Lecture 11: Brainstem Nuclei Flashcards
Why is the cerebral peduncle/cerebral crus important?
Because it is part of the pathway of the corticospinal tracts
What nerve exits between the midbrain and the pons?
The Oculomotor Nerve CN III
Where does CN III exit the brainstem?
Between the midbrain and the pons
What is the pons mainly made of?
Ascending and descending axon tracts that connect to the cerebellum
What part of the brainstem is mainly made of ascending and descending axon tracts that connect to the cerebellum?
The pons
What exits laterally on the pons?
The trigeminal nerve V
Where does the trigeminal nerve V exit the brainstem?
Laterally on the pons
What is the function of the basilar groove?
It is the part of the brainstem where the basilar artery sits laterally on the pons
What nerves are found in the pontomedullary angle?
*Abducens nerve VI
*Facial nerve VII
*Vestibulocochlear nerve VIII
In terms of part of the brainstem what pathway runs anteriorly?
The corticospinal tracts
What makes up the pyramids of the brainstem?
The corticospinal tracts
What makes up the pyramids of the brainstem?
The corticospinal tracts
What sits laterally to the pyramids on the brainstem?
The olive (the olivary nucleus or olivary complex)
What nerve exits between the olives and the pyramids?
The hypoglossal nerve CN XII
What nerves are lateral to the olives?
Glossopharyngeal CN IX
Vagus CN X
Spinal Accessory CN XI
What is the pyramidal decussation?
Where the corticospinal tracts crossover in the medulla
Where do the corticospinal tracts crossover?
At the pyramidal decussation in the medulla
Where does the pineal gland sit?
Between the posterior nuclei of the thalamus
What sits between the posterior nuclei of the thalamus?
The pineal gland
What sits posterior on the midbrain?
The inferior and superior colliculi
Where do the inferior and superior colliculi sit?
Posteriorly on the midbrain
What is tectum?
The four superior and inferior colliculi
What is the middle cerebellar peduncle?
The large axon tract that goes from the pons to the cerebellum and vice versa
What are the cerebellar peduncles?
Axon tracts coming and going from the cerebellum
What kind of nucleus is the mesencephalic nucleus?
An afferent nucleus
What is the function of the Mesencephalic nucleus V?
General sensory afferent for proprioception for the muscles of mastication
What nucleus carries general sensory afferent for proprioception for the muscles of mastication?
The mesencephalic nucleus V
What trigeminal nucleus sits at the level of the pons?
Principal/Chief Nucleus V
What is the function of the Principal/Chief Nucleus?
General sensory afferents of CN V and VII for tactile and discriminative touch
What nucleus carries general sensory afferents of CN V and VII for tactile and discriminative touch?
The Principal/Chief Nucleus V
What nerves are the principal/chief nucleus associated with?
V trigeminal
VII facial
What is the function of the spinal trigeminal nucleus?
Pain for any of the trigeminal nerve branches, touch of any of the orifices (cornea, nose, throat, etc)
How is the spinal trigeminal nucleus associated with CN V?
It carries pain and temperature of face and neck and touch of the anterior 2/3 of the tongue and cornea
How is the spinal trigeminal nucleus associated with CN IX?
It carries touch from the pharynx and esophagus and posterior 1/3 of the tongue
How is the spinal trigeminal nucleus associated with CN X?
It carries touch from the pharynx, larynx and esophagus
What nerves are associated with the spinal trigeminal nucleus?
V - Trigeminal
IX - Glossopharyngeal
X - Vagus
What is the function of the Vestibulocochlear nucleus?
- Balance and head position
- Auditory system
What CN is the vestibulocochlear nerve associated with?
CN VIII vestibulocochlear
What are the two parts of the Nucleus of the Solitary Tract?
The Rostral and Caudal part
What is the function of the Rostral part of the Nucleus of the Solitary Tract?
Special Sense
VII taste to anterior 2/3 of tongue
IX taste to post 1/3 of the tongue
Which function is associated with the Rostral part of the nucleus of the solitary tract?
