SN3
SHORT NOTE
5M
★ High-yield
Describe the submandibular gland with its relations, duct and nerve supply.
General Features
The submandibular gland is a mixed (mucoserous, predominantly serous) salivary gland lying in the digastric triangle.
- The second largest salivary gland, about 15 g
- J-shaped, with a large superficial part and a small deep part, continuous round the posterior border of mylohyoid
- It contributes about 70% of resting saliva
Relations
| Part | Relations |
|---|---|
| Superficial part | Inferior — skin, platysma, deep fascia, cervical branch of the facial nerve, facial vein. Lateral — submandibular fossa of the mandible, medial pterygoid; the facial artery grooves the gland. Medial — mylohyoid, hyoglossus, styloglossus; the lingual and hypoglossal nerves |
| Deep part | Between mylohyoid below and hyoglossus above; related to the lingual nerve above and the hypoglossal nerve below |
The Duct and its Relation to the Lingual Nerve
- Wharton duct — about 5 cm long, emerges from the deep part
- Runs forward between mylohyoid and hyoglossus, then between the sublingual gland and genioglossus
- Opens on the floor of the mouth at the side of the frenulum of the tongue, on the sublingual papilla
Nerve Supply
- The submandibular ganglion hangs from the lingual nerve on hyoglossus — its topographical relation is to the lingual nerve, but its functional relation is to the facial
- Sympathetic — from the facial artery plexus; vasomotor
Applied Aspects
- Calculi (stones) form far more often in the submandibular gland than in the parotid — the secretion is more mucous and alkaline, and the duct runs uphill against gravity
- Presents with pain and swelling at mealtimes, subsiding afterward; the stone is often palpable bimanually in the floor of the mouth and visible on a plain radiograph, as most are radio-opaque
- Excision of the gland risks three nerves — the marginal mandibular branch of the facial (drooping corner of the mouth), the lingual and the hypoglossal
- The skin incision is placed at least 2 cm below the angle of the mandible to keep clear of the marginal mandibular nerve
- Ludwig angina — cellulitis of the submandibular and sublingual spaces, usually dental in origin; the tongue is pushed up and back and the airway is threatened
- Sialography outlines the duct system and shows a stone or a stricture; ultrasound has largely replaced it
- The gland is bimanually palpable, one finger in the floor of the mouth and the other below the mandible — the only way to assess the deep part
All questions in Head & Neck
- Q1Describe the triangles of the neck with their boundaries and contents. Add a note on the posterior triangle and its applied anatomy. ★
- Q2Describe the thyroid gland under relations, blood supply and nerve relations. Add a note on the applied anatomy of thyroidectomy. ★
- Q3Describe the parotid gland under bed, structures within it, duct and nerve supply. Add a note on its applied anatomy. ★
- Q4Describe the larynx under cartilages, cavity, muscles and nerve supply. Add a note on vocal cord palsy. ★
- Q5Describe the cavernous sinus with its contents and connections. Add a note on cavernous sinus thrombosis and the dangerous area of the face. ★
- SN1Describe the course and branches of the facial nerve. Differentiate upper from lower motor neurone facial palsy. ★
- SN2Describe the temporomandibular joint with its movements. Add a note on its dislocation. ★
- SN3Describe the submandibular gland with its relations, duct and nerve supply. ★
- SN4Describe the layers of the deep cervical fascia and the fascial spaces of the neck. ★
- SN5Describe the tongue with its papillae, muscles and nerve supply. Add a note on hypoglossal nerve palsy. ★
- SN6Describe the layers of the scalp with their clinical importance. ★
- SN7Describe the trigeminal nerve with its divisions and distribution. Add a note on the associated parasympathetic ganglia.