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Oral Cavity & Salivery Glands
Head & Neck Unit – Lecture 10
‫ حيدر جليل األعسم‬.‫د‬
The Lips
• They are two fleshy folds
surrounding the oral orifice and
covered on the outside by skin and
lined on the inside by mucous
membrane.
• The substance of lips is made up
by orbicularis oris and muscles
that radiate from the lips into the
face in addition to vessels and
labial salivery gland.
• Philtrum is shallow vertical groove
seen in midline on outer surface of
upper lip.
• Labial frenulae are median folds of
mucous membrane connecting
inner surface of lips to gums.
The Mouth (Mouth Cavity)
Mouth extends from lips anteriorly to oropharynx
posteriorly. Oropharyngeal isthmus is the entrance
into oropharynx and formed by palatoglossal folds.
Mouth is divided into: Vestibule & Mouth Cavity
Proper.
Vestibule:
The vestibule is a slit like space that lies between
lips and cheeks (externally) and gums and teeth
(internally). It communicates with exterior through
oral fissure & with mouth proper behind the third
molar tooth on each side.
The lateral walls of vestibule are formed by cheeks,
which is made up by Buccinator. Parotid gland duct
opens on a small papilla into the vestibule opposite
upper 2nd molar tooth.
Mouth Proper
The mouth proper has a roof and a floor.
Roof of Mouth: Hard palate in front & soft palate behind
Floor of Mouth: formed by 3 structures:
1. Mylohyoid muscles: 2 muscles form muscular diaphragm
& fills the U-shaped gap of mandibular body.
2. Geniohyoid muscles: 2 cord-like muscles above
mylohyoid, run from mandible in front to hyoid bone
behind.
3. Tongue: located superior to geniohyoid & mouth floor is
formed largely by anterior 2/3 of tongue & reflection of
mucous membrane from sides of the tongue to gums.
Frenulum of tongue: is a fold of mucous membrane that
connects under-surface of tongue in midline to floor of
mouth.
Plica Fimbriata: is a fringed fold of mucous membrane
lateral to frenulum.
On each lateral side of frenulum, deep lingual vein and duct
of submandibular gland opens onto floor of mouth on the
summit of a small papilla. The sublingual gland projects up
into the mouth, producing a low fold of mucous
membrane, the sublingual fold. Numerous ducts of the
gland open on the summit of the fold.
Mouth Proper
Tongue: floor of the mouth is formed largely by anterior 2/3 of tongue & reflection of mucous
membrane from sides of the tongue to gums.
Frenulum of tongue: is a fold of mucous membrane connecting undersurface of tongue to floor
of mouth. Plica Fimbriata: is a fringed fold of mucous membrane lateral to frenulum.
On each lateral side of frenulum, Deep Lingual Vein & Submandibular Duct opens onto floor of
mouth on the summit of a small papilla. The sublingual gland projects up into the mouth,
producing a low fold of mucous membrane (Sublingual fold).
Sensory Innervation of the Mouth
Roof: Greater palatine, Lesser Palatine & Nasopalatine nerves
(maxillary division of trigeminal)
Floor: Lingual nerve (common sensation) a branch of mandibular
division of trigeminal nerve. Anterior 2/3 of tongue taste fibers travel
in chorda tympani nerve (facial nerve branch) & Posterior 1/3 taste
& common sensation travel in Glossopharyngeal nerve.
Cheek: Buccal nerve (mandibular division of trigeminal nerve).
The Tongue
The Tongue is a mass of striated muscle
covered with mucous membrane. The
muscles attach the tongue to Styloid
process & Soft Palate above and to the
Mandible and Hyoid bone below.
The tongue is divided into right and left
halves by a median fibrous septum.
The Tongue – Mucous Membrane
Mucous membrane of upper surface of tongue can be divided into anterior 2/3
(oral part) & posterior 1/3 (Pharyngeal Part)by a V-shaped (sulcus terminalis).
foramen cecum is a small pit at the apex of sulcus terminalis. It is an embryologic
remnant of upper end of thyroglossal duct.
3 types of papillae are present on upper surface of anterior two thirds of tongue:
Filiform papillae:
Fungiform papillae:
Vallate Papillae:
The mucous membrane of posterior
1/3 is devoid of papillae but has an
irregular surface, caused by underlying
lymph nodules (Lingual tonsils).
Blood Supply of the Tongue:
The lingual artery, tonsillar branch of
facial artery, and ascending pharyngeal
artery supply the tongue. The veins drain
into the internal jugular vein.
Muscles of the Tongue
A. Intrinsic Muscles: They are confined to the tongue and are not attached to
bone. They consist of longitudinal, transverse, and vertical fibers.
Nerve Supply: Hypoglossal nerve Action: Alter the shape of the tongue
B. Extrinsic Muscles: They are attached to bones
and the soft palate. They are Genioglossus,
Hyoglossus, Styloglossus and Palatoglossus.
• Nerve supply: Hypoglossal nerve.
Movements of the Tongue:
Protrusion: Genioglossus muscles on both sides
acting together.
Retraction: Styloglossus & Hyoglossus muscles
on both sides acting together
Depression: Hyoglossus muscles on both sides
acting together
Retraction & Elevation of posterior third:
Styloglossus & palatoglossus muscles on both
sides acting together.
Shape changes: Intrinsic muscles
The Teeth
Deciduous Teeth:
There are 20 deciduous teeth:
4 incisors, 2 canines and 4
molars in each jaw. They begin
to erupt about 6 months after
birth and completed by end of
2 years. Lower jaw teeth
usually appear before those of
upper jaw.
