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
Lesion of gracile nucleus
Deficits in fine touch, proprioception and vibration sense from ipsilateral lower limbs and lower trunk
Dorsal column nuclei
- Cuneate nucleus
- Gracile nucleus
Pontine nuclei locations
Pons
Pontine nuclei function
Principal relay tract between cerebral cortex and cerebellar cortex
Pontine nuclei relay descending cortical input to where?
Contralateral cerebellar hemisphere
Major afferent of pontine nuclei
Cortex
Effect of lesion to pontine nuclei
Ataxia, impaired coordination
Inferior olivary nuclei location
Medulla oblongata
4 is
Inferior olivary nucleus
Structure highlighted green
Inferior olivary nucleus
Inferior olivary nucleus major output
Cerebellum (via climbing fibres)
Periaqueductal grey location
Midbrain
grey
Structure highlighted in green
Periaqueductal grey
Periaqueductal grey is involved in
Pain modulation, autonomic function and behaviour
Sensory nucleus involved in pain control
Periaqueductal grey
Sensory nucleus involved in vision
Superior colliculus
Sensory nucleus involved in audition
Inferior colliculus
Locus coeruleus
Locus coeruleus is located where
Pons
Locus coeruleus is involved in
Regulation of attention, arousal and stress response
Which noradrenergic nucleus produces arousal of the cortex?
Locus coeruleus
Which brainstem nucleus is the site of most 5-HT producing neurons in the brain?
Nucleus raphe
Principal origin of noradrenergic input to the brain
Locus coeruleus
Which vessel runs along the anterior face of the pons?
Basilar artery
Which blood vessel can be seen running adjacent to the pons?
Basilar artery
The brainstem houses the majority of the cranial nerve nuclei, except which?
Olfactory nerve (CN I)
Optic nerve (CN II)
Efferent cranial nerves emerging from the brainstem do what
Provide motor functions to the structures of the head, neck and internal organs
Afferent cranial nerves emerging from the brainstem do what
Receive sensory information
Pons houses nuclei of which cranial nerves
V-VIII
Medulla oblongata houses nuclei of which cranial nerves
XI-XII
Which cranial nerve nucleus is highlighted in green?
Nucleus of oculomotor nerve
Nucleus of oculomotor nerve - afferent or efferent nucleus?
Efferent (motor)
Oculomotor nucleus:
- Location
- Associated nerve
- Efferent fibre function
- Upper midbrain; level of superior colliculus
- Oculomotor nerve (III)
- Supply superior, medial and inferior rectus, inferior oblique and elevator palpebral superioris muscles
Edinger-Westphal nucleus - afferent or efferent nucleus?
Efferent (motor)
Which cranial nerve nucleus is highlighted in green?
Edinger-Westphal nucleus (accessory nucleus of oculomotor nerve)
Edinger-Westphal nucleus:
- Location
- Associated nerve
- Efferent fibre function
- Upper midbrain; closely related to oculomotor nucleus
- Oculomotor nerve (III)
- Relay in ciliary ganglion to supply sphincter pupillae muscle and ciliates muscle
Edinger-Westphal nucleus neurotransmission
Parasympathetic
Nucleus of trochlear nerve - afferent or efferent nucleus?
Efferent (motor)
Which cranial nerve nucleus is highlighted in green?
Nucleus of the trochlear nerve
Nucleus of the Trochlear nerve:
- Location
- Associated nerve
- Efferent fibre function
- Lower midbrain; level of inferior colliculus
- Trochlear nerve
- Supplies superior oblique muscle
Which cranial nerve nucleus is highlighted in green?
Nucleus of the abducens nerve
Nucleus of abducens nerve - afferent or efferent nucleus?
Efferent (motor)
Nucleus of the abducens nerve:
- Location
- Associated nerve
- Efferent fibre function
- Lower pons, deep to facial colliculus
- Abducens nerve (VI)
- Supplies lateral rectus muscle
Which cranial nerve nucleus is highlighted in green?
Mesencephalic nucleus of the trigeminal nerve
Mesencephalic nucleus of the trigeminal nerve - afferent or efferent nucleus?
Afferent (sensory)
Mesencephalic nucleus of the trigeminal nerve:
- Location
- Associated nerve
- Afferent fibre function
- Extends from the pons to the midbrain
- Trigeminal (V)
- Carry proprioceptive impulses from muscles of mastication, muscles of eyeballs, face, tongue and teeth; site of jaw jerk reflex
Which cranial nerve nucleus is highlighted in green?
Principal sensory nucleus of trigeminal nerve
Principal sensory nucleus of trigeminal nerve - afferent or efferent nucleus?
