BIOL 1004 Lecture Notes - Nasal Septum, Semicircular Canals, Optic Vesicle
28 Jan 2013
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Document Summary
Head and neck development: initial events, sources of tissue. Neural crest cells bones of face/skull, cartilage, connective tissue. Somitomeres voluntary muscles of head and neck: principles of development. 7 somitomeres form in head region from paraxial mesoderm. Somitomeres induce segmental development of brain (e. g. rhombomeres) Ncc"s migrate to arches, carrying hox code with them (prevents segment mixing) Arch is made of mesoderm, lined by ectoderm (outside) and endoderm (inside) Clefts (outside) and pouches (inside) separate the arches. Stapes, styloid, part of hyoid mm. of mastication facial mm. , post. digastric, stylohyoid, stapedius. Tongue is occipital mesodermal muscle (inn. by xii) covered with endodermal. Anterior tongue innervation from v, viii; posterior tongue from ix, x. Anterior/posterior separation at terminal sulcus (contains foramen cecum) Frenulum is remainder of tissue connecting tongue to floor of mouth (rest degenerates) Forms in foramen cecum, descends through thyroglossal duct (obliterated: nose and palate palate. Frontonasal prominence nasal septum fuses with palate.
