1 - External Anatomy of Brainstem Flashcards
Three Divisions of Brainstem?
Developmental Origin?
Midbrain (Mesencephalon)
Pons (Metencephalon)
Medulla (Myelencephalon)
Cranial Nerves of the Brainstem?
CN III - CN XII
Major Ascending and Descending tracts in the brainstem? (Long Tracts)
Sensory:
Dorsal Column/Medial Lemniscus (ascending)
Anterolateral System (ascending)
Motor:
Motor Cortex - Corticospinal, Corticobulbar, Corticopontine (descending)
Sympathetics (descending)
Reticular Formation
Diffuse core of neurons
Consciousness/Arousal
Vertebrobasilar System
Blood supply to the brainstem and cerebellum
Ventral Surface of Medulla: Vertebral Arteries–>Basilar Artery
Pontomesencephalic Jx: Posterior Cerebral Arteries (x2)
Other branches: AICA/PICA, Superior Cerebellar Artery (SCA), Anterior Spinal Artery
Arterial Supply to Midbrain
Paramedian Branches of the Basilar Artery (Medial)
Posterior Cerebral Artery (Lateral)
Superior Cerebellar Artery (Tectum)
Arterial Supply to Medulla
Anterior Spinal Artery (medial)
Vertebral Arteries
PICA (lateral)
AICA (lateral rostral medulla)
CN III Location
Exit ventral midbrain, between PCA and SCA
Enters Interpeduncular Fossa
MIDBRAIN level
CN IV Location
Only cranial nerve to exit the ventral surface
Fibers that form the nerve cross the midline just before exiting the ventral surface of the midbrain
MIDBRAIN level
Midbrain Level Cranial Nerves?
III
IV
Pons Level Cranial Nerves
CN V
CN VI
CN VII
CN VIII
(5, 6, 7, 8)
What cranial nerves exit at the pontomedullary junction?
6, 7, 8
(medial to lateral)
Medulla Level Cranial Nerves?
CN IX
CN X
CN XI
CN XII
(9, 10, 11, 12)
What nerves exit at the post-olivary sulcus?
9, 10
What nerve exits through the jugular foramen?
XI
What nerve exits the pre-olivary sulcus?
CN XII
Surface Landmarks of the Midbrain:
Sulcus Limitans
Dividing line between motor (medial) and sensory (lateral) nuclei
Surface Landmarks of the Midbrain:
Trochlear Nerve
Border of Midbrain and Pons
Surface Landmarks of the Midbrain:
Striae Medullares
Border of Pons and Medulla
Surface Landmarks of the Midbrain:
Obex
Caudal end of 4th Ventricle
Clinical: Pineal Gland
Function?
Tumors?
Function: Produces Melatonin
Tumors: Adj to Superior Colliculi; tumors can compress Tectum/Cerebral Aquaduct
Surface Landmarks - Internal Structures:
Facial Colliculus
Abducens Nucleus; internal fibers of the facial nerve
Surface Landmarks - Internal Structures:
Hypoglossal and Vagal Trigones, Vestibular Area
Nuclei of same name
Surface Landmarks - Internal Structures:
Gracile and Cuneate Tubercles
Nuclei of the same name
