Development of the lips and palate. 13 Apr 2009 Dr. Frank C. T. Voon VVIIIXX V1 V2 V3

The mandible and lower lip are formed by the fusion of the paired mandibular processes. The upper lip develops from the intermaxillary segment and from fusion of the maxillary process with the medial nasal process on each side. The intermaxillary segment gives rise to the philtrum, incisors and the primary palate. The secondary palate develops from fusion of the palatine shelves of the maxillary process. Summary

Intermaxillary segment labial component alveolar component palatal component philtrum 4 incisors primary palate secondary palate Palatine shelves Definitive palate Hard palate Soft palate Maxillary processes Concept muscles Maxilla & Palatine bone Medial nasal processes Lip - lateral partLip - median part

Derivatives of the Germ Layers Epithelium Nerve Connective tissue Muscle Mesoderm Ectoderm Endoderm

Heart 1 st 2 nd The mesenchyme (mesoderm) of 5 facial primordia from the 1st pharyngeal arch proliferate around the stomodeum. The face begins to form in the 4th week. Brain Liver 3 rd

The 5 facial primordia are the: single frontonasal process, paired maxillary processes, and paired mandibular processes. Cardiac bulge

Medial and lateral nasal swellings also form as part of the frontonasal process. The right and left medial nasal swellings fuse to form the intermaxillary segment.

The intermaxillary segment develops into 3 parts, the philtrum, the alveolar part (4 incisors) and the primary palate. The maxillary and medial nasal process on each side fuse to form the rest of the upper lip. The right and left mandibular processes fuse to form the mandible. Maxillary process Mandibular processes

Philtrum 4 incisors Primary palate Secondary palate The palatine shelves of the right and left maxillary processes fuse with the primary palate to form the definitive palate. The incisive foramen marks the point of fusion between the two palatine shelves with the intermaxillary segment.

Cleft lip & palate Cleft secondary palate unilateralbilateral

In the adult, the definitive palate consists of the hard palate and soft palate as well. The palatine process of the maxilla and the horizontal plate of the palatine bone are the bones of the hard palate. The soft palate contains 5 muscles, namely the: Palatoglossus, Palatopharyngeus, Musculus uvulae Levator veli palatini, & Tensor veli palatini. Palatoglossus, palatopharyngeus, musculus uvulae and levator palati are supplied by the branches of the vagus nerve in the pharyngeal plexus. Tensor palati is supplied by the mandibular nerve.

The Palate The palate consists of the hard palate and soft palate. The hard palate separates the oral cavity from the nasal cavity. The soft palate separates the oropharynx from the nasopharynx. The 3 foramina in the hard palate are the: incisive foramen which transmits the nasopalatine nerve and artery, greater palatine foramen which transmits the greater palatine n & a., lesser palatine foramen which transmits the lesser palatine n & a. The mucosa of the hard palate is supplied by the nasopalatine and greater palatine nerves. The mucosa of the soft palate is supplied by the lesser palatine nerves. These are all branches of the maxillary nerve. The mucous glands are supplied by parasympathetic fibers from the pterygopalatine ganglion. There are taste fibers in the soft palate which travel with the lesser palatine nerves, pass through the pterygopalatine fossa and pterygoid canal, and then travel with the greater petrosal nerve to join the facial nerve, and their cell bodies are in the geniculate ganglion.