Small peripheral parasympathetic ganglion (pinhead-sized, 2–3 mm). Relays secretomotor fibres to parotid gland. Topographically related to mandibular nerve; functionally part of glossopharyngeal nerve.

Location

• Infratemporal fossa, just below foramen ovale
• Medial to mandibular nerve; lateral to tensor veli palatini
• Surrounds origin of nerve to medial pterygoid

Roots/Connections (4 roots)

1. Parasympathetic (Secretomotor) Root — Principal Functional Connection

• Via lesser petrosal nerve

Inferior salivatory nucleus (medulla) → glossopharyngeal nerve → tympanic branch (Jacobson’s nerve) → tympanic plexus → lesser petrosal nerve → RELAY in otic ganglion → postganglionic fibres → auriculotemporal nerve → parotid gland (secretomotor)

2. Sympathetic Root

• From plexus on middle meningeal artery (postganglionic from superior cervical ganglion; preganglionic from T1–T2)
• Passes through otic ganglion without relay; reaches parotid via auriculotemporal nerve
• Function: vasomotor

3. Sensory Root

• From auriculotemporal nerve → sensory to parotid gland

4. Motor Root (Pass-through, No Relay)

• Nerve to medial pterygoid passes through ganglion without relay → supplies:
  • Medial pterygoid
  • Tensor veli palatini
  • Tensor tympani

Distribution Summary

Applied Anatomy

• Chorda tympani connection to otic ganglion — provides alternative pathway for taste from anterior 2/3 of tongue; clinical evidence suggests parotid gland also receives some secretomotor fibres via chorda tympani in addition to the principal otic ganglion/auriculotemporal route

The otic ganglion is a small peripheral parasympathetic ganglion that relays secretomotor fibres to the parotid gland. Topographically, it is intimately related to the mandibular nerve, but functionally it is part of the glossopharyngeal nerve.

Size and Location

The otic ganglion is pinhead-sized (2–3 mm), situated in the infratemporal fossa just below the foramen ovale. It lies medial to the mandibular nerve and lateral to the tensor veli palatini, and surrounds the origin of the nerve to the medial pterygoid.

Roots/Connections

The otic ganglion has four roots — parasympathetic (secretomotor), sympathetic, sensory, and motor.

1. Parasympathetic (Secretomotor) Root

This is the principal functional connection, formed by the lesser petrosal nerve. Preganglionic parasympathetic fibres arise from the inferior salivatory nucleus and pass via:

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

These postganglionic fibres are secretomotor to the parotid gland.

2. Sympathetic Root

Derived from the plexus on the middle meningeal artery. Postganglionic fibres arise in the superior cervical ganglion (preganglionic fibres originate from T1–T2 spinal segments, ascend the sympathetic chain, and relay in the superior cervical ganglion). These postganglionic fibres pass through the otic ganglion without relay, and reach the parotid gland via the auriculotemporal nerve. They are vasomotor in function.

3. Sensory Root

Derived from the auriculotemporal nerve, providing sensory innervation to the parotid gland.

4. Motor Root

The nerve to the medial pterygoid gives off a motor root that passes through the ganglion without relay, supplying:

• Medial pterygoid (the parent nerve continues to this muscle).
• Tensor veli palatini (tensor palati).
• Tensor tympani.

These three muscles — medial pterygoid, tensor veli palatini, and tensor tympani — are thus supplied by branches that pass through, but do not relay in, the otic ganglion.

Branches/Distribution Summary

Connection with Chorda Tympani

The chorda tympani nerve is connected to the otic ganglion and also to the nerve of the pterygoid canal. These connections provide an alternative pathway for taste sensation from the anterior two-thirds of the tongue.

Clinical Correlation

Clinical evidence suggests that in humans, the parotid gland also receives secretomotor fibres through the chorda tympani nerve, in addition to the principal pathway via the otic ganglion and auriculotemporal nerve. This is relevant when considering alternative or collateral secretomotor supply in surgical or pathological contexts affecting the glossopharyngeal–otic ganglion pathway.

Diagram Placeholder

Diagram content will be added later.

• Placeholder 1
• Placeholder 2
• Placeholder 3

Previous Year Questions

1. Placeholder question
2. Placeholder question
3. Placeholder question
4. Placeholder question
5. Placeholder question