Medulla Review: Parts I and II

Upon completion of this module the student should be able to:

Identify the roots of cranial nerves 5-12 on a photograph of the brainstem

Identify the roots of cranial nerve 5-12 on a photograph of the posterior cranial fossa with the brainstem removed

Map the course of the trigeminal nerve in the brainstem including the:

Central processes of the trigeminal nerve

Spinal trigeminal nucleus and tract

Ventral trigeminothalamic tract

Map the location of the branchimeric nuclei (V, VII, IX and X) in the brainstem

Map the location of the following nuclei in the medullary brainstem:

Nucleus cuneatus Nucleus gracilis External (Lateral or accessory) cuneate nucleus Spinal trigeminal nucleus Nucleus ambiguous Inferior olivary nucleus Dorsal motor nucleus of the vagus Solitary nucleus Hypoglossal nucleus and its radiations Facial nucleus and its radiations Abducens nucleus and its radiations Medullary reticular formation Vestibular nuclei (inferior, medial, lateral & superior)

Map the trajectory of the following tracts in the medullary portion of the brainstem:

Fasciculus gracilis and fasciculus cuneatus Internal arcuate fibers and medial lemniscus Corticospinal tract and its decussation Anterolateral system (spinothalamic tract) Dorsal spinocerebellar tract and the inferior cerebellar peduncle Median longitudinal fasciculus Spinal trigeminal tract Central tegmental tract

Use the location and functions of the above listed nuclei and tracts to localize the position of a small vascular infarction in the medullary brainstem, particularly:

Lateral medullary lesions

Medial medullary lesions

Resources:

H. Blumenfeld. Neuroanatomy through Clincial Cases, Sunderland, MA:Sinauer Associates, Inc., 2010.

Chapters 12-14 concern the brainstem and the associated cranial nerves.

Both chapters12 and 14 contain much useful information on the medulla and numerous interesting cases related to medullary lesions.

Although I do not recommend attempting to read all of this material I strongly suggest that you extract the material on the medulla and its cranial nerves.

Strongly suggested readings concerning all regions of the brainstem include:

Surface features of the brainstem – pages 495-498 Sensory and motor organization of the cranial nerves – pages 500-503 Functions and course of the cranial nerves – page 503 Pupils and other ocular autonomic pathways – page 576-579 Supra nuclear control of eye-movements – pages 584-586 Brainstem sections – pages 615-622 Cranial nerve nuclei and related structures – 622-624 Long tracts – pages 624-625 Reticular formation – page 626-627 Reticular formation motor, reflex, and autonomic systems – pages 646-648 Brainstem vascular supply – pages 648-654 Vertebrobasilar vascular disease – pages 654-661

Important “Key Clinical Concepts” include:

12.4 page 518 12.7 page 535 12.8 page 536 14.3 page 654-661

Important Clinical Cases include: Case 12.3 page 542 Case 12.7 page 553 Case 12.8 page 555 Case 14.1 page 661 Case 14.2 page 663 Case 14.9 page 687