Carcinoma of tongue anatomy
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Here is a comprehensive anatomical overview of the tongue relevant to carcinoma, drawn from K.J. Lee's Essential Otolaryngology and Scott-Brown's Otorhinolaryngology Head & Neck Surgery.
Carcinoma of the Tongue - Anatomy
1. Divisions of the Tongue
The tongue is divided into two distinct anatomical and oncological regions:
| Region | Extent | Site Classification |
|---|---|---|
| Oral tongue (anterior 2/3) | Tip, dorsum, lateral borders, ventral surface - all anterior to the circumvallate papillae | Oral cavity (ICD-10 C02) |
| Base of tongue (posterior 1/3) | From circumvallate papillae to epiglottis | Oropharynx |
The sulcus terminalis marks the anterior boundary of the circumvallate papillae. The foramen cecum lies at its apex - the embryologic origin of the thyroid (source of lingual thyroid and thyroglossal duct cysts).
2. Mucosal Lining
- Lateral borders and ventral surface: lining (non-keratinizing stratified squamous epithelium) - continuous with floor of mouth. This is where most carcinomas arise.
- Dorsum and tip: specialized gustatory mucosa with thick, keratinized epithelium.
- Only 4-5% of tongue carcinomas occur on the dorsum; the majority arise on the lateral border of the middle third.
3. Papillae of the Tongue
| Papilla | Location | Function |
|---|---|---|
| Filiform | Bulk of anterior 2/3 | Tactile (no taste) - CN V endings |
| Fungiform | Diffuse, majority at anterior 2 cm | Taste buds on superior surface |
| Foliate | Lateral tongue | Taste buds on lateral surface |
| Circumvallate | V-shaped row at oral/base junction | Taste buds on lateral surface |
4. Muscles
Extrinsic Muscles (all CN XII except palatoglossus)
| Muscle | Origin | Insertion | Function | Nerve |
|---|---|---|---|---|
| Genioglossus | Mental spine of mandible | Hyoid + undersurface of tongue | Depress + protrude | CN XII |
| Hyoglossus | Body + greater cornu of hyoid | Side of tongue | Depress + retract | CN XII |
| Styloglossus | Styloid process | Tip + side of tongue | Retract + elevate | CN XII |
| Palatoglossus | Palatine aponeurosis | Side + dorsum of tongue | Elevate posterior tongue, close oropharyngeal isthmus | CN X (vagus) |
Intrinsic Muscles (CN XII)
Superior/inferior longitudinal, vertical, and transverse fibers - alter the shape of the tongue.
A fibrous midline septum (septum linguae) contains a triangular fat pad visible on axial CT - clinically important for assessing midline tumor extension.
Surgical relevance: Sacrifice of both hypoglossal nerves results in a non-functioning tongue tip with very poor functional outcome.
5. Vascular Supply
- Arterial: Lingual artery - the second branch of the external carotid artery (paired, one on each side).
- Venous: Lingual vein and the ranine vein (vena comitans of the hypoglossal nerve).
Surgical relevance: During resection of posterior tongue lesions, the contralateral vascular pedicle must be preserved if the tongue tip is to be maintained.
6. Innervation
Sensory Innervation
| Region | Modality | Nerve |
|---|---|---|
| Anterior 2/3 (oral tongue) | Touch, pain, temperature | Lingual nerve (CN V3) |
| Posterior 1/3 (tongue base) | Touch, gag (visceral afferent) | Glossopharyngeal nerve (CN IX) |
Taste Innervation
| Region | Pathway |
|---|---|
| Anterior 2/3 | Fungiform/foliate papillae → lingual nerve → chorda tympani (CN VII) → geniculate ganglion → nucleus solitarius |
| Posterior 1/3 | Foliate/circumvallate papillae → CN IX → inferior petrosal ganglion → nucleus solitarius |
Clinical relevance: Tongue base carcinoma invading CN IX causes referred otalgia (via Jacobson's nerve, tympanic branch of CN IX) - a key presenting symptom.
