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

Muscles of the pharynx aid the passage food from the mouth into the oesophagus. Excepting stylopharyngeus which is innervated by the glossopharyngeal nerve (CN IX), the rest are innervated via the pharyngeal plexus by the pharyngeal branch of the vagus nerve (CN X). The muscles are divided into inner and outer layers. Outer layer The outer layer comprises three circularly oriented muscles known as the … Continue reading Pharyngeal muscles

The pharynx is a fibromuscular tube from the base of the skull to to the lower border of the cricoid cartilage. It is divided into three parts: Nasopharynx: behind the nasal cavity Oropharynx: behind the oral cavity Laryngopharynx: behind the larynx Innervation The pharyngeal muscles are supplied by the pharyngeal branch of the vagus nerve via the pharyngeal plexus. The accessory nerve contributes to the … Continue reading Pharynx

Waldeyer’s ring consists of four groups of mucosa-associated lymphoid tissue (MALT) at the entrance of the digestive and respiratory tracts. These are the tonsils, namely: pharyngeal (adenoid) tonsil tubal tonsils at the medial end of the Eustachian tube palatine tonsils between palatine arches lingual tonsil on the posterior surface of the tongue PLAT (palatine, lingual, adenoid, tubal) Acronym (Waldeyer’s ring) As lymphoid tissue, the tonsils … Continue reading Tonsils