Week 7 Dissection

Types of Papillae: The tongue contains various types of papillae, each with distinct characteristics:
- Filiform Papillae: Most numerous, located throughout the tongue's surface.
- Fungiform Papillae: Scattered among filiform papillae but fewer in number.
- Foliate Papillae: Found on the lateral margins of the root of the tongue, rostral to the palatoglossal arch. They look leaf-like and appear as parallel grooves.
- Vallate (Circumvallate) Papillae: Situated at the junction of the body and root of the tongue. Generally, four to six vallate papillae are present in the dog, arranged in a V shape with the apex pointing caudally. They are larger than other papillae, circular in shape, and surrounded by a sulcus.
Taste Buds: Present on vallate, foliate, and fungiform papillae, these structures are responsible for the sensation of taste.

Attachment: The tongue is anchored to the floor of the oral cavity via a ventral median fold of mucosa known as the lingual frenulum.
Structure: Examining the medial cut surface of the tongue's apex reveals the lyssa, a fibrous spicule extending from the apex to the attachment level of the frenulum.

Upon turning the tongue medially, notice the sublingual caruncle, which is a slight elevation of mucosa lateral to the frenulum and protrudes from the floor of the oral cavity.
- Sublingual Fold: Extending caudally from the caruncle, contains:
- Mandibular Duct: Major duct located in the fold, leading to openings at the sublingual caruncle.
- Major Sublingual Duct: Usually opens on or beside the sublingual caruncle, potentially through a common opening.
Dissection Steps:
- Incise the mucosa above the ducts from the caruncle to the palatoglossal arch to expose the ducts and glands.
- The major sublingual duct connects caudally with the monostomatic sublingual gland, closely associated with the mandibular salivary gland.
Mandibular Salivary Gland: Located on the lateral side of the head, just caudal to the mandible angle, and covered by a thick capsule.
- Dissection Technique: Carefully incise the capsule unpacking the caudal part of the sublingual gland.

Zygomatic Gland: Found medial to the zygomatic bone, located between the eyeball and the pterygoid muscle.
Parotid Gland: Located between the mandibular gland and the ear, closely applied to the base of the auricular cartilage. The parotid duct is formed by two or three converging branches that open into the vestibule near the fourth upper premolar's caudal margin.

Anatomy: The hard palate features approximately eight transverse ridges:
- Incisive Papilla: Eminence located just caudal to the central incisor teeth.
- Incisive Duct: Opens into the ventral nasal meatus, passing through the palatine fissure.
- Vomeronasal Organ: Positioned at the base of the nasal septum, dorsal to the hard palate, functioning as an olfactory receptor for sexual stimuli, approximately 2 cm long.

Function: Serves as a common passageway for respiratory and digestive systems, connecting oral cavity to esophagus.
Anatomical Divisions:
- Oropharynx: Extends from palatoglossal arches to caudal border of soft palate. The boundaries are the soft palate (dorsally) and root of the tongue (ventrally). Contains palatine tonsils within the tonsillar fossa.
- Nasal Cavity: Divided into right and left halves by the nasal septum, contains four meatuses; the opening of the nasolacrimal duct can be found on the rostral lateral floor of the ventral meatus.
- Nasopharynx: Extends from choanae to palatopharyngeal arches at the soft palate’s caudal border, features palatopharyngeal folds and opening for auditory tube.
- Laryngopharynx: Dorsal to the larynx and extends from the palatopharyngeal arches to the esophagus, starting at the pharyngoesophageal limen corresponding to the cricoid cartilage.