Salivary glands
💡 Note: Being NBM (nil by mouth) does not mean no oral fluid intake is allowed - saliva is still produced and swallowed.
🧩 Anatomy
- Parotid Gland: Produces a watery serous fluid.
- Submandibular Gland: Produces a mixed secretion, predominantly seromucinous (serous + mucus).
- Sublingual Gland: Produces seromucinous fluid. Numerous minor salivary glands are scattered throughout the oral cavity.
💦 Saliva Production
- Normal output: 1–2 litres/day.
- Stimulation: Brainstem salivary nuclei via facial (VII) and glossopharyngeal (IX) nerves.
- Inhibition: Sympathetic activity + anticholinergic drugs (e.g. atropine) → dry mouth (xerostomia).
- 💊 Drugs such as TCAs, SSRIs, antihistamines can reduce salivation.
⚙️ Functions of Saliva
- 👅 Taste & Lubrication: Dissolves food and eases swallowing.
- 🗣️ Speech: Moistens oral cavity for clear articulation.
- 🦷 Oral Health: Antimicrobial enzymes + constant wash protect against caries.
- ⚖️ pH Balance: Slightly alkaline, buffering bacterial acids.
- 🤝 Social Role: Saliva has functions in bonding behaviours (e.g. kissing).
🧪 Saliva Composition
- 💧 99.5% Water + Mucus
- 🍞 Amylase (starch breakdown)
- 🛡️ Lysozyme (antimicrobial enzyme)
- 🧬 Immunoglobulin A (IgA)
- ⚡ Electrolytes (Na⁺, K⁺, Ca²⁺, Cl⁻, HCO₃⁻)
🚨 Pathology
- Autoimmune Infiltration: Sjögren’s syndrome, sarcoidosis → chronic dry mouth, gland swelling.
- Salivary Gland Tumours:
- 🌱 Pleomorphic Adenoma: Most common benign tumour, parotid, painless lump.
- 🌿 Warthin’s Tumour: Benign, parotid, may be bilateral. Linked to smoking.
- 🔥 Mucoepidermoid Carcinoma: Malignant; facial nerve palsy & lymph nodes suggest aggressive disease.
- 🧬 Adenocarcinoma: Malignant, often with VII palsy & nodal disease.
- Parotid Swelling: Causes include:
- 🍷 Chronic alcohol use / liver disease
- 🌸 Sarcoidosis (Mikulicz’s syndrome if lacrimal glands also swollen)
- 💧 Sjögren’s syndrome
- 🧪 Lymphoma
- ⚠️ Malignancy (red flag = facial nerve palsy)
- Parotitis (Parotid Inflammation):
- 🦠 Bacterial: Often dehydration, poor oral hygiene, duct stones. Commonly Staphylococcus aureus.
- 🦠 Viral: Mumps - can be bilateral, classically associated with orchitis.
- Sialolithiasis (Salivary Stones): 💎
- Commonest in submandibular gland.
- Painful swelling during meals (“mealtime syndrome”).
- Diagnosis: ultrasound or sialography; treatment may require stone removal or sialendoscopy.
- Xerostomia (Dry Mouth):
- Causes: 💊 drugs (anticholinergics, antidepressants, lithium), 🦠 Sjögren’s, radiation therapy, dehydration, CKD.
- Complications: dental caries, oral candidiasis.
- Sialadenitis (Salivary Gland Inflammation):
- 🦠 Bacterial (Staph, Strep species)
- 🦠 Viral (mumps, HIV)
- 🌸 Sarcoidosis → Heerfordt’s syndrome (uveitis, parotid swelling, fever, facial nerve palsy)
- Mikulicz’s Syndrome: Bilateral enlargement of salivary + lacrimal glands, often autoimmune (e.g. Sjögren’s, sarcoid, lymphoma).
