The development of the face Flashcards
What do each of the four banchial arches contain?
each has an arch cartilage, a specific cranial nerve, an aortic arch, and a core of mesennchymal cells of mesodermal and neural crest origin
What do the neural crest cells in the cranial region do?
They have potential to develop into a variety of cells and tissues and to direct the development of the branchia arches.
What are some of the factors that determine what cranial neural crest cells do?
THe area of the developing brain, genetic factors, and signaling molecules.( permissive and inhibitory factors and positive and negative chemotaxis)
What are the three initial segments that the cranial end of the neural tube is divided into? Which segment is relevant to the development of the branchial arches? what are the subsections divided into.
Rhombencephalon (hindbrain) related to branchial arches and are separated further into rhombomeres.
Mesencephalon (midbrain)
Prosencephaln (Forebrain)
What are the two main processes of the first branchial arch?
The mandibular and maxillary processes.
What is the prominence above the first branchial arch? What part of the brain does it come from
The frontonassal prominence with pair nassal placodes. forebrain
What is the first facial feature to form?
The mandibular process
What is the cartilage that forms the infrastructure for the formation of the mandible?
Meckel’s Cartilage
What type of bone formation happens in the head and face
intermembranous
What is the cranial nerve that develops with the first arch?
The trigeminal nerve (V)
What structures and nerves are involved in the second arch?
The styloid process and stapes and the facial nerve (VII)
What nerve is associated with the third arch?
The glossopharyngeal (IX)
What nerve is associated with the fourth arch?
The vagus (X)
What is the maxillary process of the first arch a precursor to?
The upper jaw, facial bones, and upper lip
What is the groove between the lateral nasal prominence and the maxillary prominence called? what does it eventually turn into?
The nasolacrimal groove. turns into the lacrimal gland and nasolacrimal duct
Describe the development of the nasolacrimal groove and issues that can occur
The groove forms a thick cord which is transformed into the lacrimal sac and the nasolacrimal duct. Insufficient mesenchymal cells in the maxillary process and/or the localized absence of an ectodermal chord results in the presence of an oblique cleft between the medial margin of the eye and the upper lip.
How is the bridge of the nose formed?
By the fusion of the medial nasal processes cranially?
What does the cadual fusion of the medial nasal prominences from?
The intermaxillary segment which becomes the philtrum of the upper lip and the primary palate (posterior tip is where the incisor foramen is)
how does the secondary palate form?
By the fusion of bilateral palatine processes projected from the inferior aspect of the maxillary processes. Myogenic cells in the posterior portion form the musculature of the soft palate.
What causes a cleft lip?
The failure of the maxillary process to fuse with the intermaxillary segment.
What causes a anterior cleft palate?
The failure of the lateral palatine process to fuse with the primary palate
What causes a posterior cleft palate?
The failure of the lateral palatine process to fuse with each other, the primary palate and the nasal septum.
Describe the composition of the tongue with respect to its origins from the branchial arches
The anterior 2/3 is from the first arch and thus innervated by the Trigeminal nerve. A section of the tongue is a second arch derivative but ends up getting buried but explains the involvement of the facial nerve (Chorda tympani). The posterior 1/3 of the tongue comes from the 3rd arch and thus the glossopharyngeal nerve. The root of the tongue is the fourth arch and has some contribution from vagus.
What do the third and fourth arch of the tongue form?
The hypocranchial eminence