Special sense of taste from VII and IX
What is the function of the Caudal part of the nucleus of the solitary tract?
IX - Baroreceptors and chemoreceptors from the carotid sinus and carotid body
X - General vagus afferents from the entire abdomen
What nucleus is responsible for taste from VII and IX?
The rostral part of the nucleus of the solitary tract
What nucleus is responsible for baro and chemoreceptors in the carotid and vagus afferent from the abdomen?
The caudal part of the nucleus of the solitary tract
What are the nuclei of the Parasympathetic Column?
*Edinger-Westphal Nucleus
*Superior/Inferior Salivary Nuclei
*DMV Nucleus
What is the function of the Edinger-Westphal Nucleus?
III: Preganglionic parasympathetic go here to synapse, then go on the ciliary ganglion, ciliary muscle and sphincter pupillae
What CN is the eddinger westphal nucleus associated with?
CN III - oculomotor
What is the function of the Superior/Inferior Salivary Nuclei?
VII - superior lacrimal gland, submandibular, sublingual salivary glands (submandibular ganglion)
XI - inferior otic ganglion, parotid salivary gland
What CN are the Superior/Inferior Salivary Nuclei associated with?
VII Facial
IX Glossopharyngeal
What is the function of the DMV Nucleus?
X - Parasympathetic efferent for cardiovascular, respiratory and GI
What CN is the DMV Nucleus associated with?
X - Vagus
What are the Somatic Muscle Nuclei?
*Oculomotor Nucleus
*Trochlear Nucleus
*Abducens Nucleus
*Hypoglossal Nucleus
What is the function of the oculomotor nucleus?
III: Levator palpebrae superioris and all extraocular muscles except LR6SO4
What CN is associated with the oculomotor nucleus?
CN III
What is the function of the Trochlear Nuclues?
Control SO4
What CN is associated with the Trochlear nucleus?
IV Trochlear
What is the function of the Abducens Nucleus?
VI Controls LR6
What CN is associated with the Abducens nucleus?
VI Abducens
What is the function of the hypoglossal nucleus?
XII: extrinsic and intrinsic muscles of the tongue
What CN is associated with the hypoglossal nucleus?
XII Hypoglossal
What is the function of the Trigeminal Motor Nucleus?
Motor control of the muscles of mastication and the Tensor Tympani
What CN is the Trigeminal Motor nucleus associated with?
V Trigeminal
What is the function of the facial motor nucleus?
Controls the muscles of facial expression and the stapedius muscle
What CN is the Facial Motor Nucleus associated with?
VII Facial
What is the function of the Nucleus Ambiguus?
IX: Stylopharyngeus (swallowing)
X: Muscles of soft palate, pharynx, larynx esophagus (speech and swallowing)
What CNs is the Nucleus Ambiguus associated with?
IX - Glossopharyngeal
X - Vagus
What is the function of the Spinal Accessory C1-C5?
Travels up foramen magnum goes through jugular foramen and innervates the SCM and trapezius muscle. Controls head and shoulder movement
What CN is the Spinal Accessory associated with?
XI Spinal Accessory
What are the nuclei of the Branchiomotor column?
*Trigeminal motor nucleus
*Facial motor nucleus
*Nucleus ambiguus
*Spinal Accessory
Which CN nuclei are in the midbrain?
III and IV
Which CN nuclei are in the pons?
V, VI, VII, VIII
Which cranial nuclei are in the medulla?
IX, X, XI, XII
What nuclei pass through the caudal medulla?
*Spinal Trigeminal nucleus
*Nucleus of the solitary tract
*Hypoglossal nucleus
*DMVN
*Nucleus Ambiguus
What can be observed in the caudal medulla?
*The pyramids
*The pyramidal decussation of the corticospinal tract
*The dorsal columns and the gracile and cuneate nucleus
*The trigeminal nucleus
What can be observed in the closed medulla?
