Organs - The Oral Cavity Flashcards
What are the three main functions of the oral cavity?
1) Digestion
2) Communication
3) Breathing
What are the divisions of the oral cavity?
The oral cavity spans between the oral fissure (opening between the lips) and the oropharyngeal isthmus (the opening to the oropharynx.
The diameter of the vestibule is controlled by the orbicularis oris.
1) Vestibule - lies between the lips/cheeks and the teeth/gums.
2) Mouth proper - lies posterior to the vestibule. The tongue fills a large proportion of the mouth proper.
Borders of the mouth proper - superior
What are the two different palates?
Types of muscosa?
Functions of the posterior palate?
Superior (roof) - consists of hard palate and soft palate.
Hard palate - anterior - bony plate that separates the nasal cavity from the oral cavity.
It is covered superiorly by respiratory mucosa (ciliated pseudostratified columnar epithelium).
It is covered inferiorly by oral mucosa (stratified squamous epithelium).
Soft palate - posterior continuation of the hard palate. It is a muscular structure.
It acts as valve to close the oropharyngeal isthmus.
It also elevates to separate the nasopharynx from the oropharynx.
Borders of the mouth proper - inferior
What structures are located here?
1) Muscular diaphragm - consists of bilateral myohyoid muscles. It provides structural support to the floor of the mouth, and pulls the larynx forward when swallowing.
2) Geniohyoid muscles - pulls the larynx forward when swallowing.
3) Tongue - connected to floor by the frenulum of the tongue, a fold of mucosa.
4) Salivary glands and ducts
Genioglossus
Attachments?
Actions?
Innervation?
Arterial supply.
Origin - superior mental spine of mandible.
Insertion - body of hyoid; intrinsic muscles of the tongue.
Actions - protrudes and depresses tongue.
Innervation - hypoglossal nerve (CN XII).
Arterial supply - sublingual and submental artery.
Geniohyoid
Attachments?
Actions?
Innervation?
Origin - inferior mental spine of mandible.
Insertion - body of hyoid bone.
Actions - depresses the mandible; elevates the hyoid bone.
Innervation - first cervical nerve, via hypoglossal nerve (CN XII).
Arterial supply - suprahyoid branch of lingual artery.
Mylohyoid
Attachments?
Actions?
Innervation?
Arterial supply?
Origin - mylohyoid line of the mandible.
Insertion - mylohyoid raphe; body of the hyoid bone.
Actions - elevates the floor of the mouth.
Innervation - nerve to mylohyoid muscle (a branch of the mandibular nerve).
Arterial supply - sublingual, submental and suprahyoid branch of the lingual artery.
The cheeks
What muscle is located here?
Attachments?
Actions?
Innervation?
The muscle found here is the buccinator, which is lined with oral mucosa.
Origin - alveolar processes of the maxilla and mandible; pterygomandibular raphe.
Insertion - angle of the mouth.
Actions - compresses the cheeks to keep food between the teeth.
Innervation - buccal branches of the facial nerve.
Arterial supply - buccal artery.
Innervation of the oral cavity
Supplied by the trigeminal nerve (CN V).
Hard palate - greater palatine nerve; nasopalatine nerve. These are branches of the maxillary nerve (CN V2).
Soft palate - lesser palatine nerve (another branch of the maxillary nerve).
The floor of the oral cavity receives sensory information from the lingual nerve (a branch of the mandibular nerve).
The tongue also receives special sensory information from the chorda tympani, a branch of the facial nerve (CN VII).
The cheeks (inner membrane of the mouth) are innervated by the buccal nerve (sensory fibres), a branch of the mandibular division of the trigeminal nerve (not to be confused with the buccal branch of the facial nerve).
Clinical relevance: gag reflex
It is a protective function against foreign bodies touching the posterior aspects of the oral cavity, which are innervated by the glosspharyngeal nerve.
When stimulated, a reflex arc leads to contraction of the pharyngeal musculature, and elevation of the soft palate. The efferent nerve in this case is the vagus nerve.
