Development of the Face PDF

DEVELOPMENT OF THE FACE School of Laboratory Medicine and Medical Sciences ANATOMY UKZN INSPIRING  OVERVIEW Develops between the 4th & 6th week of embryonic development Palate develops between 6th & 8th week Important tiss...

DEVELOPMENT OF THE FACE School of Laboratory Medicine and Medical Sciences ANATOMY UKZN INSPIRING  OVERVIEW Develops between the 4th & 6th week of embryonic development Palate develops between 6th & 8th week Important tissue structures involved: pharyngeal arches & neural crest cells Pharyngeal arches: - a.k.a branchial arches - 6 in a developing embryo - Outpocketings of mesoderm in the 4th week Neural crest cells - Originate from neuroectoderm - Contribute to derivatives of pharyngeal arches  DEVELOPMENT OF FACE Begins at about 4th week of intrauterine life from 3 main structures  frontonasal process (prominence)  Maxillary processes  mandibular processes Frontonasal process: - Made up of mesenchymal neural crest cells ventral to forebrain Stomodeum Maxillary & mandibular processes - Arises from the 1st pharyngeal arch - Between maxillary prominences is the stomodeum (which later give rise to the mouth & pituitary gland  FACIAL SWELLING & UPPER Nasal development is instigated byLIP the appearance of raised bumps called nasal placodes on both sides of the frontonasal process These then invaginate to form nasal pits, with medial and lateral nasal processes on either side  FACIAL SWELLING & 5th week: UPPER 2 ridges : lateral & medial nasal swelling surround nasal placode 5th week  FACIAL SWELLING & UPPER As the maxillary processes LIP the nasal processes are ‘pushed’ closer to the expand medially, midline Maxillary processes are separated from lateral nasal swelling : nasolacrimal (naso-optic) groove Maxillary processes are separated from the medial nasal swelling: buconasal groove  FACIAL SWELLING & UPPER LIP By the end of 6th week- Maxillary processes then fuse with the medial nasal prominences – Upper Lip Medial nasal processes fuse - Intermaxillary segments Ectoderm in nasolacrimal groove forms cord : nasolacrimal duct : its upper end widens to form lacrimal sac Nasolacrimal duct runs from medial corner of eye to inferior meatus of nasal cavity  FACIAL SWELLING & By the end of 6th UPPER LIP week- Lateral nasal processes develop into lateral nasal wall The mandibular processes fuse to form the lower jaw, all lower teeth & lower lip Mandibular + maxillary processes = Cheeks QUICK RECAP  Development of related-internal structures Palate Nasal cavity Oral cavity Paranasal sinuses  INTERMAXILLARY Derivatives : SEGMENT Bridge of the nose Philtrum (the vertical groove btw the base of the nose and border of the upper lip) Upper jaw component ( includes 4 incisor teeth) Primary palate (forms triangular primary palate) About the 7th to 8th Week  SECONDARY PALATE Definitive palate formed by palatine shelves Directed downward on either side of tongue  SECONDARY 8th to 9th PALATE week - palatine shelves ascend Attain horizontal position above tongue Fuse with each other : forms secondary palate *ectoderm & mesoderm of Frontonasal + Intermaxillary segment = Nasal Septum  CLEFT LIP & PALATE Cleft deformities may result from partial or incomplete fusion of mesenchymal tissue Caused by hereditary as well as environmental factors  NASAL CAVITIES Oronasal membrane separates nasal pits from primitive oral cavity By 8th week , membrane disintegrate – form primitive Choana – connect oral and nasal cavities Paranasal air sinuses develop as diverticula of lateral nasal wall & extend into maxilla, ethmoid, frontal & sphenoid bones. Reach maximum size during puberty -contribute to definitive shape of face In Summary  Prominences & Derivatives Prominence Derivatives Forehead, bridge of nose, medial and lateral Frontonasal nasal prominences Philtrum, primary palate, upper 4 incisors and Medial nasal associated jaw Lateral nasal Sides of the nose Cheeks, lateral upper lip, secondary palate, Maxillary (1st pharyngeal arch) lateral upper jaw Mandibular (1st pharyngeal arch) Lower lip and jaw  Dr OS Aladeyelu Email: [email protected] WhatsApp: 065 697 5373