[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Embryology](https://durgical.com/en/embryology/) › [Nervous system and senses](https://durgical.com/en/embryology/#a-nervous) › Ear: inner, middle and external ear [Embryology](https://durgical.com/en/embryology/) · [Nervous system and senses](https://durgical.com/en/embryology/#a-nervous) # Ear: inner, middle and external ear - Process The three parts of the ear come from different places in the embryo: a skin placode, the first pharyngeal pouch and the first two arches. Updated 2026-11-01 **See it in 3D:** [Cochlea](https://durgical.com/en/anatomy/cochlea/) · [Semicircular canals](https://durgical.com/en/anatomy/semicircular-canals/) · [Vestibule](https://durgical.com/en/anatomy/vestibule/) · [Malleus](https://durgical.com/en/anatomy/malleus/) · [Incus](https://durgical.com/en/anatomy/incus/) · [Stapes](https://durgical.com/en/anatomy/stapes/) · [Eardrum](https://durgical.com/en/anatomy/tympanic-membrane/) · [Auditory tube](https://durgical.com/en/anatomy/auditory-tube/) · [Ear canal](https://durgical.com/en/anatomy/external-acoustic-meatus/) · [Auricle](https://durgical.com/en/anatomy/auricle/) · [Vestibulocochlear nerve (VIII)](https://durgical.com/en/anatomy/vestibulocochlear-nerve/) ## Key points - Inner: otic placode (ectoderm). Middle: first pouch (endoderm). External: first cleft (ectoderm). - Malleus and incus from arch 1; stapes from arch 2. - Tensor tympani by V3; stapedius by VII. - Tympanic membrane: all three germ layers. - Auricle from six hillocks; auricle anomalies point to other malformations. ## What it is The inner ear forms from the otic placode of the ectoderm; the middle ear from the first pharyngeal pouch and the cartilages of arches 1 and 2; the external ear from the first pharyngeal cleft and six hillocks around it. Because their origins differ, a malformation can hit one part and spare another, which explains conductive versus sensorineural hearing loss. ## Key facts - Day 22: the otic placode appears beside the hindbrain; in week 4 it invaginates and pinches off as the otic vesicle (otocyst). - The ventral otocyst gives the saccule and cochlear duct; the dorsal part gives the utricle, semicircular canals and endolymphatic duct. - The cochlear duct completes its 2.5 turns by the end of week 8; the organ of Corti differentiates afterwards. - Malleus and incus: first-arch cartilage; stapes: second arch (its footplate also gets neural crest and mesoderm). - External acoustic meatus: first cleft; an epithelial plug fills it and recanalizes around the seventh month. - Auricle: six auricular hillocks of arches 1 and 2; the ear rises from the neck as the mandible grows. ## Structure - Inner ear (placode ectoderm): membranous labyrinth, organ of Corti, ampullary cristae and maculae. - Middle ear (first-pouch endoderm): tympanic cavity, auditory tube, mastoid air cells. - Ossicles: malleus and incus (arch 1), stapes (arch 2). - Muscles: tensor tympani (arch 1, trigeminal V3); stapedius (arch 2, facial nerve). - Tympanic membrane: three layers, ectoderm outside, mesenchyme in the middle and endoderm inside. - External ear: canal (first cleft) and auricle (hillocks of arches 1 and 2, with neural crest). ## Step by step - The otic placode thickens on each side of the hindbrain. - It invaginates into the otic vesicle, which gives off cells for the vestibulocochlear ganglion. - The vesicle divides into a cochlear (ventral) and a vestibular (dorsal) part. - Mesenchyme forms the cartilaginous otic capsule, which later ossifies into the bony labyrinth. - The first pouch forms the tubotympanic recess: tympanic cavity and auditory tube. - The ossicles stay in mesenchyme until the eighth month, when the cavity expands around them. - The hillocks fuse into the auricle and the ear rises to the side of the head. ## Markers - PAX2 - SOX2 - FGF3 - FGF10 - SHH - HOXA2 ## Clinical notes - Low-set ears: a sign of disturbed mandibular development or chromosomal