Download mandibular nerve

‫تشريح ‪ /‬د ‪ .‬سيف (م‪) 7‬‬
‫ثاني اسنان موصل‬
‫‪2015 / 12 / 7‬‬
‫د ‪ .‬سيف (م ‪)7‬‬
‫‪Human Anatomy‬‬
Parotid Region
Boundaries:
•
•
•
•
Superior :external acoustic meatus.
Inferior : angle of mandible.
Anterior : Masseter muscle.
Posterior: mastoid process.
Parotid Gland
The parotid gland is the largest salivary gland and is
composed mostly of serous acini. It lies in a deep
hollow below the external auditory meatus, behind
the ramus of the mandible, and in front of the
sternocleidomastoid muscle. The facial nerve divides
the gland into superficial and deep lobes. The
parotid duct emerges from the anterior border of
the gland and passes forward over the lateral surface
of the masseter. It enters the vestibule of the mouth
upon a small papilla opposite the upper second
molar tooth.
Contents of parotid region:
1. Parotid gland
2. The external carotid artery enters the lower part of the
posteromedial surface. Ascending within the substance of the
gland it divides into its terminal branches (superficial temporal
and maxillary) that emerge on the anteromedial surface of the
gland
3. The retromandibular vein lies in the substance of the parotid
gland superficial to the external carotid artery.
4. The trunk of the facial nerve enters the posteromedial
surface. Within the gland it divides into its terminal branches
that emerge from the anteromedial surface near its anterior
margin. The cervical branch of the nerve emerges from the
lower end of the gland.
5. The auriculotemporal nerve passes laterally between the neck
of the mandible and the superior surface of the gland. It gives
branches to the gland.
TEMPORAL REGION
The temporal region overlies the temporal fossa
present on the lateral aspect of the skull. The
fossa is bounded superiorly and inferiorly by
the temporal line and inferiorly by the
zygomatic arch. The lower part of the
temporal region is overlapped by the auricle.
A thick fibrous membrane, the temporal
fascia covers the region. This fascia is attached
superiorly to the temporal lines, and inferiorly
to the zygomatic arch.
Boundaries of the temporal region
The fossa is bounded
• superiorly and inferiorly by the temporal lines.
• inferiorly by the zygomatic arch.
• anteriorly by the frontal process of the
zygoma and the zygomatic process of the
frontal bone.
Contents of temporal region:
A. Temporalis muscle:
*Origin: The temporalis arises from the temporal fossa
on the lateral aspect of the skull. The area includes
parts of the frontal, parietal, and squamous temporal
bones and of the greater wing of the sphenoid. The
tendon passes deep to the zygomatic arch.
*Insertion: Into coronoid process of mandible.
*Nerve Supply: Deep temporal branches of the
mandibular nerve.
*Actions: The temporalis helps to close the mouth by
elevating the mandible.
B. The nerves presents in the temporal region are:
1. The auriculotemporal nerve emerges from under cover of the
upper end of the parotid gland. The nerve ascends into the
temporal region and scalp and divides into branches that supply
them.
2. The temporal branch of the facial nerve runs upwards and
forwards to reach the frontalis muscle that it supplies. It also helps
to supply the orbicularis oculi and the auricular muscles.
3. The posterior auricular branch of the facial nerve is seen behind
the auricle in the lower part of the temporal region. It runs
backwards to reach and supply the occipitalis muscle.
4. The zygomatico-facial nerve and the zygomatico-temporal nerve
are derived from the zygomatic branch of the maxillary division
of the trigeminal nerve. They help to supply the skin of the region.
5. Deep to the temporalis muscle there are the (anterior, middle
and posterior) deep temporal nerves. They arise from the anterior
division of the mandibular nerve. The deep temporal nerves
supply the temporalis muscle.
C. The blood vessels presents in the temporal
region are:
1. The superficial temporal artery is a terminal branch
of the external carotid artery. It divides into branches
that supply the temporal region and scalp.
2. The superficial temporal vein is a tributary of the
retromandibular vein.
3. The deep temporal arteries are branches of the
maxillary artery.
INFRATEMPORAL FOSSA
The term infratemporal fossa is an irregular space lying
below temporal fossa , deep and inferior to the
zygomatic arch, deep to the ramus of the mandible,
and posterior to the maxilla.
The boundaries of the infratemporal fossa are:
• Laterally: the ramus of the mandible.
• Medially: the lateral pterygoid plate.
