Salivary Glands (Parotid, Sublingual, Submandibular)

What are the salivary glands?

The salivary glands produce and secrete saliva into the mouth cavity. There are three pairs of salivary glands :

  1. Parotid glands
  2. Submandibular glands
  3. Sublingual glands

In addition, several small salivary glands (accessory glands) are located throughout the palate, cheeks, lips, tongue and tonsils.

The process of saliva production and secretion are discussed under Saliva Secretion.

Picture from Wikimedia Commons

Parotid Glands

Anatomy and Location

This is the largest of the salivary glands and is wedged between the ramus of the mandible (jawbone) and the mastoid process of the skull. Simply, it is located behind the angle of the jaw, slightly in front of and below the ear. The parotid gland is enveloped by a fibrous capsule known as the parotid sheath. Fatty tissue between the lobes of the parotid gland allow it a significant degree of flexibility.

Apart from being the largest gland, it is also a very significant part of the face anatomy because the parotid plexus of the facial nerve (CN VII), retromandibular vein and external carotid artery are embedded in it. It is important to note that the parotid plexus of facial nerve does not innervate the parotid gland and the retromandibular vein does not drain the gland.

The parotid gland resembles an inverted, irregularly-shaped pyramid. The apex of the gland is pointing downwards with the apex just behind (posterior) to the angle of the mandible and the base in line with the zygomatic arch. The parotid duct leaves the anterior edge of the gland, passes medially (towards the middle) through the buccinator muscle and enters the oral cavity opposite the second maxillary (upper) molar tooth.

Blood and Lymph

Oxygenated blood reaches the parotid gland via the external carotid artery which is embedded in it. Small veins drain the parotid gland and empties into the jugular veins (internal and external).

Lymph drains into parotid nodes that lie on the parotid sheath and within the gland and empties into the superficial and deep cervical lymph nodes.

Nerve Supply

The innervation of the parotid gland is via :

  • PARASYMPATHETIC (increases saliva secretion)
    • glossopharyngeal nerve (presynaptic secretory fibers) -> otic ganglion -> auriculotemporal nerve (postsynaptic parasympathetic fibers)
  • SYMPATHETIC (reduces saliva production)
    • cervical ganglia -> external carotid nerve plexus
  • SENSORY
    • great auricular and auriculotemporal nerve

Submandibular Glands

Anatomy and Location

The submandibular gland (also known as sumbaxillary gland) lies along the body of the lower jaw (mandible), extending slightly below and above the mandible. It sits in the roof of the mouth where it is divided into two lobes by the mylohyoid muscle – superficial and deep lobes. Like the parotid gland, it has an outer capsule.

The submandibular duct (Wharton’s duct) runs anteriorly and empties saliva via the sumbandibular papilla (caruncle) that is located on either side of the base of the tongue (lingual frenulum). The lingual nerve runs under the duct.

Blood and Lymph

Oxygenated blood reaches the submandibular glands via the submental artery (branch of the facial artery)  and deoxygenated blood exits via the submental vein.

Lympatic vessels from the submandibular glands empty into deep cervical lymph nodes.

Nerve Supply

  • PARASYMPATHETIC (increases saliva secretion)
    • facial nerve (presynaptic parasympathetic fibers) -> chorda tympani nerve -> lingual nerve -> submandibular ganglion (postsynaptic fibers)
  • SYMPATHETIC (reduces saliva production)
    • superior cervical ganglion -> postsynaptic sympathetic fibers

Sublingual Glands

Anatomy and Location

These ovoid-shaped glands are the smallest of the salivary glands and lie deep in the floor of the mouth. The sublingual gland on each side unite to form a single mass around the root of the tongue (lingual frenulum). It does not contain a capsule like the parotid and submandibular glands.

Several sublingual ducts open into into the mouth on either side of the tongue although the largest duct may join with the submandibular duct to empty saliva through the submandibular caruncle.

Blood

Oxygenated blood reaches the sublingual glands via the sublingual branch of the lingual artery and submental artery. Venous drainage is via the sublingual and submental veins.

Nerve Supply

  • PARASYMPATHETIC (increases saliva secretion)
    • facial nerve (presynaptic parasympathetic fibers) -> chorda tympani nerve -> lingual nerve -> submandibular ganglion (postsynaptic fibers)