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Biology 340 Comparative Embryology Lecture 11 Dr. Stuart Sumida

Biology 340 Comparative Embryology Lecture 11 Dr. Stuart Sumida. Overview of Embryology of the Vertebrate Skull Emphasis on Amniota. Initial introduction to components parts of a vertebrate head.

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Biology 340 Comparative Embryology Lecture 11 Dr. Stuart Sumida

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  1. Biology 340 Comparative Embryology Lecture 11 Dr. Stuart Sumida Overview of Embryology of the Vertebrate Skull Emphasis on Amniota

  2. Initial introduction to components parts of a vertebrate head.

  3. This lecture will revolve around the early embryology of the vertebrate skull. One of the landmark achievments in this was the summary of that topic – based initially the developing embryonic shark head – by Edwin S. Goodrich. Thus it has come to be known as the “Goodrich Diagram”. We will draw our own version of it before we go on to a slide review.

  4. If you’re working with the PowerPoint files, save space in your notes to draw here.

  5. The developing skull has three component origins: • Condrocranium (base of skull / braincase) • Dermatocranium (flat bones of skull) • Splanchnocranium (bones derived from gill arch elements)

  6. Mode of Germ Layer • Formation Origin • Condrocranium Endochondral Mesoderm • Dermatocranium Dermal Neural Crest • Splanchnocranium Endochondral Neural Crest

  7. CHONDROCRANIUM: Bones of the base of the skull. • Most major cranial nerves escape the skull through these. • Endochondral • Mesodermal • Include: ethmoid, sphenoid (part), occipital (part) right and left temporal (parts).

  8. Initial component parts of the vertebrate braincase.

  9. How the parts of the braincase grow together.

  10. orbit II/ Ethmoid Sphenoid Petrous temporal Basioccipital

  11. Flat bones of skull: DERMATOCRANIUM (These and others.)

  12. Gill slit bones: become SPLANCHNOCRANIUM

  13. Contribution of somite-derived musculature and gill-slit associated musculature in the vertebrate head.

  14. Contribution of somite-derived musculature and gill-slit associated musculature in the vertebrate head.

  15. Biology 323 Human Anatomy for Biology Majors Week 10; Lecture 1; Tuesday Dr. Stuart S. Sumida Cranial Nerves and Other Soft Tissues of the Skull

  16. Start with BRAIN STUFF…

  17. The Brain and Cranial Nerves

  18. FOREBRAIN MIDBRAIN HINDBRAIN

  19. Forebrain: Cerebrum – Perception, movement of somatopleure, sensoro-motor integration, emotion, memory, learning. Diencephalon – Homeostasis, behavioral drives in hypothalamus; sensory relay and modification in thalamus; melatonin secretion in pineal gland. Midbrain (Mesencephalon) Control of eye movement. Hindbrain Cerebellum and Pons – control of movement, proprioreceptive input; relays visual and auditory reflexes in pons. Medulla Oblongata – Involuntry functions: blood pressure, sleep, breathing, vomiting.

  20. See in Part 3 of your Laboratory Protocols....

  21. Development • Special Sense organs = nose, eyes and ears, begin as small outcrops of ectoderm called placodes

  22. Development Placode 1 = nose Placode 2 = eye Placode 3 = ear

  23. Development • In the nose, the ectoderm become nerve cells that send their fibres through the cribriform plate of the ethmoid, back to the brain • This is Cranial Nerve I = the Olfactory Nerve

  24. Development • The second placode becomes the lens of the eye. • It sinks below the surface of the skin, and an outgrowth of the brain wraps around it. • The outgrowth is the retina, and the stalk connecting it is Cranial Nerve II = The Optic Nerve

  25. Eye starts out as photosensitive lobe of brain underlying surface of skin. • Lobe eventually becomes two-layered cup = retina. • Connected to brain by “stalk” that is the OPITC NERVE (cranial nerve II). • Lens from ectodermal placode. • Marginal cells of retina become specialized as MUSCLE CELLS that regulate opening of pupil: • Sphinctor pupillae (parasympathetically regulated) • Dilator pupillae (sympathetically regulated)

  26. Developing Retina Developing Lens

  27. Ventral Root Cranial Nerves Somite Associated

  28. Development • Head somites can be divided into 2 sets. Pre-otic and post-otic

  29. Development • The sklerotomes of the post otic somites formthe floor of the brain case

  30. Development ….and their myotomes develop into muscles of the tongue

  31. Development The myotomes of the pre-otic somites form the muscles that move the eyeballs.

  32. Development Each is supplied by a different cranial nerve:

  33. Development Cranial Nerve III = Occulomotor Nerve

  34. Development Cranial Nerve IV = Trochlear Nerve

  35. Development Cranial Nerve VI = Abducens Nerve

  36. EYEBALL MOVING MUSCLES: • Rectus Muscles • Superior rectus - III • Inferior rectus - III • Lateral rectus - VI • Medial rectus - III • Oblique muscles • Superior oblique - IV • Inferior oblique - III • Lavator palpebrae superioris - III

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