Sensory Pathways Flashcards
What are the receptors for pain?
free nerve endings
What are the receptors for pressure?
pacinuan corpuscle
Describe the pathway of sensory information of crude touch/pressure and pain/temperature
What is it called?
Trigeminothalamic Tract Part 1
3 neuron system
Stimuli signals travel via the trigeminal nerve’s sensory branches to the spinal nucleus of the trigeminal nerve (Spinal Nucleus V), located in the brainstem medulla
> Here, signals for crude touch, pain, and temperature are processed.
> Second-order neurons from Spinal Nucleus V decussate (cross the midline) and ascend via the trigeminothalamic tract.
> These signals synapse in the (VPM) nucleus of the thalamus.
> Third-order neurons project to the somatosensory cortex for perception.
Where does the trigeminal axons enter the brainstem?
middle cerebellar peduncle
What is the spinal nucleus V a part of?
trigeminal nuclear complex
What additional cranial nerves synapse at the spinal nucleus V and join the TTT?
where do they carry sensory information from?
Facial nerve
* Ear
Glossopharyngeal nerve
* Ear, posterior one third of tongue, upper pharynx and auditory tube
Vagus nerve
* Ear, Lower pharynx, larynx and upper esophagus
What does spinal tract damage cause?
ipsilateral (pain/temp/crude touch/pressure loss)
What does TTT damage in spinal tract cause?
contralateral loss of pain/temp/crude touch/pressure
What are the receptors for discriminatory touch?
meissner’s corpuscle
What are the receptors for warmth?
raffini’s end organ
Describe the pathway of sensory information of discriminatory touch and vibration
Trigeminothalamic Tract Part 2
3 neuron system
These signals travel via the trigeminal nerve’s sensory branches to the chief sensory nucleus (also called the principal sensory nucleus) in the pons.
> first-order neurons synapse with second-order neurons.
> second-order neurons decussate (cross the midline) and ascend to the thalamus via the ventral trigeminothalamic tract.
> contralateral pathways synapse in the ventral posteromedial (VPM) nucleus of the thalamus.
> third-order neurons project to the somatosensory cortex for perception of fine touch, vibration,
Describe the pathway of sensory information of prociception
signals is carried by specialized proprioceptive fibers from the mandibular division (V3) of the trigeminal nerve.
> primary sensory neurons synapse in the mesencephalic nucleus of the trigeminal nerve (found in the midbrain)
> after mesencephalic nucleus second order neurons decussate to the thalamus (VPM nucleus) via the trigeminothalamic tract where they synapse with third order neurons
> third order neurons synapse in the somatosensory cortex.
F
What does chief sensory tract damage cause?
ipsilateral loss
What does TTT in the chief sensory tract damage cause?
contralateral (all sensory loss from head)