• Anteriorly: the posterior aspect of the maxilla.
• Posteriorly: the tympanic plate and the mastoid and
styloid processes of the temporal bone.
• Superiorly: the inferior (infratemporal) surface of the
greater wing of the sphenoid.
• Inferiorly: where the medial pterygoid muscle attaches
to the mandible near its angle
Contents of the infratemporal fossa:
• muscles of mastication “Inferior part of the
temporalis muscle, Lateral and medial
pterygoid muscles”
• Maxillary artery and Mandibular nerve.
• Pterygoid venous plexus.
• Otic ganglion.
Communications of the Infratemporal Fossa
• infratemporal fossa communicates superiorly with
middle cranial fossa through foramen ovale and
foramen spinosum those open to roof of
infratemporal fossa
• lnfratemporal fossa communicates with temporal
fossa though the foramen formed by the zygomatic
arch
• infratemporal fossa communicates with orbit
via inferior orbital fissure .
• infratemporal fossa communicates Medially with
pterygopalatine fossa via pterygomaxillary fissure.
MUSCLES OF MASTICATION
1. Temporalis muscle: previously discussed
2. Masseter muscle
#Origin:
The muscle arises from the zygomatic arch .
#Insertion:
Into lateral surface of ramus and angle of the mandible.
#Nerve Supply:
Anterior division of the mandibular nerve.
#Actions:
The masseter elevates the mandible to close the mouth.
Its anterior fibers help in forward movement of the
jaw.
3. Lateral Pterygoid muscle
The muscle has two heads of origin, upper and lower.
#Origin:
The upper head arises from the infratemporal surface of
the greater wing of the sphenoid bone.
The lower head arises from the lateral surface of the
lateral pterygoid plate.
#Insertion:
Into a depression (pterygoid fovea) on the anterior aspect
of the neck of the mandible.
#Nerve Supply:
Mandibular nerve (anterior division).
4. Medial Pterygoid muscle
#Origin:
The medial pterygoid muscle takes origin mainly from the medial
surface of the lateral pterygoid plate. A superficial slip arises from
the lateral aspect of the maxillary tuberosity.
#Insertion:
Medial surface of angle of mandible.
#Nerve Supply:
Mandibular nerve.
#Actions of Pterygoid Muscles:
1. The medial and lateral pterygoids of both sides acting together
protract the mandible.
2. The medial and lateral pterygoids of the two sides acting
alternately produce side to side chewing movements.
3. The medial pterygoid elevates the jaw. The lateral pterygoid helps
in opening the mouth by pulling the head of the mandible
forwards.
Maxillary artery
is the larger of the two terminal branches of the external
carotid artery. The artery runs forwards deep to the neck of
the mandible to enter the infratemporal fossa and is divided
into three parts based on its relation to the lateral pterygoid
muscle. The first part passes forwards deep to the neck of
the mandible to reach the infratemporal fossa. Here it runs
forwards along the lower border of the lateral pterygoid
muscle . The second part of the artery runs forwards and
upwards superficial to the lower head of the lateral
pterygoid muscle. The third part of the artery passes
between the upper and lower heads of the lateral pterygoid
muscle to pass through the pterygomaxillary fissure thus
entering the pterygopalatine fossa.
A. Branches of first part:
1. The deep auricular artery supplies the external
acoustic meatus, the tympanic membrane and
the temporomandibular joint.
2. The anterior tympanic branch supplies the
middle ear and the tympanic membrane.
3. The middle meningeal artery runs upward deep
to the lateral pterygoid muscle. It passes between
the two roots of the auriculotemporal nerve . The
artery enters the cranial cavity through the
foramen spinosum. It runs forwards and laterally
over the floor of the middle cranial fossa and
divides into frontal and parietal branches.
4. The accessory meningeal artery enters the cranial
cavity through the foramen ovale.
5. The inferior alveolar artery runs downwards and
forwards medial to the ramus of the mandible to reach
the mandibular foramen. Passing through this foramen
the artery enters the mandibular canal (within the
body of the mandible) in which it runs downwards and
then forwards. Before entering the mandibular canal
the artery gives off a lingual branch to the tongue; and
a mylohyoid branch that descends in the mylohyoid
groove (on the medial aspect of the mandible) and
runs forwards above the mylohyoid muscle. Within the
mandibular canal the artery gives branches to the
mandible and to the roots of each tooth attached to
the bone. It also gives off a mental branch that passes
through the mental foramen to supply the chin.
