Introduction to the Brainstem Flashcards
Mesencephalon
Midbrain
Metencephalon
Pons
Myelencephalon
Medulla
What are the 4 main components of the brain stem?
- Cranial nerve nuclei and related structures
- Long tracts
- Cerebellar circuitry
- Reticular formation and related structures
What are the 3 main divisions of the brainstem?
Midbrain, pons, and medulla
What does the tegmentum do?
Forms a thick covering over the bases of the cerebral penduncles, basal pons, and pyramids
What important structures are contained within the tegmentum?
- Reticular formation
- Cranial nerve nuclei
- Most ascending and descending tracts
What is the only cranial nerve that comes off posterior side of the brainstem?
Trochlear
What are 2 examples of sensory long tracts?
- Posterior column-medial lemniscus pathway
2. Anterolateral pathway
What sensory info does the Posterior column-medial lemniscus pathway provide?
Tactile proprioception
What sensory info does the Anterolateral pathway provide?
Pain, temperature, crude touch
What is an example of a motor long tract?
Corticospinal pathway (Pyramidal tract)
What sensory info does the Spinothalamic tract provide?
Pain and temperature from head
What sensory info does the Medial lemniscus pathway provide?
Tactile and proprioceptive info from head
What sensory info does the Dorsal trigeminal tract provide?
Sensory info from the oral cavity
Describe the Inferior Olivary Nucleus.
Start of climbing fibers; aids cerebellum in coordination of movement
Pontine nuclei give rise to axons that travel into the cerebellum via the what?
Middle cerebellar peduncle
Input to the cerebellum from the inferior olivary nuclei and spinal cord travel through what?
Inferior cerebellar peduncle
Output from the cerebellum travels in the what?
Superior cerebellar peduncles
What is the function of the Edinger-Westphal nuclei?
Visceromotor via occulomotor nerve to pupillary sphincter and ciliary muscle
What is the function of the occulomotor nerve?
Motor to all eye muscles, except lateral rectus and superior oblique
What is the function of the trochlear nerve?
Motor to superior oblique
What is the function of the trigeminal nerve?
Motor to muscles of mastication
What is the function of the abducens nerve?
Motor to lateral rectus
What is the function of the facial nerve?
Motor to muscle of facial expression
What is the functions of the salivatory nuclei?
Visceromotor via facial and glossopharyngeal nerves to salivary glands
What is the function of the dorsal motor nuclei?
Visceromotor via vagus to thorax and abdomen
What is the function of the nucleus ambiguus?
Lower motor neurons to pharynx/larynx, visceromotor to heart
What is the function of the accessory nerve?
Motor to sternocleidomastoid and trapezius
What is the function of the mesencephalic nuclei?
Mostly cell bodies of muscle spindle fibers from head
What is the function of the trigeminal main accessory nuclei?
Touch, proprioception from head
What is the function of the cochlear nuclei?
Auditory input
What is the function of the vestibular nuclei?
Input from vestibular apparatus
What is the function of the nucleus of the solitary tract?
Taste and visceral afferent input from facial, glossopharyngeal, and vagus nerves
What is the function of the spinal trigeminal nuclei?
Pain, temperature, crude touch from the head
The pathway of the vestibulo-ocular reflex is the response to what?
Rotation to the left
Describe the vestibule-ocular reflex.
Excitation of the left horizontal semicircular duct causes increased contraction of the right lateral rectus and left medial rectus by way of excitatory interneurons in the left vestibular nuclei. Simultaneously, motor neurons for the left lateral rectus and right medial rectus are inhibited by way of inhibitory interneurons.
What is the reticular formation comprised of?
Numerous relatively small and diverse nuclei scattered throughout the tegmentum
What does the various nuclei of the reticular formation do?
Contact all levels of the CNS and are involved in virtually every activity from visceral functions to consciousness.
The brainstem does not contain what 2 cranial nerves?
Olfactory and optic
What does fine/proprioceptive information enter?
- Fasciculus gracilis and Tuberculum gracile (below T6)
2. Fasciculus cuneatus and tuberculum cuneatum (above T6)
What is the obex?
floor of 4th ventricle
Inferior cerebellar peduncle receives inform the what?
Olive
Middle cerebellar peduncle receives input from what?
Pons
The Anterolateral pathway include what tract?
Spinothalamic tract
Describes the Auditory pathway.
Fibers enter from cochlea to synapse on cochlear nuclei. Fibers then synapse on superior olive. Fibers run up lateral lemniscus and then synapse on inferior colliculus. Fibers then run to medial geniculate body, and then to the primary auditory cortex.
In an embryo sensory nuclei are located where?
Dorsal horn
In an embryo motor nuclei are located where?
Ventral horn
Motor nuclei are located where in relation to the sulcus limitans?
Medial to sulcus limitans
Sensory nuclei are located where in relation to the sulcus limitans?
Lateral to sulcus limitans