CNS Anatomy Brainstem Spinal Cord Lecture 6 Mesencephalon

CNS Anatomy: Brainstem & Spinal Cord Lecture 6

Mesencephalon Surrounds cerebral aqueduct n Tectum l Superior Colliculi - vision l Inferior Colliculi - audition n Tegmentum ~ n

Thalamus Tectum Superior Colliculi Inferior Colliculi

Tegmentum Periaqueductal Gray l analgesia n Reticular Formation – l sleep and arousal l attention n Red Nucleus and Substantia Nigra l motor system n Ventral Tegmental Area (VTA) l reinforcement ~ n

Cross-section of Tegmentum PAG Substantia Nigra Ventral Tegmental Area Dorsal Reticular formation Red Nucleus

Metencephalon Surrounds fourth ventricle n Cerebellum l coordinates movements n Pons l Sleep and arousal l Reticular formation ~ n

Cerebellum Pons

Myelencephalon n n Medulla - “Vital Centers” Reticular formation ~

Thalamus Medulla

Spinal Cord Gray Matter Dorsal White Matter Central Canal Ventral

Dorsal Horns Dorsal Lateral Ventral

Spinal cord Dorsal horn l sensory input l via dorsal root ganglion n Lateral horn - autonomic N. S. n Ventral horn l motor output l via ventral root ~ n

Spinal Cord Tracts Clinically important anatomy l Descending & ascending tracts n Motor 1. corticospinal tract n distal muscles l only descending tract with overt effects ~

Spinal Cord Tracts Sensory 2. Dorsal column-medial lemniscal tract l touch, vibration, & proprioception l axons ascend ipsilaterally l synapse then decussate at medulla 3. Spinothalamic tract (lateral) l pain & temperature l decussate at SC entry level l ascends contralaterally ~ n

Corticospinal tract Medulla Spinothalamic path Dorsal column-medial lemniscal path

Spinal Cord Dorsal columns Dorsal Corticospinal tract Rubrospinal tract Ventral anterolateral columns