*Sensory decussation of the dorsal columns (gracile and cuneate tract)
*Gracile and Cuneate nucleus
*Medial lemniscal tract
*Corticospinal tract
What mainly occurs at the Caudal medulla?
Pyramidal Decussation
What mainly occurs at the closed medulla?
Sensory decussation of the dorsal columns
What level of the brainstem does Pyramidal decussation occur?
The Caudal Medulla
What level of the brainstem does the sensory decussation occur?
Closed medulla
What is the squiggly part of the open medulla?
The olivary nucleus
What can be seen in the rostral (open) medulla?
*Inferior olivary nucleus
*The pyramids
*Medial Lemniscal pathway
*Corticospinal tract
*Spinothalamic tract
*Fourth ventricle
*Inferior cerebellar peduncle
What is mainly seen at the open (rostral) medulla?
The inferior olivary nucleus
At what level is the inferior olivary nucleus seen?
The open medulla
What nuclei pass through the closed medulla?
*Spinal Trigeminal nucleus
*Nucleus of the solitary tract
*Hypoglossal nucleus
*DMVN
*Nucleus Ambiguus
What nuclei pass through the open medulla?
*Spinal Trigeminal nucleus
*Nucleus of the solitary tract
*Hypoglossal nucleus
*DMVN
*Nucleus Ambiguus
*Vestibulospinal
What nuclei are at the level of the caudal pons?
*Abducens nuclei
*Facial nuclei
*Trigeminal motor nucleus
What level of the brainstem is the:
*Abducens nuclei
*Facial nuclei
*Trigeminal motor nucleus
The caudal pons
What is the inferior cerebellar peduncle?
Where the dorsal spinocerebellar, and the cuneocerebellar tracts go from the ipsilateral spinal cord to the cerebellum
What level of the brainstem is the inferior cerebellar peduncle found?
At the rostral (open) medulla
What is seen at the level of the caudal pons?
*Fourth ventricle and some cerebellum
*Middle cerebellar peduncle
*Pontine nuclei
*Axon tracts descending (corticospinal)
*Axon tract ascending (medial lemniscal)
What are the different axon tracts seen in the pons?
*Middle cerebellar peduncle - axon tracts running horizontally to the cerebellar lobes
*Axon tracts descending - corticospinal
*Axon tract ascending - medial lemniscal
What is found in the mid-pons?
*Level of the trigeminal nerve
*Middle cerebellar peduncle
*Axon tracts
*Nuclei
What is mainly found at the mid-pons?
The trigeminal nerve
What level of the brainstem is the trigeminal nerve found?
The mid-pons
What is found at the level of the rostral pons?
Ascending and Descending fiber tracts and some nuclei
What lets you know that you are at the level of the midbrain?
Seeing mickey mouse
What is mainly found in the caudal midbrain?
The inferior colliculus and substantia nigra
Where is the inferior colliculus found?
In the caudal midbrain
What is found at the level of the rostral midbrain?
The superior colliculus
Cerebral crus and peduncle
Substantia nigra
Red nucleus
Periaqueductal grey matter
What is the main thing found at the Rostral midbrain?
The superior colliculous
What level of the brainstem is the superior colliculus found?
The Rostral Midbrain
What are the major ascending tracts of the brainstem?
*Dorsal Columns/Media Lemniscal pathway
*Spinothalamic tract
*Trigeminothalamic tract
What are the afferent pathways in the Inferior Cerebellar Peduncle?
*Spinocerebellar tract
*Cuneocerebellar tracts
*Oliviocerebellar tracts
*Vestibulocerebellar tracts
What is the pathway of the spinocerebellar tracts?
They go from the brainstem to the cerebellum
What is the inferior cerebellar peduncle?
Axon tracts going from the brainstem to the cerebellum
What is the purpose of the vestibulocerebellar tract?
Allows us to know the position of the head in space
What are the major descending tracts in the brainstem?
*Corticospinal
*Corticopontine
*Corticobulbar
*Vestibulospinal
*Reticulospinal
*Rubrospinal
Where do the descending tracts of the brainstem go through?
