Parotid Gland and Parotid Duct in HOF
- Highlighted area
Quick facts
- Definition
- The largest of the salivary glands, producing serous saliva, located in front of and below the ear.
- Location
- Over the posterior part of the masseter and the ramus of the mandible, extending behind it.
- Parotid duct
- Leaves the front edge of the gland, crosses the masseter below the zygomatic arch, passes through the buccinator and opens into the mouth near the upper second molar.
- Internal structures
- The facial nerve branches inside it; the external carotid artery and the retromandibular vein also run through it.
- Relevance in HOF
- Posterior limit of toxin in the masseter and a differential diagnosis for increased volume at the angle of the jaw.
The parotid gland is the largest of the salivary glands. It sits on each side of the face, in front of and below the ear, covering the posterior part of the masseter muscle and the ramus of the mandible. Its saliva reaches the mouth through the parotid duct, which crosses the cheek. In HOF, the parotid matters for three reasons: it is the posterior limit of toxin in the masseter, it houses the facial nerve, and it can be the cause of increased volume at the angle of the jaw that is not muscular.
Where are the parotid and its duct?
| Structure | Position |
|---|---|
| Gland | Between the ear, the ramus of the mandible and the sternocleidomastoid muscle, extending forward over the masseter |
| Capsule | Wrapped in a firm fascia, continuous with the fascia of the neck |
| Parotid duct | Leaves the front edge of the gland and crosses the masseter below the zygomatic arch |
| Duct exit | Passes through the buccinator and opens into the cheek mucosa, at the level of the upper second molar |
| Accessory gland | A small portion of glandular tissue that may accompany the duct over the masseter |
The duct runs in a band parallel to the transverse facial artery, just below it. In many people it can be palpated as a cord over the contracted masseter.
What passes through the gland?
The facial nerve enters the parotid from behind and splits into its branches inside it, dividing the gland into a superficial portion and a deep one. The branches fan out from the front edge: temporal, zygomatic, buccal, marginal mandibular and cervical. The external carotid and the retromandibular vein also run through the gland, and the superficial temporal artery arises there.
Why does it matter in HOF?
- Toxin in the masseter: the parotid covers the posterior part of the muscle. Injections that are too posterior or too superficial raise the chance of unwanted effects, and planning usually treats the front edge of the gland as the limit. The topic is covered in botulinum toxin in the masseter.
- A wide face at the base: not every bit of volume at the mandibular angle is masseter. Enlargement of the parotid, from glandular or systemic causes, also widens the contour and does not respond to toxin.
- Filler in the lateral cheek: the duct and the branches of the facial nerve pass through the same band. Injuries are rare, but anatomy guides the plane and the area, at the discretion of the qualified professional.
How does it show up in the assessment?
- Frontal view: width of the lower third and symmetry between the sides.
- Palpation with contraction: separates muscle from gland.
- History: bruxism, dry mouth, swelling when eating and systemic diseases.
Also called: parotid, major parotid gland; Stensen's duct (for the parotid duct).
Frequently asked questions
Can toxin in the masseter reach the parotid?
The parotid covers the posterior part of the masseter, and toxin injected too far back or too superficially can reach the gland. That is why the parotid is one of the anatomical limits considered for toxin in the masseter, at the professional's discretion.
Where is the parotid duct?
It crosses the cheek horizontally over the masseter, a little below the zygomatic arch. At the front edge of the masseter it dips deeper, passes through the buccinator and opens into the cheek mucosa, at the level of the upper second molar.