Anatomy salivary glands

anatomy of salivary glands overview

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ANATOMY
SALIVARY GLANDS

Parotid gland
 Largest salivary gland
 Composed mostly of serous acini
 Entirely outside the boundaries of the oral cavity in a shallow triangular-shaped trench formed by:
o Sternocleidomastoid muscle behind
o Ramus of mandible in the front
o Superiorly the base of the trench formed by the external acoustic meatus and the posterior aspect of the
zygomatic arch
 Gland normally extends anteriorly over the masseter muscle and inferiorly over the posterior belly of the digastric muscle.
 Facial nerve divides the gland into superficial and deep lobes.
 The parotid duct (Stensen’s duct) emerges from the anterior border of the gland and passes anteriorly across the external
surface of the masseter muscle and then turns medially to penetrate the buccinator muscle of the cheek and open into the
oral cavity adjacent to the crown of the second upper molar tooth.
 The parotid gland encloses the external carotid artery, the retromandibular vein, and the origin of the extracranial part of the
facial nerve [VII].

Nerve supply
Parasympathetic secretomotor supply arises from the glossopharyngeal nerve. The nerves reach the gland via the tympanic
branch, the lesser petrosal nerve, the otic ganglion, and the auriculotemporal nerve.

Submandibular gland
 The elongate submandibular glands are smaller than the parotid glands, but larger than the sublingual glands. Each is hook-
shaped:
o The larger arm of the hook is directed forward in the horizontal plane below the mylohyoid muscle and is therefore
outside the boundaries of the oral cavity – this larger superficial part of the gland is directly against a shallow
impression on the medial side of the mandible (submandibular fossa) inferior to the mylohyoid line.
o Smaller arm of the hook (or deep part) of the gland loops around the posterior margin of the mylohyoid muscle to
enter and lie within the floor of the oral cavity where it is lateral to the root of the tongue on the lateral surface of
the hyoglossus muscle.
 Consists of a mixture of serous and mucous acini.
 Lies beneath the lower border of the body of the mandible.
 Divided into superficial and deep parts by the mylohyoid muscle.
 The deep part of the gland lies beneath the mucous membrane of the mouth on the side of the tongue.
 The submandibular duct (Wharton’s duct) emerges from the medial side of the deep part of the gland in the oral cavity and
passes forward to open on the summit of a small sublingual caruncle (papilla) beside the base of frenulum of the tongue
 The lingual nerve loops under the submandibular duct, crossing first the lateral side and then the medial side of the duct, as
the nerve descends Anteromedially through the floor of the oral cavity and then ascends into the tongue.

Nerve supply
Parasympathetic secretomotor supply is from the facial nerve via the chorda tympani, and the submandibular ganglion. The
postganglionic fibers pass directly to the gland

Sublingual gland
 Smallest of the three major paired salivary glands.
 Each is almond shaped and immediately lateral to the submandibular duct and associated lingual nerve in the floor of the
oral cavity.
 Lies beneath the mucous membrane (sublingual fold) of the floor of the mouth, close to the frenulum of the tongue. Lies
directly against the medial surface of the mandible where it forms a shallow groove (sublingual fossa) superior to the
anterior one-third of the mylohyoid line.
 It has both serous and mucous acini, with the latter predominating.
 The sublingual ducts (8 to 20 in number) open into the mouth on the summit of the sublingual fold.

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Nerve supply
Parasympathetic secretomotor supply is from the facial nerve via the chorda tympani, and the submandibular ganglion.
Postganglionic fibers pass directly to the gland

Vessels
 Vessels that supply the parotid gland originate from the external carotid artery and from its branches that are adjacent to
the gland.
 The submandibular and sublingual glands are supplied by branches of the facial and lingual arteries.
 Veins from the parotid gland drain into the external jugular vein
 Veins from the submandibular and sublingual glands drain into lingual and facial veins.
 Lymphatic vessels from the parotid gland drain into nodes that are on or in the gland. These parotid nodes then drain into
the superficial and deep cervical nodes.
 Lymphatics from the submandibular and sublingual glands drain mainly into submandibular nodes and into deep cervical
nodes, particularly the jugulo-omohyoid node.

Functions of saliva
 Moistens oral mucosa
 Moistens and cools food
 Medium for dissolved food
 Buffer (HCO3)
 Digestion (amylase and lipase)
 Antibacterial (lysozyme, IgA, peroxidase, FLOW)
 Mineralization
 Protective pellicle

Salivary glands (Lecture notes)
 Major salivary glands
o Parotid
o Submandibular
o Sublingual
 Minor salivary glands

Parotid region
Part of the face in front of ear, below zygomatic arch is the parotid region

Major and minor groups of salivary glands
Major groups of salivary glands which consist of three major glands
1. The parotid
2. Submandibular
3. Sublingual

The parotid and submandibular glands each drain into the mouth in a single long duct
Sublingual → many small ducts opening below the tongue

Minor groups
Found in lips, cheeks, tongue, floor of mouth, palate, larynx, trachea, tonsils and lacrimal gland.
Liable to undergo some pathological change as the major groups.

Deficiency
Deficiency of saliva causes dry mouth (xerostomia)
E.g. dehydration, Sjögren’s syndrome, atropine blocks, action of parasympathetic nerves on the glands.

Surface anatomy
Has a triangular profile when viewed externally and in cross section

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Below ear interval between mandible and anterior border of sternocleidomastoid muscle.

 Largest of salivary glands
 Broad superficial and small deep lobe
 Facial nerve between the two lobes
 Mainly a serous gland (thin watery secretions)
 Stensen’s duct (main duct) empties into oral cavity opposite the crown of second maxillary molar.

Relations of the parotid gland

Lateral / superficial surface
 Skin and superficial fascia
 Great auricular nerve

Anteromedial surface
 Posterior border of mandibular ramus
 Masseter and medial pterygoid muscle
 Temporomandibular joint
 Branches of facial nerve

Posteromedial relations
 Mastoid process with sternocleidomastoid and posterior belly of digastric muscle
 Styloid process and its attached muscles (stylohyoid, styloglossus)
 Carotid sheath and its contents
o Internal carotid artery
o Internal jugular vein
o Vagus nerve
o Glossopharyngeal nerve
o Accessory nerve
o Hypoglossal nerve

Structures passing through parotid gland
 Facial nerve
 Retromandibular nerve
 External carotid artery
 Auriculotemporal nerve (form V3)

Blood supply
 External carotid artery
o Superficial temporal
o Maxillary arteries
 Vein drains into the retromandibular vein

Submandibular gland
 May be divided into superficial and deep parts
o Superficial part lies beneath the lower margin of the body of the mandible
o Deep part of submandibular gland, the submandibular duct and sublingual gland may be palpated through the
mucous membrane covering the floor of the mouth in the interval b/w the tongue and lower jaw
 Its duct opens beside the frenulum of the tongue