DH 356 - Chapter 4 Development of the Face and Neck.pptx

Chapter 4: Development of the Face and Neck 1 CHAPTER OUTLINE Development of the face  Stomodeum and oral cavity formation  Mandibular arch and lower face formation  Frontonasal process and upper face formation  Maxillary process and midface formation Devel...

Chapter 4: Development of the Face and Neck 1 CHAPTER OUTLINE Development of the face  Stomodeum and oral cavity formation  Mandibular arch and lower face formation  Frontonasal process and upper face formation  Maxillary process and midface formation Development of the neck  Primitive pharynx formation  Branchial apparatus formation 22 REVIEW 33 OVERVIEW OF FACIAL DEVELOPMENT Embryonic period Begins in 4th week and ends in 12 wk (fetal period) Oropharyngeal membrane 44 EMBRYO AT FOURTH WEEK Figure 4-1 5 OVERVIEW OF FACIAL DEVELOPMENT 4th – 10th wks:  5 prominences formed: Frontonasal prominence 2 Maxillary prominences 2 Mandibular prominences Facial Development Process 66 ADULT FACE AND ITS EMBRYONIC DERIVATIVES Figure 4-3 77  OVERVIEW OF FACIAL DEVELOPMENT Fusion Fusion: swellings or tissue on the same surface of the embryo. A cleft or furrow is initially located between these adjacent swellings due to proliferation, differentiation, and morphogenesis. 88 FACIAL FUSION 9 9 OVERVIEW OF FACIAL DEVELOPMENT With facial fusion, these furrows are usually eliminated as the underlying mesenchyme migrates into the furrow making the embryonic facial surface smooth. This migration takes place because adjacent mesenchyme grows and merges beneath the external ectoderm during the maturation of the structure. 1 10  STOMODEUM AND ORAL CAVITY FORMATION The primitive mouth is now the stomodeum shallow depression in the embryonic surface ectoderm at the cephalic end before the fourth week. At this time, the stomodeum is limited in depth by the oropharyngeal membrane. 11 11 STOMODEUM AND ORAL CAVITY FORMATION The membrane also separates the stomodeum from the primitive pharynx. The primitive pharynx is the cranial part of the foregut, the beginning of the future digestive tract. https://slideplayer.com/slide/10647346/36/images/34/ Floor+of+primitive+pharynx.jpg 12 STOMODEUM AND ORAL CAVITY FORMATION Disintegration of the oropharyngeal membrane enlarges the stomodeum of the embryo and allows access between the primitive mouth and the primitive pharynx. 13 MANDIBULAR ARCH AND LOWER FACE FORMATION After formation of the stomodeum but still within the fourth week, two bulges of tissue appear inferior to the primitive mouth, the two mandibular processes. These processes consist of a core of mesenchyme formed in part by neural crest cells that migrate to the facial region, covered externally by ectoderm and internally by endoderm. 14 MANDIBULAR ARCH AND LOWER FACE FORMATION These paired mandibular processes then fuse at the midline to form the mandibular arch, the developmental form of the future lower dental arch, the mandible. After fusion, the mandibular arch then extends as a band of tissue inferior to the stomodeum and between the developing brain and heart. 15  MANDIBULAR ARCH AND LOWER FACE FORMATION In the midline on the surface of the mature bony mandible is the mandibular symphysis, indicating where the mandible is formed by fusion of right and left mandibular processes. 16 MANDIBULAR ARCH AND LOWER FACE FORMATION Mandibular arch directly gives rise to:  lower face lower lip mandibular teeth and associated tissues. 1 17 FRONTONASAL PROCESS AND UPPER FACE FORMATION During this fourth week, the frontonasal process also forms as a bulge of tissue in the upper facial area. This process is at the most cephalic end. placodes: rounded areas of specialized, thickened ectoderm Lense placode Nasal placode 18  NOSE AND PARANASAL SINUS FORMATION During the fourth week, the tissue around the nasal placodes on the frontonasal process undergoes growth, thus starting the development of the nasal region and the nose. The placodes then become submerged, forming a depression in the center of each placode, the nasal pits (or olfactory pits). 1 19  NOSE AND PARANASAL SINUS FORMATION The middle part of the tissue growing around the nasal placodes appears as two crescent‑shaped swellings located between the nasal pits. These are the medial nasal processes. On the outer part of the nasal pits are two other crescent‑shaped swellings, the lateral nasal processes. 2 20 DEVELOPMENT OF INTERMAXILLARY SEGMENT  The development of the intermaxillary segment from the fused medial nasal processes on the inside of the stomodeum. https://o.quizlet.com/mLGr1QNbzf0luXFbFrNUuQ.jpg 21 Figure 4-7 2 22 MAXILLARY PROCESS AND MIDFACE FORMATION During the fourth week of prenatal development, within the embryonic period, an adjacent swelling forms from increased growth of the mandibular arch on each side of the stomodeum, the maxillary process. Then each maxillary process will grow superiorly and anteriorly around the stomodeum. https://pocketdentistry.com/wp-content/uploads/285/F000135f04-03- 97803230825631.jpg 23 MALFORMATIONS OF THE MAXILLARY PROCESSES 24  UPPER AND LOWER LIP FORMATION 4th wk:  the upper lip is formed when each maxillary process fuses with each medial nasal process on both sides of the stomodeum due to the underlying growth of the mesenchyme. maxillary processes contribute to the sides of the upper lip, and the two medial nasal processes contribute to the philtrum. 