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The submandibular region lies between the mandible and hyoid bone, below the floor of the mouth.
It forms part of the anterior triangle of the neck, bounded by:
Superiorly – Base of mandible.
Inferiorly – Body of hyoid bone.
Laterally – Skin and superficial fascia.
Medially – Mylohyoid and hyoglossus muscles.
Major contents include:
Suprahyoid muscles
Submandibular gland and duct (Wharton’s duct)
Sublingual gland
Submandibular ganglion
Facial artery and vein
These muscles lie above the hyoid bone and connect it to the mandible or skull base.
Their main function is to elevate the hyoid and floor of the mouth during swallowing and depress the mandible.
Has two bellies:
Anterior belly – from digastric fossa of mandible.
Posterior belly – from mastoid notch of temporal bone.
Intermediate tendon connects both bellies, attached to hyoid by a fibrous loop.
Nerve supply:
Anterior belly → Mylohyoid nerve (from inferior alveolar, V₃).
Posterior belly → Facial nerve.
Action: Depresses mandible; elevates hyoid during swallowing.
Origin: Styloid process of temporal bone.
Insertion: Splits around digastric tendon and attaches to hyoid.
Nerve: Facial nerve.
Action: Pulls hyoid upward and backward.
Forms the muscular floor of the mouth.
Origin: Mylohyoid line of mandible.
Insertion: Median raphe and hyoid bone.
Nerve: Mylohyoid nerve (branch of inferior alveolar nerve, V₃).
Action: Elevates floor of mouth and hyoid.
Lies above mylohyoid, below genioglossus.
Origin: Inferior genial tubercle of mandible.
Insertion: Hyoid bone.
Nerve: C₁ fibers through hypoglossal nerve.
Action: Pulls hyoid upward and forward.
Skin incision along the lower border of mandible to expose platysma and superficial fascia.
Identify facial vein (superficial) and facial artery (deep).
Reflect platysma to expose:
Anterior and posterior bellies of digastric
Stylohyoid and mylohyoid muscles
The submandibular gland lies superficial and deep to the mylohyoid.
It is the excretory duct of the submandibular salivary gland.
Length: Approximately 5 cm long.
Course:
Begins from the deep part of the submandibular gland.
Runs forward and upward between mylohyoid (laterally) and hyoglossus–genioglossus (medially).
Crossed superficially by the lingual nerve, which loops under it.
Opens into the floor of the mouth at the sublingual papilla, on either side of the frenulum linguae.
Relations:
Medially: Hyoglossus, genioglossus.
Laterally: Mylohyoid, sublingual gland, and mucosa of the floor of mouth.
Superiorly: Lingual nerve (first lateral, then inferior, finally medial to duct).
Inferiorly: Hypoglossal nerve and its accompanying veins.
Clinical Anatomy:
The lingual nerve looping around the duct is a surgical landmark during duct stone removal (sialolithiasis).
The duct may become obstructed by calculi—the most common site of salivary stones due to the duct’s long, upward course.
Smallest of the three paired major salivary glands.
Location: Beneath the mucosa of the floor of mouth, above the mylohyoid muscle.
Shape: Almond-shaped and flattened.
Weight: Around 2 grams.
Superiorly: Oral mucosa.
Inferiorly: Mylohyoid muscle.
Medially: Genioglossus and submandibular duct.
Laterally: Mandible.
Each gland has about 8–20 small ducts:
The largest duct (duct of Bartholin) may join the submandibular duct.
Others open independently along the sublingual fold in the floor of the mouth.
Secretomotor: Parasympathetic fibers from facial nerve via chorda tympani and submandibular ganglion.
Sympathetic: From the superior cervical ganglion.
Sensory: Lingual nerve.
Ranula – a cystic swelling due to obstruction of sublingual ducts, resembling a “frog’s belly”.
Mucous retention cysts are common in this gland due to multiple small ducts.
A small parasympathetic ganglion associated functionally with the facial nerve, though anatomically connected to the lingual nerve.
Shape: Oval, about 2–3 mm in size.
Location: Suspended from the lingual nerve by two roots, on the superficial surface of hyoglossus, above the deep part of the submandibular gland.
Parasympathetic root: From chorda tympani → joins lingual nerve → to ganglion.
Sympathetic root: From facial artery plexus (superior cervical ganglion).
Sensory root: From lingual nerve.
To submandibular gland – postganglionic secretomotor fibers.
To sublingual gland – via lingual nerve branches.
Relays secretomotor fibers to both submandibular and sublingual glands.
Type: Predominantly serous, with a few mucous alveoli.
Acini:
Serous acini – pyramidal cells with spherical nuclei; secretory granules in apical cytoplasm.
