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The Mouth The mouth cavity is divided into vestibule &mouth
cavity proper. Vestibule of mouthlies between lips + cheeks
(buccinator) externally, /and gums + teeth internally. The mouth
cavity proper : Boundaries : In front and at the sides : gums &
teeth 2- Roof :hard palatein front &soft palatebehind. 3- Floor
: anterior 2/3 of tongue & sublingual region. 4-Posteriorly :
mouth communicates with oropharynx by oropharyngeal isthmus. . The
cheek forms the lateral wall of the vestibule and is made up of the
buccinator muscle, which is covered on the outside by fascia and
skin and is lined by mucous membrane. The parotid duct opens at the
vestibule of mouth opposite upper 2nd molar tooth. Sublingual
Region : lies in the floor of mouth below tongue, contains : The
frenulum of the tongue is a fold of mucous membrane in the midline
connects undersurface of tongue to floor of mouth Duct of
submandibular gland opens on each side of frenulum Sublingual gland
is covered by m.m calledsublingual fold, which extends laterallyon
both sides from lower part of frenulum, and sublingual ducts open
by many aperatures on its summit. Sensory nerve supply of mucous
membrane of mouth :
Roof(palate) : greater palatine & Nasopalatine nerves from
Maxillary N. Floor(anterior 2/3 of tongue) :lingual N. of
mandibular N. (general sensation), chorda tympani N. of facial N.
(taste sensation). Cheek : buccal nerve, a branch of mandibular N.
The Tongue It is a mass of striated muscle covered with mucous
membrane. Its anterior 2/3 lies in mouth (oral part), while
posterior 1/3 lies in pharynx (pharyngeal part). It is divided into
right & left halves by a median fibrous septum. The Tongue
Mucous membrane of the Upper surface of tongue (dorum of tongue)
Oral &pharyngeal parts are separated by a V-shaped groove
called sulcus terminalis, the apex of sulcus is marked by a pit
called foramen coecum ( is an embryologic remnant ofupper end of
thyroglossal duct) The mucous membrane of oral part(anterior 2/3)
contains vallate papillae The mucous membrane of pharyngeal part
(post.1/3) devoid of papillae, but it has a nodular irrigular
surface caused by underlyinglymph nodules (lingual tonsils in
submucosa). The Tongue Mucous membrane of inferior surface of the
tongue : The mucosa is smooth In the midline, it is connected to
the floor of mouth by a fold of m.m. called frenulum of tongue On
lateral side of frenulum, deep lingual vein lies in submucosa, can
be seen through the mucosa.But Lingual N. & lingual artery run
at deeper plane from mucosa Lateral to vein, a serrated fold of
mucosa is seen plica fimbriata Innervation of the Tongue :
Motor Nerves : All intrinsic & extrinsic muscles are supplied
by hypoglossal N. EXCEPT palatoglossus is supplied by pharyngeal
plexus via vagus N. Sensory Nerves : Anterior 2/3 : general
sensations: by lingual N.taste sensations (excluding vallate
paoillae) : by chorda tympani Posterior 1/3, including vallate
papillae : general& taste sensations by glossopharyngeal N Root
of tongue ( most posterior part) : internal laryngeal branches of
vagus. (vagus) Blood Supply of Tongue Lingual artery : branch of
external carotid artery, it supply most oftongue(the main arterial
supply) Tonsillar (branch of facial) Ascending pharyngeal artery
(branch of ext.carotid artery) : they supply posterior part of
tongue. Veins of tongue form lingual vein ,which drains into
internal jugular vein. Lymph Drainage of Tongue
Tip of tongue : drain into submental L.Ns. The remainder of
anterior 2/3 of tongue : drains into submandibular + inferior deep
cervical L.Ns. Posterior 1/3 of tongue : drains into superior deep
cervical L.Ns. Muscles of Tongue Intrinsic muscles : They are not
attached to bone They consist oflongitudinal, transverse &
vertical fibers (inside the tongue) Origin : median septum &
submucosa Insertion : mucous membrane Nerve supply : hypoglossal N
function : Alter the shape of tongue. Extrinsic Muscles of
Tongue
Extrinsic muscles : They connect tongue to styloid process &
soft palate above, /and to mandible & hyoid bone below They are
: Genioglossus Hyoglossus Styloglossus palatoglossus. Extrinsic
Muscles of Tongue
Genioglossus : Origin : superiormental tubercle of mandible
Insertion : it is fan-shaped, blends with other muscles of tongue
(into tongue, & body of hyoid bone) Action : The 2 muscles :
protrude tip of tongue through mouth One muscle : protrudes the
tongue to opposite side. Extrinsic Muscles of Tongue
Hyoglossus : Origin : body + greater cornu of Hyoid bone Insertion
: it is quadrilateral, runs upward deep to mylohyoid muscle to
insert at side of post.part of tongue Action : Depress tongue and
increase mouth cavityduring swallowing. Structures Superficial to
Hyoglossus
Superficial relations : Mylohyoid + Styloglossus Lingual N
Hypoglossal N Submandibular ganglion Deep part of submandibular
gland. ligual artery (deep to hyoglossus) Extrinsic Muscles of
Tongue
Styloglossus : Origin : styloid process Insertion :blends with
other muscles of tongue.(whole length of side of tongue) Action :
Pulls tongue upward and backward (retraction + elevation) during
swallowing. It passes between superior & middle constrictors of
pharynx to reach tongue. Extrinsic Muscles of Tongue
Palatoglossus : Origin : from undersurface of palatine aponeurosis
(soft palate) Insertion : into the side of post.1/3 of tongue
Action : pulls root of tongue upward & backward, (retraction +
elevation), so narrows oropharyngeal isthmus and prevents
regurgitationof food. Movements of Tongue Protrusion : genioglossus
on both sides acting together. Retraction : styloglossus +
hyoglossus Ms. on both sides. Depression : hyoglossus +
genioglossus Ms. on both sides. Retraction & elevation of
posterior 1/3 of tongue : Styloglossus +Palatoglossus,on both
sides. The Palate It forms the roof of mouth.
