Neuro Exam 3 Prep (Ch. 10, 11, and 12)

Match the following somatosensory pathways.

• Third-order neuron

• Conveys information from the thalamus to the cerebral cortex

• First-order neuron

• Brings information from sensory receptors into the spinal cord

• Second-order neuron

• Conveys information between the spinal cord or brainstem to the thalamus

(T/F): Nociception is the perception of tissue damage or potential tissue damage. The brain usually interprets stimuli that activate nociceptors as painful.

• True

• False

Match the following.

• Light touch

• Tactile information conveyed by end-organs is categorized as _____ because the vibration, skin stretch, and skin pressure they communicate is typically perceived as innocuous.

• Phasic receptors

• Respond the entire time a stimulus is present

• Tonic receptors

• Adapt to a constant stimulus and stop responding while the stimulus is still present

• Crude touch

• Tactile information conveyed by free nerve endings is termed _____ because it provides information that a mechanical stimulus has occurred, but not the specific localization of that stimulus.

What type of receptors respond to mechanical deformation of the receptor by touch, pressure, stretch, or vibration?

• Mechanoreceptors

• Chemoreceptors

• Thermoreceptors

Answer explanation

Chemoreceptors: Responds to exogenous chemicals or substances released by cells, including damaged cells following injury or infection.

Thermoreceptors: Responds to heating or cooling.

All of the following is true regarding receptive fields EXCEPT for:

• Receptive fields tend to be smaller proximally and larger distally.

• Receptive fields tend to be smaller distally and larger proximally.

• Distal regions of the body have a greater density of receptors than proximal areas.

• The combination of smaller receptive fields and greater density of receptors distally enables us to distinguish between two closely applied stimuli on a fingertip.

(T/F): Dermatomes connect motor or sensory end-organs with the central nervous system.

• True

• False

Answer explanation

Peripheral nerves connect motor or sensory end-organs with the central nervous system.

A dermatome is the area of skin innervated by axons that enter the spinal cord through a single dorsal root and are used to determine the sensory level affected by a spinal cord injury.

If an individual experienced a complete lesion of the median nerve above the wrist in the posterolateral forearm _____.

• They would not perceive any sensation below the lesion or in their hand, neither on the posterior nor anterior side of the forearm.

• They would lack sensation of the entire posterolateral forearm and hand of sensation.

• They would lack sensation in the posterolateral fingertips, but would retain intact sensation in the areas innervated by the radial nerve and lateral cutaneous nerve of the forearm.

Answer explanation

Chapter 10, p. 151, Fig. 10.6

Match the following.

• Joint receptors

• Respond to both quick and prolonged stretch of the muscle

• Golgi tendon organs

• Respond to mechanical deformation of joint capsules and ligaments

• Muscle spindle

• Signal the tension generated by muscle contraction or by passive stretch of the tendon

Where are proprioceptors located?

• In the skin

• Located in muscle spindles, joints, ligaments, and tendons

• Located in all types of tissues

(T/F): The peripheral somatosensory system conveys information about touch, proprioceptive, thermal, and noxious stimuli to the spinal cord or brainstem.

• True

• False