Supplied by multiple cranial nerves reflecting complex pharyngeal arch developmental origin. Two types of sensation: general (touch, pain, temperature) + special (taste).

Divided by sulcus terminalis (V-shaped groove) + foramen caecum into regions.

Summary Table

By Region

Anterior 2/3 (oral part) — develops from 1st pharyngeal arch (lingual swellings + tuberculum impar)

• General: Lingual nerve (V3) — post-trematic nerve of 1st arch
• Taste: Chorda tympani (VII) — pre-trematic nerve of 1st arch; fibres hitch-hike with lingual nerve

Exception: Circumvallate (vallate) papillae — near sulcus terminalis — taste = glossopharyngeal (IX) despite being in anterior part; only general sensation = lingual nerve

Posterior 1/3 (pharyngeal part) — develops from 3rd pharyngeal arch

• General + Taste: Glossopharyngeal nerve (IX) — nerve of 3rd arch (same nerve for both modalities)

Posteriormost part + vallecula — develops from 4th pharyngeal arch

• General + Taste: Internal laryngeal branch of superior laryngeal nerve (CN X) — nerve of 4th arch

Developmental Basis

Pre-trematic nerve (crosses anterior to pharyngeal cleft) = carries taste; post-trematic (crosses posterior) = carries general sensation; for 1st arch: chorda tympani = pre-trematic (taste), lingual = post-trematic (general)

Applied Anatomy

Referred pain in carcinoma of tongue — pain in ear, TMJ, temporal fossa, lower teeth despite lesion in tongue = referred via lingual nerve

Carcinoma most commonly involves anterior 2/3 (lingual nerve territory) — explains above patterns

Anaesthesia — lingual nerve block + chorda tympani block → anaesthesia of anterior 2/3 for intraoral procedures

Taste testing — loss of taste in anterior 2/3 with intact posterior 1/3 → lesion in chorda tympani or facial nerve proximal to lingual nerve junction

Glossopharyngeal neuralgia — stabbing pain in posterior 1/3, tonsillar region, ear on swallowing; nerve involved = IX

The tongue is supplied by multiple cranial nerves reflecting its complex developmental origin from several pharyngeal arches. Sensation from the tongue is of two types:

• General sensation (touch, pain, temperature) — equivalent to exteroceptive sensation
• Special sensation (taste) — via the gustatory pathway

The tongue is divided into three regions for the purpose of nerve supply, separated anatomically by the sulcus terminalis (V-shaped groove) and the foramen caecum.

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Sensory Supply by Region

1. Anterior Two-Thirds of the Tongue (Oral Part)

Lies in the mouth cavity; develops from the 1st pharyngeal arch (lingual swellings + tuberculum impar).

Important exception: The circumvallate (vallate) papillae, although situated in the anterior part near the sulcus terminalis, receive their taste supply from the glossopharyngeal nerve (IX) — not from the chorda tympani. Only general sensation in this region is carried by the lingual nerve.

2. Posterior One-Third of the Tongue (Pharyngeal Part)

Lies in the oropharynx; develops from the 3rd pharyngeal arch (cranial part of the hypobranchial eminence).

3. Posteriormost Part of the Tongue and Vallecula

Develops from the 4th pharyngeal arch (caudal part of the hypobranchial eminence).

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Summary Table

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Developmental Basis for Nerve Supply

The nerve supply of the tongue directly reflects its embryological origin — each region of the tongue is supplied by the nerve of the pharyngeal arch from which it developed.

Pre-trematic vs post-trematic: The pre-trematic nerve of an arch crosses anterior to the pharyngeal cleft (carries taste); the post-trematic nerve crosses posterior (carries general sensation). For the 1st arch, the pre-trematic nerve is the chorda tympani (taste), and the post-trematic nerve is the lingual nerve (general sensation).

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Applied Anatomy

Referred Pain in Carcinoma of Tongue

Patients with carcinoma of the tongue frequently complain of pain in the ear, temporomandibular joint, temporal fossa, and/or lower teeth — even though the primary lesion is in the tongue. This is referred pain arising from branches of the lingual nerve.

Mechanism:

Carcinoma most commonly involves the anterior 2/3 of the tongue, which is supplied by the lingual nerve — explaining the patterns above.

Clinical Importance of Knowing Nerve Supply

• Anaesthesia — lingual nerve block + chorda tympani block provides anaesthesia for the anterior 2/3 of the tongue for intraoral procedures
• Taste testing — loss of taste in anterior 2/3 with intact posterior 1/3 localises a lesion to the chorda tympani or facial nerve proximal to its junction with the lingual nerve
• Glossopharyngeal neuralgia — stabbing pain in the posterior 1/3 of the tongue, tonsillar region, and ear precipitated by swallowing; the nerve involved is IX

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