Brainstem Flashcards
What sulci do the following nerves exit from?
- 12
- 11
- 10
- 9
- 12: Anterior lateral sulcus
- 11: Posterolateral sulcus
- 10: Posterolateral sulcus
- 9: Posterolateral sulcus
What is the surface marking which represents the surface marking of the spinal nucleus of the trigeminal nerve?
Tuberculum cinereum
BETWEEN THE CUNEATE TUBERCLE AND THE POSTEROLATERAL SULCUS
What are the structures on the floor of the 4th ventricle?
Hypoglossal trigone
Vagal trigone
Facial colliculus
Explain how hemiplegia cruciata works.
This happens with injuries to the lower medulla. One side with crossed upper extremity fibers is injured along with uncrossed lower extremity fibers!
Also note that the UE and neck fibers cross first AND ARE MORE SUPERFICIALLY LOCATED.
Which fibers project to nucleus cuenatus and which ones go to nucleus gracilis?
C: C1 to T7
G: Below T7
How can one have bilateral upper extremity paresis form a medullary lesion?
A lesion that hits the area where both UE fibers decussate.
The spinal trigeminal nuclei
- Descends up to what spinal level?
- Continuous with what nuclei rostrally and caudally
C3
Rostral main sensory nucleus of the trigeminal nerve in the pons
Substantia gelatinosa of the spinal cord
What are the 3 divisions of the spinal trigeminal nucleus and what are their functions
- Caudal nucleus: Pain and temp on the ipsilateral face
- Nucleus interpolaris: Dental pain
- Nucleus oralis: Tactile sensation from the oral mucosa
T or F: The perioral region projects to a more rostral portion of the spinal trigeminal nuclei while the region anterior to the mandible projects to a more inferior division.
T
What nucleus of the thalamus does the trigeminal thalamic tract carrying CN 5, 7, 9, 10 fibers synapse on?
VPM
Which fibers in the spinothalamic tract subserve temperature? More dorsal or more ventral?
Dorsal fibers
Ventral fibers subserve pain more
What fibers come from the nucleus gracilis and cuneatus to form the medial lemnisci?
Internal arcuate fibers
What are the functions of the accessory cuneate nucleus located dorsolaterally to the cuneate nucleus?
- Unconscious proprioreception: fibers from the dorsal spinocerebellar system
- Autonomic functions: Fibers from the vasopressor and cardioaccelaratory areas of the posterior hypothalamus, CN 9 and CN 10
What is the area posterma formed from?
Astroblast like cells, arterioles, sinusoids and apoloar and unipolar neurons
induces vomiting
What are the areas of the brain without BBB?
- Area posterma
- Subcommisural organ
- Pineal gland
- Subfornical corgan
- Organum vasculosum
- Neurohypophysis
- Median eminence
What are the 3 peduncles that connect the brainstem and the cerebellum?
- brachium conjunctivum to midbrain
- brachium pontis to pons
- restiform body to medulla
What are involved in the Jackson and Tapia syndromes?
Jackson: 9 10 11 12 and hemiparesis
Tapia: 9, 10 12
What is also known as Galen’s nerve?
Recurrent laryngeal nerve
Name the CN 10 nuclei and their functions:
EFFERENT
- Dorsal motor nucleus of Vagus: Preganglionic parasympathetic responsible for
- Nucleus ambiguus: ventral motor nucleus of vagus for the muscles of the pharynx and larynx
AFFERENT
- Nucleus of the spinal tract of CN 5 receiving somatic afferent fibers from the external ear, external auditory canal, external surface of the tympanic membrane
- Nucleus solitarius: Taste from the epiglottis (rostral) and general visceral (caudal) afferent from the pharynx and larynx, trachea and esophagus– also receives taste from 7 and 9
Name the CN 9 nuclei and their functions:
- Nucleus ambiguus: motor to the stylopharyngeus msucle
- Inferior salivatory nucleus for the parotid gland
- Nucleus of the spinal tract of CN 5 for the retroauricular region
- Nucleus solitarius: taste from the posterior 1/3 of the tongue and general visceral afferent from the posterior 1/3 of tongue and tonsils and eustachian tube
How does the CN9 contribute to the regulation of BP and HR?
Receives the carotid sinus nerve which innervates the carotid body (chemoreceptor) and carotid sinus (baroreceptor)– based on these inputs it can send volleys of signals to the dorsal vagal nucleus to effect HR and BP changes.
Nucleus is solitarius
Which vestibular nuclei are in the medulla?
Medical and inferior
Where do taste fibers synapse at the thalamus?
Ventroposteromedial
Lesions where cause Ondine’s curse?
Failure of automatic respiratory function asleep
Nucleus ambiguus and the adjacent reticular formation
Where are the inspiratory and expiratory neurons?