Mucous acini – larger, with flattened basal nuclei.
Duct System:
Intercalated → Striated → Excretory ducts (lined by columnar epithelium).
Striated ducts show basal striations due to mitochondria, aiding ion transport.
Myepithelial cells present between acinar cells and basement membrane aid secretion.
| Feature | Parotid Gland | Submandibular Gland | Sublingual Gland |
|---|---|---|---|
| Situation | Below and in front of ear, in parotid fossa | Beneath lower border of mandible | Beneath mucosa of floor of mouth |
| Type of Secretion | Purely serous | Mixed (predominantly serous) | Mixed (predominantly mucous) |
| Weight | ~25 g | ~10–15 g | ~2 g |
| Duct | Stenson’s duct (~5 cm) | Wharton’s duct (~5 cm) | Bartholin’s ducts (8–20 small) |
| Duct Opening | Opposite upper 2nd molar tooth | Beside frenulum of tongue | Along sublingual fold |
| Parasympathetic Source | Glossopharyngeal nerve → otic ganglion → auriculotemporal nerve | Facial nerve → chorda tympani → submandibular ganglion | Facial nerve → chorda tympani → submandibular ganglion (via lingual nerve) |
| Sympathetic Source | External carotid plexus | Facial artery plexus | Facial artery plexus |
| Histology | Serous acini only | Mainly serous, some mucous | Mainly mucous, few serous demilunes |
| Capsule | Dense and unyielding (causes pain in mumps) | Thin and loose | Very thin or absent |
| Clinical Note | Site of mumps, tumors, and Frey’s syndrome | Common site of duct stones (sialolithiasis) | Site of ranula (mucous cyst) |
Most common in the submandibular duct due to:
Long upward course against gravity
Serous secretion (thicker and more alkaline)
Tortuous duct passage
Symptoms: Swelling and pain under jaw, especially during meals (“meal-time syndrome”).
Treatment: Surgical removal of the calculus (ensure lingual nerve is preserved).
Cystic swelling beneath the tongue caused by obstruction of sublingual duct.
Resembles the underbelly of a frog (rana = frog).
Treatment: Marsupialization or excision of cyst and sublingual gland.
Inflammation of salivary glands, usually secondary to infection or duct obstruction.
Parotid gland → often affected in mumps (paramyxovirus).
Submandibular gland → bacterial infection from oral cavity due to poor drainage.
Complication after parotidectomy.
Misguided regeneration of parasympathetic fibers (that normally stimulate saliva) → stimulate sweat glands on cheek during eating → gustatory sweating.
Pleomorphic adenoma: Most common benign tumor (usually parotid).
Mucoepidermoid carcinoma / adenoid cystic carcinoma: Common malignant forms.
Clinical Significance: In parotid tumors, surgical removal risks facial nerve injury.
Lingual nerve loops under Wharton’s duct — easily injured in submandibular duct surgery.
Hypoglossal nerve passes deep to the gland and may be at risk during deep gland excision.
Chorda tympani nerve carries secretomotor fibers to the submandibular ganglion. It also conveys taste sensations from most of the anterior two-thirds of the tongue.
Submandibular lymph nodes are located both within and outside the submandibular gland.
In cancer of the tongue, this gland is often excised to remove lymph nodes containing secondary deposits.
The facial artery is tortuous, allowing it to adapt to movements of the pharynx.
It is also the chief arterial supply to the palatine tonsil.
The suprahyoid muscles are arranged in four layers:
First layer: Digastric and Stylohyoid
Second layer: Mylohyoid
Third layer: Geniohyoid and Hyoglossus
Fourth layer: Genioglossus
The submandibular gland can be palpated by placing one finger inside the mouth and one outside the mandible.
During surgical excision of the gland, the incision must be made 4 cm below the angle of the jaw to avoid injuring the marginal mandibular branch of the facial nerve.
A patient is diagnosed with carcinoma of the tongue, with the lesion located on the dorsum near its lateral border.
Into which lymph nodes will the cancerous lesion drain?
Which additional structures need to be removed during surgery?
The lymph from the dorsum of the tongue, especially near its lateral border, drains mainly into the submandibular group of lymph nodes.
Some lymphatic vessels cross the midline and drain into the opposite submandibular lymph nodes, explaining bilateral spread in tongue cancer.
Since submandibular lymph nodes lie within and around the submandibular salivary gland, this gland must be removed along with affected lymph nodes during neck dissection.
The incision for gland or lymph node removal is made about 4 cm below the angle of the mandible to protect the marginal mandibular branch of the facial nerve, which runs posteroinferior to the angle before curving upward across the jaw.
