Embryology of the Ear I (Easy to Understand)

The development of the inner ear explained in 15 minutes. For the embryology of the middle and outer ear, tap here:    • Embryology of the Ear II (Easy to Understand)   If you are completely new to embryology and you want to understand it quickly, this should be the first video you watch:    • Introduction to Embryology - Fertilisation...   -------------------------------- Recommended Text -------------------------------- Easy Embryology is a book that is dedicated to the simplification of embryology. It is available at https://drminass.com/product/easyembr.... Contact Dr. Minass for more information. ---------------------------------------- Interact With Dr. Minass! ---------------------------------------- Website - https://www.drminass.com Email - info@drminass.com Patreon -   / drminass   Facebook -   / m1na55   Instagram - @m1.nass Post - Address to: Minass Parcel Locker 10106 04448 59 Penshurst Street Willoughby, NSW Australia 2068 ------------------------------------------------------------------------ SUMMARY OF THE VIDEO FOR YOUR NOTES ------------------------------------------------------------------------ The internal ear The otic placode is seen in the day 22 embryo as a thickened part of the ectoderm on both sides of the rhombencephalon (developing CNS / neural tube). the otic placode invaginates quickly forming the otic vesicles. Also known as auditory vesicles, or otocysts. the otic placode divides itself into both a ventral component and a dorsal component the ventral part gives rise to the saccule and the cochlear duct the dorsal part forms the utricle, semicircular canals, and endolymphatic duct. these are collectively the membraneous labyrinth by week 6, the saccule has an outgrowth that eventually forms the cochlear duct by growing and coiling 2.5 times around itself. It grows into the surrounding tissue to do this. the connection between the saccule and the cochlear duct is by the ductus reuniens the tissue that the cochlear duct penetrated will differentiate into cartilage some of this cartilage will become hollow, to allow for the development of the scala vestibuli and tympani, each having their own membrane. cochlear duct is attached to the rest of the cartilage by the spiral ligament epithelial cells of the cochlear duct differentiate these become the outer ridge and the inner ridge the outer ridge becomes the hair cells which are covered by the tectorial membrane the inner ridge becomes the spiral limbus the hair cells and the tectorial membrane are known as the Organ of Corti the Organ of Corti sends impulses to the brain via cranial verve VIII (CN8, vestibulocochlear nerve) by week 6 semicircular canals appear by walls that grow together the walls disappear leaving the three semicircular canals one of the ends become the crus ampullare that dilates and contains sensory cells, the other end doesn't dilate and is thus called the crus nonampullare the cells in the crus amopullare are known as the crista ampullaris and these maintain equilibrium inside the utricle and saccule , maculae acusticae develop, which send information about the bodies position in space to the brain for processing - this is done via the vestibular portion of CNVIII the statoacoustic ganglion is formed by both neural crest cells and by some cells that divide off the optic placode (so all ectoderm) the statoacoustic ganglion divides into both vestibular and cochlear segments (CNVIII)