🥇 ANATOMÍA DE LA GLÁNDULA PARÓTIDA, SUBMAXILAR Y SUBLINGUAL. Fácil, Rápido y Sencillo

Major Salivary Glands Overview

Introduction to Salivary Glands

• Juan José Sánchez introduces the topic of major salivary glands, distinguishing them from minor salivary glands which are studied histologically.

• The discussion will focus on three major salivary glands: the parotid gland, submandibular gland, and sublingual gland.

Parotid Gland Anatomy

• The parotid gland is located in the parotid region of the anterior triangle of the neck, with specific anatomical boundaries defined by surrounding structures.

• Anterior limit: ascending root of the lower jaw; upper limit: external auditory canal (EAC); posterior limit: mastoid process; inferior limit: anterior edge of sternocleidomastoid muscle; lower limit: posterior digastric muscle.

Structure and Secretion

• The parotid gland is surrounded by a membrane known as parotid fascia and is in contact with skin and platysma muscle.

• Saliva produced by the parotid gland consists mainly of serous secretions, often described as almost purely serous.

Shape and Faces of Parotid Gland

• The shape resembles an inverted pear or pyramid, with its apex directed downward between sternocleidomastoid muscle and lower jaw.

• The parotid gland has three faces:

• External face in contact with skin and cutaneous muscles.

• Anterior face divided into two lips (external lip near masseter muscle and inner lip near medial pterygoid muscle).

• Posterior face in contact with mastoid process and sternocleidomastoid muscle.

Nervous Structures Involved

• Important vascular and nervous structures pierce through the parotid gland.

Anatomy of the Parotid Gland and Its Innervation

Overview of the Parotid Gland

• The parotid gland is associated with the auriculotemporal nerve, a branch of the mandibular nerve (lower maxillary nerve), which itself is a part of the trigeminal nerve (fifth cranial nerve).

Vascular Structures Related to the Parotid Gland

• The external carotid artery perforates the parotid gland, giving rise to two terminal branches: the superficial temporal artery and the internal maxillary artery.

• Dissection reveals that both terminal branches emerge from within the thickness of the parotid gland.

• A branch from the superficial temporal artery, known as the transverse facial artery, also pierces through the parotid gland at different locations compared to other arteries.

Venous Structures Associated with the Parotid Gland

• The external jugular vein forms outside but is believed by many authors to originate within the parotid gland.

• Two veins contributing to this formation are identified: posterior auricular vein and retromandibular vein, both piercing through the parotid gland.

Salivary Duct Functionality

• As an exocrine gland, it requires an excretory duct for saliva transport; this duct is called Stensen's duct or simply parotid duct.

• The duct measures approximately five centimeters and passes laterally to masseter muscle before piercing buccinator muscle at upper second molar level.

Innervation of Parotid Gland

Parasympathetic Innervation

• The innervation involves several cranial nerves: trigeminal (V), facial (VII), and glossopharyngeal (IX).

• Glossopharyngeal nerve gives rise to tympanic branch which forms a plexus at eardrum level without innervating it directly.

Pathway of Nerve Fibers

• From tympanic plexus emerges lesser superficial petrosal nerve carrying preganglionic fibers towards otic ganglion where synapses occur.

• Post-synaptic fibers join with auriculotemporal nerve (a branch of mandibular nerve), providing parasympathetic innervation to parotid gland.

Sympathetic Innervation

What is the Submandibular Gland?

Anatomy and Structure

• The submandibular gland, previously known as the submaxillary gland, consists of two portions: a greater or superficial portion (body) and a lesser or deep portion.

• It produces mixed saliva, primarily waxy with some mucous secretion. The two portions join at the posterior edge of the mylohyoid muscle.

Relationships and Surroundings

• The gland has three faces:

• An inferior face in contact with the platysma muscle and submaxillary lymph nodes.

• An external face that contacts the lower jaw, forming a fossa known as the submaxillary fossa.

• An internal face in contact with both mylohyoid and hyoglossus muscles.

Duct System

• The excretory duct, called Wharton's duct (or submaxillary duct), is approximately five centimeters long. It empties into the lingual fold near the frenulum of the tongue through an opening known as the submandibular papilla.

Blood Supply and Drainage

• Blood supply comes from the facial artery while venous drainage occurs via the facial vein. This vein collects blood from various structures including the submandibular gland.

Understanding the Sublingual Gland

Location and Structure

• The paired sublingual glands are located beneath the hyoglossus muscle and above the mucosa lining of the floor of the mouth. They are separated by an unseen genioglossus muscle.

Secretion Mechanism

• Unlike other salivary glands, each sublingual gland secretes saliva through multiple ducts (10 to 30), which open along the lingual alveoli fold into openings called sublingual papillae or caruncles.

Vascularization

• The irrigation for these glands is provided by branches of the lingual artery (a branch of external carotid). Venous blood drains through a specific pathway leading to internal jugular vein via facial vein.

Innervation of Salivary Glands

Nerve Supply

Understanding the Facial Nerve and Its Branches

The Chorda Tympani Nerve

• The chorda tympani nerve is a branch of the facial nerve that connects to the lingual nerve, which is a branch of the trigeminal nerve (fifth cranial nerve).

• This connection allows for the transmission of pre-ganglionic fibers from the facial nerve through the chorda tympani to various ganglia.

Submaxillary Ganglion Functionality

• The submaxillary ganglion receives these pre-ganglionic fibers and subsequently carries post-ganglionic fibers to both the submaxillary gland and sublingual gland.

• Sympathetic innervation for these glands originates from thoracic segments T1 and T2, ascending through the cervical sympathetic chain.

Sympathetic Innervation Pathway