Parotid & Submandibular Region

• This lecture explores the parotid and the submandibular regions
• It also looks at the different structures in the regions, and the different types of the salivary glands

Parotid Region

• The region around the ear
• The anterior boundary is the anterior border of the masseter
• The superior boundary is the zygomatic arch
• The posterior boundary is the mastoid process
• The inferior boundary is the angle and inferior border of the mandible
• The principal structure here is the parotid gland and the facial nerve

Parotid Gland

• The largest of the salivary glands
• Composed of serous alveoli
• Lobulated in shape, and yellowish-brown in color
• Lays in the retromandibular fossa
• Weighs about 25g
• Its anterior boundary is the posterior border of the ramus of the mandible
• The posterior boundary is the mastoid process
• Its superior boundary is the external acoustic meatus
• The medial boundary is the styloid process

Parotid Capsule

• A fibrous capsule enclosing the parotid gland
• Formed by the investing layer of the deep cervical fascia
• The parotid fascia splits around the angle of the mandible and the mastoid process
• This encloses the parotid gland
• Layers include the superficial lamina and the deep lamina
• The superficial lamina is thick and attached to the parotid gland
• It blends with the epimysium of the masseter to form the parotidomasseteric fascia
• Attached to the zygomatic arch
• The deep layer is a thin deep lamina
• Attached to the tympanic plate and styloid process
• Thickens to form the stylomandibular ligament
• Separates the parotid gland from the submandibular gland

Accessory Parotid Gland

• Considered a forward extension of the parotid gland
• Often detached from the rest of the parotid gland
• Lies between the zygomatic arch superiorly and the parotid duct inferiorly
• Opens into several ducts of the parotid duct

External Features

• Appears like a 3-sided pyramid
• Contains an apex
• Four surfaces: superior, superficial, anteromedial, and posteromedial
• Three borders: anterior, posterior, and medial

Relations

• Related to the posterior belly of the digastric muscle, and the carotid triangle
• Cervical branch and retromandibular vein pass apex
• Related to the external acoustic meatus and the temporomandibular joint

Structures Emerging from the Base

• Superficial temporal vessels
• Auriculotemporal nerve

Superficial Surface

• Covered by skin, superficial fascia, and parotid fascia
• Contains preauricular and deep parotid lymph nodes
• Anteromedial surface is related to the posterior border of the ramus, the masseter, and the medial pterygoid

Posteromedial Surface

• Related to the mastoid process, sternocleidomastoid, posterior belly of digastric, and styloid process (muscles)
• The styloid process separates the gland from the internal carotid artery and internal jugular vein
• Facial and external carotid arteries enter through it

Anterior border

• Separates the superficial surface from the anteromedial surface
• Emerging structures are the temporal, zygomatic, buccal and mandibular branches, transverse facial vessels, and parotid duct
• Surface Anatomy: middle third of the line extending from the lower border of tragus to the nose ala, and the red margin of the upper lip

Medial border

• Separates the anteromedial surface from the posteromedial surface
• Related to the lateral wall of the pharynx

Structures

• Facial nerve
• Retromandibular vein
• External carotid artery: pierces through the posteromedial surface, divides into superficial temporal and maxillary arteries
• Transverse facial artery (branch of superficial temporal artery) emerges through the anterior border
• Deep parotid lymph nodes

Parotid Duct

• Also known as Stenson's duct
• Approximately 5 cm long
• It emerges from the middle of the anterior border
• Runs forward over the masseter, pierces buccinator muscle, then forwards through mucous membrane and opens into the vestibule of the mouth
• Lies opposite to the crown of the upper second molar.

Nerve Supply of Palatine Gland

• Parasympathetic supply (secretomotor): auriculotemporal nerve, stimulation produces watery secretion
• Sympathetic supply (vasomotor fibers): plexus around external carotid artery, stimulation produces thick sticky secretion
• Sensory supply: auriculotemporal nerve and great auricular nerve (C2 and C3)

Vascular Supply

• Arterial supply: external carotid/superficial temporal arteries
• Venous drainage: retromandibular/external jugular veins
• Lymphatic drainage: superficial/deep parotid lymph nodes to deep cervical lymph nodes

Clinical Conditions

• Frey's syndrome (auriculotemporal nerve syndrome): wound of gland
• Damage to auriculotemporal and great auricular nerves affects parasympathetic, sensory, and sympathetic function
• While eating: parotid region becomes red, hot, and painful, beads of perspiration (gustatory sweating)
• While shaving: Cutaneous hyperesthesia in front of ear
• Mumps (viral parotitis): contagious disease caused by mumps virus (myxovirus)
• Show acute inflammation, swelling of the affected parotid gland, pain, fever, and accentuated by jaw movement; also, opening of parotid duct becomes swollen and congested
• Mostly affects children below 15 years of age
• Parotid abscess: spread of infection from the oral cavity, in parapharyngeal spaces or the external auditory meatus.

Hyoid Bone

• Component of the axial skeleton
• A bone that does not articulate with any other bone and suspended by ligaments and muscles
• Located in the anterior neck between the mandible and the larynx, provides attachment for muscles of the neck and pharynx, and consists of the horizontal body, lesser and greater horns.

Submandibular Region

• Cover of the body of the mandible, mylohyoid line and hyoid bone
• Floor of the mouth and the root of the tongue are parts of this region
• Submandibular/submental triangles consist of: suprahyoid muscles, digastric, stylohyoid, mylohyoid, geniohyoid, extrinsic muscles of the tongue: hyoglossus, styloglossus, and genioglossus
• Also includes submandibular/sublingual salivary glands, facial and lingual arteries, lingual, hypoglossal/glossopharyngeal nerves

Glands

• Salivary: two pairs in the submandibular region.
• Submandibular: Below floor of mouth
• Sublingual: Above floor of mouth

Submandibular Gland

• Below, deep to the posterior half of the mandible
• weighs 10-20 g, mixed gland (mucus and serous), mostly serous secretion
• parts: large superficial, superficial to the mylohyoid muscle, and small deep parts, deep to it
• Covering/capsule: investing layer
• Superficial part encloses deep cervical fascia, splits at cornu of Hyoid bone, superficial layer, inferior surface of gland attach. to base of mandible, deep layer, medial surface, attached to Mylohyoid line

Submandibular Duct

• Wharton's duct, about 5 cm long
• Emerges anterior end of deep part, forwards between hyoglossus
• Lingual hyoglossal nerves open at the summit of the tongue
• Nerve supply: parasympathetic, preganglionic/postganglionic fibers
• Sympathetic fibres, and sensory by the lingual nerve

Arterial Supply and Lymphatic Drainage

• Arterial supply: sublingual/submental arteries
• Venous drainage: common facial/lingual veins
• Lymphatic drainage: submandibular lymph nodes, then into jugulodigastric nodes.

Sublingual Gland

• The smallest
• Floor of mouth between mucus membrane/mylohyoid muscle
• Rests in the sublingual fossa, and weighs 3-4 g, mostly mucous
• Includes ~20 ducts open into oral cavity
• Some into the Submandibular Duct
• Blood supply/lymphatic drainage/nerve is the same as submandibular glands
• Clinical Connection: Ranula. Large mucous, the floor of the mouth due to Sublingual gland, soft bluish swelling