syndromes. - Defects of arches 1 and 2 (Treacher Collins) cause conductive hearing loss. - Rubella after week 7 can spare the lens but damage the cochlea. - A fetus responds to sound in the late second trimester. ## Memory aid 'Skin outside, gut inside, placode deepest': the cleft (ectoderm) gives the canal, the pouch (endoderm) the middle-ear box and the placode the labyrinth. ## Test yourself Think of the answer, then tap the question to see it. ## Which embryonic structure does the tympanic cavity come from? The first pharyngeal pouch (endoderm), through its tubotympanic recess. ## Which ossicle comes from the second pharyngeal arch? The stapes; the malleus and incus come from the first arch. ## Which part of the otic vesicle forms the cochlea? The ventral part, which gives the saccule and cochlear duct. ## How many layers does the tympanic membrane have, and from which germ layers? Three: ectoderm outside, mesenchyme in the middle and endoderm inside. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/embryology/ear-inner-middle-and-external-ear/) ## See it in 3D The structures of Durgical's 3D anatomy where it is found. - [Cochlea](https://durgical.com/en/anatomy/cochlea/) - [Semicircular canals](https://durgical.com/en/anatomy/semicircular-canals/) - [Vestibule](https://durgical.com/en/anatomy/vestibule/) - [Malleus](https://durgical.com/en/anatomy/malleus/) - [Incus](https://durgical.com/en/anatomy/incus/) - [Stapes](https://durgical.com/en/anatomy/stapes/) - [Eardrum](https://durgical.com/en/anatomy/tympanic-membrane/) - [Auditory tube](https://durgical.com/en/anatomy/auditory-tube/) - [Ear canal](https://durgical.com/en/anatomy/external-acoustic-meatus/) - [Auricle](https://durgical.com/en/anatomy/auricle/) - [Vestibulocochlear nerve (VIII)](https://durgical.com/en/anatomy/vestibulocochlear-nerve/) ## Related - [Congenital hearing loss, microtia and preauricular pits](https://durgical.com/en/embryology/congenital-hearing-loss-microtia-and-preauricular-pits/) - [The pharyngeal apparatus: arches, pouches, clefts and membranes](https://durgical.com/en/embryology/the-pharyngeal-apparatus-arches-pouches-clefts-and-membranes/) - [Pharyngeal clefts and membranes: external ear and cervical sinus](https://durgical.com/en/embryology/pharyngeal-clefts-and-membranes-external-ear-and-cervical-sinus/) - [Pharyngeal pouches: tonsil, thymus, parathyroids and C cells](https://durgical.com/en/embryology/pharyngeal-pouches-tonsil-thymus-parathyroids-and-c-cells/) - [First pharyngeal arch (mandibular arch) and the trigeminal nerve](https://durgical.com/en/embryology/first-pharyngeal-arch-and-the-trigeminal-nerve/) - [Second pharyngeal arch (hyoid arch) and the facial nerve](https://durgical.com/en/embryology/second-pharyngeal-arch-and-the-facial-nerve/) - [First-arch syndromes: Treacher Collins and Pierre Robin sequence](https://durgical.com/en/embryology/first-arch-syndromes-treacher-collins-and-pierre-robin-sequence/) - [Congenital rubella syndrome](https://durgical.com/en/embryology/congenital-rubella-syndrome/) ## Related conditions - [Hearing loss (conductive and sensorineural, including sudden hearing loss)](https://durgical.com/en/conditions/hearing-loss/) [← All of embryology](https://durgical.com/en/embryology/) Educational content on embryonic development; not a guide to prenatal diagnosis or to medicines in pregnancy and no substitute for a health professional's advice. No doses are given. Sources: [Anotia/Microtia](https://www.cdc.gov/birth-defects/about/anotia-microtia.html) (Centers for Disease Control and Prevention, 2024); [Fetal development: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/002398.htm) (U.S. National Library of Medicine, 2024); Langman's Medical Embryology, 13th ed., ch. 19: Ear (Wolters Kluwer, 2015). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/embryology/ear-inner-middle-and-external-ear/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/embryology/ear-inner-middle-and-external-ear/