Afferent (sensory)
Principal sensory nucleus of trigeminal nerve:
- Location
- Associated cranial nerve
- Function of afferent fibres
- Upper pons; lateral part of reticular formation
- Trigeminal (V)
- Mediates proprioceptive impulses, touch, pressure
Which cranial nerve nucleus is highlighted in green?
Spinal nucleus and tract of trigeminal nerve
Spinal nucleus of trigeminal nerve - afferent or efferent nucleus?
Afferent (sensory)
Spinal nucleus of trigeminal nerve:
- Location
- Associated cranial nerve
- Function of afferent fibres
- Extends from pons to medulla and upper two segments of spinal cord where it associated with the substantia gelatinosa
- Trigeminal (V); also receives general somatic sensations from facial, glossopharyngeal and vagus nerves
- Mediation of pain and thermal senses
Which cranial nerve nucleus is highlighted in green?
Motor nucleus of trigeminal nerve
Motor nucleus of trigeminal nerve - afferent of efferent nucleus?
Efferent (motor)
Motor nucleus of trigeminal nerve:
- Location
- Associated cranial nerve
- Function of efferent fibres
- Upper, dorsal pons
- Trigeminal (V)
- Innervates mastication muscles, mylohyoid muscle and tensor palati
Which cranial nerve nucleus is highlighted in green?
Nucleus of the facial nerve
Nucleus of the facial nerve - afferent or efferent nucleus?
Efferent (motor)
Nucleus of the facial nerve:
- Location
- Associated cranial nerve
- Lower pontine tegmentum
- Facial (VII)
Cochlear nucleus is in which part of the brainstem
Medulla
First order relay of auditory information
Cochlear nucleus
Brainstem nucleus involved in central auditory pathway
Cochlear nucleus
Cochlear nucleus is associated with which cranial nerve
Vestibulocochlear (VIII)
Vestibular nucleus receives input from which cranial nerve
Vestibulocochlear (VIII)
Vestibular nucleus receives input from CN VIII, which carries info from where
Semicircular canals
Which cranial nerve nucleus contains maps of the body and visual space?
Vesibular nucleus
Which cranial nerve nucleus is highlighted in green?
Nucleus ambiguus
Nucleus ambiguus - afferent or efferent nucleus?
Efferent (motor)
Nucleus ambiguus:
- Location
- Associated cranial nerves
- Medulla
- Contributes fibres to glossopharyngeal, vagus and accessory nerves (IX, X, XI)
Which cranial nerve nucleus is highlighted in green?
Nucleus solitarius
Nucleus solitarius - afferent or efferent nucleus?
Afferent (sensory)
Nucleus solitarius:
- Location
- Associated cranial nerves
- Function
- Medulla
- Facial, glossopharyngeal and vagus (VII, IX, X)
- Taste, cardiorespiratory functions
Which cranial nerve nucleus is highlighted in green?
Nucleus of the vagal nerve
Nucleus of the vagal nerve - afferent or efferent nucleus?
Efferent (motor)
Nucleus of the vagal nerve:
- Location
- Associated cranial nerve
- Efferent fibres supply where
- Medulla
- Vagus nerve (X)
- Heart, lungs, bronchi, oesophagus, stomach, small intestine, large intestine
Which cranial nerve nucleus is highlighted in green?
Hypoglossal nucleus
Hypoglossal nucleus - afferent or efferent nucleus?
