Largest of 3 paired salivary glands. Almost entirely serous; lobulated; yellowish-brown; ~25 g. Lies in retromandibular fossa — pyramidal space posterior to ramus of mandible.

Location and Extent

• External auditory meatus (above) → upper carotid triangle (below)
• Wraps around neck of mandible; extends medially to styloid process; overlaps SCM posteriorly; over masseter anteriorly

Capsule

• From investing layer of deep cervical fascia (splits between angle of mandible + mastoid process)
• Superficial lamina — thick, strong; blends with masseter epimysium → parotidomasseteric fascia; attached to zygomatic arch
• Deep lamina — thin; attached to tympanic plate + styloid process; thickened inferiorly = stylomandibular ligament (separates parotid from submandibular gland; pierced by ECA)

Swellings very painful — tough unyielding capsule (richly innervated by great auricular nerve) stretches; pain increases at meal-time (↑parasympathetic stimulation → ↑secretion + turgor)

External Features

Resembles 3-sided pyramid with apex directed downwards.

• Apex — overlaps posterior belly of digastric + carotid triangle; cervical branch of facial nerve + 2 divisions of retromandibular vein emerge here
• Superficial surface — skin, superficial fascia (anterior branches of great auricular nerve, superficial parotid lymph nodes, platysma), parotid fascia, deep parotid lymph nodes
• Anterior border — parotid duct, terminal facial nerve branches, transverse facial vessels; accessory parotid gland lies on duct close to this border

Structures Within the Gland (Superficial → Deep)

Memory: Facial nerve (most superficial) → Retromandibular vein → External carotid artery (deepest)

Facial Nerve (Most Superficial)

• Exits through stylomastoid foramen → curves around lateral aspect of root of styloid process → enters gland through upper part of posteromedial surface
• Within gland: runs superficial to retromandibular vein ~1 cm → divides:

• 5 terminal branches radiate from anterior border = pes anserinus (goose’s foot)
• Branches leave through anteromedial surface

Retromandibular Vein (Intermediate)

• Formed within gland — union of superficial temporal vein + maxillary vein
• In lower gland, divides into:
  • Anterior division → joins facial vein → common facial vein
  • Posterior division → joins posterior auricular vein → external jugular vein

External Carotid Artery (Deepest)

• Enters through lower part of posteromedial surface
• Divides into terminal branches within gland:
  • Maxillary artery → leaves through anteromedial surface
  • Superficial temporal artery → gives off transverse facial artery; emerges at anterior part of superior surface

ICA does NOT pass through gland — lies deep to styloid process, posteromedial to gland

Parotid Lymph Nodes

• Superficial (preauricular): in superficial fascia over gland
• Deep: embedded within gland
• Drain: temple, scalp, lateral auricle, EAM, middle ear, upper cheek, eyelids
• Efferents → upper deep cervical nodes

Patey’s Faciovenous Plane

• Large superficial lobe + small deep lobe + isthmus connecting them (collar-stud/H appearance in coronal section)
• Facial nerve + retromandibular vein pass through isthmus
• Surgical cleavage plane used during parotidectomy

Parotid Duct (Stenson’s Duct)

• ~5 cm long, thick-walled
• From middle of anterior border → forward over masseter → at anterior masseter border, turns medially (~90° — 1st bend) → pierces buccal fat, buccopharyngeal fascia, buccinator obliquely → runs forward between buccinator + buccal mucosa (2nd bend) → turns medially (3rd bend) → opens in vestibule of mouth opposite crown of upper 2nd molar tooth
• Surface marking: middle 1/3 of line from lower border of tragus to midpoint between ala of nose + red margin of upper lip
• Tortuous oblique course through buccinator = valve (prevents inflation during blowing)

Accessory Parotid Gland

• Detached forward extension; between zygomatic arch (above) + parotid duct (below); its ducts open into main duct

Nerve Supply

Parasympathetic (secretomotor): Inferior salivatory nucleus → CN IX → tympanic branch (Jacobson’s nerve) → tympanic plexus → lesser petrosal nerve → relay in otic ganglion → postganglionic fibres → auriculotemporal nerve → parotid gland

Sympathetic (vasomotor): superior cervical ganglion → plexus on middle meningeal artery → through otic ganglion (no relay) → auriculotemporal nerve → parotid; produces thick, sticky secretion

Sensory: auriculotemporal nerve (gland); great auricular nerve C2, C3 (parotid fascia)

