*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

The thyroid gland begins at around the 3rd and 4th weeks of embryonic development as a proliferation of endodermal cells at the foramen cecum of the developing tongue. The gland descends to its final location anterior and inferior to the larynx but is still connected to the foramen cecum via the thyroglossal duct until that is broken down in the 5th week of development. CLINICAL … Continue reading Thyroid gland development

The pharyngeal clefts and pouches are grooves on the ectoderm and endoderm respectively that seperate the pharyngeal arches. Some of them develop into structures of the head and neck including glands and tubes. Derivatives of pharyngeal clefts On the outside, the 1st cleft forms the external auditory meatus. Since the 2nd overgrows the 3rd and 4th arches, the 2nd, 3rd and 4th clefts become buried … Continue reading Pharyngeal clefts & pouches