2

• chiari 1 is due to downward displacement of the cerebellar tonsils through foramen magnum appears in adults as headache and cerebellar abnormalits
• chiari 2 is due to downward placement of the cerebellum and the medulla through the foramen magnum. appears early and as stridor apnea dysphagia limb weakness and associated with meningomyelocele
• anencephaly is due to failure of the rostral neuroporeto close leading to open cavalirum and no forebrain and polyhydraminos
• dandy walker is due to agenesis of the cerebellar vermis which leads to widening of the 4 th ventricle and its pertrusion through the posterior fossa. associated with non communicating hydrocephalus and spina bifida
• Syringomyelia is the presence of a fluid filled cyst in the spinal cord. Associated with bud chiari 1. Fibers crossing anterior commissure injured(spinothalamic tract) loss of the pain and temperature sensation in a cape distribution and may progress to lmn due to damarge to anterior motor neurons
• anterior 2/3 of the tongue is derived from the 1st pharyngeal rch
• posterior 1/3 is derived from the 3rd and 4th pharyngeal arches
• anterior 2/3 sensation is from cranial 5 ( trigeminal) and taste via cranial 7
• posterior taste is via cranial 9 and extreme posterior via vagus
• motor innervation via cranial 12 to hyoglossus
• hyoglossuses depresses the tongue and retracts
• Palatoglossal via vagus and it elevates posterior tongue during swallowing
• genioglossuses protrudes tongue
• styloglossuses draws side of tongue upwards to create trough during swallowing