Inspiratory neurons are driven by nucleus solitarius
N ambiguus and n retroambiguus contains both
What is the effector site for neurogenic pulmonary edema?
N. Solitarius
Where are the
dorsal swallowing group and dorsal respiratory group
ventral SG and ventral RG
Located?
Dorsal N ambiguus
Ventral N solitarius
What are the inputs to the vomiting center in the nucleus solitarius?
Area postrema
Tast: CN 7, 9, 10
Autonomics
Vestibular system
What NT is secreted by:
- CN 12 nucleus
- Dorsal motor nucleus of vagus
- Nucleus ambiguus
- Reticular formation
- Raphe nucleus
- CN 12 nucleus Ach
- Dorsal motor nucleus of vagus Ach
- Nucleus ambiguus Ach
- Reticular formation: NE, Enkephalin
- Raphe nucleus Serotonin, Enkephalin
What are the sxs of
- Dejerine anterior bulbar syndrome/ Medial medullary syndrome
- Wallenburg
- Ipsilateral 12, contalateral hemiparesis with sparing of the face, contralateral loss of position sense
- Contralateral loss of pain and temp on the body but ipsilateral on the face
Ipsilateral horner’s syndrome
N ambiguus: dysphagia and dysarthria
Vestibular nuc: Dizziness, vomiting
Inferior cerebellar peduncle: ataxia
Hiccups
Olivoverebellar fibers: Ocular lateropulsion
saccadic eye movements with hypermetria toward the side of the lesion and hypometria away from it
What areas are affected with the babinski nageotte syndrome?
Combined lateral and medial medullary syndrome
What are affected:
- Vernet
- Collet Sicard
- Villaret
- Vernet: 9 10 11
- Collet Sicard: 9 10 11 12
- Villaret: 9 10 11 12 sympathetic
What is the largest group of fibers in the basis pontis?
The corticopontocerebellar fibers responsible for rapid correction of movements
What percentage of the tegementum needs to be lost before loss of consciousness occurs?
25%
Going from medial to lateral what is the arrangement of the sensory lemniscal system?
Medial L
Spinal L
Trigeminal L
Lateral L for hearing
What NT is released from the locus coeruleus?
Where is it found?
Roles?
Norepinephrine
Generalized cell loss in PD
Rostral part loss in AD
Location: Rostral pons and caudal midbrain
Roles: Regulation of respiration and REM sleep
Dorsal cochlear nucleus? or ventral?
Fibers from the basal turns of cochlea for high frequency sounds
Fibers from the apical turns for low frequency sounds
Dorsal
Ventral
Re: Auditory pathway:
The ventral acoustic striae is also known as?
Where does it project?
Which striae is the largest?
Trapezoid body
Projects to the superior olivary complex– functions to detect interaural sound intensity and provide feedback control of cochlear mechanism and process cochlear signals via the ascending auditory pathway
Ventral is largest
From the lateral lemnisci where do auditory fibers go?
Identify the 4 decussations.
Inferior colliculi, Medial geniculate body, Transverse Heschl’s gyri B41 and 42
- Pontine tegmentum acoustic striae
- Olivocochlear bundle efferent bundle of rasmussen in the pontine tegmentum as well– protective against loud sound!
- Nuclei of the lateral lemniscus– connected by Probst’s commissure passing through the bachium conjunctivum
- Midbrain level between two IC
What is the Olivocochlear bundle for?
Feedback inhibition to the organ of Corti– protective against loud sound and for selective auditory attention
Match the following:
- Deiter’s Nucleus
- Schwalbe’s nucleus
- Spinal nucleus
- Bechterew’s nucleus
Superior
Inferior
Lateral
Medial
- Deiter’s Nucleus Lateral
- Schwalbe’s nucleus Medial
- Spinal nucleus Inferior
- Bechterew’s nucleus Superior
Match the following:
- Deiter’s Nucleus
- Schwalbe’s nucleus
- Spinal nucleus
- Bechterew’s nucleus
Flexor motor neurons
Extensor motor neurons
Connects with doral motor nucleus of the vagus to effect autonomic functions associated with vestibular stimulation
Flexor motor neurons Schwalbe
Extensor motor neurons Deiter
Connects with doral motor nucleus of the vagus to effect autonomic functions associated with vestibular stimulation Schwalbe
Placing warm water in the right ear will result in what kind of nystagmus.
Slow to the left
Fast to the right
COWS Warm Same (After fast component)
Crawling away from the heat!
In INO why is there nystagmus in the contralateral eye?
Convergence mechanism– driving the contralateral eye to be in the same position as the ipsilateral eye to avoid diplopia
Without the MLF there is no inhibition of adduction of the contralateral eye
What are the 2 types of fibers carried by CN 7?
