The nervous system can be damaged in situations such as nerve damage or brain trauma. Neuroregeneration is only successful in peripheral nervous system (PNS) but not central nervous system (CNS) injuries. PNS repair The PNS is often damaged when nerves are cut or crushed (e.g. limb injuries). The recovery process is as follows: The axon distal to the damage (and associated myelin) degenerates in a … Continue reading Nervous system damage & repair
The nervous system begins as a midline thickening of ectoderm dorsal to the notochord to form a neural plate. The neural plate invaginates, then folds into a neural tube in a process known as neurulation. Problems in this process give rise to neural tube defects such as spina bifida. Nervous system patterning CNS patterning Pattering of the neural tube occurs in three dimensions to create … Continue reading Nervous system development
*For more about the circle of Willis and blood supply to the brain, please see intracranial blood supply All arterial supply to the head and neck occurs via the common carotid and vertebral arteries. Common carotid artery The right common carotid artery branches from brachiocephalic artery (a branch of the aorta) while the left common carotid artery branches directly from the aorta. Each travel upwards … Continue reading Head & neck blood supply
The skull contains and protects the brain plus special organs such as the ears and the eyes. It is can be split into the cranium (neurocranium/braincase) and facial skeleton (vicerocranium). The cranium creates a cranial cavity that houses the brain. The base of the cranium, the skull base (cranial base/floor) contains many foramina and canals through which pass arteries, veins, and nerves. Informally, “cranium” can … Continue reading Skull
Neurogenic placodes are bilateral patches of thickened neurogenic surface ectoderm that give rise to neurons and other structures in the sensory nervous system. In the cranium, this includes all peripheral ‘special sensory’ neurons (CN I, VIII), some somatosensory neurons in the trigeminal ganglion (CN V) and all viscerosensory neurons (inferior ganglia of CN VII, IX and X). Besides the olfactory receptor neuron cell bodies that … Continue reading Cranial neurogenic placodes
MedMule 