1
Q
developing fetus composed of three layers of tissue
A
- ectoderm
- mesoderm
- endoderm
2
Q
third week
A
- 3mm
- early forebrain - prosencephalon
- below is furrow - oral groove- stomadeum
- early mouth
3
Q
fourth week
A
- 4.5 mm
- branchial apparatus emerges
- developed by 28 days
- branchial arches, pharyngeal pouches, branchial grooves
4
Q
branchial arches
A
-5 in human numbered 1-6
only 1&2 named
-much of face derived from these
5
Q
arch 1
A
mandibular skeletal: -mandible -anterior tongue -lower lip -malleus -incus muscles: -muscles of mastication -ABD -tensor tympani -tensor palatini innervation: -CN V - V3
6
Q
arch 2
A
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
7
Q
arch 3
A
skeletal: -lower part of hyoid -posterior tongue muscles: -stylopharyngeus innervation: -CN IX - glossopharyngeal
8
Q
arch 4-6
A
skeletal: -laryngeal cartilages muscles: -cricothyroid -pharyngeal constrictors -intrinsic laryngeal muscles innervation: -CN X
9
Q
brachial cleft 1
A
- external auditory meatus
- ectodermal aspect of TM
10
Q
brachial cleft 2-4
A
-cervical sinus
11
Q
fourth week processes
A
- 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
12
Q
fifth week
A
9 mm
- branchial arches reach most prominent appearance
- face divided in 4 regions
13
Q
frontonasal process
A
- medial/lateral processes
- lateral - globular process
14
Q
mandibular arch
A
- 1st branchial arch fuse in midline
- forms caudal border of stomadeum
15
Q
maxillary process
A
-2 small processes from laterally between 2 mandibular arch and lateral nasal process
16
Q
hyoid arch
A
- partially interrupted by bulge of rapidly growing heart
- appears as two sac-like pouches on either side of neck region
17
Q
early face
A
- 32 days
- 5th week
18
Q
sixth week
nasal processes
A
- 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
19
Q
sixth week
A
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
20
Q
seventh week
A
- pronounced change in face
- nasal area becomes prominent but decreases in width
- eyes move into anterior surface
- critical period for palate formation
21
Q
primary palate begins to develop
A
- 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
22
Q
primary palate formation
A
- forms upper lip, anterior alveolar process and premaxillary palate
- completed by 8 weeks
23
Q
week 8
A
- head begins to expand vertically
- increases height of oral cavity
- allows growth of nasal septum
- no separation of oral and nasal cavity
24
Q
development of secondary palate
A
- 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
25
risk factor period
-week 4-8
| cleft-lip palate risk
26
general development
- week 3-8 face
| - week 6-9 palate
27
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
28
development of tongue
| week 5
-tuberculum and copula prominently developed
29
tongue development
| week 6
-primitive tongue shape evident
30
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
31
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
32
tongue muscles formed from
occipital somites
33
somites
- masses of mesoderm distributed along two sides of neural tube
- eventually become dermis, skeletal muscle, and vertebrae
34
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
SHS 300
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