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IMF-086-03-0001-en	Why are the retina and optic nerve central nervous tissue rather than peripheral nerve?	Optic vesicles are neuroectodermal outgrowths of the diencephalon, so the retina and optic nerve develop as part of the central nervous system.	Integrated Medical Foundations; chapter 86, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 4c2b64bea339001ba36a6f4f2326564955aae3461b832fb47ff0b4be0fb18137; editorial review pending	imf lang::en chapter::086 module::086-03 review::pending
IMF-086-03-0002-en	Why do brainstem cranial sensory nuclei lie lateral to motor nuclei, unlike the spinal cord's dorsal-ventral arrangement?	In the hindbrain, the pontine flexure opens the roof of the fourth ventricle and displaces the alar plates laterally to the basal plates, so sensory derivatives lie lateral to motor ones.	Integrated Medical Foundations; chapter 86, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 4c2b64bea339001ba36a6f4f2326564955aae3461b832fb47ff0b4be0fb18137; editorial review pending	imf lang::en chapter::086 module::086-03 review::pending
IMF-086-03-0003-en	Why can a tethered spinal cord cause progressive neurological and urological symptoms?	The vertebral column grows faster than the cord, so the cord end normally rises; abnormal fixation or a thickened filum makes continued growth impose traction on the cord.	Integrated Medical Foundations; chapter 86, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 4c2b64bea339001ba36a6f4f2326564955aae3461b832fb47ff0b4be0fb18137; editorial review pending	imf lang::en chapter::086 module::086-03 review::pending
IMF-086-03-0004-en	What distinguishes the migration of radial-glia-guided cortical neurons from that of inhibitory interneurons, and what do migration defects alter?	Radial glia guide many cortical neurons outward in an inside-out sequence, whereas inhibitory interneurons migrate tangentially from the ventral forebrain; migration defects alter cortical layering.	Integrated Medical Foundations; chapter 86, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 4c2b64bea339001ba36a6f4f2326564955aae3461b832fb47ff0b4be0fb18137; editorial review pending	imf lang::en chapter::086 module::086-03 review::pending
IMF-086-03-0005-en	What fusion failure causes cleft lip, and why can the cleft extend into the primary palate?	Cleft lip results when the maxillary prominence fails to fuse with the medial nasal prominence; because that fusion forms both the upper lip and the primary palate, the cleft may extend through the primary palate.	Integrated Medical Foundations; chapter 86, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 4c2b64bea339001ba36a6f4f2326564955aae3461b832fb47ff0b4be0fb18137; editorial review pending	imf lang::en chapter::086 module::086-03 review::pending
IMF-086-03-0006-en	Why can cleft palate arise from many different failures, with or without cleft lip?	The secondary palate requires palatal shelves to grow, elevate from vertical beside the tongue to horizontal, contact, adhere and fuse, so failure at any of these steps leaves a cleft.	Integrated Medical Foundations; chapter 86, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 4c2b64bea339001ba36a6f4f2326564955aae3461b832fb47ff0b4be0fb18137; editorial review pending	imf lang::en chapter::086 module::086-03 review::pending
IMF-086-03-0007-en	Why is the innervation of the tongue mixed?	The tongue forms from several arch swellings: anterior mucosa mainly first arch with taste via second-arch chorda tympani, posterior third mainly third arch with glossopharyngeal supply, and muscles from occipital myoblasts with hypoglossal supply.	Integrated Medical Foundations; chapter 86, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 4c2b64bea339001ba36a6f4f2326564955aae3461b832fb47ff0b4be0fb18137; editorial review pending	imf lang::en chapter::086 module::086-03 review::pending
IMF-086-03-0008-en	Why does a thyroglossal duct cyst lie in the midline and move with swallowing or tongue protrusion?	The thyroid descends from near the foramen caecum through the thyroglossal duct to the anterior neck; remnants of this midline tract form the cyst, and thyroid tissue can remain ectopic along the route.	Integrated Medical Foundations; chapter 86, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 4c2b64bea339001ba36a6f4f2326564955aae3461b832fb47ff0b4be0fb18137; editorial review pending	imf lang::en chapter::086 module::086-03 review::pending
IMF-086-03-0009-en	Why does premature fusion of a skull suture produce a characteristic head shape?	Fusion restricts growth perpendicular to that suture and redirects expansion in other directions, sometimes also raising intracranial pressure.	Integrated Medical Foundations; chapter 86, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 4c2b64bea339001ba36a6f4f2326564955aae3461b832fb47ff0b4be0fb18137; editorial review pending	imf lang::en chapter::086 module::086-03 review::pending
IMF-086-03-0010-en	Why does failed closure of the choroidal fissure cause coloboma of variable extent?	The fissure admits the hyaloid vessels and must then close; failure leaves a defect involving iris, retina, choroid or optic nerve according to its extent.	Integrated Medical Foundations; chapter 86, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 4c2b64bea339001ba36a6f4f2326564955aae3461b832fb47ff0b4be0fb18137; editorial review pending	imf lang::en chapter::086 module::086-03 review::pending
IMF-086-03-0011-en	Why can an external ear anomaly be a clue to renal, cardiac or mandibular conditions, and when is it reassuring?	The ear shares pharyngeal-arch and neural-crest development with other structures, so its anomalies can signal renal, cardiac, mandibular or chromosomal conditions, but an isolated minor variant is often benign.	Integrated Medical Foundations; chapter 86, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 4c2b64bea339001ba36a6f4f2326564955aae3461b832fb47ff0b4be0fb18137; editorial review pending	imf lang::en chapter::086 module::086-03 review::pending
IMF-086-03-0012-en	Why can the same teratogenic drug be hazardous in one pregnancy or window and relatively low risk in another?	Outcome depends on dose reaching the embryo, timing and duration, maternal absorption and metabolism, placental transport, interacting exposures and fetal genotype.	Integrated Medical Foundations; chapter 86, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 4c2b64bea339001ba36a6f4f2326564955aae3461b832fb47ff0b4be0fb18137; editorial review pending	imf lang::en chapter::086 module::086-03 review::pending
IMF-086-03-0013-en	How does the effect of an exposure change between preimplantation, weeks three to eight, and later gestation?	Preimplantation injury often causes embryonic loss or compensation by surviving cells; weeks three to eight are the peak for major structural malformations; later exposure more often affects growth, maturation and brain function.	Integrated Medical Foundations; chapter 86, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 4c2b64bea339001ba36a6f4f2326564955aae3461b832fb47ff0b4be0fb18137; editorial review pending	imf lang::en chapter::086 module::086-03 review::pending
IMF-086-03-0014-en	Why should necessary antiseizure treatment in pregnancy not simply be stopped abruptly?	Although valproate and some other antiseizure drugs raise specific malformation and neurodevelopmental risks, seizure control remains essential, and untreated maternal disease can cause greater harm than appropriately selected therapy.	Integrated Medical Foundations; chapter 86, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 4c2b64bea339001ba36a6f4f2326564955aae3461b832fb47ff0b4be0fb18137; editorial review pending	imf lang::en chapter::086 module::086-03 review::pending