Salivary Gland Anatomy and Physiology

The salivary glands comprise three pairs of major glands, the parotid, submandibular, and sublingual, together with numerous minor glands of the oral mucosa. They secrete saliva, which lubricates the oral cavity, begins the digestion of starch, buffers acids, and protects the teeth and mucosa. Their secretion is controlled by autonomic nerves.

Definition

The salivary glands are exocrine glands of the oral region, comprising the paired parotid, submandibular, and sublingual glands and numerous minor glands, that secrete saliva through a duct system under autonomic neural control.

Scope

This entry describes the location and duct systems of the major and minor salivary glands, the serous and mucous acinar cells, the composition and functions of saliva, and the autonomic control of secretion. It is a reference account of normal structure and physiology and does not address salivary gland disease or its management.

Core questions

• Where are the major and minor salivary glands and how do they drain?
• How do serous and mucous acinar cells differ?
• What does saliva contain and what does it do?
• How is salivary secretion controlled by the autonomic nervous system?

Key concepts

• Parotid, submandibular, and sublingual glands
• Minor salivary glands
• Serous and mucous acini
• Duct system and ductal modification of saliva
• Saliva composition and functions
• Autonomic (parasympathetic and sympathetic) control
• Resting and stimulated salivary flow

Mechanisms

Acinar cells secrete a primary fluid that is then modified as it passes along the duct system, which reabsorbs and secretes electrolytes to produce the final hypotonic saliva. Parasympathetic stimulation chiefly drives the large fluid volume of secretion, while sympathetic stimulation modifies protein content and composition, so that the character of saliva depends on the pattern of autonomic input. Serous acini produce a watery, enzyme-rich secretion and mucous acini a more viscous mucin-rich one, and the proportion of each varies between glands.

Clinical relevance

The anatomy of the gland ducts and the autonomic control of flow underlie the interpretation of dry mouth, salivary flow measurement, and the protective role of saliva for the dentition. This entry describes normal structure and physiology for reference and is not guidance on diagnosing or treating salivary disorders.

Evidence & guidelines

The account draws on a chapter-length review of salivary gland anatomy and physiology, a review of autonomic regulation of secretion, and standard anatomical references; it is descriptive reference material rather than graded clinical evidence.

History

Salivary physiology developed from early studies of reflex secretion toward a detailed account of acinar fluid formation, ductal modification, and the distinct roles of parasympathetic and sympathetic innervation in determining salivary volume and composition.

Seminal works

• hernandez-2020
• proctor-2007

Frequently asked questions

Which are the major salivary glands?

The three pairs of major salivary glands are the parotid, submandibular, and sublingual glands, supplemented by numerous minor glands throughout the oral mucosa.

How is saliva production controlled?

Salivary secretion is governed by autonomic nerves: parasympathetic activity drives most of the fluid volume, while sympathetic activity mainly alters the protein content and composition of saliva.