Oral Cavity
Key functions of the Oral Cavity:
Initiates chemical and mechanical (aka, physical) digestion:
- The teeth and tongue physically manipulate the food;
- Salivary enzymes chemically digest carbohydrates.
Anatomical divisions
- Oral vestibule
- External to the teeth.
- Oral cavity proper
- Enclosed by the teeth.
Boundaries of the mouth:
- Superiorly, the palate forms the roof of the mouth.
- Inferiorly, the right and left mylohyoid muscles form the "floor" of the mouth; they extend from the mandible ("mylo") to the hyoid bone.
- Anteriorly, the lips enclose and regulate the oral fissure (aka, opening).
- Laterally, the cheeks comprise soft tissues (including muscles) that compress the walls of the mouth.
- Posteriorly, the oral cavity is open to the oropharynx, which accepts the swallowed foods and liquids.
- Internally, the oral mucosa lines the mouth.
Structures
- Lips
- Muscles, including the orbicularis oris and superior and inferior labial muscles
- Neurovascular structures.
- Teeth
- Gingivae (aka, gums)
- Cover the bones of the jaws and with overlying mucosal membrane;
- Labial frenulum
- Superior and inferior labial frenulum attach the gingivae to the lips.
- Lingual frenulum
- A mucosal fold that attaches the inferior surface of the tongue to the floor of the oral cavity
- Extrinsic salivary glands
- Sublingual gland lies beneath the tongue in the floor of the mouth; secretes saliva across this lining via several small ducts. "Sublingual" refers to the gland's location below the tongue.
- Submandibular gland lies along the medial side of the mandible and wraps around the mylohyoid muscle; its duct drains into the floor of the mouth.
- Salivary duct orifices
- Release saliva into the floor of the mouth via orifices under the anterior tongue.
- Hard palate
- Forms anterior 2/3rds of the palate
- Comprises the maxillary and palatine bones
- Palatine raphe is raised midline ridge that signifies where the right and left sides of the palate fused during fetal development
- Transverse palatine folds aka, palatine rugae, are ridges of connective tissue that provide friction to faciliatate bolus formation.
- Soft palate
- Comprises the palatine aponeurosis (which attaches anteriorly to the hard palate) and 4 sets of paired muscles.
- During swallowing, the soft palate raises to block foods and liquids from the posterior opening to the nasal cavity.
- Uvula extends from the free edge of the soft palate at the midline; comprises the musculus uvulae and connective tissues.
- Two posterior arches:
- Palatoglossal arch extends from the soft palate to the tongue.
- Palatopharyngeal arch attaches to the pharynx.
- These arches are formed by the bilateral palatopharyngeus muscles, which elevate the pharynx during swallowing.
- Palatine tonsils
- Lie between the arches
- Collections of lymphoid tissue housed within the tonsillar sinuses (aka, fossae); the palatine tonsils monitor and respond to ingested infectious materials.
- Fauces
- Posterior opening of the oral cavity; it leads to the oropharynx.