Accessory meningeal
artery
B. Branches of second part:
The branches of the second part of the maxillary
artery are mainly muscular. The deep
temporal branches (anterior and posterior)
ascend on the lateral aspect of the skull deep
to the temporalis muscle. Branches are also
given off to the pterygoid muscles and to the
masseter. A buccal branch supplies the
buccinator muscle.
C. Branches of third part:
1.The posterior superior alveolar artery descends on the
posterior surface of the maxilla and gives branches that
supply the molar and premolar teeth, and the maxillary
air sinus.
2.2. The infraorbital artery enters the orbit through the
inferior orbital fissure. It runs forwards in relation to the
floor of the orbit, first in the infraorbital groove and then
in the infraorbital canal to emerge on the face through
the infraorbital foramen. It gives off some orbital
branches to structures in the orbit, and anterior superior
alveolar branches that reach the incisor and canine teeth.
After emerging on the face the infraorbital artery gives
branches to the lacrimal sac, the nose and the upper lip.
The remaining branches of the third part arise within the
pterygopalatine fossa
3. The greater palatine artery runs downwards in the greater
palatine canal to emerge on the hard palate through the
greater palatine foramen. It then runs forwards near the
lateral margin of the palate. Branches of the artery supply
the palate and gums. Within the greater palatine canal it
gives off the lesser palatine arteries that emerge on the
palate through lesser palatine foramina and run backwards
into the soft palate and tonsil.
4. The pharyngeal branch supplies part of the nasopharynx,
the auditory tube and the sphenoidal air sinus.
5. The artery of the pterygoid canal helps to supply the
pharynx, the auditory tube and the tympanic cavity.
6. The sphenopalatine artery passes medially through the
sphenopalatine foramen to enter the cavity of the nose. It
gives off branches to the nose and the paranasal sinuses.
MANDIBULAR NERVE
The mandibular nerve (CN V3) is the inferior and largest
division of the trigeminal nerve .It is formed by the
union of sensory fibers from the sensory ganglion and
the motor root of CN V in the foramen ovale to
enter the infratemporal fossa, then divides into a
small anterior and a large posterior division
A. Branches from the Main Trunk of the
Mandibular Nerve
• Meningeal branch which accompany the middle
meningeal artery.
• Nerve to the medial pterygoid muscle, which
supplies medial pterygoid muscle.
• Nerve to tensor velli palatini muscle.
• Nerve to tensor tympani muscle.
B. Branches from the Anterior Division of the
Mandibular Nerve
•
•
•
•
Masseteric nerve to the masseter muscle .
Deep temporal nerves to the temporalis muscle.
Nerve to the lateral pterygoid muscle.
Buccal nerve to the skin and the mucous membrane
of the cheek. The buccal nerve does not supply the
buccinator muscle (which is supplied by the facial
nerve), and it is the only sensory branch of the
anterior division of the mandibular nerve.
C. Branches from the Posterior Division of the
Mandibular Nerve
1. Auriculotemporal nerve, which supplies the skin of the
auricle,
the
external
auditory
meatus,
the
temporomandibular joint, and the scalp. This nerve also
conveys postganglionic parasympathetic secretomotor
fibers from the otic ganglion to the parotid salivary gland.
2. Lingual nerve, which descends in front of the inferior
alveolar nerve and enters the mouth. It then runs
forward on the side of the tongue and crosses the
submandibular duct. In its course, it is joined by the
chorda tympani nerve , and it supplies the mucous
membrane of the anterior two thirds of the tongue and
the floor of the mouth. It also gives off preganglionic
parasympathetic
secretomotor
fibers
to
the
submandibular ganglion.
3. Inferior alveolar nerve, which enters the mandibular
canal to supply the teeth of the lower jaw and
emerges through the mental foramen (mental nerve)
to supply the skin of the chin. Before entering the
canal, it gives off the mylohyoid nerve, which
supplies the mylohyoid muscle and the anterior belly
of the digastric muscle.
Note: The branches of the posterior division of the
mandibular nerve are sensory (except the nerve to
the mylohyoid muscle).
The Otic Ganglion
The otic ganglion is situated just below the foramen
ovale medial to the trunk of the mandibular nerve.
Presynaptic parasympathetic fibers, derived mainly
from the glossopharyngeal nerve, synapse in the otic
ganglion. Postsynaptic parasympathetic fibers, which
are secretory to the parotid gland, pass from the otic
ganglion to this gland through the auriculotemporal
nerve.