Injury to this nerve causes paralysis of the muscles of the lower lip, leading to facial asymmetry.
Clinical Case:
A 45-year-old patient presents with painful swelling beneath the mandible that worsens during meals.
Explanation:
The submandibular duct has a long, upward, tortuous course and its secretion is viscous, predisposing it to stone formation.
When saliva is secreted during eating, the stone obstructs the duct, causing painful distension of the gland (“meal-time syndrome”).
Radiographs or sialography confirm the diagnosis, as the calculus is often radio-opaque.
Treatment Note:
The duct can be incised intraorally to remove the stone.
Care must be taken to preserve the lingual nerve, which loops beneath the duct before ascending medially.
Clinical Case:
A patient requires excision of the submandibular gland due to chronic infection or tumor.
Explanation:
The marginal mandibular branch of the facial nerve runs posteroinferior to the angle of the mandible before curving upward.
During surgery, an incision must be placed more than 4 cm below the angle of the jaw to avoid injury.
Damage to this branch leads to paralysis of lower lip muscles, resulting in facial asymmetry during smiling.
Precaution:
The nerve also crosses the submandibular lymph nodes, so special care is needed during biopsy or lymph node excision.
Clinical Case:
In carcinoma of the tongue, the patient experiences pain in the mandible or ear.
Explanation:
The lingual nerve, carrying sensations from the anterior two-thirds of the tongue, joins the mandibular nerve (V₃).
Pain impulses are referred via its branches to lower teeth, mandible, or external ear, leading to misdiagnosed dental or ear pain.
Clinical Case:
A carcinoma near the lateral border of the tongue shows bilateral lymph node enlargement.
Explanation:
Lymph from this area drains mainly into submandibular lymph nodes, but a few vessels cross the midline.
Hence, bilateral spread is common, and the entire submandibular gland with lymph nodes must be removed during neck dissection.
Clinical Case:
Dental abscess or infected lower molar leads to swelling under the jaw.
Explanation:
Infection from the oral cavity can spread to the submandibular space via the mylohyoid gap.
This space communicates with the sublingual and parapharyngeal spaces, allowing infection to spread rapidly to deep neck regions (Ludwig’s angina).
Complication:
Untreated infection may cause airway obstruction due to elevation of the tongue and floor of the mouth.
Q1. What are the main salivary glands?
→ The three pairs of large salivary glands are:
Parotid gland
Submandibular gland
Sublingual gland
Q2. What type of gland is the submandibular salivary gland?
→ It is a mixed gland, predominantly serous in nature.
Q3. Name the duct of the submandibular gland and its opening site.
→ The submandibular (Wharton’s) duct opens on the sublingual papilla, beside the frenulum of the tongue.
Q4. Which nerve supplies secretomotor fibers to the submandibular gland?
→ Chorda tympani nerve (a branch of facial nerve), via the submandibular ganglion.
Q5. What is the relation between the lingual nerve and Wharton’s duct?
→ The lingual nerve first lies lateral, then below, and finally medial to the duct — it loops around it like a hook.
Q6. Which muscle divides the submandibular gland into two parts?
→ The mylohyoid muscle divides it into superficial and deep parts.
Q7. What is the parasympathetic pathway to the submandibular and sublingual glands?
→ Facial nerve → Chorda tympani → Lingual nerve → Submandibular ganglion → Gland.
Q8. What are the common diseases of the submandibular gland?
→
Sialolithiasis (salivary calculi) – stone formation in Wharton’s duct.
Sialadenitis – inflammation due to infection or obstruction.
Ranula – cystic swelling due to blocked sublingual ducts.
Q9. What is Frey’s syndrome?
→ A condition of gustatory sweating following parotid gland surgery, due to misdirected regeneration of parasympathetic fibers that stimulate sweat glands instead of salivary glands.
Q10. What is the significance of the marginal mandibular branch of the facial nerve in surgery?
→ During submandibular gland excision, incision should be placed more than 4 cm below the angle of the mandible to avoid injuring this nerve, which supplies muscles of the lower lip.
