Overview of the Brainstem Flashcards
What are the three functions of the brainstem
1) Conduit - longitudinal tracts to and from the brain, cerebellum and spinal cord.
2) Cranial nerve functions via brainstem nuclei,
3) Integrative and modulatory functions through the reticulum
Label this diagram of the external view of the brainstem
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Label the internal features of the brainstem
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What occurs to the lateral corticospinal tract if there is a lesion in the brainstem?
Contralateral UMN signs
What is the rubrospinal tract?
Descending tract originating from the brainstem. It starts at the red nucleus and goes on to supply the flexors of the upper limb.
What is the tectospinal tract?
Decending tract which originates in the brainstem. Starts in the superior colliculus and goes on to synapse in the cervical spinal cord to supply neck muscularture.
What is the vestibulospinal pathway?
Decending tract which starts in brainstem at lateral and medical vestibular nuclei. Medial vestibulospinal tract goes on to supply bilateral neck muscles. Lateral vestibulospinal tract sends ipsilateral excitatory signals to extensors and inhibitory to flexors
What is the reticulospinal pathways
Descending tract that starts in the brain stem. Starts at pontine and medullary reticular formation and goes on to supply cervical spinal cord, helps control posture and locomotion
What occurs if there is a lesion in the brainstem that disrupts the DCML, spinothalamic tract and spinocerebellar tracts?
DCML-Contralateral loss of joint position sense and discriminating touch.
Spinothalamic - Contralateral loss of pain and temp.
Spinocerebellar - ipsilateral loss of unconscious proprioception
In the brainstem, what tracts will you find laterally?
at the Side so;
- Spinothalamic (will have crossed),
- Spinocerebellar,
- Sympathetic.
In the brainstem what tracts will you find Medially?
- Medial lemniscus (will have crossed)
- Motor fibres (corticospinal and corticobulbar)
- Medial longitudinal fasciculus.
What is the reticulum?
It is located throughout the brainstem in the central tegmentum. It is a network of neurons without detectable nuclei but are responsible for a wide variety of functions such as regulation of pain sensation, arousal of cortex and modulation of descending motor output.
Describe how the brainstem cranial nuclei are organised in modalitites.
From the medial to later;
- Somatic motor,
- Pharyngeal motor,
- Visceral motor.
Then,
- Visceral sensory,
- Somatic sensory,
- Special sensory.
Name the cranial nerves
CNI - Olfactory nerve,
CNII - Optic nerve,
CNIII - Oculomotor nerve,
CNIV - Trochlear Nerve,
CNV - Trigeminal nerve,
CNVI - Abducens,
CNVII - Fascial nerve,
CNVIII - Vestibulocochlear nerve,
CNIX - Glossopharyngeal nerve,
CNX - Vagus nerve,
CNXI - Spinal accessory nerve,
CNXII - Hypoglossal nerve
Name these nuclei that control the somatic motor output to eye and tongue
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Name the nuclei controlling special visceral (pharyngeal derived) motor output
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Name the cranial nerve nuclei that are responsible for autonomic control
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Name the cranial nerve nuclei that receive sensory information
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What are the non-cranial nerve nuclei of the midbrain?
- Medial geniculate,
- Red nucleus,
- Substantia nigra (motor modulation),
- Superior colliculus,
- Inferior colliculus,
- Reticular formation
What are the non-cranial nerve nuclei of the pons
- Pontine nuclei (link between cerebral cortex and cerebellum),
- Reticular formation
What are the non-cranial nerve nuclei of the medulla
- Olive (superior does auditory control, inferior does motor control),
- Vital centres (regulate heart rate, breathing, blood vessel diameter.),
- Non-vital centres (Co-ordinate swallowing, vomiting, cough, sneezing and hiccuping),
- Reticular formation
How can lesions affecting the cranial nerve function present?
Eye muscle weakness, no sensation on the face, autonomic dysregulation, problems speaking or swallowing, vertigo and changes in taste and hearing.
How can lesions affecting the reticular formation present?
- Uncontrolled movement such as choria, tremor or ataxia, autonomic dysfunction, lethargy, locked-in syndrome