Efferent (motor)
Hypoglossal nucleus:
- Location
- Associated cranial nerve
- Function of efferent fibres
- Upper medulla
- Hypoglossal (XII)
- Motor supply to tongue
Corticospinal tract - origin
Primary motor cortex
Corticospinal tract - leaves origin via
Internal capsule
Corticospinal tract - tract travels in
Lateral funiculus
Corticospinal tract - destination
Motor neurons in the spinal cord (ventral horn of grey matter)
Corticospinal tract - function
Contralateral voluntary movement:
- Lateral = limb muscles
- Anterior = axial muscles of trunk
Corticospinal tract - tract type
Descending motor (mainly contralateral)
Corticospinal tract - lesion effect
Spastic paralysis; loss of motor control, increased muscle tone and stiffness
Corticobulbar tract - origin
Primary motor cortex
Corticobulbar tract - travels via
Internal capsule
Corticobulbar tract - destination
Cranial nerve nuclei (III-XII but only the mandibular branch of V)
Corticobulbar tract - tract type
Descending motor (bilateral)
Corticobulbar tract - function
Movements of muscles in face, tongue and throat
Corticobulbar tract - lesion
Difficulty speaking, swallowing and facial movement
Corticopontine tract - origin
Primary motor cortex
Corticopontine tract - destination
Pons
Corticopontine tract - tract type
Descending motor (ipsilateral)
Corticopontine tract - function
Coordination and regulation of movement, including eye movement and posture control
Corticopontine tract - lesion effects
Ipsilateral ataxia, dysmetria and nystagmus
Dorsal columns - origins
Sensory/proprioceptive receptors in the skin, joints and muscles
Dorsal columns - destination
Medulla oblongata - gracile and cuneate nuclei
Dorsal columns - tract type
Ascending sensory (ipsilateral)
Dorsal columns - function
Fine touch, proprioception and vibration sensations from the body to brain
Dorsal columns - lesion
Ipsilateral loss of proprioception, fine touch and vibration sensations
Internal arcuate lemniscus - origin
Dorsal horn of spinal cord
Internal arcuate lemniscus - destination
Ventral posterior nucleus of thalamus
Internal arcuate lemniscus - tract type
Ascending sensory (contralateral)
Internal arcuate lemniscus - function
Carry information about pain and temperature sensation from the contralateral side of the body to the thalamus
Internal arcuate lemniscus - lesion
Contralateral loss of pain and temperature sensation
Medial lemniscus - origin
Dorsal columns of spinal cord
Medial lemniscus - destination
Ventral posterior nucleus of thalamus
Medial lemniscus - tract type
Ascending sensory (contralateral)
Medial lemniscus - function
Carry information about fine touch, vibration and proprioception from the contralateral side of the body
Medial lemniscus - lesion effects
Deficit in contralateral sense of fine touch, vibration and proprioception sensation
Lateral lemniscus - origin
Cochlear nuclei in brainstem
Lateral lemniscus - destination
Inferior colliculus in midbrain
Lateral lemniscus - tract type
Ascending sensory (contralateral; receives input from opposite ear)
Lateral lemniscus - function
Carry auditory information from cochlea to brain
Lateral lemniscus - lesion
Contralateral loss of hearing and impaired sound localisation
Spinothalamic tract - origin
Dorsal horn of spinal cord
Spinothalamic tract - destination
Thalamus
Spinothalamic tract - tract type
Ascending sensory (contralateral)
Spinothalamic tract - function
Modulation of pain and temperature sensation from the contralateral side of the body to the thalamus
Spinoreticular tract - origin
Dorsal horn of the spinal cord
Spinoreticular tract - destination
Reticular formation of brainstem
Spinoreticular tract - tract type
Ascending sensory (contralateral)
Spinoreticular tract - function
Modulation of pain perception and arousal
Spinomesencephalic tract - origin
Dorsal horn of spinal cord
Spinomesencephalic tract - destination
Midbrain
Spinomesencephalic tract - tract type
Ascending sensory (contralateral)
Spinomesencephalic tract - function
Modulation of pain perception (nociception) and reflexive movement of head and neck
Spinomesencephalic, spinoreticular and spinothalamic tract all form the
Anterolateral column
Which fibres decussate in the spinal cord?
Those of the anterolateral column - spinothalamic, spinoreticular, and spinomesencephalic
Medial longitudinal fasciculus - origin
Brainstem nuclei
Medial longitudinal fasciculus - destination
Eye muscles and vestibular nuclei
Medial longitudinal fasciculus - tract type
Descending motor tract (bilateral)
Medial longitudinal fasciculus - function
Controlling eye movements, especially during head movements, and maintenance of balance; vestibulo-ocular reflex
Medial longitudinal fasciculus - lesion effects
Double vision and difficulty maintaining balance
Spinocerebellar tract - origin
Proprioceptive receptors in the skin, muscles and joints
Spinocerebellar tract - destination
Cerebellum
Spinocerebellar tract - tract type
Ascending sensory (ipsilateral)
Spinocerebellar tract - function
Carries info about muscle and joint position and movement to the cerebellum for coordination and regulation of movement; proprioception
Spinocerebellar tract - lesion
Ataxia or uncoordinated movement
Which is the main tract conveying proprioceptive information from the lower limbs to the cerebellum?
Spinocerebellar
Superior cerebellar peduncle - origin
Deep cerebellar nuclei
Superior cerebellar peduncle - destination
Thalamic nuclei and motor cortex
Superior cerebellar peduncle - tract type
Descending motor
Superior cerebellar peduncle - function
Regulating and coordinating movements and posture
Superior cerebellar peduncle - lesion effects
Ataxia, dysmetria, tremor
Spinal tract of the trigeminal - origin
Sensory receptors in the face and mouth
Spinal tract of the trigeminal - destination
Trigeminal nucleus
Spinal tract of the trigeminal - tract type
Ascending sensory
Spinal tract of the trigeminal - function
Carries sensations of touch, temp and pain from the face and mouth to the brain
Carries sensations of touch, temp and pain from the face and mouth to the brain
Afferent (sensory)