Question

11. compare the early embryonic spinal cord to the full developed sponal cord

12. ourline the divisions of the brain and brain stem and the major structures located in each region.

14. in general, describe rhe formation of the PNS, differentiating cranial and sensory nerves as well as para sympathetic and sympathetic.

16 discuss the strutures derives from pharyngeal arches, puches and/or clefts

17. list structures derives from aortic arch 1-6.

Answer 1

16.Below is a table shows the derivatives of the branchial pouches: Arch Derivatives 1st Eustachian tube and middle ear cavity 2nd Lining of the palatine tonsils 3rd Dorsal – Inferior parathyroid glands Ventral – Thymus 4th Dorsal – Superior parathyroid glands Ventral – Ultimobranchial body (C cells) 17.The first and second arches disappear early. A remnant of the 1st arch forms part of the maxillary artery, a branch of the external carotid artery. The ventral end of the second develops into the ascending pharyngeal artery, and its dorsal end gives origin to the stapedial artery.  The infraorbital and mandibular branches arise from a common stem, the terminal part of which anastomoses with the external carotid artery. Arch 3 The third aortic arch constitutes the commencement of the internal carotid artery, and is therefore named the carotid arch. It contributes to the common carotid artery and the proximal portion of the internal carotid artery. Arch 4 The fourth right arch forms the right subclavian as far as the origin of its internal mammary branch. The fourth left arch forms the arch of the aorta between the origin of the left carotid artery and the terminus of the ductus arteriosus.the fourth arches called systemic arch Arch 5 The fifth arch either never forms or forms incompletely and then regresses. Arch 6Edit The proximal part of the sixth right archpersists as the proximal part of the right pulmonary artery while the distal section degenerates; The sixth left arch gives off the left pulmonary artery and forms the ductus arteriosus. 11.Stages of Embryonic Development -
Neural tube	Primary vesicle stage	Secondary vesicle stage	Adult structures	Ventricles
Anterior neural tube	Prosencephalon	Telencephalon	Cerebrum	Lateral ventricles
Anterior neural tube	Prosencephalon	Diencephalon	Diencephalon	Third ventricle
Anterior neural tube	Mesencephalon	Mesencephalon	Midbrain	Cerebral aqueduct
Anterior neural tube	Rhombencephalon	Metencephalon	Pons cerebellum	Fourth ventricle
Anterior neural tube	Rhombencephalon	Myelencephalon	Medulla	Fourth ventricle
Posterior neural tube			Spinal cord	Central canal