Sievert-Head and Neck Development and Superficial Face Anatomy Flashcards
What are the three primordia of head and neck development?
placodes
somites
pharyngeal/branchial arches (clefts and pouches)
What is this:
an ectodermal thickening that forms structures for some of our special senses
placodes
What are the types of placodes?
olfactory placode
lens placode
otic placode
What do preotic somites turn into?
extraocular muscles
what do postotic somites turn into?
tongue muscles
What is the nasal placode induced by?
adjacent olfactory bulb of the forebrain
What does the nasal placode form?
the primary olfactory epithelium (i.e cell of smell)
So you have the olfactory bulb which makes the nasal placode which forms the primary olfactory epithelium which then pierces what?
the olfactory bulb through the ethmoid bone (cribiform plane)
What does the olfactory bulb have within it that connects with primary neurosensory cells?
secondary neurosensory cells
How does the lens placode form?
the optic cup (neuroectoderm from diencephalon) induces a thickening of the surface ectoderm which forms the lens placode. (i.e the optic cup pac mans the ectoderm to create a lens)
Does the lens placode contain sensory cells?
no
What are the three parts to the ear?
external, middle and inner ear
What does the otic placode make?
the inner ear
labryrinth and sensory neurons of cranial nerve 8
What sensory neurons are made from the otic placode of cranial nerve 8?
hair cells
What is the membranous labyrinth of the otic placode of cranial nerve 8?
utricle, semicircular canal, endolymphatic duct
What is significant about the development of the inner ear and why is this worrisome?
it is very slow
makes it susceptible to environmental defects
Cranial nerves that carry sensory info will have a cranial nerve ganglion (blank) the CNS where there would be no synpase present.
outside
What becomes the future middle ear?
the pharyngeal pouch lined by the endoderm of the pharynx
What becomes the external ear?
the surface ectoderm of the first pharyngeal cleft (groove)
How does the tympanic membrane form?
three germ layers endoderm, mesenchyme, ectoderm meet up and form the tympanic membrane : )
What are masses of mesoderm that form skeletal muscles?
somites
(blank) somites from muscles that move the eye not the muscles of the iris or the lens.
preotic
(blank) somites form muscles of the tongue
postotic
What are extraocular muscles?
muscles outside the eyeball that move the eyeballe (i.e. levator ptosis)