Craniofacial Growth & Development Flashcards
Organogenesis takes place during what weeks. What is this period?
week 3-8
Embryonic period (development of organs)
- critical time
Gastrulation goes from ___ layers to ___ layers. What are these layers & what develops from them?
2 to 3
Embryonic ectoderm, mesoderm, endoderm
All structures in body develop from these 3 layers
Vesicles during weeks 4 & 5
Week 4
Prosencephalon (forebrain)
Mesencephalon (midbrain)
Rhombencephalon (hindbrain)
Week 5
Prosencephalon (forebrain) → Telencephalon & Diencephalon
Mesencephalon (midbrain) → Mesencephalon
Rhombencephalon (hindbrain) → Metencephalon & Mylencephalon
What neurological structures develop from the telencephalon, diencephalon, mesencephalon, metencephalon, & mylencephalon?
Telencephalon → Cerebrum
Diencephalon → eye cup, thalamus, hypothalamus, & epithalamus
Mesencephalon → Midbrain
Metencephalon → pons & cerebellum
Myelencephalon → medulla oblongata
Briefly describe ectoderm, mesoderm & endoderm
Ectoderm = think things on the outside, nervous tissue
Mesoderm = think everything in the middle, CT, bones, skeletal muscle
Endoderm = think gut
Dentin of the teeth is ___ derived. Enamel of teeth is ___ derived
Neural crest
Ectoderm
Endoderm is closely associated w/ structures in the ___
neck
Some neural crests can migrate to ___ & do what? Migration is determined by?
to face & do mesoderm like things even though they’re ectoderm
Basal cell lamina
Neuralation order
Neural groove → median hinge point (neural crests coming together) → neural tube
What are neural crest cell derivatives?
Pigment cells, schwann cell, satellite cell, unipolar & multipolar neuron, chromaffin cells, parasympathetic plexus, adrenal gland, sympathetic ganglion, dorsal root ganglion
Weeks 4-8 are characterized by ___ differentiation
Somite
- differentiates into structures like limbs
Craniofacial development occurs during ___ weeks. What are the 5 facial prominences?
5-8 weeks
frontonasal process, maxillary process (x2), & mandibular process (x2)
What’s a philtrum?
The pinching of 2 maxillary processes
Primary palate is formed at ___ weeks. When does it fuse?
5.5 weeks
Fuses 5-8 weeks
How does the secondary palate fuse? At ___ weeks the palatine shelves elevate rapidly. At 10 weeks what happens?
As heart grows, it pushes head up, so tongue drops down, & palates can meet & fuse
7.5 weeks
Full fusion of shelves
First pharyngeal Arch (“mandibular arch”) nerve, cartilage, vasculature, muscles
nerve: Trigeminal n. (CN V)
cartilage: Meckel’s cartilage
Vasculature: Maxillary aa. & external carotid aa.
Muscle: Muscles of mastication
Skeletal derivatives of first pharyngeal arch
Malleus, incus, sphenomandibular ligament, Meckel’s cartilage, tympanic ring
Second pharyngeal Arch (“hyoid arch”) nerve, cartilage, vasculature, muscles
Nerve: Facial n. (CN VII)
Cartilage: Reichert’s cartilage
Vasculature: Stapedial aa. & hyoid aa.
Muscles: Muscles of facial expression
Skeletal derivatives for second pharyngeal arch
Stapes, styloid process, stylohyoid ligament, lesser horn of hyoid, part of body of hyoid
Third pharyngeal Arch nerve, cartilage, vasculature, muscles
Nerve: Glossopharyngeal n. (CN IX)
Cartilage: Parts of hyoid
Vasculature: Common carotid aa. & internal carotid aa.
Muscles: Stylopharyngeus mm.
Skeletal derivatives for third pharyngeal arch
Greater horn of hyoid, part of body of hyoid
Fourth pharyngeal Arch nerve, cartilage, vasculature, muscles
Vagus n. (CN X)
Laryngeal
Right subclavian a. & aortic arch
Pharyngeal & laryngeal muscles
Skeletal derivatives for fourth pharyngeal arch
Laryngeal cartilages
How many pharyngeal pouches are there? What are they lined with?
4
Lined w/ endoderm
What does the 2nd pouch turn into?
2nd pouch = palatine tonsil
What does the 1st pouch turn into?
1st pouch = tympanic membrane
What do the 4th pouch turn into?
4th pouch = parathyroid & ultimobranchial body
Head & neck muscles get pulled into ___ arch
Pharyngeal
Tongue develops around ___ weeks
4
What swells in the 1st & 2nd swelling for the tongue?
1st swelling: tuberculum impar swells
2nd swellings: lateral lingual swellings
The 3rd arch, in the tongue, gives rise to
mucous of tongue root (posterior ⅓)
Define foramen cecum
point when thyroid begins to descend
- Thyroid starts in tongue & descends to neck
What is the 1st & 2nd muscle to develop embryologically?
Heart = 1st
Tongue = 2nd
Mandible develops in association w/ ___. It develops from ___
Meckel’s cartilage
Develops from 2 blastemas lateral to Meckel’s cartilage
Mandible develops from ___ at ___ weeks
Periosteum at ~6 weeks
TMJ growth is affected by
biomechanical loading associated w/ muscle action
What does the 3rd pouch turn into?
3rd pouch = parathyroids & thymus
