AHE: BLOCK 2: CNS 2 (OF 2): SPINAL CORD & PATHWAYS

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Questions and Answers

Which neuron type has cell bodies located in the dorsal root or cranial nerve ganglia?

Tertiary neuron

Secondary neuron

Interneuron

Primary neuron (correct)

What is the primary function of the Dorsal Column System?

Proprioception and discriminative touch (correct)

Temperature regulation

Reflex actions

Pain perception

Which structure do secondary neurons in the Dorsal Column System synapse with after traveling from the spinal cord?

Brainstem nucleus (correct)

Medulla oblongata

Thalamus

Primary somatosensory cortex

In which part of the nervous system does decussation occur for the Dorsal Column System?

Medulla oblongata Signup and view all the answers

Which sensory receptor type is responsible for detecting temperature?

Thermoreceptors Signup and view all the answers

Which pathway is wholly responsible for unconscious proprioception?

Spinocerebellar pathway Signup and view all the answers

What type of pathway is the Spinothalamic pathway?

Ascending sensory pathway Signup and view all the answers

Which of the following is NOT a motor pathway discussed in the content?

Spinocerebellar pathway Signup and view all the answers

What type of neuron is the secondary neuron in sensory pathways?

Interneuron Signup and view all the answers

What is the main function of the Spinocerebellar pathway?

Transmit proprioceptive information Signup and view all the answers

The cuneate fasciculus transmits sensory information for which body regions?

Upper limbs and superior trunk Signup and view all the answers

Why is decussation significant in the central nervous system pathways?

It allows for contralateral processing of sensory and motor signals Signup and view all the answers

Which type of sensation does the discriminative touch pathway primarily detect?

Textures and shapes Signup and view all the answers

What type of sensory information does proprioception primarily relate to?

Position of joints and muscle stretch Signup and view all the answers

What role does the dorsal column system play in the sensory pathways?

It detects discriminative touch and proprioception Signup and view all the answers

Which part of the central nervous system is primarily responsible for filtering sensory information before it reaches the cerebrum?

Thalamus Signup and view all the answers

What is the primary role of the Spinothalamic Pathway?

Conveying crude touch and pressure, pain, temperature, and itch sensations Signup and view all the answers

Where do primary neurons from the Spinothalamic Pathway enter the spinal cord?

Dorsal root Signup and view all the answers

What happens to the axons of the Spinothalamic Pathway at the entry level in the spinal cord?

They immediately decussate Signup and view all the answers

Which of the following accurately describes the pathway of sensory information in the Spinothalamic Pathway?

Synapse in the posterior horn upon entering the spinal cord Signup and view all the answers

What does decussation in the Spinothalamic Pathway refer to?

The crossing over of nerve fibers to the opposite side Signup and view all the answers

Which type of sensations is processed primarily through the dorsal column system instead of the Spinothalamic Pathway?

Fine touch and proprioception Signup and view all the answers

Which structures are involved in the transmission of sensory information to the primary somatosensory cortex via the Spinothalamic Pathway?

Tertiary neurons in the thalamus Signup and view all the answers

What type of neurons are primarily responsible for processing temperature and pain sensations in the Spinothalamic Pathway?

Secondary neurons Signup and view all the answers

Study Notes

CNS Pathways

Pathways, or tracts, are bundles of axons that transmit information between the CNS and the body.
Tracts are paired and named for their origin (prefix) and termination (suffix), e.g., the spinocerebellar pathway originates in the spine and terminates in the cerebellum.
Sensory pathways are ascending (afferent) and carry information from the body to the CNS.
Motor pathways are descending (efferent) and carry information from the CNS to the body.
90% of pathways decussate (cross to the opposite side of the body), resulting in contralateral (opposite side) control.
Some pathways remain ipsilateral (same side).

Sensory Pathways

Sensory pathways transmit information from the body to the brain.
The three primary sensory pathways are the dorsal column system, the spinothalamic pathway, and the spinocerebellar pathway.

Dorsal Column System

The dorsal column system carries information about proprioception (limb position), discriminative touch (precise pressure and vibration), and fine touch.
The dorsal column system consists of two divisions: the cuneate fasciculus and the gracile fasciculus.
The cuneate fasciculus carries sensory information from above T6, including the upper limb, superior trunk, neck, and posterior head.
The gracile fasciculus carries sensory information from below T6, including the lower limb and inferior trunk.
In the brainstem, the cuneate and gracile fasciculi converge to form the medial lemniscus.

Dorsal Column System: Pathway

The dorsal column system utilizes three neurons to transmit information:
- Primary Neuron: Cell bodies in dorsal root ganglia, enter spinal cord via the dorsal root, and ascend ipsilaterally.
- Secondary Neuron: Synapses in the medulla on secondary neurons; fibers then decussate.
- Tertiary Neuron: Synapses in the thalamus on tertiary neurons; axons travel to the primary somatosensory cortex, contralateral to the sensory receptor origin.

Spinothalamic Pathway (Anterolateral System)

Carries information about crude touch and pressure, pain, temperature, and itch.
The pathway has two divisions: the anterior spinothalamic tract (crude touch) and the lateral spinothalamic tract (pain and temperature).

Spinothalamic Pathway: Pathway

Information is transmitted through three neurons:
- Primary Neuron: Cell bodies in dorsal root ganglia, enter spinal cord via dorsal root.
- Secondary Neuron: Synapses in the posterior horn and immediately decussates at the spinal cord entry level.
- Tertiary Neuron: Axons ascend the spinal cord contralaterally and synapse in the thalamus on tertiary neurons; axons project to the primary somatosensory cortex.

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Description

Explore the fundamental aspects of central nervous system pathways with this quiz. Understand the distinction between sensory and motor pathways, as well as the specific functions of the dorsal column system, spinothalamic pathway, and spinocerebellar pathway. Test your knowledge on decussation and ipsilateral pathways.