1.1 The External Features of the Brainstem and Diencephalon Flashcards
What is the Brainstem?
The Part of the Brain which lies just Superior to the Spinal Cord
What are the 3 parts of the Brainstem?
Superior to Inferior
- The Midbrain
- The Pons
- The Medulla (Oblongata)
Which Cranial Cavity does the Brainstem lie in?
The Posterior Cranial Fossa
Embryologically, which 2 Vesicles of the Neural Tube give rise to the Brainstem?
- The Mesencephalon (The Midbrain)
2. The Rhombencephalon (The Hindbrain)
What are the Cavities (of the Ventricular System) which lie within the Brainstem?
- The Cerebral Aqueduct
2. The 4th Ventricle (IV Ventricle)
What is the name of the Groove which separates the Pons from the Medulla?
The Pontomedullary Junction
What Cranial Nerves emerge from the Pontomedullary Junction?
- The Abducens Nerve (Cranial Nerve VI)
- The Facial Nerve (Cranial Nerve VII)
- The Vestibulocochlear Nerve (Cranial Nerve VIII)
Which Foramina do the Cranial Nerves which leave the Pontomedullary Junction, exit the Cranium?
The Abducens Nerve (Cranial Nerve VI) exits via the Superior Orbital Fissure
The Facial Nerve (Cranial Nerve VII) and the Vestibulocochlear Nerve (Cranial Nerve VIII) exit via the Internal Auditory Meatus
Which of the Cranial Nerves which emerges from the Pontomedullary Junction, has the Longest Intracranial Course?
What is the Clinical Significance of this?
The Abducens Nerve (Cranial Nerve VI) is vulnerable to injury by raised Intracranial Pressure, and other mechanical factors. This can cause loss of motor innervation to the Lateral Rectus Muscle of the Eye
What is the function of the Medullary Pyramids?
These are Descending Motor Fibers
What is the function of the Decussation of the Pyramids?
This is where the Descending Motor Fibers cross over to the Contralateral side
What is the function of the Superior Olive?
This contains the Olivary Nuclei associated with the Perception of Sound (This is part of the Pons)
What is the function of the Inferior Olive?
This contains the Olivary Nuclei associated with Cerebellar Motor Learning and Function
Is the Superior part of the Posterior Medulla the “Open” or the “Closed” part?
The Open Part
Is the Inferior part of the Posterior Medulla the “Open” or the “Closed” part?
The Closed Part
What structure does the “Open” part of the Posterior Medulla open onto?
The 4th Ventricle (IV Ventricle)
Through which Foramen does the Medulla pass through to become the Spinal Cord?
The Foramen Magnum
Which Cranial Nerve arises from the Pons?
The Trigeminal Nerve
What connects the Pons to the Cerebellum?
The Cerebellar Peduncles
What kind of fibers make up the Cerebellar Peduncles?
Centripital Fibers (Afferent Sensory fibers from the Pontine Nucleus)
What lies immediately Superior to the Midbrain?
The Diencephalon
What lies immediately Inferior to the Midbrain?
The Pons
What connects the Midbrain to the Cerebrum?
The Cerebral Peduncles
What kind of fibers make up the Cerebral Peduncles?
Motor Fibres (Efferent Motor Fibers destined for Lower Motor Neuron Synapses in the Spinal Cord)
What is the Diencephalon made up of?
- The Thalamus
2. The Hypothalamus
What 2 parts of the Brain does the Diencephalon lie between?
Superiorly - The Fornix
Inferiorly - The Midbrain
Can all of these structures be seen from the surface?
No, only a small part of the Hypothalamus can
What are the surface projections visible on the surface of the Hypothalamus called?
Mamillary Bodies
