Transcript facial nerve

PAROTID GLAND
BY: DR.RIZWAN SAGHIR
CHATHA
Salivary Glands
 There are 3 pairs of large salivary glands :
 Parotid (largest)
 Sub-mandibular salivary gland
 Sub-lingual salivary gland
Acinar cells of Salivary Glands
 Classified as either:
 Serous cells: produce a thin watery secretion
 Mucous cells: produce a more viscous secretion
 Parotid: serous
 Submandibular: mucous & serous
 Sublingual: mucous
Introduction to Parotid Gland
 Para = around
 Otic = ear
 It is the largest of salivary gland.
 Weighs about 15g.
 Situated below the external acoustic meatus , b/w the
ramus of mandible and sternocleidomastoid.
 Anteriorly gland overlap the masseter muscle.
Surface Marking of Parotid Gland
 (a) 1st point at the upper border of the condyle of
mandible.
 (b) 2nd point just above the centre of the masseter
muscle.
 (c) 3rd point postero-inferior to the angle of the
mandible.
 (d) 4th point on the anterior border of the mastoid
process.
Parotid Duct----Surface marking
 One point at the lower border of the Tragus.
 2nd point mid-way b/w the ala of the nose and the
red margin of the upper lip.
 Middle 3rd of this line represents the parotid duct.
PAROTID CAPSULE
 Parotid capsule:
 Investing layer of deep cervical fascia forms a capsule.
 Fascia splits into:
Superficial lamina (thick)
ii. Deep lamina (thin)
 Portion of deep lamina thickened to form the stylomandibular ligament.
i.
 Stylo-mandibular ligament separates the parotid gland
from the sub-mandibular salivary gland.
PAROTID GALND
 External features:
 Gland resembles a 3-sided pyramid. Apex of pyramid
directed downwards.
 Gland has 4-surfaces:
i. Superior
ii. Superficial
iii. Anterior
iv. posterior
Surfaces
(1) Superior surface or base: forms the upper end
of the gland , which is small and concave.
 It is related to:
External acoustic meatus (cartilaginous part)
2. Posterior surface of TMJ. (temporo-mandibular joint)
3. Vessel: superficial temporal vessels
4. Nerve: auriculo-temporal nerve
1.
Surfaces
(2) Superficial surface: it is largest of the 4surfaces.
 It is covered with:
1. Skin
2. Superficial fascia: contins
 Great auricular nerve + superficial parotid lymph
nodes + posterior fibers of platysma and risorius
3. Parotid fascia
4. Deep parotid lymph nodes
Surfaces
(3) Anterior surface:
 It is related to:
1.
2.
3.
4.
5.
Posterior border of ramus of mandible
Masseter muscle
Lateral surface of TMJ
Medial pterygoid
Facial nerve--- branches
Surfaces
(4) Posterior surface: structures attached to
mastoid and styloid process.
 It is related to:
 Mastoid process-----Muscle: sternocleidomastoid ,
posterior belly of digastric
 Styloid process-----External carotid artery and
internal carotid artery
Parotid Duct
 It is thick walled and is about 5-cm long.
 It emerges from the middle of the anterior border of
the gland.
 And then it runs forwards and slightly downwards on
the masseter.
 Finally the duct turns medially and open into the
mouth, opposite to the upper 2nd – molar tooth.
Parotid Duct or Stenson’s Duct
Structures within the Parotid Gland
 (1) Arteries : external carotid artery enters the
gland posteriorly and give its branches in parotid
gland. i.e maxillary artery , posterior auricular
artery , superficial artery
 (2) Veins: Retromandibular vein , superficial vein ,
maxillary vein
 (3) Nerve : facial nerve and its terminal branches
i.e temporal , zygomatic , buccal , mandibular ,
cervicle
 (4) Parotid lymph nodes
Parotid
 ARTERIAL SUPPLY:
 Artery: external carotid artery and its branches that
arise near the gland.i.e maxillary , superficial
temporal , posterior auricular
 Vein: external jugular vein
 NERVE SUPPLY:
 Sensory nerves of the gland: Auriculo-temporal
nerve.
 But the parotid fascia is innervated by the sensory
fibers of great auricular nerve C2
Para-sympathetic Nerves
 Gland secretion is stimulated by parasympathetic
nerves which are secretomotor.
 They reach the gland through the auriculotemporal
nerve.
 The pre-ganglionic fibers begin in the inferior
salivatory nucleus pass through the glossopharyngeal
nerve , its tympanic branch , tympanic plexus , lesser
petrosal nerve and relay in the otic ganglion.
 The post ganglionic fibers pass through the
auriculotemporal nerve and reach the parotid gland
Sympathetic Nerve
 The sympathetic nerves are vasomotor. and are
derived from the plexus around the external carotid
artery.
Facial Nerve (CN VII)
 Branches and distribution:
 Within the facial canal:
Greater petrosal nerve
2. Chorda tympani
3. Nerve to the stapedius
 At stylo-mastoid foramen:
1. Stylo-hyoid
2. Digastric
3. Posterior-auricular
1.
Facial Nerve (CN VII)
 Terminal branches within the parotid gland.
(T,Z,B,M,C)
 Communicating branches with adjacent cranial
and spinal nerves
Ganglia
 Ganglia associated with facial nerve are:
Geniculate ganglia
2. Sub-mandibular ganglia
3. Pterygo-palatine ganglia
1.
Frey’s Syndrome (Clinical)
 Frey’s syndrome is a complication in which after
penetrating wounds of the parotid gland. when
patient eats, beads of perspiration appear on the skin
covering the parotid. This condition is caused by
damage to the auriculo-temporal nerve and
great auricular nerves. By this means , a stimulus
intended for saliva production produces sweat
secretion
CLINICAL
 Parotid swellings are very painful. mumps is an
infectious disease of the salivary glands caused by a
specific virus.
 Parotid abscess may be caused by spread of infection
from the mouth cavity.
 Benign parotid tumor is a slowly growing , lobulated ,
painless tumor without any involvement of facial nerve.
While malignant tumor is indicated by pain , rapid
growth , involvement of the facial nerve and enlargement
of cervical lymph nodes