Brain stem Cerebellum DLA Flashcards
What are the major events in the development of the brainstem?
• In the neural tube, the alar plate sits dorsal to the sulcus limitans (SL) and is largely somatosensory in function. The basal plate is located ventral to the SL and is largely motor in function.
• Major events occur during maturation of the brainstem.
– The central canal enlarges into the fourth ventricle.
– The cerebellum develops.
– The dorsal portion of the neural tube (alar plate) rotates laterally.
– Consequently, bulbar efferent (motor) structures lie medial to the SL, and the afferent (sensory) structures sit laterally.
How are the creation of cranial nerves dictated?
• Creation of the 4th ventricle shifts the alar plate from dorsal to lateral positions, dictating the nuclear organization of cranial nerves
What are the landmarks oof the dorsal brainstem?
- Midbrain with superior and inferior colliculi (corpora quadrigemina) and cranial nerve IV.
- Pons with superior cerebellar peduncles (normally bridged by the superior medullary velum) and the laterally situated middle cerebellar peduncles and the sulcus limitans, which sits laterally to the facial colliculi and the more rostrally located the medial eminence.
• Rhomboid fossa.
– Rostral (pontine) rhomboid fossa.
– Caudal(medullary)rhomboid fossa.
- Lateral recesses and striae medullares of 4th ventricle (junction of medulla and pons).
- Posterior median sulcus (pontine and medullary).
- Medulla with hypoglossal and vagal trigones, obex, and gracile and cuneate tubercles
What are the anatomical structures of the dorsal brain stem?
• Midbrain
– Superior colliculi
– Inferior colliculi
– CNIV
What are the anatomical structures on the dorsal pons?
Pons – Rostral 4th ventricle – Superior and middle cerebellar peduncles – Facial colliculus
What are the anatomic structures of the dorsal medulla?
Medulla – Inferior cerebellar peduncle – Obex – Central canal – Gracile and cuneate tubercles – Foramen of Magendie – Foramina of Luschka
What are the landmarks of the ventral brainstem?
• Midbrain with peduncles, interpeduncular fossa, and cranial nerve III.
• Pons with basilar groove and ventral aspects of the middle cerebellar peduncles (along with cranial nerves V – VIII).
• Pontomedullary junction (between pons and medulla).
• Medulla with anterior median fissure,
pyramids, preolivary sulcus, and olives (along
with cranial nerves IX – XII)
What are anatomic structures of the ventral midbrain?
• Midbrain
– Crus cerebri
– Interpeduncular fossa
– CN III
What are the anatomic structures of the ventral pons?
Pons – Basilar groove – CNs V – VIII – Cerebellopontine angle
What are the anatomic structures of the ventral medulla?
• Medulla – Anterior median fissure – Pyramids – Olives – CNs IX - XII
What are the landmarks of the lateral brainstem?
• Cerebral peduncle (midbrain)
• Cerebellar peduncles (middle most visible)
• Medulla
– Pyramid
– Olive
– Preolivary sulcus
– Postolivary sulcus
– Cuneate tubercleWhat are the anatomical structures of the lateral midbrain?
Midbrain
– Crus cerebri
– CNIV
What are the anatomical structures of the lateral pons?
Pons
– CNs V, VII, VIII
– Superior and middle cerebellar peduncles
– Cerebellopontine angle
Whaat are the anatomical structures of the lateral medulla?
Medulla – Inferior cerebellar peduncle – Foramen of Magendie – Foramina of Luschka – Pyramid – Olive – CNsIX-XIII
Wwhat re ascending tracts in the brainstem?
Many tracts ascend (travel caudo-rostrally) through the brainstem, typically carrying sensory information derived from spinal or cranial nerves.
– Damage yields sensory losses.
What are the main ascending tracts of the brainstem?
• Dorsal column-medial lemniscal system (with cuneate and gracile fasciculi and nuclei)
– Touch, proprioception, vibration (spinal origin)
• Spinothalamic tract (anterolateral system)
– Pain and temperature (spinal origin)
• Lateral lemniscus
– Hearing (bulbar origin)
What are the descending tracts of the brainstem?
• Many tracts descend (travel rostro-caudally) through the brainstem, typically carrying motor information from the cortex
– Corticobulbar
• Terminate in the brainstem to innervate lower motor
neurons tied to cranial nerves – Corticospinal
• Pass through the brainstem to innervate lower motor neurons tied to spinal nerves
– Damage yields motor deficits (e.g., weakness
Give examples of the main descending tracts of the brain stem
• Corticobulbar
– Many innervate lower motor neurons tied to cranial nerves
• Corticospinal
– Many innervate lower motor neurons tied to spinal nerves
Summarize reticular formation
The reticular formation is a netlike nucleated mass of gray, occupying the core of the brainstem.
• The reticular nuclei support a vast array of diverse functions.
– Eye movements
– Yawning
– Sleeping
What are reticular in the brainstem?
• Net-like distribution of grey matter extending from the spinal gray matter through the brainstem
What do vertebral arteries and posterior spinal arteries?
- The vertebral arteries and related branches supply the brainstem and cerebellum.
- The vertebral arteries supply the ventral medulla, following the pyramids rostrally.
- The posterior spinal arteries emerge laterally, either directly or from the posterior inferior cerebellar artery. These spinal arteries travel dorsally to supply the tubercles and the dorsal columns (eventually exiting the skull through the foramen magnum).
What do anterior spinal arteries and posterior inferior cerebellar arteries?
- The anterior spinal arteries travel medially to unify, thereafter supplying the pyramids and other midline structures before also exiting the skull.
- The posterior inferior cerebellar arteries travel laterally, supplying the medullary cranial nerves en route to the dorsal medulla, inferior cerebellar peduncle, fourth ventricle, and cerebellar vermis and hemisphere
How are the basilar artery formed, and what does the anterior inferior cerebellar arteries supply?
- The vertebral arteries unify to form the basilar artery, commonly near the pontomedullary junction (near the roots of cranial nerve VI).
- The anterior inferior cerebellar arteries emerge laterally from the basilar artery, often directly or indirectly (via the labyrinthine artery) supplying cranial nerves VII and VIII and the middle cerebellar peduncle en route to the fourth ventricle and the cerebellar hemisphere
What are the variations of the basilar artery?
• The basilar artery may also emit the labyrinthine artery but invariably emits a succession of long and short transversely oriented pontine arteries that supply the core and lateral aspects of the pons.
