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What is the signal for Outgrowth in facial development
Fibroblast Growth Factors
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What is the signal for patterning in facial development
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Patterning of arches is dependent on
HOX genes carried by migrating neural crest cells
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HOX gene expression is regulated by
SHH
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Deficiencies or excesses of Retinoids (retinoic acid) have what effect on facial development
Craniofacial abnormalities
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What are the two parts of the neurocranium
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The flat bones in the membranous neurocranium are derived from
Neural crest cells and paraxial mesoderm
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What does the membranous portion of the neurocranium consist of
Flat bones that surround the brain as a vault
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Where are the bones in the neurocranium derived from
Those anterior to the pituitary gland are derived from neural crest cells, and those posterior from occipital somites
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What does the cartilaginous neurocranium consist of
The bones that make the base of the skull
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What portion of the neurocranium is formed by Endochondral ossification
- Ethmoid
- Sphenoid
- Base of Occipital
- Temporal (petrous portion)
- "BEST portion"
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What bones in the skull are derived from membranous ossification
- Frontal
- Parietal
- Occipital (top portion)
- Squamous Temporal
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The bones of the face are derived primarily from what arches
The first two pharyngeal arches
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How is membranous ossification initiated in the facial bones
Neural crest cells invading the first two pharyngeal arches providing the mesenchyme for membranous ossification
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The Dorsal part of the first pharyngeal arch forms
- Maxilla
- Zygomatic bone
- Squamous part of the Temporal
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The ventral portion of the 1st pharyngeal arch forms
Mandible
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Malleus Incus are formed buy what arch
1st
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What are the first bones to ossify and when does this happen
- Malleus, Incus, and Stapes
- 4th month of development
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Laryngeal cartilages (Cricoid and Thyroid cartilages) develop from which arch
4th and 6th
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What bones in the viscerocranium develop from cartilaginous ossification
Malleus, Incus, Stapes, Hyoid, and Laryngeal cartilages
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What bones in the viscerocranium developed from intermembranous ossification
- Squamous temporal
- Maxillary
- Zygomatic bones
- Mandible
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The stapes develops from what arch
Second
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What results when the oropharyngeal membrane does not rupture
Polyhydramnios - excess of Amnionic fluid
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Amniotic fluid is formed by what
Maternal circulation and the fetal urine from kidneys
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How is the amnionic fluid resorbed
Fetus swallows and it is absorbed into the fetal circulation, the excess is removed from the placenta and passed into the maternal circulation
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Duodenal, and Esophogeal atresia results in
Polyhydramnios
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What can polyhydramnios lead to
- Over extended uterus
- Premature rupture of membranes
- Early detachment of placenta
- Umbilical cord prolapse (cord precedes baby)
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Amniotic fluid is especially important for the development of
Lungs
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Each pharyngeal arch is supplied by
Its own cranial nerve, artery, and cartilage
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What nerves supply the arches respectively
- 1st - Trigeminal (V)
- 2nd - Facial (VII)
- 3rd - Glossopharyngeal (IX)
- 4th - Superior laryngeal branch of the vagus (X)
- 6th - Recurrent laryngeal branch (X)
- "Same order as tongue and epiglottis taste innervation"
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The external auditory meatus and auditory tube develop from
Pouching between the 1st and 2nd arches
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Palatine tonsil develops from
Invagination between the 2nd and 3rd arches
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The thymus develops from
Invagination between the 3rd and 4th arches
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Lateral cervical cyst
Develops between the 2nd and 3rd arches and descends to just anterior to the sternocleidomastoid
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The parathyroid develops from
- Superior from the 4th arch
- Inferior from the 3rd arch
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DiGeorges syndrome
Deficiency or excess of Retinoic acid in development causing failure of the 3rd pouch
- Cardiac defects
- Abnormal facial development
- Thymic Hypoplasia
- Cleft palate
- Hypocalcemia
- "CATCH 22"
- Immune deficiency
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The body of the tongue develops from
1st pharyngeal arch
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The 3rd arch overgrows the 2nd arch to develop
Posterior part of the tongue and Eustachian tube both innervated by CN IX
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The epiglottis and root of the tongue develop from
4th and 6th Pharyngeal arches and are innervated by CN X
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Most tongue muscles develop from
Occipital somites
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What can be the result of the thyroid not developing properly
Mental retardation (Cretinism)
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Thyroglossal cyst
Cyst formed from the remnants of the thyroglossal duct, usually found in the hyoid region
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The intermaxillary segment gives rise to
- Philtrum of the upper lip
- Median part of the maxillary bone
- Four incisor teeth
- Triangular primary palate
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What happens in locational changes in the development of the tongue and palate
The tongue drops between the palate before the two ends fuse
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What is the most common facial defect
Unilateral cleft lip
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The entire pharyngeal apparatus is apparent when
4th week of development
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Teacher Collins syndrome
Underdevelopment of the maxillary portion of the 1st arch
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Robin Sequence
Underdevelopment of the mandibular portion of the 1st arch
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The major portion of the definitive palate develops from
Lateral palatine shelves from maxillary prominence
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What is the only sinus that is present at birth
Maxillary
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Constrictors of the pharynx develop from
Arch 4
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Intrinsic muscles of the Larynx develop from
Arch 6
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What is the most common site of ectopic thyroid
Foramen cecum (root of tongue)
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