Which of the following systems is NOT directly involved in the regulation or function of the salivary glands?

Correct answer: C. The skeletal system

• A. The AUTONOMIC NERVOUS SYSTEM is the primary controller. PARASYMPATHETIC stimulation (CN VII to submandibular and sublingual via the chorda tympani and submandibular ganglion; CN IX to parotid via the otic ganglion) produces copious watery serous saliva. SYMPATHETIC stimulation produces scant, viscous, protein-rich saliva.
• B. The ENDOCRINE system influences salivary composition and flow; aldosterone modifies ductal sodium and potassium handling, and conditions such as diabetes and thyroid disease alter salivary function.
• C. CORRECT — this is the exception. The SKELETAL SYSTEM has no regulatory role in salivary secretion. The glands sit in relation to bony landmarks anatomically, but bone neither controls secretion nor participates in salivary function.
• D. Saliva is the first step of DIGESTION — salivary amylase begins starch breakdown, lingual lipase begins fat digestion, and the fluid lubricates the bolus for swallowing and dissolves molecules for taste.

Note: Saliva's other roles are worth holding in mind because they explain almost every consequence of xerostomia: buffering (bicarbonate and phosphate), remineralisation (supersaturated calcium and phosphate), antimicrobial defence (lysozyme, lactoferrin, secretory IgA), clearance of substrate, pellicle formation, and retention of complete dentures.