PAROTID GLAND
INTRODUCTION:-
It is the largest of the salivary gland. It weights about 25g.
Site:-
It is situated below the external acoustic meatus, between the ramus of mandible and the sternocleidomastoid.
Shape:-
It is pyramidal in shape.
EXTENT:-
1. Superiorly to zygomatic arch.
2. Inferiorly to angle of mandible.
3. Anteriorly to overlap the posterior border of masseter.
4. Posteriorly to overlap anterior border of sternocleidomastoid.
CAPSULE:-
Derived from deep fascia of neck (cervical fascia).
It's superficial layer is attached to zygomatic arch and extends to cover masseter.
It's deep layer is attached to mandible, styloid and mastoid process.
A thickening of deep fascia extends from styloid process to angle of mandible (stylomandibular ligament) and separates the capsule of parotid from that of submandibular gland.
It is tense (swelling of parotid gland are painful).
EXTERNAL FEATURES:-
The gland resembles a three sided pyramid.
The apex of the pyramid is directed downwards.
The gland has FOUR surface:-
1. Superior (base of the pyramid)
2. Superficial
3. Anteromedial
4. Posteromedial
The surface are separated by three borders:-
1. Anterior
2. Posterior
3. Medial edge or pharyngeal border
RELATIONS:-
PARTS:-
1. Apex
2. Base
3. Superficial
4. Anteromedial
5. Posteromedial
Apex:-
It overlaps posterior belly of digastric.
Structures passing through
- Cervical branch of facial nerve.
- Divisions of retromandibular veins.
Base (superior surface):-
Concave in shape.
Related to
- External acoustic meatus.
- Superficial temporal vessels.
- Auriculotemporal nerve.
Superficial:-
Largest of all surface
Covered with
- Skin
- Superficial fascia
- Parotid fascia
- Parotid lymph nodes
Anteromedial:-
Grooved by posterior border of ramus of mandible
Related to
- Masseter
- Lateral surface of TMJ
- Medial pterygoid
- Emerging branches of facial nerve
Posteromedial:-
Related to
- The mastoid process with sternocleidomastoid and posterior belly of digastric.
- Styloid process
- External carotid artery enters the gland through this surface.
BORDERS:-
1. Anterior border:-
Separates the superficial surface from anteromedial surface.
Following structures emerge at this border.
1. Parotid gland
2. Terminal branch of facial nerve
3. Transverse facial nerve
2. Posterior border:-
Separates superficial surface from posteromedial surface.
Emerging structures
1. Posterior auricular branch of facial nerve.
2. Posterior auricular vessels.
3. Medial edge or pharyngeal border:-
Separates anteromedial surface from the posteromedial surface.
Related to
- Lateral wall of pharynx.
STRUCTURES PASSING WITHIN THE PAROTID GLAND:-
1. Facial nerve
2. External carotid artery
3. Retromandibular vein
1. FACIAL NERVE:-
It gives rise to five terminal branches within the parotid gland. These branches innervate the muscles of facial expressions.
2. EXTERNAL CAROTID ARTERY:-
It ascends through the parotid gland. Within the gland, the external carotid artery gives rise to the posterior auricular artery. The external carotid artery then divides into its two terminal branches.
1. Maxillary artery
2. Superficial temporal artery
3. RETROMANDIBULAR VEIN:-
It is formed within the parotid gland by the convergence of the superficial temporal and maxillary veins. It is one of the major structures responsible for venous drainage of the face.
BLOOD SUPPLY OF PAROTID GLAND:-
Arterial blood:-
External carotid artery and superficial temporal artery.
Venous blood:-
To external jugular vein and retromandibular vein.
NERVE SUPPLY:-
1. PARASYMPATHETIC NERVE (SECRETOMOTOR) :-
Reach gland through auriculotemporal nerve.
2. SYMPATHETIC NERVE (VASOMOTOR) :-
Sympathetic fibres reach the parotid gland by forming a plexus around the external carotid artery.
3. SENSORY NERVE:-
It is by auriculotemporal nerve. Skin over the parotid gland is innervated by great auricular nerve.
LYMPHATIC DRAINAGE:-
Lymph drains first to superficial and deep parotid lymph nodes from there to upper deep cervical nodes.
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