Download 12. Infratemp.f.II2010-10

Contents of infratemporal fossa
1-Lateral & medial
pterygoids
(muscles of mastication).
2-Branches of mandibular
N.
3-Otic ganglion.
4- Chorda tympani.
5-Maxillary artery.
6-Pterygoid venous plexus.
Contents of infratemporal
fossa : 2-Mandibular Nerve
Origin & course :
 It is a mixed N.,formed by 2
roots : Large sensory & Small
motor roots.
They unite together in
foramen ovale to form the
main trunk of mandibular N.
(mixed).
The main trunk emerge
from skull through foramen
ovale to reach infratemporal
fossa, then divides into a
small anterior & a large
posterior division.
Branches from main trunk
Meningeal branch
(Nervous Spinosus) –
sensory nerve : it enters
skull through foramen spinosum
(with middle meningeal artery) to
supply meninges in middle
cranial fossa.
Nerve to medial
pterygoid –motor nerve :
It gives off 2 branches, which
pass without relay through otic
ganglion to supply : tensor
tympani (middle ear) & tensor
vili palatini (soft palate).
Branches from
Anterior Division :
2 deep temporal nerves
(motor) : enter deep surface of
temporalis muscle to supply it.
Masseteric nerve (motor).
Nerve to lateral pterygoid
muscle (motor).
Buccal nerve ( sensory) :
supplies skin over cheek + mucous
membrane lining cheek,
(it does not supply buccinator muscle,
which is supplied by buccal branch of
facial nerve).
Branches from
Posterior Division :(mainly sensory)
1-Auriculotemporal nerve
(sensory) :
- It arises by 2 roots that surround
middle meningeal artey, then it
ascend in company with superficial
temporal vessels behind TM joint.
- It gives sensory branches to : skin
of auricle, external auditory meatus,
tympanic membrane, scalp +
parotid gland, TM joint.
- It gives postganglionic parasympathetic secretomotor fibres from
otic ganglion, to supply parotid gland.
2-Lingual nerve (sensory) :
- It arises from posterior division of
mandibular nerve, in front of inferior
alveolar N.
- It lies deep to lateral pterygoid, where it
is joined by chorda tympani nerve
(branch of facial N. carrying taste &
parasympathetic fibres).
- It descends between ramus of mandible
& medial pterygoid.
-Then, it passes on the inner surface of
the socket of lower 3rd molar tooth
(dangerous area during tooth extraction)
- It passes into the submandibular region
superficial on the lateral surface of
hyoglossus, here the sub-mandibular
ganglion hangs from it.
- It ends by dividing into terminal branches to
the tongue to carry general & taste sensation
from anterior 2/ 3 of m.m of tongue & floor of
mouth. Also, it gives secretomotor para-symp.
Fs.to submandibular & sublingual glands.
3- Inferior alveolar N. (mixed) :
-It is the largest branch of post.division
of mandibular N.
- It descends on lateral surface of
sphenomandibular ligament.
-Then, it enters mandibular canal
through mandibular foramen and
runs below teeth, supplying the teeth
of lower jaw.
- Finally it emerges from mental
foramen to supply skin of chin
(sensory)
-N. to mylohyoid (motor) : arises from
inferior alveolar N. before it enters
the mandibular foramen, it runs in
mylohyoid groove of mandible. It
ends by supplying mylohyoid m.+
anterior belly of digastric.
3-Otic Ganglion
It is a small parasympathetic
ganglion that is functionally
associated with glosspharyngeal N.
It lies below foramen ovale, medial
to mandibular N.
It receives preganglionic parasympathetic fibres via tympanic
branch , tympanic plexus & lesser
petrosal N. originate from
glossopharyngeal N.(relay in the
ganglion).
It sends postganglionic
parasympathetic secretomotor
fibres via the auriculo-temporal N.
to supply the parotid gland.
4-Chorda Tympani
It is a branch of facial N., it leaves
the middle ear cavity to enter
infratemporal fossa through
petrotympanic fissure to join
lingual N.
It carries secretomotor
parasympathetic fibres to
submandibular & sublingual
salivary glands.
