18.2.2 Brainstem and Cerebellum Neuroanatomy Flashcards
Part of the CNS found posteriorly to the brainstem, in charge of motor learning, coordination and precision of motor functions
Cerebellum
Parts of the cerebellum
- Two hemispheres; left and right
- 3 lobes; anterior, posterior and flocculonodular
Which number represents the cerebellum?
3
Most caudal part of the brain, connecting subcortical structures and spinal cord and overseeing vital functions like the sleep-wake cycle, consciousness, respiratory and heart rates
Brainstem
Parts of the brainstem
- Medulla oblongata
- Pons
- Midbrain
Majority of the cranial nerve nuclei are found where
Brainstem
Most inferior part of the brainstem
Medulla oblongata
Brainstem structure sitting in the posterior cranial fossa
Medulla oblongata
Brainstem structure continuous with the spinal cord
Medulla oblongata
Which structure is the medulla oblongata continuous with above?
Pons
General function of medulla oblongata
Autonomic functions; contains cardiac, respiratory, reflex and vasomotor centres
Which number represents the medulla oblongata?
9
Medulla oblongata
Which part of brainstem: pyramids
Ventral surface of medulla oblongata
Pyramidal tract general function
Voluntary control of muscular movement; descending motor control
Pyramidal tract =
Corticospinal pathway
Pyramids
7
Pyramid
5
Pyramid
Decussation of pyramids
Corticospinal tract carries (i) signals from the (ii) in the brain to the (ii)
(i) Motor
(ii) Primary motor cortex
(iii) Muscles of the trunk and limbs
Pyramidal decussation occurs where
Anterior aspect of the lower medulla oblongata
Proportion of pyramidal fibres decussating in the anterior lower medulla oblongata
75-90%
Pyramidal fibres that cross the pyramidal decussation form which tract
Lateral corticospinal tract
Lateral corticospinal tract provides voluntary motor information to muscles where
Limbs
Pyramidal fibres that remain uncrossed at the pyramidal decussation form which tract
Anterior corticospinal tract
Anterior corticospinal tract provides voluntary motor information to muscles where
Axial muscles of the trunk
At which number does the decussation of the pyramidal tract occur?
9
Lesion of pyramids
Contralateral motor deficit
Major afferents of pyramids
Cerebral cortex and basal ganglia
Which part of brainstem: olive
Anterior surface of medulla oblongata lateral to the pyramids
The pyramid lies ventral to
Olive
Olive
8
Inferior olive
8
Olive
5
Olive
Function of olives
Modulation of motor learning and coordination
Structure sending climbing fibres to the cerebellar cortex
Inferior olive
Which nucleus in the brainstem has major output to the cerebellum?
Inferior olive
Role of medial superior olive
Processing interaural time differences
Olive receives input from where
Spinal cord and cerebellum
Which number represents the pons?
8
Pons
The pons is the middle portion of the brainstem, bridging which two structures
Medulla oblongata and midbrain
Anterior surface of the pons has what appearance and why
Striated; parallel lines created by the corticopontocerebellar fibres running through them
Pons is separated from midbrain by what
Superior pontine sulcus
Pons is separated from the medulla oblongata by which structure
Inferior pontine sulcus
Cerebellum
Embryological origin of the cerebellum
Alar plates of metencephalon
6
Cerebellum
Cerebellar peduncles - general function
- Anchor cerebellum to brainstem
- Provide pathway for neuronal tracts to/from cerebellum
Superior cerebellar peduncles connect to which part of the brainstem
Midbrain
Superior cerebellar peduncles
Middle cerebellar peduncles
Middle cerebellar peduncles connect to which part of brainstem
Pons
Inferior cerebellar peduncle
Inferior cerebellar peduncle
Inferior cerebellar peduncles connect to which part of brainstem
Medulla oblongata
Cerebellar hemispheres are found bilateral to which structure in the cerebellum
Vermis
Vermis of the cerebellum
Colour of the flocculonodular lobe
Purple
What are the functional divisions of the cerebellum?
- Spinal
- Vestibular
- Cortical
Site of the spinal division of the cerebellum
Vermis
Input and function of the spinal division of the cerebellum
Input: Proprioceptive receptors in the muscles and joints of the body via spinocerebellar tracts
Function: Regulation of muscle tone, posture and movement coordination
Site of vestibular division of cerebellum
Near flocculonodular lobe
Input and function of the vestibular division of the cerebellum
Input: Semicircular canals and otolith organs of vestibular system; input about head position and movement
Function: Regulation of balance and eye movements
Site of cortical division of cerebellum
Lateral hemispheres
Input and function of cortical division of cerebellum
Input: Input from cerebral cortex via pontine nuclei
Function: Planning, execution & coordination of voluntary movements, cognitive functions like attention, language and WM
Cerebellar nuclei -
Don’t Eat Greasy Food
Dentate
Emboliform
Globos
Fastigial
7
Fastigial nucleus
Input to fastigial nuclei
Spinocerebellar and labyrinthine efferents from the vermis
Output from fastigial nuclei
- Spinal cord via vestibular nuclei
- Ventral lateral thalamic nucleus
Fastigial nucleus function
Efferent pathway to proximal and trunk muscles for maintenance of balance
Globose nucleus
Emboliform nucleus
Together, the globose and emboli form nuclei form the
Interposed nucleus
Main inputs to interposed nucleus are from
- Cerebellar cortex
- Inferior olive
Main outputs from interposed nucleus
- Red nucleus
- Thalamus
Interposed nucleus function
Coordination of limb movements, especially those requiring fine motor control
2
Midbrain
Which number represents the midbrain?
10
The most superior portion of the brainstem - the midbrain - lies between which two structures
Pons and thalamus
Midbrain is divided into two halves by which structure
Cerebral aqueduct
Anterior half of midbrain
Tegmentum
Posterior half of midbrain
Tectum
Structures of the anterior surface of midbrain
- 2 cerebral peduncles
- Red nucleus
- Optic tracts
- Oculomotor nerve
Each cerebral peduncle contains
- Substantia nigra
- Crus cerebri (corticospinal tracts)
Structure dividing the cerebral peduncles
Interpenduncular fossa, containing the perforating arteries
Swellings on the posterior midbrain
Colliculi
Superior colliculi are relay station for what
Visual reflexes
Inferior colliculi are relay station for what
Auditory pathway
D
Superior colliculus
E
Inferior colliculus
Where are the dorsal column nuclei?
Bottom of medulla oblongata
Dorsal column nuclei receive information related to what
Sensory info related to fine touch, proprioception and vibration from the ipsilateral side of the body
Cuneate nucleus receives sensory information about which areas of the body
Upper limbs and upper trunk
Gracile nucleus receives sensory information about which areas if the body
Lower limbs and lower trunk
Output of dorsal column nuclei travels to where
Thalamus, which then relays to primary somatosensory cortex
Lesion of dorsal column nuclei
Impaired fine touch, proprioception and vibration sense from the ipsilateral side of the body
Lesion of cuneate nucleus
Deficits in fine touch, proprioception and vibration sense from the ipsilateral upper limbs and upper trunk