Oral Cavity Anatomy: Mouth Structures, Muscles | Study Guide

Oral Cavity (Mouth)  Oral Cavity (Mouth)  Extends from the lips to the oropharyngeal isthmus  The oropharyngeal isthmus Is the junction of mouth and pharynx.  Boundary of oropharyngeal isthmus  Above by the soft palate and the palatoglossal folds  Below by the dorsum of the tongue...

Oral Cavity (Mouth)  Oral Cavity (Mouth)  Extends from the lips to the oropharyngeal isthmus  The oropharyngeal isthmus Is the junction of mouth and pharynx.  Boundary of oropharyngeal isthmus  Above by the soft palate and the palatoglossal folds  Below by the dorsum of the tongue  Oral cavity (Mouth) is subdivided into 1. Vestibule 2. Oral cavity proper  Vestibule  Slit like space between the cheeks and the gums  Communicates with the exterior through the oral fissure  When the jaws are closed, communicates with the oral cavity proper behind the 3rd molar tooth on each side  Superiorly and inferiorly limited by the reflection of mucous membrane from lips and cheek on to the gums  The lateral wall of the vestibule is formed by the cheek  A small papilla on the mucosa opposite the upper 2nd molar tooth marks the opening of the duct of the parotid gland  Oral Cavity Proper  It is the cavity within the alveolar margins of the maxillae and the mandible  Its roof is formed by the hard palate anteriorly and the soft palate posteriorly  Its floor is formed by the mylohyoid muscle and anterior 2/3rd of the tongue  Floor of the Mouth  Covered with mucous membrane  In the midline, a mucosal fold, the frenulum, connects the tongue to the floor of the mouth  On each side of frenulum a small papilla has the opening of the duct of the submandibular gland  A rounded fold extending backward & laterally from the papilla is produced by the sublingual gland  Oral mucosa Three type:  Lining mucosa  Masticatory mucosa  Specialized mucosa  Structures of oral cavity Includes  Lips  Cheeks  Gingivae (gum)  Teeth  Tongue  Lips  Structure and extension  Contains  Covering  Labial frenula  Functions  Blood supply  Nerve supply  Lymph drainage  Clinical nodes  Cleft lip Gyanosis of the lips Large labial frenula  Cheeks  Structure and boundary  Covering  Contents  Function  Blood supply  Nerve supply  Gingivae (gum)  Structure  Attachment  Gingivae mucosa Nerve and blood supply of the gum  Teeth  Parts and structure  Permanent dentition  Number  Types and functions  Clinical dentistry  Distinguish between teeth by  Root  Crown  Time of eruption  First molars (6 years)  Central incisors(7 years)  lateral incisors(8 years)  First premolars (9 years)  Second premolars (10 years)  Canines (11 years)  Second molars (12 years)  Third molars (18 years+) (wisdom teeth)  Deciduous dentition  Number  Type  Time of eruption  Lower central incisors(6 month)  Upper central incisors(7 month)  Upper lateral incisors(8 month)  Lower lateral incisors(9 month)  Firsts molar (1 year)  Canines (18 months)  Second molars (2 years) Blood supply of teeth Nerve supply of teeth Nerve supply of teeth Lymphatic drainage of the teeth  Tongue  Mass of striated muscles covered with the mucous membrane  Divided into right and left halves by a median septum  Main parts:  Root  Tip  Body has two surfaces  Dorsum (Dorsal surface)  Ventral surface  Dorsal surface of the tongue  Divided into anterior two third and posterior one third by a V-shaped sulcus terminalis.  The apex of the sulcus faces backward and is marked by a pit called the foramen cecum  Foramen cecum, an embryological remnant, marks the site of the upper end of the thyroglossal duct  Anterior two third: mucosa is rough, shows three types of papillae:  Vallate papillae, Filliform papillae, Fungiform papillae  Posterior one third: No papillae but shows nodular surface because of underlying lymphatic nodules, the lingual tonsils  Posterior one third connected to epiglotis by 3 glossoepiglottic folds one median & two lateral  Ventral surface of the tongue  Smooth (no papillae)  In the midline anteriorly, a mucosal fold, frenulum connects the tongue with the floor of the mouth  Lateral to frenulum, deep lingual vein can be seen through the mucosa  Lateral to lingual vein, a fold of mucosa forms the plica fimbriata  Muscles of the tongue  The tongue is composed of two types of muscles:  Intrinsic muscle  Extrinsic muscle  Intrinsic muscles of the tongue  Confined to tongue  No bony attachment  Consist of:  Longitudinal (superior & inferior)  Transverse  Vertical  Function: Alter the shape of the tongue  Extrinsic muscles of the tongue  Connect the tongue to the surrounding structures: the soft palate and the bones (mandible, hyoid bone, styloid process)  Include:  Palatoglossus  Genioglossus  Hyoglossus  Styloglossus  Function: Movements of the tongue  Movements of the tongue  Protrusion: Genioglossus on both sides acting together  Retraction: Styloglossus and hyoglossus on both sides acting together  Depression: Hyoglossus and genioglossus on both sides acting together  Elevation: Styloglossus and palatoglossus on both sides acting together Sensory nerve supply of the tongue  Anterior ⅔:  General sensations: Lingual nerve  Special sensations : Chorda tympani  Posterior ⅓:  General & special sensations: Glossopharyngeal nerve  Base:  General & special sensations: Internal laryngeal nerve  Motor nerve supply of the tongue  Intrinsic muscles:  Hypoglossal nerve  Extrinsic muscles:  All supplied by the hypoglossal nerve, except the palatoglossus  The palatoglossus supplied by the pharyngeal plexus Innervations of the tongue Blood supply of the tongue  Lymphatic drainage of the tongue  Tip: Submental nodes bilaterally & then deep cervical nodes  Anterior two third: Submandibular unilaterally & then deep cervical nodes  Posterior third: Deep cervical nodes (jugulodigastric mainly)  Functions of the tongue  Articulator for speech production.  The primary function of the tongue is to provide a mechanism for taste  They are sensitive to four main tastes:  Bitter  Sour  Salty  Sweet  Sucking  Chewing  Swallowing  Eating  Drinking  Kissing  Sweeping the mouth for food debris and other particles  Making funny faces (poking the tongue out, waggling it)  Clinical Notes  Tongue-Tie (ankyloglossia) (due to large frenulum)  Lesion of the hypoglossal nerve  The protruded tongue deviates toward the side of the lesion  Tongue is atrophied & wrinkled Salivary glands  Function of salivary glands  Partial digestion of the carbohydrate and lipids  Immune functions : bactericidal (lysozymes)  Buffering function (bicarbonate)  Facilitates the process of swallowing  Facilitates the process of speech  Play role in the process of the taste  Protects mouth from infection with its rinsing action.  Parotid gland  Largest salivary gland  Weighs 15 - 25 G  Type  Shape  Position and capsule  External features: it has  Two poles  Three surfaces  Three borders  Structure within the gland  Parotid duct (of stensen)  Accessory parotid gland  Blood supply  Lymph drainage  Submandibular gland  Type  Position  Consists of :  Large superficial part It has three surfaces  Small deep part  Submandibular duct (of wharton)  Blood supply  Lymph drainage  Sublingual gland  Shape  Type  Position  Ducts  Blood supply  Lymph drainage  Secretomotor (parasympathetic) innervation of the salivary glands Thank you