7. Lymphatic Drainage - Most Critical for Carcinoma
Lymphatic drainage of the oral tongue and oropharynx (K.J. Lee's Essential Otolaryngology)
| Site | Primary Drainage |
|---|---|
| Tip of tongue | Submental nodes (level IA) - bilaterally |
| Central tongue | Bilateral deep cervical nodes |
| Lateral border | Ipsilateral levels I-III (submental, submandibular, upper jugular); can have skip metastasis to level IV |
| Tongue base (posterior 1/3) | Bilaterally to levels II-IV (jugulodigastric and deep cervical) |
Key Clinical Points:
- Oral tongue: 25-33% of nodal metastases are clinically detectable; 20-25% are occult (hence elective neck dissection is often recommended even in N0 disease).
- Midline/ventral/base tumors carry a greater risk of bilateral nodal spread.
- Tongue base: >60% have clinically detectable cervical nodes at presentation; 20% are bilateral.
- Depth of invasion >2-4 mm correlates with higher rates of regional metastasis - this is why depth of invasion is now incorporated into the AJCC 8th edition T-staging (pT1 vs pT2 reclassification).
8. Anatomical Basis of Common Presentations
| Symptom | Anatomical Explanation |
|---|---|
| Tongue fixation | Invasion of intrinsic/extrinsic muscles or CN XII |
| Referred otalgia | CN IX involvement (base of tongue) or CN V3 (oral tongue) via auriculotemporal nerve |
| Dysphagia/dysarthria | Loss of tongue mobility, muscle invasion |
| Odynophagia | Base of tongue invasion with CN IX involvement |
| Bilateral nodal disease | Midline tumors draining bilaterally |
9. Site-Specific Oncological Points
- Oral tongue is the second most common site of oral cancer (~30%), after the buccal mucosa in tobacco-chewing populations.
- Most tumors arise on the lateral border of the middle third.
- The incidence of SCC in young patients without risk factors has risen significantly (4% in 1971 to 18% by 1993), with a postulated genetic susceptibility.
- Base of tongue SCC has a strong association with HPV (especially HPV-16); these patients often present with cervical lymphadenopathy and a small, occult primary - early detection is rare because the tongue base is poorly visualized.
Sources:
- K.J. Lee's Essential Otolaryngology, Chapter 45 (Carcinoma of the Oral Tongue, Base of Tongue, Anatomy of the Tongue)
- Scott-Brown's Otorhinolaryngology Head & Neck Surgery (Tongue Carcinoma - Surgical Anatomy section)
For mbbs 1st yesr
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Here is the MBBS 1st Year level anatomy of the tongue, focused on what is tested in exams - structured simply and clearly, sourced from Gray's Anatomy for Students.
Anatomy of the Tongue - MBBS 1st Year
Parts of the Tongue
The tongue is divided into two parts by the terminal sulcus (a V-shaped groove):
| Part | Extent | Lies in |
|---|---|---|
| Oral part (anterior 2/3) | Tip → terminal sulcus | Oral cavity |
| Pharyngeal part (posterior 1/3) | Terminal sulcus → epiglottis | Oropharynx |
- At the apex of the terminal sulcus is the foramen cecum - the embryological origin of the thyroid gland (important for MCQs!)
- The root of the tongue is attached to the mandible and hyoid bone
- A median fibrous septum divides the tongue into right and left halves - all muscles are therefore paired
Papillae (on Dorsum of Oral Tongue)
| Papilla | Shape | Taste Buds? | Note |
|---|---|---|---|
| Filiform | Cone-shaped, pointed | ❌ No | Most numerous; give rough texture |
| Fungiform | Mushroom-shaped | ✅ Yes | On margins and tip |
| Vallate (Circumvallate) | Large, blunt cylinders in a moat | ✅ Yes | 8-12 in a V-row just in front of terminal sulcus |
| Foliate | Mucosal folds | ✅ Yes | On lateral sides near terminal sulcus |
Memory tip: "Filiform has False taste (no buds), all others have taste buds"
Muscles of the Tongue
All muscles supplied by CN XII (Hypoglossal) EXCEPT palatoglossus → CN X (Vagus)
Extrinsic Muscles (move the tongue as a whole)
| Muscle | Origin | Insertion | Action |
|---|---|---|---|
| Genioglossus | Superior mental spines of mandible | Hyoid + full length of tongue | Protrudes tongue (most important!) |
| Hyoglossus | Body + greater horn of hyoid | Lateral tongue | Depresses tongue |
| Styloglossus | Styloid process | Lateral tongue | Retracts + elevates tongue |
| Palatoglossus | Palatine aponeurosis | Lateral tongue | Elevates posterior tongue; closes oropharyngeal isthmus |
Exam point: Palatoglossus is supplied by vagus (CN X) - the only tongue muscle NOT supplied by CN XII
Intrinsic Muscles (change tongue shape - all CN XII)
| Muscle | Action |
|---|---|
| Superior longitudinal | Shortens tongue, curls tip upward |
| Inferior longitudinal | Shortens tongue, turns tip downward |
| Transverse | Narrows + elongates tongue |
| Vertical | Flattens + widens tongue |
Nerve Supply - The Most Important Topic for Exams!
