Download Parotid duct

The parotid region
•
The parotid region is the part of the •
face below and in front of ear and
below the zygomatic arch but above the
limits of the anterior triangle .the
parotid gland lie in this region.
**The parotid region is actually part of •
the neck but it extends into the facial
region as well..
The parotid gland
[parotis-by the side of ear ]is the •
largest of the main salivary glands
,lobulated and yellowish brown in color
. it is predominantly serous ,with only
few scattered mucous acini . The
parotid gland divided by facial nerve
into deep part and superficial part ,lies
in space called parotid bed or
reteromandibular fossa
parotid gland
is a superficial structure located in the upper •
neck above the posterior belly of the
digastric muscle. It is a salivary gland that
has a large duct which crosses the masseter
muscle to pierce the buccinator muscle
opposite the upper 2nd molar tooth.
frequently be rolled between the finger and
The parotid gland the masseter muscle
divided by facial nerve into deep part and
superficial part
- The parotid gland secrete a hormone
called parotin which:
a. Promotes growth of mesnchymal
tissues.
b. Lowers serum calcium level.
c. Stimulates calcifications
&leucocytes production in bone
marrow.
**parotid gland enclosed within a fascial •
capsule derived from investing layer of deep
cervical fascia of the neck which splits to
ensheath it .
The superfaicial layer known as parotid fascia •
is adherent to the gland and attached above to
the zygomatic arch.
•The deep layer has attachment to the lower
edge of of the tympanic plate of temprol bone
,the styloid process and posterior edge of
tympano- squmous fissure on the base of the
skull
• **[If the parotid gland is carefully
removed , you can identify the
structures located within it. The first
plane is the venous plane and consists
of the retromandibular vein (rm) and its
tributaries and branches
Boundaries : •
Anteriorly: raums of mandible sandwiched •
between the asserter and medial pterygoid
muscles .
Poseriorly: mastoid process between the •
sternomastoid and the posterior belly of
digastric
Superiorly: exsternal auditory meutus . •
Medially: styloid process with the •
styloidhyoid ,styloglosseus and
stylopharyngal muscles
Laterally :parotid fascia •
Lobes and processes
the gland is often described to consist of a
superficial and a deep lobe connected by a
short narrow part called the isthmus. this
gives the gland the shape of a collar stud
with superficial lobe forming the large part.
the facial nerve with its branches passes
forwards on either side of the neck of the
stud .the plane between the superficial and
deep lobe in which the nerve and the vein lie
has been designated by patey as the
faciovenous plane of the gland.
•
The superficial lobe:
extends anteriorly on to the face to •
cover part of the masseter ,the neck of
the mandible and the lateral aspect of
the temporo_mandibular joint .it is
called the facial process and may
separate to form the accessory parotid
gland.
The deep lobe:
The deep lobe which extends medially •
to the styloid process may form two
process _the pharyngeal process
which reaches the pharyngeal wall
_the pterygoid process which extends
anteriorly between the ramus of the
mandible and the medial pterygoid
muscle.
Relations
* base :is seen as a small superior surface •
and is concave. It is related to _the condyle
of the mandible. - the tympanic plate and the
external auditory meatus
*apex: lies between the sternomastoid •
muscle and the angle of the mandible .it lies
on _the posterior belly of the digastrics.
*superficial -lateral surface is covered •
with ((skin ,superficial fascia with some
fibers of platysma ,parotid fascia ,facial
branches of the great auricular nerve
,superficial parotid lymph nodes)
*anteromedial surface :is grooved by the •
posterior border of the ramus of mandible
and extends anteriorly on its superficial and
deep aspects to get related to _posterior
inferior part of the masseter muscle by the
facial process _lateral aspect of the tempro
mandibular joint.
*Posteromedial surface is related to •
(mastoid process ,sternomastoid muscle,
posterior belly of digastrics,styloid process
and the muscle attached to it are:
stylohyoid styloglossus and stylopharyngeus)
•
parotid duct :
The duct is about 2 in. (5 cm) long. it emerges •
from the anterior border of the gland and
runs forwards across the masseter below the
facial process and the transverse facial
vessels. It turns medially around the anterior
border of the masseter at the level of the
upper lip and pierces the following
structures.:
buccal pad of fat ,buccopharyngeal fascia
•
,buccinator muscle ,mucous membrane of
the mouth. The ducts of the other two main
salivary gland open into the mouth cavity
proper and not into the vestibule.
STRUCTURE INCIDE THE GLAND
There are three main structures passing
through the gland .
.
1-The most superficial is the facial nerve
2-deep to the nerve is the retro- mandibular vein
.