It is divided into :hard palate anterior &soft palateposterior
Hard palate : It forms anterior 2/3 of palate it is formed by
palatine processes of maxillae + horizontal plates of palatine
bones. -It is bounded laterally by alveolar arches and continuous
behind with soft palate It forms floor of nasal cavities It is
covered with muco-periosteum. Soft Palate It forms the posterior
1/3 of palate.
It is a mobile fold attached anteriorlyto the hard palate. Its
posterior free end forms a conical projection in the midline called
the Uvula. It lies between the naso -pharynx&oropharynx.
Laterally , it is attached to side wall of pharynx. Soft palate
Structures of Soft Palate
Mucous Membrane : covers its upper & lower surfaces. Palatine
aponeurosis : it is a fibrous sheet in the middle, attached to
posterior border of hard palate, it is the expanded tendon of
Tensor veli palatini on both sides. Muscles of Soft Palate : Tensor
vili palatini Levator vili palatini Palatoglossus Palatopharyngeus
Musculus uvulae. Palatine aponeurosis Muscles of Soft Palate Tensor
veli palatini : Origin : spine of sphenoid + auditory tube
Insertion :with muscle of other side forms palatine aponeurosis
which is inserted into palatine crest (posterior border of hard
palate) N.supply :N. to medial perygoid from mandibular N Action
:tense soft palate. Muscles of Soft Palate Levator veli palatini :
Origin : Petrous part of temporal bone + auditory tube Insertion :
palatine aponeurosis N.supply : pharyngeal plexus Action : elevates
soft palate, shutting off nasopharynxfronoropharynx in swallowing.
Palatopharyngeus: Origin : palatine aponeurosis Insertion :
posterior border of thyroid cartilage+ wall of pharynx. It lies in
a fold of m.m of lateral wall of pharynx, calledpalatopharyngeal
arch N.supply : pharyngeal plexus Action : The 2 muscles elevate
wall of pharynx + closing of pharyngealisthmusduring swallowing
(communicating channel between nasal & oral parts of pharynx).
Muscles of Soft Palate Palatoglossus : Origin : palatine
aponeurosis Insertion : side of post.1/3 of tongue, it lies in a
fold of m.m. of lateral wall of oro-pharynx, called palatoglossal
arch, which lies in front of palatine tonsile N.supply : pharyngeal
plexus Action : the 2 muscles pull root of tongue upward &
backward, causingnarrowing of oropharyngealisthmus and prevent
regurgitation of food. Musculus uvulae : Origin : posterior border
of hard palate (post. Nasal spine) Insertion : m.m.of uvulae
N.supply : pharyngeal plexus Action : elevates uvulae.
palatoglossal & palatopharyngeal arches :are folds of mucous
membranes covering the muscles of sot palte, palatoglossus &/
palatopharyngeus in the oropharynx. Oropharyngeal isthmus : it is a
sphincter between mouth & oral part ofpharynx, and it is marked
by the interval between 2 palatoglossal arches. Pharyngeal isthmus
: it is the opening between the free end of soft palate &
posterior wall of pharynx ( communication between the nasal and /
oral parts of pharynx) Innervations of Soft Palate
Motor : all palatine muscles are supplied by pharyngealplexus
EXCEPT tensor veli palatini (by N.to medial pterygoid from
mandibular N.). Sensory : Greater & Lesser palatine Ns.
ofmaxillary, NasopalatineN. of maxillary N. Blood Supply &
Lymph Drainage of soft Palate :
Greater palatine from maxillary artery. Ascending palatine from
facial artery. Ascending pharyngeal artery from external carotid
artery. Veins of palate : end in pterygoid & tonsillar venous
plexus. Lymph vessels of palate : end in deep cervical L.Ns.