Submandibular gland

The submandibular glands(historically also known as the submaxillary glands) are one of the three paired major salivary glands, located inferior and posterior to the body of the mandible, in the submandibular (digastric) triangle. They secrete mixed serous and mucous saliva into the oral cavity via the submandibular duct that opens at the floor of the mouth ⁵.

Gross anatomy

The submandibular gland is U-shaped, wrapping around the posterior border of the mylohyoid muscle. It is divided into a superficial (inferior) and deep (superior) part by the plane of the mylohyoid.:

• The the superficial part is larger and lies horizontally, below the mylohyoid muscle. It projects forward to lie on the submandibular fossa, a shallow groove on the internal surface of the mandible. It is situated in the submandibular space.

• The the deep part of the gland is smaller and loops around the posterior border of the mylohyoid to lie within the sublingual space, lateral to the root of the tongue.

The submandibular gland is separated from the parotid gland by the stylomandibular ligament.

The gland is surrounded by a fibrous capsule, formed by the split layers of the superficial (investing) layer of the deep cervical fascia. It does not usually contain lymph nodes as it is encapsulated early during development.

The submandibular duct emerges from the deep part of the gland medially, before coursing forward to open at the papilla, lateral to the frenulum of the tongue.

Relations

The marginal mandibular branch of the facial nerve and facial vein is superficial and inferior to the gland.

The facial artery travels deep to the gland posterosuperiorly, before curving around the inferior border of the mandible to travel superficially and anterior to the masseter muscle.

The deep part of the gland extends forwards and lies between the mylohyoid inferolaterally inferolaterally (floor of the mouth), and hyoglossus and and styloglossus medially medially (root of the tongue). The hypoglossal nerve travels in between the gland and the hyoglossus.

Arterial Supply

The submandibular gland is supplied mainly by the facial, lingual, and submental artery,

Venous drainage

It drains into the facial and submental veins.

Innervation

Autonomic innervation is from the lingual nerve via via the submandibular ganglion with with parasympathetic fibres arising from the chorda tympani and sympathetic fibres from the superior cervical ganglion.

Variant anatomy

• congenital absence +/- contralateral submandibular gland hypertrophy ⁴

Related pathology

• sialolithiasis

• submandibular gland enlargement