Norden- brainstem Anatomy Flashcards
The nuclei for which CN’s lie in the brainstem?
III-X and XII
Major landmark structures present in the ventral medulla at both rostral and caudal levels?
Pyramids
Where is the pyramidal decussation? (Where 85% of corticospinal axons deccusate)
In the caudal medulla
In medulla, a unilateral lesion to the descending sympathetic axons will cause _?
Ipsilateral horner’s syndrome
Horner’s syndrome symptoms?
Ptosis, miosis, anhydrosis
What part of the medulla do the fasciculus gracilis and fasciculus cuneatus synapse in ?
Caudal medulla
What three sensory components are in the trigeminal nerve ?
- Pain and temperature
- Fine touch, conscious proprioception, vibration
- Unconscious proprioception
When the first order neurons of the semilunar ganglion enter the brainstem (at the level of the pons), what are they called as they descend in the dorsolateral area?
Spinal trigeminal tract
Where does the spinal trigeminal tract synapse to ?
The spinal trigeminal nucleus
Axons from the second order spinal trigeminal nucleus decussate at various levels and ascend as part of the ______, before synapsing onto the medial division of the ventral posterior nucleus (VPM)
Trigeminothalamic tract
A lesion of the spinal tract/ nucleus of V results in?
Loss of pain and temperature in the ipsilateral face.
Above about the midpons, a lesion of the trigeminothalamic tract result in loss of ?
Temperature and pain to the contralateral face.
The cerebellum is connected to the brainstem by which three paired fiber pathways?
Inferior (restiform body)
Middle (brachium pontis)
Superior (brachium conjuctivum)
Peduncles
The inferior cerebellar peduncle is a major feature of the dorsal part of the ____
Rostral medulla
Works to relay unconscious proprioceptive information fromo above C8 to the cerebellum
Accessory cuneate nucleus
What part of the medulla are the olives in ?
Rostral
How do axons from the inferior olive project to the cerebellum?
Through the inferior cerebellar peduncle
This important cranial nerve lies most medial in the dorsal medulla
Hypoglossal nucleus
What muscle of the tongue does the hypoglossal nerve NOT innervate?
Palatoglossus (X)
What is the main function of the genioglossus?
Protrude tongue
Lies in the dorsal medulla, lateral to the hypoglossal nucleus; parasympathetic axons of _ will innervate viscera of the thorax and abdomen
Dorsal motor nucleus of the vagus nerve
Receives gustatory afferents rostrally and visceral afferent fibers caudally
Nucleus of the tractus solitarius
Contains LMN’s for CN IX and X
Nucleus ambiguus
Contains LMN’s that innervate striated muscles of the soft palate, larynx, pharynx, and upper esophagus.
Also preganglionic sympathetic axons involved in control of heart rate
Nucleus ambiguus
Difficulty swallowing
Dysphagia
Difficulty speaking; pt will have hoarse voice
Dysphonia
LMN lesion of nucleus ambiguus will cause what symptoms?
(Will lose CN IX and X) Ipsilateral: Dysphagia Dysphonia Dyspnea Gag reflex gone Uvula deviates towards normal side
Main blood supply to vestibular nuclei?
PICA (these nuclei are in dorsal medulla)
Sensation of the room spinning?
Vertigo
A number of vestibular nuclei lie in the dorsal medulla; in general, lesions of these (PICA) cause?
Vertigo, nausea, vomiting, nystagmus
Ipsilateral lesions up to and including dorsal and ventral cochlear nuclei produce:
Ipsilateral deafness
AICA
What is contained in the pontine tegmentum?
Nucleus of VI and VII
Ascending sensory pathways (medial, spinal, lateral lemnisci)
Two functions of the abducens nucleus (which is located medially in the caudal pons)
Motor to lateral rectus muscle
Conjugate horizontal eye movements
What happens in LMN lesions of CN VI
Ipsilateral loss of abduction —> medial strabismus —> horizontal diplopia (which is worse when looking towards the side of lesion)
CN VI weakness NOT due to lesion in the pons is referred to as
False localizing sign
Vertical gaze center is in the midbrain, horizontal gaze center is in the _____
Pons
What is the facial colliculus?
A bulge in the floor of the 4th ventrical which comes from axons of the motor nucleus of VII which run medially and dorsally over top of the abducens nucleus
Unilateral lesion in the caudal pons involving the motor nucleus of CN VII or its output will produce?
Paralysis of the entire face ipsilateral to lesion
UMN lesion to CN VII will cause?
Contralateral paralysis of the muscles of the lower face, with sparing of muscles of the upper face
Trapezoid body and the superior olivary nucleus are located where?
Caudal pons
Pontine nuclei will project to the contralateral cerebellum via
The middle cerebellar peduncle
The major pathway that allows the cerebral cortex to communicate with the cerebellum
Middle cerebellar peduncle
Unilateral lesions in the chief sensory nucleus of V will result in
Ipsilateral loss of discriminative touch, conscious proprioception, vibration.
Relays unconscious proprioception from muscles of mastication and makes up the afferent component of the jaw jerk reflex.