The cerebral peduncle
What is the pathway of the Corticospinal, Corticopontine and corticobulbar descending tracts?
- Neurons in cerebral cortex
- Internal capsule
- Ventral midbrain where they form cerebral peduncles
- Some axons synapse on
a. Neurons in the pontine nuclei (corticopontine)
b. Cranial nerve nuclei (corticobulbar)
c. Some descend to the ventral horn of spinal cord (CST)
Where do the Vestibulospinal and reticulospina tracts project to?
Spinal motor neurons controlling postural (anti-gravity) muscles
What does the Rubrospinal Tract do?
Facilitates unconscious flexion of upper limbs
What level of the brainstem is the Red Nucleus?
The midbrain
What is the red nucleus?
Where the cell bodies for the rubrospinal tract are found which control unconscious flexion
What level of the brainstem is the substantia nigra?
The midbrain
What is the function of the Substantia Nigra?
Houses dopaminergic neurons that project to the striatum (basal ganglia) and is associated with Parkinson’s disease
What is the reticular formation?
Loosely arranged neuron cell bodies intermingled with bundles of axons
What is the overall function of the Reticular Formation?
It receives and integrates input from all regions of the CNS and processes a great deal of neural information
How does the Reticular formation control arousal and conciousness?
*Reticular Activating System (RAS)
*Involved in Sleep (especially REM)
*Biological Clock
What does the reticular formation having the reticulospinal tracts do?
Helps to maintain tone and posture
How is the Reticular Formation involved in autonomic relays?
It houses the interneuron between the tracts
How does the Reticular Formation affect pain?
Pain can be controlled by the reticular formation through the release of opioids
Where does the RF receive signals from?
Every sensory pathway
What are the afferent projections of the RF?
All sensory pathways (general or special sensation)
Cerebral cortex
Cerebellum
Basal ganglia (corpus striatum)
Vestibular nuclei, visual pathway
Thalamus and Hypothalamic nuclei
What are the efferent projections of the RF?
Reticulobulbar and reticulospinal tracts
Descending pathway to sympathetic and parasympathetic outflow of ANS
Cerebellum
Basal ganglia (corpus striatum)
Thalamus and Hypothalamic nuclei
What are the three zones of the RF?
Raphe Nuclei
Medial zone
Lateral zone
What is mainly found in the raphe zone of the RF?
Serotonergic neurons
What does the serotonin released by the raphe do?
Projects to the limbic system and affects sleep. Also projects to the periaqueductal grey (PAG)
What do the serotonin neurons in the PAG do?
Alters pain perception by projecting to the dorsal horn and blocking pain transmission from the spinothalamic tract
What is the main part of the medial zone of the RF?
The reticular activating system
What does the reticular activating system do?
Projects to the thalamus and the cortex to promote arousal and consciousness vis cholinergic neurons
Why is the lateral zone affected by damage?
Because it sits laterally and can be easily suppressed
What does the lateral zone of the Rf do aside from the tracts it sends out?
Controls the cardiorespiratory reflex and receives inputs from chemo and baroreceptors to the NTS to modulate breathing and HR
What can a lesion or tumour to the lateral zone of the RF do?
Lead to unconsciousness or death because this is where the breathing and HR zones are
Where do the reticulospinal tracts come from?
The Medial and Lateral zones of the RF
What do the Reticulospinal tracts do?
Unconsciously act on motor neurons and spinal reflex arcs
Where do reticulospinal tracts receive inputs from?
The basal ganglia, vestibular nuclei, and substantia nigra, somatosensory and motor cortex
What do the Medial zone reticulospinal tracts do?
Control posture and balance vis axial (core) musculature
What do the Lateral Zone Reticulospinal tracts do?
Inhibits limb muscular during sleep
What are the steps in the medial reticulospinal tract?
It starts ipsilateral and excites leg extensors and flexors so it carries info telling the hamstrings to contract before you bend forward which prevents you from falling forward
Which reticulospinal tract is bilateral?
The lateral reticulospinal tract
