Descending Pathways: Neuroanatomy | Medical Science Optional Notes for UPSC PDF Download

Descending Tracts

• Routes through which motor signals travel from the brain to lower motor neurons
• Categorized into pyramidal and extrapyramidal tracts

Extrapyramidal tracts

Pyramidal vs Extrapyramidal tracts

Circle of Willis

• Circulus arteriosus 
• Interpeduncular fossa

Clinical Significance

• Trajectory and distribution of the Trochlear nerve
• Trochlear nucleus
• Clinical significance

• It is the cranial nerve with the fewest axons.
• It possesses the longest intracranial length.
• It uniquely emerges from the dorsal (rear) aspect of the brainstem.
• It provides innervation to the superior oblique muscle, located contralaterally to its nucleus.

Ventricles of Brain - Repeats

• Describe the ventricles of brain. Add a note on the circulation of CSF. Mention the usual site of collection of CSF and state the anatomical reason for selecting this site. (2010) 
• Describe the structures forming floor of fourth ventricle of brain. (2013) 

Cranial Nerves - Repeats

• Describe functional components orgin course and distribution of third cranial nerve (2004). 
• Give an outline of anatomy of facial nerve mentioning its clinical significance (2007). 
• Explain the orgin and course of Facial Nerve. Describe its functional components and distribution. What is Bell's palsy and give the anatomical reasons for the presenting signs? (2010).  
• Tabulate the extrinsic and intrinsic muscles of eyeball along with their nerve supply and action(s).  (2012) 
• Enumerate the branches of facial nerve and write a brief note on Bell's palsy. (2014)
• Discuss the Functional components, Nucleus, Course and distribution of 4th cranial nerve. ADD a note on its clinical significance. (2018)