Anatomical features of the brain Flashcards
What is the medulla continuous with?
The spinal cord - through a hole in the base of the skull called the foramen magnum
What does the medulla oblongata contain?
- nuclei for cranial nerves 9-12
- respiratory and cardiovascular centre
- ascending and descending neural pathways between brain and spinal cord
- medullary olives - bundles of neurons connected to cerebellum
Why is the medulla important for processing sensory information?
Because several groups of ascending sensory neurons from the spinal cord pass through it
Neurons carrying sensory information about what pass through the medulla?
- texture, grip and joint position
- pain
- temperature
What descending neurons pass through the medulla?
motor neurons from the motor cortex
What do motor neurons form in the medulla?
Two ridges on the anterior surface on the midline known as the ‘pyramids’
What do the medullary olives do?
Communicate with the cerebellum to help control movement
Where is the pons?
The middle section of the brainstem bridging between the two halves of the cerebellum
What does the pons contain?
- axons linking the two halves of the cerebellum
- axons linking cerebral cortex and spinal cord
- cranial nerves 5 and 6
Which important pathways does the pons contain?
- sensory axons travelling up from spinal cord
- sensory axons travelling across and up from cochlear nuclei to auditory cortex to form the lateral lemniscus
- motor axons travelling down to the spinal cord form the pyramidal tract anteriorly
What does the midbrain contain?
- cerebral penduncles anteriorly
- tectum posteriorly
The areas are separated by and imaginary line through the cerebral aqueduct
What are the cerebral penduncles made up of?
- motor axons travelling down from the cortex to the brainstem and spinal cord
- sensory axons travelling up from brainstem and spinal cord to cortex
What is the tectum made up of?
- superior colliculi
- inferior colliculi
What does the superior colliculi do?
coordinates eye and head movements to follow objects in a visual fieldW
What do the inferior colliculi do?
Centres for coordination of auditory reflexes to turn the head towards a sound source
Which important pairs of nuclei are found in the anterior part of the midbrain?
- red nuclei
- substantia niagra
What do the red nuclei do?
Connect the cerebellum with descending motor pathways
What do the substantia niagra do?
Part of the basal nuclei involved in movement control
What is the cerebellum involved in?
- control of motor activity (rate, range, and force)
- learning motor skills
- balance
What do the cerebellar peduncles connect the cerebellum to?
- cerebral hemispheres - superior cerebellar peduncles
- pons - middle cerebellar peduncles
- medulla oblongata - inferior cerebellar peduncles
Which parts of the cerebellum have developed over the course of evolution?
- flocculondular lobe (vestibulocerebellum)
2 spinocerebellum/vermis - cerebrocerebellum
What does the flocculonodular lobe do?
- receives input from the vestibular nuclei in the pons and medulla via the inferior cerebellar peduncles
- sends efferent info back to vestibular nuclei and then to descending motor neurons
- primarily concerned with balance
What is the role of the spinocerebellum?
Influences muscle tone and posture through spinal motor nerves
What inputs and outputs are in the spinocerebellum?
- majority of inputs are from neurons carrying proprioceptive info from muscles and joints
- major outputs are the red nucleus in midbrain - muscle contraction and joint control
- input and output mainly via superior cerebellar peduncle
What are the main inputs of the cerebrocerebellum?
- areas of the cerebral cortex involved in planning and execution of movement
- connect to the cerebellum via the pons through the middle cerebellar peduncles
What are the main outpputs of the cerebrocerebellum?
- red nuclei in midbrain
- thalamus -> motor cortex
- most axons exit through the superior cerebellar peduncles
What are the basal ganglia?
System of nuclei located deep in each cerebral hemisphere (corpus striatum) and the midbrain
What makes up the basal ganglia?
- caudate nucleus
- lentiform nucleus
- substantia niagra