Permanent Teeth:
There are 32 permanent teeth:
4 incisors, 2 canines, 4
premolars and 6 molars in
each jaw. They begin to erupt
at 6 years of age. The last
tooth to erupt is 3rd molar
between age of 17 and 30.
Lower jaw teeth appear before
those of upper jaw.
The Palate
It forms roof of mouth & floor of nasal cavity. It is
divided into 2 parts: hard palate (Ant.) & soft palate
(Post.).
Hard Palate: is formed by the palatine processes of
the maxillae and the horizontal plates of the palatine
bones. It is continuous behind with the soft palate.
Soft Palate: is a mobile fold attached to posterior
border of hard palate. Its free posterior border
presents in the midline a conical projection called
Uvula. Soft palate is continuous at the sides with the
lateral wall of the pharynx. The soft palate is
composed of mucous membrane, palatine
aponeurosis, and muscles.
Palatine Aponeurosis: is a fibrous sheet attached to
posterior border of hard palate & represents an
expanded tendon of tensor veli palatini muscle.
Muscles of soft palate are tensor veli palatini,
levator veli palatini, palatoglossus,
palatopharyngeus and the musculus uvulae.
Muscles of the Palate
Muscle fibers of tensor veli palatini converge to
form a narrow tendon, which turns medially
around the pterygoid hamulus. Tendons of two
opposite sides, expands to form palatine
aponeurosis. When muscle of two sides of soft
palate contract, soft palate is tightened & may be
moved upward or downward as a tense sheet.
Palatoglossal Arch: is a fold of mucous
membrane containing palatoglossus muscle,
which extends from soft palate to side of tongue.
It marks where the mouth becomes the pharynx.
Palatopharyngeal Arch: is a fold of mucous
membrane behind palatoglossal arch that runs
downward & laterally to join pharyngeal wall. It
contain palatopharyngeus muscle.
Palatine Tonsils are masses of lymphoid tissue
located between palatoglossal and
palatopharyngeal arches.
The Palate
Nerve Supply of the Palate:
Greater & lesser palatine nerves enter the
palate through greater & lesser palatine
foramina.
Nasopalatine nerve enters the front of the
hard palate through the incisive foramen.
Glossopharyngeal nerve also supplies soft
palate.
Blood Supply of the Palate:
Greater Palatine Artery of maxillary artery
Ascending Palatine Artery of facial artery
Ascending Pharyngeal Artery.
Lymph Drainage of the Palate: is by deep
cervical lymph nodes
The Salivary Glands
Parotid Gland
It is the largest salivary gland and
composed mostly of serous acini. It lies
in a deep hollow space below external
auditory meatus, behind the ramus of
mandible, and in front of sternocleidomastoid muscle.
Facial nerve divides it into superficial &
deep lobes. The parotid duct emerges
from its anterior border & passes
forward over lateral surface of
masseter. It enters the vestibule of
mouth upon a small papilla opposite
upper 2nd molar tooth.
Nerve Supply: Parasympathetic
secretomotor supply arises from
glossopharyngeal nerve. The nerves
reach the gland via the tympanic
branch, lesser petrosal nerve, otic
ganglion, and auriculotemporal nerve.
Submandibular Gland
It consists of a mixture of serous and
mucous acini. It lies beneath lower
border of mandible & is divided into
superficial and deep parts by
mylohyoid muscle.
Submandibular duct emerges from
anterior end of deep part & runs
forward beneath mucous membrane of
the mouth & opens into on a small
papilla at the side of frenulum of
tongue.
Nerve Supply: Parasympathetic
secretomotor supply is from facial
nerve via chorda tympani &
submandibular ganglion.
Sublingual Gland
It lies beneath mucous membrane (sublingual fold)
of mouth floor, close to frenulum of tongue. It has
both serous and mucous acini (mucous
predominant).Sublingual ducts (8 to 20) open into
mouth floor on summit of sublingual fold.
Nerve Supply: Parasympathetic secretomotor
supply is from facial nerve via chorda tympani, and
submandibular ganglion.
Facial Nerve
It has a motor & sensory root.
It enters internal acoustic meatus in petrous part of temporal bone. At bottom of
meatus, it enters facial canal & runs laterally through inner ear. On reaching
medial wall of middle ear (tympanic cavity), it swells to form geniculate ganglion.
The nerve then bends sharply backward above promontory and bends down on
medial side of aditus. It then descends behind pyramid & emerges from temporal
bone through stylomastoid foramen. The facial nerve now passes forward
through the parotid gland to its distribution.
Facial Nerve
Branches of the Facial Nerve
A.Greater petrosal nerve:
B.Nerve to stapedius: supplies the
stapedius muscle in the middle ear.
C. Chorda tympani:
D.Posterior auricular nerve, nerve of
posterior belly of digastric, and
stylohyoid nerves
E. Five terminal branches to the
muscles of facial expression:
emerges in the substance of the
parotid gland. (Temporal,
Zygomatic, Buccal, Mandibular &
Cervical branches).
Hypoglossal Nerve
Hypoglossal nerve is a motor nerve. It leaves
the skull through Hypoglossal canal then
passes downward & forward in the neck to
cross internal & external carotid arteries and
reach the tongue.
In upper part of its course, it is joined by C1
fibers from cervical plexus.
Important Branches of the Hypoglossal Nerve
1. Meningeal branch.
2. Descending branch (C1 fibers) passes
downward and joins descending cervical nerve
(C2 & C3) to form Ansa Cervicalis. Branches
from this loop supply omohyoid, sternohyoid
and sternothyroid muscles.
3. Nerve to the thyrohyoid muscle (C1).
4. Muscular branches to all muscles of tongue
except palatoglossus (pharyngeal plexus)
5. Nerve to geniohyoid muscle (C1).
End of the Lecture
GOOD LUCK