What are the primary ganglia of both?
What cranial nuclei do they go to?
External ear sensation goes to the spinal trigeminal ganglion and taste from anterior 2/3 of the tongue goes to the gustatory part of nucleus solitarius
Geniculate ganglion
The peripheral lateral root of the facial nerve subserving taste is called the?
Nervus intermedius or the Wrisberg’s nerve– MORE PROXIMAL to chorda tympani nerve
What explains the central facial palsy in those with pontine tegmenutm and medullary infarcts?
There is an aberrant bundle headed for the CN7 nuclei that separates from the corticobulbar fibers in the caudal basis pontis, heads to the facial nucleus in the tegmentum but forms a loop down into the medulla oblongata before reaching the facial colliculus
What glands are innervated by CN 7?
Greater superficial petrosal nerve»_space; Pterygopalatine ganglion»_space; Lacrimal gland
Chorda tympani and lingual nerves»_space; submandibular ganglion»_space; Submandibular gland and sublingual gland
Besides the facial muscles what other muscles are innervated by CN 7?
What muscles are innervated by CN 5 besides muscles of mastication?
7: Stapedius
Stylohyoid
Posterior belly of the digastric
5: Tensory tympani
Tensor palati
Mylohyoid
ANTERIOR belly of the digastric
Distal to the geniculate gagnlion what CN7 function would still be intact if transection were to occur?
Lacrimation
What are the two connections of the PPRF?
Caudal to the abducens nucleus for ipsilateral gaze
Rostral to the rostral interstitial nucleus of the MLF
Identify which nuclei of cranial nerve 5 subserve these sensations?
- Mechanisms that control the force of the bite
- Proprioreceptive inputs: pressue and kinesthesia from teeth, mastication stretch receptors etc
- oral mucosa tactile sensibility
- dental pain
- paint and temp sensation of the face
- discriminative touch
- Mechanisms that control the force of the bite: Mesencephalic
- Proprioreceptive inputs: pressue and kinesthesia from teeth, mastication stretch receptors etc: Mesencephalic
- oral mucosa tactile sensibility: Spinal rostral
- dental pain: Spinal interpolaris
- paint and temp sensation of the face: Spinal caudalis
- discriminative touch: Main sensory
The internal auditory artery that arises from the AICA or the basilar a supplies what?
Which part of the pons is supplies by the AICA?
Auditory, vestibular and facial nerves
Lateral part of the lower 2/3– the upper pons is mostly basilar artery with a little SCA
What are the basal pontine syndromes:
- Ipsilateral facial paralysis, ipsilateral abduction paralysis, contralateral hemiparesis
- Variable Ipsilateral facial, unilateral deafness, contralateral hemiparesis
- Ipsilateral facial spasm with contralateral hemiparesis
- Ipsilateral facial paralysis, ipsilateral abduction paralysis, contralateral hemiparesis: Millard gubler
- Variable Ipsilateral facial, unilateral deafness, contralateral hemiparesis: Gelle syndrome
- Ipsilateral facial spasm with contralateral hemiparesis: Brissaud-sicard syndrome
What is type 2 INO?
cavernous sinus thrombosis– CN6 with ICA involvement
What are the tegemental pontine syndromes:
- Ipsilateral facial paralysis, Gaze palsy, Contralateral paralysis
- ipsilateral INO, contralateral hemisensory loss, ipsilateral ataxia
- Ipsilateral facial paralysis, Gaze palsy, Contralateral paralysis: Foville syndrome
- ipsilateral INO, contralateral hemisensory loss, ipsilateral ataxia: Raymond-cestan-chenais
Ocular bobbing are seen in what brainstem lesions?
Pontine
What are the components of the basis pedunculi of the midbrain?
Substantia nigra and the cerebreal peduncles
What are the 3 nuclei of the inferior colliculus?
- Central nucleus: major relay nucleus
- Pericentral nucleus for directing to auditory attention
- External nucleus: Acousticomotor reflexes
Re: Midbrain
Connections of the IC and SC serves to?
Turn neck and eyes in response to sound
What part of the midbrain is the brachium conjunctivum located in?
How about the red nucleus?
The inferior colliculus level
Superior colliculus
They both occupy the central tegmentum
A trochlear lesion will result in a head tilt going towards the?
Tilt away from the side with the lesion
Diplopia is worse looking contralaterally and downward
What NT is secreted by the dorsal raphe nuclei in the midbrain?
Serotonin
Starting from the lateral portion, what composes the cerebral peduncle?
Parieto-occipito-temporo pontine projections
Corticospinal and corticobulbar
Frontopontine fibers
What 2 disease entities have loss of both the pigmented and non-pigmented neurons of the SN?
