoid adjacent to body of
mandible.
Note:
gland is partly enclosed in a capsule derived from investing layer of deep
cervical fascia; fascia is attached to mandible.
b.
Submandibular duct ‑ arises from gland between mylohyoid and hyoglossus
muscles; opens by one to three orifices on sublingual papilla (adjacent to
lingual frenulum).
2. Sublingual glands
a. Location ‑
in floor of mouth between mandible and genioglossus muscle; horseshoe‑shaped
glandular masses around lingual frenulum.
b. Ducts ‑
numerous (