Mesencephalic tract and nucleus
Reticular formation nucleus that lies in the dorsolateral part of the rostral pontine tegmentum. Provides noradrenergic input to many different brain structures. Functions related to arousal, selective attention, stress response, pain modulation and mood
Nucleus locus coeruleus
Midbrain contains nuclei of CN ? And ?
III and IV
In the tectum of the midbrain. Plays a role in visual reflexes and facilitates sudden, reactive foveation
Superior colliculus
The superior colliculus receives afferents from all of the major sensory pathways. Where does it send efferents?
Cervical spinal cord (to turn head)
Horizontal and vertical gaze centers (to allow for conjugate eye movements)
Pulvinar ( to relay visual info to extrastriate visual cortex )
Which cranial nerve’s LMN is contralateral ?
CN IV
LMN at the trochlear nucleus or initial segment lesion to CN IV causes what?
Contralateral extorsion and elevation of the eye
What is the neurotransmitter in the rostroventral medullary area (part of regulation of pain of lat spinothalamic tract)
Glutamate
What is the neurotransmitter in the nucleus raphus magnus (in the descending reg of pain in the lat spinothalamic tract)
5-HT or Serotonin
What three major nuclei exist in the periaqueductal gray area of the midbrain?
Mesencephalic nucleus of V
Neurons involved in the descending regulation of the transmission of pain by the lateral spinothalamic tract
Vertical gaze center
Connects the cerebellum with the red nucleus.
Decussates in the midbrain at the level of the inferior colliculus
Superior cerebellar peduncle
Axons from the red nucleus, which are involved in the indirect cortico-spinal system, arise from the cortex (area 4) and the cerebellum. They synapse where, primarily?
In the contralateral cervical spinal cord
Isolated unilateral lesions of the red nucleus (are rare) will produce ?
A tremor of the contralateral upper limb (rubral tremor)
Unilateral lesions in the brainstem above the level of the red nucleus
Decorticate (flexion of arm, extension of leg) posturing contralaterally
Decorticate posturing
Flexion of arm, extension of leg
Unilateral lesions below the red nucleus, but above the vestibular nuclei cause what?
Decerebrate posturing contralaterally
What is decerebrate posturing?
Extension of both arm and leg
The two subdivisions of the substantia nigra are?
Pars compacta
Pars reticularis
The main afferent subdivision of the substantia nigra.
Uses glutamate as neurotransmitter
Pars reticularis
Projects neurons to caudate and putamen (deep nuclei) in the hemisphere.
Dopamine used for neurotransmitter
Degeneration of these causes parkinsons
Pars compacta
Unilateral lesion in the middel 1/3 of the crus cerebri causes?
Contralateral spastic paralysis in both arm and leg.
Babinski
Other signs and symptoms from involvement of UMN’s of Cranial nerves
The inability to carry out on command or mimic a voluntary motor movement, despite intact sensory, motor and language. Test by having patient show you how to brush their teeth
Apraxia
What are 3 main inputs to the neostriatum?
Nigro-striatum
Cortico-striatum
Thalamo-striatum
Restiform body
Inferior cerebellar peduncle
Brachium pontis
Middle cerebellar peduncle
Brachium conjuctivum
Superior cerebellar peduncle
The inferior cerebellar peduncle is a major feature of ?
Dorsal part of the ROSTRAL medulla
The accessory cuneate nucleus receives collaterals from?
Fasciculus cuneatus, above C8
The dorsal nucles of the vagus nerve lies ____ to the hypoglossal nucleus
Lateral
Lateral to the dorsal motor nucleus of X is the ?
Nucleus of the tractus solitarius
The vestibular nuclei lie mostly in the __________. A lesion of PICA will affect these.
Symptoms of lesions are vertigo, n/v, nystagmus
Dorsal medulla
Cochlear nuclei blood supply
AICA
Cardio and resp centers in the medulla lie predominantly where?
Caudally
Nucleus of CN VII is located where?
Caudally in the pontine tegmentum
A unilateral lesion in the caudal pons involving the motor nucleus of CN VII will produce what?
An ipsilateral paralysis of the entire face.
The pontine nuclei receive collaterals from many corticospinal axons. Where do these project to?
They project to the contralateral cerebellum via the middle cerebellar peduncle
Where are the pontine nuclei?
In the basal portion of the pons
Facilitates reactive foveation
Superior colliculus
The superior colliculus receives afferents from?
All major sensory pathways
Where is the trochlear nucleus located?
Dorsal midbrain tegmentum. At the level of the inferior colliculus
Nuclear groups in the periaqueductal gray
Mesencephalic nucleus of V
Neurons involved int he descending regulation of the transmission of pain by the lateral spinothalamic tract
Vertical gaze center
Unilateral lesions below the red nucleus but ABOVE the vestibular nuclei will cause?
Contralateral decerebrate posturing
Pars reticularis uses ___ as NT
GABA
Pars compacta uses ____ as NT
Dopamine
This nucleus has axons which travel back along CN VIII and terminate on the hair cells in the organ of corti. This allows for individual pitches (such as in speech) to be disproportionately accentuated for.
Superior olivary nucleus (SON)