3-And deepest of all is the external carotid
artery ,it also contains lymph nodes
4-and filaments of the auriculo-temporal nerve
FACIAL NERVE Emerging from the stylomastoid
foramen .
After that crosses the lateral side of the root of
the styloid process ,and pierces the
posteriomedial surface of the parotid gland
Intertragic notch of the auricle is directly
situated over the facial n. It divides into its two
division which embrace the isthmus of the
gland connecting the superficial and deep
lobes of the gland .Branches of the two
division radiate on the face forming
Serinus (goose foot pattern )
RETROMANDIBULAR VEIN :is formed by the
union of the superficial temporal and
maxillary veins below the zygomatic process
of temporal bone .It descends within the
parotid gland ,deep to its two lobes ,toward
the angle of the mandible
External carotid artery ;.pierces the medial
border of the parotid ,from behind forward
,to emerge on its anteriomedial surface .It
ends posteriomedial to the neck of mandible
by dividing into its two terminal branches:
maxillary and superficial
Horizontal section of the parotid gland and its relations
STRUCTURE RADIATING FROM THE
GLAND
Superiorly :the following structures emerge
after piercing the gland .
-Auriculo-temporal nerve .
-Superficial temporal vessels .
-Temporal branch of the facial nerve.
Inferiorly:
-Cervical branch of facial nerve
-Anterior and posterior division of the
retro-mandibular vein which join the
external jugular &Facial vein respectively
Anteriorly :from above downwards the following
structure appear after piercing the anteriomedial
surface close to anterior border .
-zygomatic branch of facial nerve .
-Transverse facial vessels.
-Parotid duct .
-Buccal &mandibular branches of the facial nerve.
Posterioly :passing over the sternomastoid are :
-Occipital vein .
-Posterior auricular branch of the external carotid
artery.
;
The parasympathetic fibers reach the parotid •
gland by a vary circuitous route
1-Preganglionic nucleus is the inferior salivatory •
nucleus in the medulla
2-preganglionic nerve is the sympathetic branch of
pharyngeal nerve which carries the -the glosso
fibres through the lesser petrosal nerve to the
otic ganglion which is the ganglion of the relay
postganglionic branches are convyed through the temporal branch of the posterior division -auriculo
of the mandibular
the sensory fibers from the gland pass through
temporal nerve-the branches of the auriculo
the parotid fascia receives its sensory
innervation from the great auricular nerve
come from the external carotid plexus
the sympathetic fibers
come from the external
- )vasoconstrictor(
carotid plexus with their source in the
first thoracic segment after their relay in
)C2( .the superior cervical ganglion
. •
The arterial supply is from the external •
.carotidand, the superficial temporal arteries
The venous drainage is into the •
retromandibular and the external jugular
.veins
Lymphatic drainage •
The lymphatic drian from superficial and the •
deep parotid nodes and ultimately from the
.deep cervical nodes
The salivary gland arise from the •
proliferation of the oral fissure and
The bud .grows back toward the ear
branches and canalizes and
differentiates into glandular tissue
a groove on its :As the check forms •
inner aspect closes over to form the
parotid duct.
Clinical Notes
1-the tumors of the parotid gland usually arise in the •
superficial lobe without involvement of the facial nerve
;but an injury to the nerve during excision causes facial
.palsy
2-painful )parotitis( inflammation of the parotid gland •
because the gland swells within the tight fibrous
capsule
3-parotid calculi may form within the gland or the •
.duct
They can be located radiologically by a parotid •
opaque contrast material -sialogram by injecting a radio
through the duct
4-after parotidectomy there may be •
regeneration of the secretomotorfibres
of the parotid gland contained in the
this cause .temporal nerve -auriculo
stimulation of the sweat gland in this
temporal nerve -area of the auriculo
producing redness and sweating in
the skin of the temple supplied by the
nerve this is called the Frey's
syndrome
***Frey's Sdromeyn •
Frey's syndrome is an interesting complication •
that sometimes develops after penetrating wounds
of the parotid gland. When the patient eats, beads
of perspiration appear on the skin covering the
parotid. This condition is caused by damage to the
auriculotemporal and great auricular nerves.
During the process of healing, the
parasympathetic secretomotor fibers in the
auriculotemporal nerve grow out and join the
distal end of the great auricular nerve. Eventually,
these fibers reach the sweat glands in the facial
skin. By this means, a stimulus intended for saliva
production produces sweat secretion instead.
Parotid Duct Injury •
The parotid duct, which is a •
comparatively superficial
structure on the face, may be
damaged in injuries to the face or
may be inadvertently cut during
surgical operations on the face.