Submandibular Region Anatomy

• The lecture is about the submandibular region
• The presenter is Dr. Ramya Rathan

Objectives

• Describe the site of the submandibular region
• Describe its presenting parts and relations
• Describe its blood supply, nerve supply, and venous and lymphatic drainage
• Describe the duct of the salivary gland and its clinical significance

Submandibular Region Overview

• Part of the suprahyoid region
• Extends from the mylohyoid line of the mandible to the hyoid bone
• Contains structures in the floor of the mouth and root of the tongue
• The hyoid bone is the region's key landmark

Structures in the Submandibular Region

• Suprahyoid muscles
• Tongue muscles
• Nerves
• Vessels
• Salivary glands

Submandibular Gland Details

• Large salivary gland
• Weighs 10-20 grams
• Situated in the digastric triangle
• Roughly 'J' shaped
• About the size of a walnut

Parts and Surfaces of the Submandibular Gland

• Has superficial and deep parts
• Has anterior and posterior ends
• Features inferior, lateral, and medial surfaces

Relations of the Superficial Part - Medial Surface

• Includes the mylohyoid muscle, nerve, and vessels, and the submental artery
• Includes the hyoglossus, lingual nerve, submandibular ganglion, & hypoglossal nerve
• Includes the Styloglossus, Stylopharyngeus, 9th nerve, stylohyoid ligament, middle constrictor, lingual artery

Relations of the Superficial Part - Inferior Surface

• Includes the skin
• Includes the platysma
• Cervical branch of the facial nerve
• Deep fascia
• Facial vein
• Submandibular lymph node

Relations of the Superficial Part - Lateral Surface

• Includes the submandibular fossa of the mandible
• Insertion of the medial pterygoid
• The facial artery

Deep Part

• Extends between the mylohyoid & hyoglossus muscles
• Related laterally to the mylohyoid
• Related medially to the hyoglossus
• The lingual nerve and submandibular ganglion are located above
• The hypoglossal nerve, accompanied by a pair of veins, is below

Submandibular Duct (Wharton's Duct) Details

• ~5 cm long
• Begins in the superficial part of the gland
• Proceeds between the hyoglossus and mylohyoid muscles
• The duct lies between the lingual and hypoglossal nerves
• Opens into the floor of the mouth on the summit of the sublingual papilla beside the frenulum of the tongue

Blood Supply, Nerve Supply, & Lymphatic Drainage

• Arterial supply comes from branches of the facial & lingual arteries
• Veins correspond to the arteries and drain into the internal jugular vein (IJV)
• Sympathetic nerve supply comes from the superior cervical ganglion by a plexus around the facial artery
• Parasympathetic nerve supply is from the submandibular ganglion
• Lymphatic drainage flows into the submandibular group of lymph nodes

Applied Anatomy

• Enlargement of the gland can occur due to obstruction of the duct by a calculus or tumor, palpable during bimanual examination
• Sialography is used to visualize the duct system using X-ray after injecting a radio-opaque dye through the duct's terminal opening

Hyoglossus Muscle

• The hyoglossus muscle is a key rhomboid-shaped muscle in the region
• Originates from the hyoid bone
• Inserts into the side of the tongue deep to the mylohyoid
• Depresses the side of the tongue, making the dorsal surface convex

Lateral Relations of Hyoglossus

• Includes the styloglossus muscle
• The lingual Nerve
• and the Submandibular Ganglion
• The deep part of the Submandibular gland
• The Hypoglossal nerve

Medial Relations of the Hyoglossus

• Includes the Genioglossus
• The Middle Constrictor of the Pharynx
• The Glossopharyngeal nerve
• The Stylohyoid Ligament
• and the Lingual Artery