development of face Flashcards
developing fetus composed of three layers of tissue
- ectoderm
- mesoderm
- endoderm
third week
- 3mm
- early forebrain - prosencephalon
- below is furrow - oral groove- stomadeum
- early mouth
fourth week
- 4.5 mm
- branchial apparatus emerges
- developed by 28 days
- branchial arches, pharyngeal pouches, branchial grooves
branchial arches
-5 in human numbered 1-6
only 1&2 named
-much of face derived from these
arch 1
mandibular skeletal: -mandible -anterior tongue -lower lip -malleus -incus muscles: -muscles of mastication -ABD -tensor tympani -tensor palatini innervation: -CN V - V3
arch 2
hyoid skeletal: -stapes -styloid process -stylohyoid ligament -body of hyoid -lesser horns of hyoid muscles: -stapedius -stylohyoid -muscles of facial expression -PBD innervation: -CN VII
arch 3
skeletal: -lower part of hyoid -posterior tongue muscles: -stylopharyngeus innervation: -CN IX - glossopharyngeal
arch 4-6
skeletal: -laryngeal cartilages muscles: -cricothyroid -pharyngeal constrictors -intrinsic laryngeal muscles innervation: -CN X
brachial cleft 1
- external auditory meatus
- ectodermal aspect of TM
brachial cleft 2-4
-cervical sinus
fourth week processes
- area cephalic to stomadeum forms the frontonasal process - frontonasal prominance
- thickenings appear on sides of process
- nasal - olfactory placodes
- pits = early nasal openings
- pits divide face into lateral and medial nasal processes
fifth week
9 mm
- branchial arches reach most prominent appearance
- face divided in 4 regions
frontonasal process
- medial/lateral processes
- lateral - globular process
mandibular arch
- 1st branchial arch fuse in midline
- forms caudal border of stomadeum
maxillary process
-2 small processes from laterally between 2 mandibular arch and lateral nasal process
hyoid arch
- partially interrupted by bulge of rapidly growing heart
- appears as two sac-like pouches on either side of neck region
early face
- 32 days
- 5th week
sixth week
nasal processes
- medial nasal processes forms upper border of mouth
- maxillary processes formed into wedge like processes below early eye
- not fused
- separated by small grooves that must disappear
- medial and lateral nasal processes fuse
- thin shelf of tissue separates a portion of oral and nasal cavities *primary plate
- forms nasal laminae - septum
- philtrum on face is point of fusion of lateral and medial nasal processes
sixth week
9 mm
- anterior directed growth of face begins
- eyes developing at sides of face drawn medially
- small buds form at first branchial groove
- buds = auricle
seventh week
- pronounced change in face
- nasal area becomes prominent but decreases in width
- eyes move into anterior surface
- critical period for palate formation
primary palate begins to develop
- tissue begins to develop in 4th week
- maxillary process fuses with medial nasal process
- fusion between lateral and medial nasal processes
- bar of tissue separating nasal duct from oral cavity IS primary palate
primary palate formation
- forms upper lip, anterior alveolar process and premaxillary palate
- completed by 8 weeks
week 8
- head begins to expand vertically
- increases height of oral cavity
- allows growth of nasal septum
- no separation of oral and nasal cavity
development of secondary palate
- initially developing tongue fills oral and nasal cavities
- maxillary processes are folds of tissue on either side of tongue
- development of palate and growth of head allows tongue to drop into oral cavity
- maxillary processes grow rapidly and extend horizontally
- palatine processes fuse with each other and nasal septum
- fusion takes places in anterior to posterior direction
- palatine processes form posterior hard palate and soft palate
- globular process from early nasal processes grows inward to form tectal plate
- tectal plate is early premaxillary process
risk factor period
-week 4-8
cleft-lip palate risk
general development
- week 3-8 face
- week 6-9 palate
development of tongue
week 3
- lateral lingula swellings on internal mandibular arch
- in between swellings is elevation called tuberculum impar
- rapidly proliferating mesoderm
- lateral lingula & tuberculum merge together to form anterior tongue
- also coupla in midline behind TI
- copula bridges 2 & 3 branchial arches
- posterior portion of copula forms epiglottis
development of tongue
week 5
-tuberculum and copula prominently developed
tongue development
week 6
-primitive tongue shape evident
tongue development
week 7
- tuberculum impar grows backwards in a V shape to form sulcus terminalis
- tissues on either side of copula form quickly to produce a tongue like structure
- copula forms posterior tongue while tuberculum impar forms anterior tongue
- rapid exponential growth of tongue fills in oral cavity
development of tongue
-composition
- initially just composed of mucous membrane
- tongue muscles eventually migrate in
- tongue membrane derived from branchial arches but muscles are NOT
tongue muscles formed from
occipital somites
somites
- masses of mesoderm distributed along two sides of neural tube
- eventually become dermis, skeletal muscle, and vertebrae
what do somites form
- rib and vertebrae cartilage
- muscles (skeletal muscles - tongue and ocular)
- rib cage
- limbs
- abdominal wall
- back and tongue
- dorsal skin dermis
