38 Questions
What is the theory that suggests the type of sensation felt is determined by the specific area in the sensory cortex?
Labeled Line Principle
What is the name of the phenomenon where a person feels sensations in a limb that is no longer present?
Phantom limb phenomenon
What happens when a nerve fiber specific for pain is stimulated by heat or pressure?
The individual will only feel pain
What would happen if there is an interruption to the pathway for a particular sensation?
The individual will experience a deficit for that particular sensation
What is the term for the process of mapping specific sensory information to specific areas of the brain?
Neuroanatomical Localization
What is the Doctrine of Specific Nerve Energies?
A theory that explains how nerve fibers are specific to certain sensations
What is the main idea behind the Labeled Line Principle?
That separate neural channels carry sensory information from specific receptors
What is the significance of the specific area in the sensory cortex where afferent fibers terminate?
It determines the type of sensation felt
What is the primary function of the pain receptors in the skin?
To detect painful stimuli
Which of the following structures is NOT involved in the pathway of pain sensation from the right toe?
Cerebellum
What is the characteristic of the first type of pain transmitted by various fibers?
Fast and prickling
What is the term for the sense of touch, which is composed of many different sensory modalities?
Somatic sensation
Which pathway is involved in the transmission of general somatic sensations from the body?
Anterolateral (Spinothalamic) Tract System
What is used to elicit thermal sensations in the skin?
Unmarked glass bottles with warm or cold water
Which of the following is NOT a type of somatic sensation?
Hearing
What is the name of the system involved in unconscious proprioception?
Dorsal Column (Medial Lemniscal) System
What is the role of the dorsal root ganglion in the pathway of pain sensation from the right toe?
To transmit pain signals to the spinal cord
Which pathway is responsible for transmitting general somatic sensations from the face region?
Dorsal Trigeminothalamic Tract
What is the function of the Ventral White Commmissure?
Not mentioned in the text
What is the characteristic of the second type of pain transmitted by various fibers?
Slow and dull
What is the name of the pathway involved in the direct and consensual corneal blink reflexes?
Trigeminothalamic tract
What is the pathway responsible for transmitting general somatic sensations from the body to the thalamus?
Anterolateral (Spinothalamic) Tract System
What is the name of the system involved in transmitting general somatic sensations from the body to the primary sensory cortex?
Anterolateral (Spinothalamic) Tract System
What is the name of the structure involved in transmitting general somatic sensations from the face region to the thalamus?
Dorsal Trigeminothalamic Tract
What is the outcome when the cornea on one side is stimulated lightly?
The contralateral eye will close simultaneously with the ipsilateral eye
What is the afferent arm of the indirect corneal reflex pathway?
The same as the direct corneal blink reflex
Which structure is responsible for crossing the midline to synapse with the contralateral facial motor nucleus?
The medial longitudinal fasciculus
What is the result of an injury or lesion at a particular part of the reflex arc?
One or both reflexes will be affected on either eye
What is the purpose of checking for the direct and consensual corneal blink reflexes on both eyes?
To identify the location of a lesion in the trigeminal and facial nerves
What is the muscle responsible for closing the eye in the indirect corneal reflex pathway?
The orbicularis oculi
What is the afferent arm of the indirect corneal blink reflex pathway?
CN V1 (Ophthalmic)
What is the location of the sensory receptor in the scenario where you feel an itch between the 2nd and 3rd toes of your left foot?
Free Nerve Ending
Which nerve is involved in the transmission of sensory information from the tip of the right middle finger touching a hot coffee cup?
C7
What is the spinal cord level involved in the transmission of sensory information from the tip of the right middle finger touching a hot coffee cup?
C7
What is the type of sensory receptor involved in the transmission of vibratory sensations from the lateral malleolus of the left ankle?
Encapsulated joint receptor
What is the pathway involved in the transmission of vibratory sensations from the lateral malleolus of the left ankle?
Dorsal Column/ Medial Lemniscal Pathway
What is the response to a speck of dust falling into the right eye causing irritation of the cornea?
Blinking of both eyes
What is the location of the sensory receptor in the scenario where a speck of dust falls into the right eye causing irritation of the cornea?
CN V1 (Ophthalmic)
Study Notes
Doctrine of Specific Nerve Energies
- The nature of perception is defined by the pathway over which the sensory information is carried
- Labeled Line Principle: separate neural channels carry sensory information from specific receptors to the specific area in the brain
Sensory Cortex
- The type of sensation felt is determined by the specific area in the sensory cortex to which their specific afferent fibers terminate
- Even if a nerve fiber for pain is stimulated by heat or pressure, only pain will be experienced by the individual
Neuroanatomical Localization
- Interruption of the pathway for a particular sensation due to damage to any of its components would lead to a deficit for that particular sensation
- A patient who manifests a particular sensory deficit in a particular modality at a specific body location may have a lesion involving any of the structures of the pathway from the receptor up to the sensory cortex
Somatic Sensation Modalities and Receptors
- Also known as the sense of touch
- Composed of many different sensory modalities, each having its own proper stimulus and set of receptors that respond to such stimuli
Pain Modalities
- Transmitted by various fibers:
- First pain: initial sharp, acute, or prickling pain
- Second pain: slow, dull/burning, aching
Thermal Sensation
- Changes in temperature:
- Warmth: increase in temperature
- Cold: decrease in temperature
Pathways for General Somatic Sensation
- From the body:
- Anterolateral (Spinothalamic) Tract System
- Dorsal Column (Medial Lemniscal) System
- From the face region:
- Dorsal Trigeminothalamic Tract
- Ventral Trigeminothalamic Tract
Corneal Blink Reflex
- Indirect/consensual blink reflex anatomy
- Afferent arm of this pathway is the same as the direct corneal blink reflex
- Injury or a lesion at a particular part at the reflex arc will manifest with failure to elicit one or both reflexes on either eye
Test your knowledge on localizing neurologic lesions in somatosensory pathways. Identify components of the pathways for general somatic afferent systems and more. Review questions to help you master neurology concepts.
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