2 25 CLEFT LIP AND PALATE https://encrypted-tbn0.gstatic.com/images? q=tbn:ANd9GcRAPgJxtQBfIc2TU7WqBotsp_at8rcoxpKb0A&usqp=CAU 2626  COMMISSURAL LIP PITS Epithelium-lined blind tracts located at the labial commissure May be shallow or several millimeters deep. Congenital lip pits may also be observed near the midline of the vermilion border. Treatment None 2727 PHARYNX FORMATION 28 DEVELOPMENT OF PHARYNX  The foregut gives rise to the primitive pharynx, which will form the oropharynx. 29 DEVELOPMENT OF PHARYNX Figure 4-10 3 30  Development of Branchial branchial Arches arches/pharyngeal arches 4th week: stacked bilateral swellings of tissue appear inferior to the stomodeum and include the mandibular arch. 6 pairs of U-shaped bars Sometimes the 5th arch is missing or combined with the 4th arch 3 31 BRANCHIAL ARCHES AND DERIVATIVE STRUCTURES Figure 4-11 3 32 DEVELOPMENT OF BRANCHIAL ARCHES Each paired branchial arch has its own developing cartilage, nerve, vascular, and muscular components within each mesodermal core. The first two pairs of arches become developed to the greatest extent of all the arches and are also the only ones specifically named. The third branchial arch has an unnamed cartilage associated with it. This cartilage will be responsible for the formation of parts of the hyoid bone. 3 33 BRANCHIAL GROOVE AND MEMBRANE FORMATION Between neighboring branchial arches, external grooves are noted on each side of the embryo. These are the branchial grooves (or pharyngeal grooves). Only the first branchial groove, which is located between the first and second branchial arches at approximately the same level as the first pharyngeal pouches, gives rise to a definitive mature structure of the head and neck. 34 PHARYNGEAL POUCH FORMATION Four well-defined pairs of pharyngeal pouches develop as endodermal evaginations from the lateral walls lining the pharynx. The pouches develop as balloon-like structures in a craniocaudal sequence between the branchial arches. 3 35 PHARYNGEAL POUCHES AND DERIVATIVE STRUCTURES 3636  CASE STUDY 4.0 Age 18 YRS Scenario Sex Male A new patient is concerned about Height 6’ 2” a swelling in his 155 LBS neck. His parents Weight want him to have BP 100/70 it checked out before he returns Chief “What is the to college after Complaint swelling on my the holidays. A neck?” limited examination was Medical Allergy to performed. History pollen A clinical Current Allergy photograph was Medications medications taken. The swelling is College located on the Social right side of his History student neck near the angle of the mandible. The swelling is slowly growing and Fehrenbach, MJ, Weiner J. Saunders Review of Dental Hygiene, painless. ed 2. Saunders, Philadelphia, 2009 37  CASE STUDY 4.0 Question: What could be occurring to cause the swelling of his neck? Answer: May possibly be a cervical cyst. Most congenital malformations in the neck originate during transformation of the branchial apparatus into its mature derivatives. Some of these are a result of the persistence of parts of the branchial apparatus that normally disappear during development of the neck and its associated tissues. Fehrenbach, MJ, Weiner J. Saunders Review of Dental Hygiene, ed 2. Saunders, Philadelphia, 2009 The branchial grooves occasionally do not become obliterated, and thus parts remain as cervical cysts. 38 MULTI-DIMENSIONAL HUMAN EMBRYO  MULTI-DIMENSIONAL HUMAN EMBRYO Embryo is 28 postovulatory days old and measures 4 to 6 mm in length. Multi-Dimensional Human Embryo, National Institute of Child Health and Human Development. Accessed 2010 at http://embryo.soad.umich.edu/ 40  MULTI-DIMENSIONAL HUMAN EMBRYO Embryo is 32 postovulatory days old and measures 5 to 7 mm in length. Multi-Dimensional Human Embryo, National Institute of Child Health and Human Development. Accessed 2010 at http://embryo.soad.umich.edu/ 41  MULTI-DIMENSIONAL HUMAN EMBRYO Embryo is 33 postovulatory days old and measures 7 to 9 mm in length. Multi-Dimensional Human Embryo, National Institute of Child Health and Human Development. Accessed 2010 at http://embryo.soad.umich.edu/ 42  MULTI-DIMENSIONAL HUMAN EMBRYO Embryo is 37 postovulatory days old and measures 11 to 14 mm in length. Multi-Dimensional Human Embryo, National Institute of Child Health and Human Development. Accessed 2010 at http://embryo.soad.umich.edu/ 43 MULTI-DIMENSIONAL HUMAN EMBRYO Embryo is 44 postovulatory days old and measures 13 to 17 mm in length. Multi-Dimensional Human Embryo, National Institute of Child Health and Human Development. Accessed 2010 at http://embryo.soad.umich.edu/ 44 FURTHER EMBRYONIC DEVELOPMENT: MULTI-DIMENSIONAL HUMAN EMBRYO Embryo Development over Time: http://www.visembryo.com/baby/index.html Courtesy Bradley Smith. 45 FURTHER EMBRYONIC DEVELOPMENT: MULTI-DIMENSIONAL HUMAN EMBRYO 46 Courtesy Bradley Smith. FURTHER EMBRYONIC DEVELOPMENT: MULTI-DIMENSIONAL HUMAN EMBRYO 47 Courtesy Bradley Smith. Multi-Dimensional Human Embryo, National Institute of Child Health and Human Development. Accessed 2010 at http://embryo.soad.umich.edu/ 48