It carries also sensory taste fibres
continue with lingual N. from
anterior 2/3 of tongue & floor of
mouth.
5-Maxillary Artery
It arises behind to the neck of mandible
within the substance of parotid gland, as the
larger of the 2 terminal branches of external
carotid artery.
It runs upward and forward, superficial to
lower head of lateral pterygoid muscle, then
it dips between 2 heads of lateral pterygoid
to enter pterygopalatine fossa.
Branches :
1-inferior alveolar artery : follows
inf.alveolar N. into mandibular canal.
2-middle meningeal artery : it passes
upward between 2 roots of auriculotemporal N. it enters skull through foramen
spinosum to supply meninges.
3-deep auricular artery : to supply external
auditory meatus + tympanic membrane.
4-numerous branches to muscles of
mastication.
6-Pterygoid venous plexus
It is a network of veins lying around
and inside the substance of lateral
pterygoid muscle.
It is drained posteriorly by maxillary v.
It communicates anteriorly with facial
vein through deep facial vein.
Maxillary Vein
It drains the posterior end of pterygoid
venous plexus.
It runs backward with maxillary artery
on medial side of neck of mandible and
joins superficial temporal vein within
parotid gland to form retromandibular v.
Submandibular Region
 It lies under cover of body of mandible,
between mandible & hyoid bone.
 It contains the following structures :
 Muscles : digastric, mylohyoid, hyoglossus,
geniohyoid, genioglossus and styloglossus.
 Salivary glands : submandibular + sublingual.
 Nerves : lingual, glossopharyngeal, &
hypoglossal.
 Parasympathetic ganglion : submandibular.
 Blood vessels : facial & lingual.
 Lymph nodes : submandibular.
Muscles of submandibular
region :
1-digastric muscle :
Origin : by 2 bellies
-anterior belly : from digastric fossa on
the lower border of body of mandible
close to symphysis menti.
-posterior belly : from medial surface of
mastoid process.
Insertion : into the intermediate
tendon which is cnnected to hyoid bone
by a fibrous loop of deep fascia. This
intermediate tendon pierces stylohoid
insertion.
Nerve supply : anterior belly : by
N.to mylohyoid from mandibular.
Posterior belly : by facial N.
Action : depress mandible or elevate
hyoid bone during swallowing.
2-mylohyoid muscle :
Origin : flate triangular sheet of
muscle arise from mylohyoid line of
mandible.
Insertion : the anterior fibres into a
median fibrous raphe, the mylohyoid
raphe which extends in the median plane
from symphysis menti to hyoid bone.
The posterior fibres into body of hypoid
bone.
Nerve supply : mylohyoid N. from
inferior alveolar N.
Action :
-they supports tongue & floor of mouth.
-they elevate floor of mouth & hyoid
bone during 1st stage of swallowing.
-they depress mandible (open mouth)
when hyoid bone is fixed.
3-hyoglossus muscle :
Origin :upper border of body and
greater cornu of hyoid bone.
Insertion : it lies deep to mylohyoid to
be inserted to side of posterior ½ of
tongue.
Nerve supply : hypoglossal N.
Action :depresses the tongue.
4-styloglossus muscle :
Origin : styloid process.
Insertion : it passes downward on
lateral surface of superior constrictor
muscle to insert into side of tongue
decussating with hyoglossus m.
Nerve supply : hypoglossal N.
Action : retracts the tongue backward.
5-Geniohyoid muscle :
Origin : inferior mental spine, behind
symphysis menti of mandible.
Insertion : into anterior surface of body of
hyoid bone.
Nerve supply : 1st cervical N. via hypoglossal
N.
Action : elevate hyoid bone or depress
mandible if hyoid bone is fixed.
6-Genioglossus muscle : it is a fanshaped m.lies medial to hyoglossus m.
Origin : superior mental spine, behind
symphysis menti of mandible.
Insertion : into whole length of tongue +
superior fs.into tip of tongue + few inferior fs. Into
body of hyoid bone.
Nerve supply : hypoglossal N.
Action : 1-single m. : pulls tongue to opposite
side. 2-The 2 ms. Protrude the tongue forward.