Development

• Ectodermal origin — only major salivary gland from ectoderm (submandibular + sublingual = endoderm)
• Develops from buccal epithelium lateral to angle of mouth

Applied Anatomy

Mumps (viral parotitis) — mumps virus (paramyxovirus); acute swelling, pain ↑at meals; does not suppurate (viral); complications: orchitis, pancreatitis

Parotid abscess — drained by horizontal incision (Hilton’s method) — avoids facial nerve branches (run horizontally); incision below angle of mandible, parallel to branches

Parotidectomy — facial nerve identified at stylomastoid foramen + traced forwards through gland; gland removed in 2 parts along Patey’s faciovenous plane preserving nerve

Mixed parotid tumour (Pleomorphic adenoma) — most common parotid tumour; slow-growing, lobulated, painless; in large superficial lobe; no facial nerve involvement initially

• Malignant transformation: pain, rapid growth, fixity/hardness, facial nerve palsy, cervical lymphadenopathy

Frey’s syndrome (auriculotemporal syndrome) — follows parotid surgery/trauma; damaged auriculotemporal nerve (secretomotor + sympathetic fibres) regenerates aberrantly into sweat gland endoneurial sheaths → salivation stimulus evokes gustatory sweating, flushing, hyperaesthesia over cheek/preauricular area

The parotid gland is the largest of the three paired salivary glands (parotid, submandibular, sublingual). It is composed almost entirely of serous alveoli, is lobulated, yellowish-brown, and weighs about 25 g. It lies in the retromandibular fossa (parotid bed) — the pyramidal space posterior to the ramus of the mandible.

Location and Extent

The gland extends from the external auditory meatus above to the upper part of the carotid triangle below. It wraps around the neck of the mandible, extends medially to the styloid process (close to the side wall of the pharynx), overlaps the sternocleidomastoid posteriorly, and extends over the masseter anteriorly.

Boundaries of the parotid bed:

Capsule

The parotid gland is enclosed by a tough fibrous capsule derived from the investing layer of deep cervical fascia, which splits between the angle of the mandible and the mastoid process to enclose the gland.

• Superficial lamina — thick, strong, adherent; blends with epimysium of masseter to form the parotidomasseteric fascia; attached above to the zygomatic arch.
• Deep lamina — thin; attached to the tympanic plate and styloid process; thickened inferiorly to form the stylomandibular ligament, which separates the parotid from the submandibular gland and is pierced by the external carotid artery.

Parotid swellings are very painful because the tough, unyielding parotid capsule (richly innervated by the great auricular nerve) is stretched. Pain increases at meal-time (parasympathetic stimulation → increased secretion and turgor) and is relieved after eating (secretion released).

External Features

The gland resembles a three-sided pyramid with the apex directed downwards.

Borders:

Structures Within the Parotid Gland

Three main structures traverse and branch within the gland. From superficial (lateral) to deep (medial):

Memory: Facial nerve (most superficial) → Retromandibular vein → External carotid artery (deepest)

Facial Nerve (Most Superficial)

• Exits the cranial cavity through the stylomastoid foramen → curves around the lateral aspect of the root of the styloid process → enters the gland through the upper part of its posteromedial surface.
• Within the gland, runs superficial to the retromandibular vein for ~1 cm, then divides into two trunks:

• The 5 terminal branches radiate from the anterior border of the gland like a goose’s foot — pes anserinus.
• Branches leave through the anteromedial surface and emerge on the face underneath the anterior border.

Retromandibular Vein (Intermediate)

• Formed within the gland by union of the superficial temporal vein and maxillary vein.
• In the lower part of the gland, divides into:
  • Anterior division → joins the facial vein → common facial vein
  • Posterior division → joins the posterior auricular vein → external jugular vein

External Carotid Artery (Deepest)

• Enters the gland through the lower part of the posteromedial surface.
• Within the gland, divides into its two terminal branches:
  • Maxillary artery → leaves through the anteromedial surface
  • Superficial temporal artery → gives off the transverse facial artery, emerges at the anterior part of the superior surface

The internal carotid artery does not pass through the gland — it lies deep to the styloid process, posteromedial to the gland. The deepest structure within the parotid gland is the external carotid artery.

Parotid Lymph Nodes

• Superficial parotid (preauricular) nodes — in the superficial fascia over the gland.
• Deep parotid nodes — embedded within the substance of the gland.
• Drain: temple, side of scalp, lateral surface of auricle, EAM, middle ear, upper cheek, parts of eyelids and orbit.
• Efferents → upper deep cervical nodes.