1. Which of the following salivary glands is mixed but predominantly serous?
A. Parotid gland
B. Submandibular gland
C. Sublingual gland
D. Buccal glands
✅ Answer: B. Submandibular gland
2. The submandibular duct (Wharton’s duct) opens into the oral cavity —
A. Opposite the upper second molar tooth
B. At the tip of the tongue
C. Beside the frenulum of the tongue
D. In the vestibule of the mouth
✅ Answer: C. Beside the frenulum of the tongue
3. Which muscle divides the submandibular gland into superficial and deep parts?
A. Digastric
B. Stylohyoid
C. Mylohyoid
D. Hyoglossus
✅ Answer: C. Mylohyoid
4. The submandibular ganglion is functionally related to which cranial nerve?
A. Facial nerve
B. Glossopharyngeal nerve
C. Trigeminal nerve
D. Vagus nerve
✅ Answer: A. Facial nerve
5. The lingual nerve crosses the submandibular duct —
A. Laterally only
B. Medially only
C. From lateral to medial side
D. From medial to lateral side
✅ Answer: C. From lateral to medial side
6. Which gland is most commonly affected by salivary calculi (sialolithiasis)?
A. Parotid
B. Submandibular
C. Sublingual
D. Buccal
✅ Answer: B. Submandibular
7. The parasympathetic secretomotor fibers to the submandibular gland reach it through —
A. Auriculotemporal nerve
B. Lingual nerve and submandibular ganglion
C. Glossopharyngeal nerve
D. Great auricular nerve
✅ Answer: B. Lingual nerve and submandibular ganglion
8. The largest salivary gland is —
A. Parotid
B. Submandibular
C. Sublingual
D. Palatine
✅ Answer: A. Parotid
9. The ranula is caused by obstruction of —
A. Parotid duct
B. Wharton’s duct
C. Sublingual duct
D. Duct of Bartholin
✅ Answer: C. Sublingual duct
10. In carcinoma of the tongue, lymph from the anterior two-thirds mainly drains into —
A. Parotid nodes
B. Submandibular nodes
C. Retropharyngeal nodes
D. Deep cervical nodes directly
✅ Answer: B. Submandibular nodes
Q1. What are the boundaries of the submandibular triangle?
→ Superiorly by the lower border of the mandible,
→ Anteriorly by the anterior belly of digastric,
→ Posteriorly by the posterior belly of digastric and stylohyoid.
Q2. What are the main contents of the submandibular triangle?
→ Submandibular gland, facial artery and vein, submandibular lymph nodes, and the mylohyoid nerve.
Q3. Which muscle forms the floor of the submandibular triangle?
→ The mylohyoid forms the main part, with hyoglossus and middle constrictor deeper to it.
Q4. Which nerve supplies the mylohyoid muscle?
→ The nerve to mylohyoid, a branch of the inferior alveolar nerve (from mandibular division of trigeminal).
Q5. Name the suprahyoid muscles and their nerve supply.
→
Digastric: Anterior belly – mylohyoid nerve; posterior belly – facial nerve.
Stylohyoid: Facial nerve.
Mylohyoid: Mylohyoid nerve.
Geniohyoid: C1 via hypoglossal nerve.
Q6. What type of gland is the submandibular gland?
→ It is a mixed gland, mainly serous in nature.
Q7. Through which nerve does the submandibular gland receive parasympathetic fibers?
→ Through the chorda tympani branch of the facial nerve, relayed in the submandibular ganglion.
Q8. What is the course of Wharton’s duct?
→ It runs forward on the hyoglossus, between mylohyoid and genioglossus, crossed by the lingual nerve, and opens beside the frenulum of the tongue.
Q9. What is the relation between Wharton’s duct and lingual nerve?
→ The lingual nerve passes lateral → inferior → medial to the duct (loops around it).
Q10. What is the embryological origin of the submandibular gland?
→ It develops from the endoderm of the floor of the mouth around the 6th week of intrauterine life.
Q11. What are the functions of the submandibular gland?
→ Secretes seromucous saliva that aids in digestion, lubrication, and maintaining oral pH.
Q12. Why is submandibular gland prone to calculus formation?
→ Because the duct is long, narrow, and runs upward; its secretion is viscous and alkaline, favoring stone deposition.
Q13. What is a ranula?
→ A cystic swelling in the floor of the mouth due to obstruction of sublingual ducts.
Q14. What structures are at risk during submandibular gland excision?
→
Marginal mandibular branch of facial nerve
Lingual nerve
Hypoglossal nerve
Q15. Which gland is most commonly affected in mumps?
→ Parotid gland, due to its enclosed fascial capsule that causes painful swelling.
Q16. What is Frey’s syndrome?
→ Gustatory sweating following parotidectomy due to misdirected parasympathetic fibers supplying sweat glands.
Q17. How can the submandibular gland be palpated?
→ One finger is placed in the floor of the mouth and another beneath the mandible — the gland lies between them.
Q18. Which nerve supplies the geniohyoid muscle?
→ C1 fibers carried by the hypoglossal nerve.
Q19. Which artery supplies the submandibular gland?
→ Branches of the facial artery and lingual artery.
Q20. What is the importance of the submandibular lymph nodes clinically?
→ They drain the face, tongue, and floor of mouth — often enlarged in tongue carcinoma or oral infections.
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