Huntington disease and PD dementia
In PD there is a central loss pattern of pigmented neurons ONLY!
What are the parts of the Substantia nigra and their contents?
Pars compacta: Melanin
Pars reticulata: Iron
What are the three divisions of the mesencephalic dopaminergic system?
Mesostriatal: Putamen, caudat, GP (PD with hypoactivity and HD hyperactivity)
Mesoallocortica/limbic: Amygdala, olfactory tubercle (Cognition with hypoactivity, Pyschosis with hyperactivity)
Mesoneocortical: Frontal, temporal, parietal and occipital cortices (Cognition, photosensitive epilepsy if with hypoactivity)
What are the components of the Sylvian aqueduct syndrome AKA Koerber Salus Elschnig syndrome?
Parinaud
- Vertical gaze palsy
- Anisocoria/ Light near dissociation
- Conversion retraction nystagmus
- Lid retraction (Collier’s sign)
- Imparied convegence
What part of the brainstem does the lateral lemniscus terrminate in?
Caudal midbrain at the IC!
Palatal myoclonus occurs with a lesion in?
Mollaret triangle: Red nucleus in the midbrain, Dentate nucleus in the cerebellum OF THE OPPOSITE SIDE, Inferior olive in the medulla
Rubrospinal tract facilitates what motor neurons?
Facilitates flexor motor neurons and inhibits extensor motor neurons
A lesion of the red nucleus of the MB results in tremor where?
Contralateral side
What projects to the CN3 nuclei for
- Upward gaze
- Downward gaze
- Pupilloconstriction
- Upward gaze: Interstitial nucleus of Cajal
- Downward gaze: RiMLF
BUT IF BILATERAL DAMAGE TO RIMLF BOTH UPWARD AND DOWNWARD GAZE ARE AFFECTED! Also– Cajal lesions also result in ABOLITION OF THE OCULOCEPHALIC RESPONSE
1 and 2 project to the motor cell column (compare with #3 below)
- Pupilloconstriction: Pretectal olivary nucleus– projects to the visceral cell column where Edinger Westphal nucleus is
What are the only nuclei of CN3 that are unpaired?
Levator and Edinger Westphal
What are the components of CN3 after they bifurcate anterior to the cavernous sinus?
Superior: Levator and Superior rectus
Inferior: Medial rectus, inferior oblique, iris sphincter
Injury of what nucleus in the midbrain results in bilateral eyelid retraction?
Nuclei of the posterior commissure
What is an extension of the hypothalamus in the midbrain and serves to connect it with the periaqueductal gray matter and the autonomic nuceli in the pons and medulla?
Dorsal longitudinal fasciculus
Contains autonomic fibers
What are the roles of the periaqueductal gray matter in the midbrain?
Modulate analgesic mechanisms– and essentially all autonomic functions!
Escape behaviour, micturition, erection
What are the effector muscles of the light reflex?
Sphincter pupillae and ciliaris muscle
What is an Adie’s pupil?
Widely dilated pupil with a sluggish, prolonged pupillary contraction in reaction to light– when constricted takes along time to dilate as well!
Pathology is within the ciliary ganglion!
What are the 3 components of the accommodation reflex?
Convex lens
Contraction of both medial recti
Pupillary constriction
Describe the argyll robertson pupil.
Constricts to accommodation but not to light
Describe the posterior pathway for saccadic movements
Originates in the pariteo occipital cortex unto the SC then to the brainstem centers for REFLEX SACCADIC MOVEMENTS
VS anterior pathway from FEF
What is the main midbrain blood supply especially at the superior colliculus level?
PCA
Describe the midbrain syndromes
- Weber
- Claude
- Benedict
- Nothnagel
- Plus minus lid syndrome
- Walleyed syndrome
- Weber: Basis– Ipsilateral CN3, contralateral hemiparesis
- Claude: Tegmentum– Ipsilateral CN3, contralateral tremor
- Benedict: Basis with tegmentum: Combined!
- Nothnagel: Tectum/ quadrigeminal plate– Bilateral asymmetric CN3 palsy, contralateral or ipsilateral ataxia, vertical gaze palsy!
- Plus minus lid syndrome: Posterior commissure– Ptosis in one and retraction in the other
- Walleyed syndrome: Bilateral INO– exotropic eyes looking outwards UNABLE TO ADDUCT BILATERALLY!
TREMOR IS RUBRAL TREMOR: Rest tremor from involvement of the SN while there is also a kinetic tremor from the red nucleus and cerebellar peduncle involvement
What is seen in peduncular hallucinosis?
Animals! And people– allegedly from midbrain tegmentum damage