The tongue has four different nerve supplies. Learn this table cold:
| Nerve | Region | Modality |
|---|---|---|
| Lingual nerve (CN V3) | Anterior 2/3 | General sensation (touch, pain, temperature) |
| Chorda tympani (CN VII) | Anterior 2/3 | Taste |
| Glossopharyngeal (CN IX) | Posterior 1/3 | Both general sensation AND taste |
| Vagus (CN X) | Near epiglottis (valleculae) | Taste only |
| Hypoglossal (CN XII) | All of tongue | Motor (muscles) |
Memory aid: "Very Fine Girls Vote Hard" = V3 (sensation ant 2/3), Facial/VII (taste ant 2/3), Glossopharyngeal/IX (post 1/3), Vagus/X (near epiglottis), Hypoglossal/XII (motor)
Blood Supply
Arterial: Lingual artery - a branch of the external carotid artery (loops deep to hyoglossus muscle to enter the tongue)
Venous: Lingual vein → internal jugular vein (the ranine vein on the undersurface is easily visible)
Hyoglossus as a landmark: The lingual artery passes deep to hyoglossus; the lingual nerve and hypoglossal nerve pass superficial to hyoglossus - this is a classic surgical anatomy question!
Lymphatic Drainage - KEY for Carcinoma
| Part of Tongue | Drains to | Side |
|---|---|---|
| Tip | Submental nodes → jugulo-omohyoid node | Bilateral |
| Central oral tongue | Submandibular nodes → deep cervical nodes | Bilateral |
| Lateral oral tongue | Submandibular nodes → deep cervical chain (Levels I-III) | Ipsilateral |
| Posterior 1/3 (base) | Direct to jugulodigastric (tonsillar) node | Bilateral |
Why this matters in carcinoma:
- Lateral border carcinoma - ipsilateral neck dissection is sufficient
- Tip or midline carcinoma - risk of bilateral nodal spread, so both sides of the neck must be assessed
- Base of tongue carcinoma - almost always bilateral nodal drainage, high rate of occult nodes
Clinical Correlations for MBBS Exams
| Condition | Anatomy Involved | Consequence |
|---|---|---|
| Hypoglossal nerve palsy | CN XII | Tongue deviates to the affected/paralysed side on protrusion (genioglossus of normal side pushes it over) |
| Carcinoma lateral tongue | Lateral border mucosa | Spreads to ipsilateral levels I-III; midline tumors spread bilaterally |
| Lingual thyroid | Foramen cecum | Failed descent of thyroid during embryogenesis |
| Tongue tie (ankyloglossia) | Short lingual frenulum | Difficulty protrusion + speech |
| Referred otalgia in tongue cancer | CN IX (posterior 1/3) → tympanic branch to middle ear | Ear pain with no ear disease |
| Taste loss after middle ear surgery | Chorda tympani damage | Loss of taste in anterior 2/3 of tongue |
Quick Revision Summary
TONGUE
├── Oral 2/3 (oral cavity) ──── Pharyngeal 1/3 (oropharynx)
├── Divided by terminal sulcus
├── Foramen cecum = thyroid origin
│
├── MUSCLES: All CN XII except Palatoglossus (CN X)
├── SENSATION: Ant 2/3 = V3 (lingual n.) | Post 1/3 = IX
├── TASTE: Ant 2/3 = VII (chorda tympani) | Post 1/3 = IX
├── MOTOR: All CN XII (except palatoglossus = CN X)
│
├── BLOOD: Lingual a. (branch of external carotid)
└── LYMPH: Lateral → ipsilateral; Tip/midline/base → bilateral
Sources: Gray's Anatomy for Students, Chapter 8; K.J. Lee's Essential Otolaryngology, Chapter 45
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