Summary — Medial to Lateral Arrangement in Horizontal Section

Patey’s Faciovenous Plane

The parotid gland is composed of a large superficial lobe and a small deep lobe, connected by an isthmus of glandular tissue (H-shaped or collar-stud appearance in coronal section). The facial nerve and retromandibular vein pass through the isthmus. The plane containing these structures is Patey’s faciovenous plane — the surgical cleavage plane used during parotidectomy.

Parotid Duct (Stenson’s Duct)

• About 5 cm long, thick-walled.
• Emerges from the middle of the anterior border of the gland.
• Runs forward over the masseter, between the upper and lower buccal branches of the facial nerve.
• At the anterior border of masseter, turns medially (~90° — first bend), pierces the buccal pad of fat, buccopharyngeal fascia, and buccinator obliquely.
• After piercing the buccinator, runs forward between it and buccal mucosa (second bend), then turns medially (third bend) to open in the vestibule of the mouth opposite the crown of the upper second molar tooth.

Relations on the masseter:

The tortuous/oblique course of the duct through the buccinator acts as a valve, preventing inflation of the duct during blowing. Surface marking: middle third of the line from lower border of tragus to the midpoint between the ala of nose and red margin of the upper lip.

Accessory Parotid Gland

A detached forward extension of the gland, lying between the zygomatic arch (above) and the parotid duct (below), along the course of the duct. Its ducts open into the main parotid duct.

Blood Supply

• Arterial: External carotid artery and its branches arising within the gland.
• Venous: External jugular vein and internal jugular vein.

Nerve Supply

1. Parasympathetic (secretomotor):

Inferior salivatory nucleus (medulla)
            │
   Glossopharyngeal nerve (CN IX)
            │
   Tympanic branch (Jacobson's nerve)
            │
       Tympanic plexus
            │
    Lesser petrosal nerve
            │
   ── Relay in OTIC GANGLION ──
            │
   Postganglionic fibres
            │
   Auriculotemporal nerve
            │
      Parotid gland

2. Sympathetic (vasomotor):

• Postganglionic fibres from the superior cervical ganglion (preganglionic from lateral horn of T1).
• Travel via the plexus around the middle meningeal artery.
• Pass through the otic ganglion without relay → auriculotemporal nerve → parotid gland.
• Stimulation produces thick, sticky secretion.

3. Sensory:

• Auriculotemporal nerve — to the gland itself.
• Great auricular nerve (C2, C3) — to the parotid fascia.

Lymphatic Drainage

Lymph drains first to the parotid nodes (superficial and deep), then to the upper deep cervical lymph nodes.

Development

The parotid gland is ectodermal in origin — the only major salivary gland to develop from ectoderm (submandibular and sublingual develop from endoderm). It develops from buccal epithelium just lateral to the angle of the mouth; the outgrowth branches repeatedly to form the duct system and acini.

Applied Anatomy

Mumps (viral parotitis):

• Caused by the mumps virus (myxovirus/paramyxovirus). Acute inflammation and swelling of the parotid gland.
• Pain increases during meals (increased turgor) and is partially relieved after eating.
• Does not suppurate (viral).
• Complications: orchitis (epididymo-orchitis), pancreatitis.

Parotid abscess:

• May result from spread of infection via the parotid duct.
• Drained by a horizontal incision (Hilton’s method) — to avoid cutting facial nerve branches which run horizontally. Incision below the angle of the mandible, parallel to the branches.

Parotidectomy:

• Facial nerve is identified at the stylomastoid foramen and traced forwards through the gland.
• Gland is removed in two parts (superficial and deep) along Patey’s faciovenous plane, preserving the nerve.

Mixed parotid tumour (Pleomorphic adenoma):

• Most common tumour of the parotid gland.
• Slow-growing, lobulated, painless; arises in the large superficial lobe; no facial nerve involvement initially.
• Malignant transformation is indicated by: pain, rapid growth, fixity/hardness, facial nerve involvement (palsy), cervical lymphadenopathy.

Frey’s syndrome (auriculotemporal syndrome):

• Follows parotid surgery or trauma to the parotid region.
• Damaged auriculotemporal nerve (containing secretomotor and sympathetic fibres) regenerates aberrantly into sweat gland endoneurial sheaths.
• Result: a stimulus for salivation evokes gustatory sweating, flushing, and hyperaesthesia over the cheek/preauricular region.

Parotid calculi:

• Form in the gland or Stenson’s duct; demonstrated by parotid sialogram (radiopaque dye injected via duct opening).

Golden facts:

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