Anatomy of the Palate and Throat

Soft and Hard Palates, Throat, and Sinuses

• Soft palate is a mobile soft-tissue fold posterior to the hard palate that separates the oral cavity from the nasopharynx.
• The roof of the mouth is 1/3 soft palate and 2/3 hard palate.
• Most skeletal muscles that comprise the soft palate are innervated by the pharyngeal nerve plexus except tensor veli palatini.
• Tensor veli palatini is the only soft palate muscle innervated by the mandibular division (V3) of the trigeminal nerve.
• Most blood supply to the hard palate is directly vascularized by the greater palatine artery.
• The greater palatine nerve block provides anesthesia to the palatal mucosa anterior to the maxillary first premolar and to the posterior hard palate up to the midline, but does not innervate teeth.

Sensory Receptors

• Meissner corpuscles are rapidly adapting encapsulated mechanoreceptors of light pressure, discriminative touch, and low-frequency vibration.
• Pacinian corpuscles are rapidly adapting encapsulated mechanoreceptors of deep pressure, stretch, and high-frequency vibration.

Pharynx and Sinuses

• The pharyngeal tonsils are the simplest lymphoid structures found in the posterior wall of the nasopharynx.
• The larynx is evaluated by being moved gently side-to-side by bimanual palpation.
• The paranasal sinuses drain through the nasal meatuses.
• The nasal cavity is separated from the oral cavity by the palatine bone.
• There are four paranasal sinuses: maxillary, frontal, ethmoidal, and sphenoidal sinuses.

Maxillary Sinus

• The maxillary sinus floor is formed from the alveolar process of the maxilla.
• The shape of the maxillary sinus most closely resembles a pyramid.
• Maxillary sinusitis may often accompany a toothache.

Muscles of Mastication

• The masseter originates from the zygomatic arch (cheekbone) and inserts on and covers the lateral surface of the ramus (angle) of the mandible.
• All muscles of mastication are innervated by the trigeminal nerve (mandibular division-V3).
• Blood supply to the muscles of mastication comes from the pterygoid branch of the maxillary artery.
• The muscles of mastication are the masseter, temporalis, medial pterygoid, and lateral pterygoid.
• The greatest masticatory force is produced by the masseter muscle.

Muscle Functions

• Repeated muscle contraction from clenching teeth causes hypertrophy of the masseter muscle.
• The muscle of mastication responsible for elevating and retracting the mandible is the temporalis.
• The muscle of mastication that inserts into the coronoid process is temporalis.
• Mandibular movements produced by the lateral pterygoids are opening (depression), protrusion, and lateral excursion (side-to-side).
• The lateral pterygoid is mainly contained in the infratemporal fossa with the maxillary artery and vein.
• Temporalis, medial pterygoid, and masseter all close (elevate) the mandible.