55 Questions
Which column is responsible for both ascending and descending tracts?
Ventral column
Which type of sensory information is carried in ascending tracts?
Both proprioceptive and exteroceptive information
How many neurons are typically involved in the circuit of ascending tracts?
Three neurons
Which pathway is responsible for carrying light touch and vibration information?
Dorsal column-medial lemniscus pathway
Which neurons enter the spinal cord via the dorsal root?
First order neurons
Where do first-order neurons synapse on second-order neurons in the medulla?
Nucleus cuneatus
Which tract is responsible for carrying pain, thermal, and non-discriminative touch information?
Spinothalamic tract
Where do second-order neurons cross in the spinal cord?
Dorsal horn
Which part of the spinal cord receives sensory input?
Dorsal horn
Which part of the spinal cord contains motor neuronal cell bodies?
Ventral horn
Which part of the spinal cord is expanded at levels that supply the limbs?
Lumbosacral enlargement
Which tracts carry afferent (sensory) impulses to centers within the brain?
Long ascending tracts
Which tracts carry efferent (motor) impulses from centers within the brain?
Long descending tracts
Which region of the spinal cord has lateral horns only in the thoracic region?
Thoracic region
Which part of the spinal cord organization has excellent organization of the dorsal, ventral, and lateral horns?
Grey matter
Which part of the spinal cord contains tracts that carry sensory impulses to/from the cerebral hemispheres?
White matter
Which tract carries proprioceptive information from the trunk and lower limb?
Dorsal spinocerebellar tract
Which tract carries proprioceptive information from the upper limb?
Cuneocerebellar tract
Where do the spinocerebellar tracts terminate?
In the cerebellum
Which tract ascends in the lateral column to the cerebellum?
Dorsal spinocerebellar tract
What is the main function of the corticospinal tract?
Control of muscular activity
How many neurons are there in the corticospinal tract pathway?
Two
Where do the upper motor neurons in the corticospinal tract originate from?
Cerebral cortex
Where do the lower motor neurons in the corticospinal tract originate from?
Ventral horn
What is the clinical presentation of upper motor neuron disease?
Increased muscle tone and overactive tendon reflexes
Which part of the spinal cord contains the cell bodies of lower motor neurons?
Ventral horn
What is the function of the dorsal horn in the spinal cord?
Receives sensory input
Which part of the spinal cord is responsible for innervating skeletal muscles?
Ventral horn
What is the basic organization of the spinal cord?
White matter in columns
Which part of the spinal cord contains more grey matter?
Cervical region
Which tracts carry motor information from the brain down towards the spinal cord and out towards the periphery?
Descending tracts
Which type of sensory information is carried in the ascending tracts?
Extra receptive information
Where do the primary sensory neurons (first-order neurons) enter the spinal cord?
Dorsal roots
Which pathway is responsible for carrying information about light touch and vibrations?
Dorsal column medial lemniscus pathway
What type of information is carried in the dorsal column medial lemniscus pathway?
Light touch and vibrations
Where do the first-order neurons of the dorsal column medial lemniscus pathway synapse on second-order neurons?
In the brainstem
Which part of the spinal cord contains tracts that carry sensory impulses to/from the cerebral hemispheres?
White matter
Which region of the spinal cord contains tracts that carry sensory impulses to/from the cerebral hemispheres?
Cervical region
Which part of the spinal cord is expanded at levels that supply the limbs?
Cervical enlargement
What is the main function of the corticospinal tract?
Carrying motor impulses from the brain to the spinal cord
Which column in the spinal cord is responsible for carrying ascending and descending tracts?
Lateral column
Which tracts are responsible for carrying proprioceptive information from the upper and lower limbs respectively?
Dorsal ventral spinal cerebellar tracts and Cuneo cerebellar tracts
Which side of the cerebellum controls the left side of the body?
The left cerebellar hemisphere
Where do the pyramidal tracts pass through?
The pyramids of the medulla
Which pathway controls all of the skeletal muscles?
The corticospinal tract
Which part of the brain receives information from the third order neurons in the somatic sensory pathway?
Thalamus
What is the term used to describe the loss of balance and coordination due to a lack of proprioceptive input to the somatic sensory cortex?
Sensory ataxia
What is the clinical test used to assess for sensory ataxia in patients with lesions of the dorsal column?
Romberg sign
Which tract carries information about pain, thermal sensations, and non-discriminative touch to the brain?
Spinothalamic tract
Which part of the brain stem do the axons of the upper motor neurons pass through?
Cerebral pyramids
Which part of the medulla do the axons of the upper motor neurons enter?
Cerebral pyramids
What do the axons of the upper motor neurons form within the medulla?
Lateral cortical spinal tracts
What percentage of fibers in the corticospinal tract cross the midline to enter the spinal cord?
80%
What is the main function of the corticospinal tract?
Carrying motor information from the brain
Which parts of the motor cortex innovate the lower limb and upper limb, respectively?
Medial and lateral parts
Study Notes
Spinal Cord Tracts and Functions
- The spinal cord columns responsible for both ascending and descending tracts are the dorsal and ventral columns.
- Ascending tracts carry sensory information such as touch, pain, vibration, proprioception, and temperature to the brain.
- Typically, three neurons are involved in the circuit of ascending tracts: first-order, second-order, and third-order neurons.
- The dorsal column-medial lemniscus pathway is responsible for carrying light touch and vibration information.
- Afferent fibers of sensory neurons enter the spinal cord via the dorsal root.
- In the medulla, first-order neurons synapse on second-order neurons in the nuclei of the dorsal column.
- The spinothalamic tract carries pain, thermal, and non-discriminative touch information.
- Second-order neurons typically cross at the spinal cord level before ascending to the brain.
- The dorsal horn of the spinal cord receives sensory input.
- The ventral horn contains motor neuronal cell bodies.
- Enlargements in the spinal cord occur at levels that supply the limbs.
- Ascending tracts carry sensory impulses to the brain; descending tracts carry motor impulses from the brain.
Spinal Cord Organization and Regional Functions
- Lateral horns are present only in the thoracic region of the spinal cord.
- The cervical and lumbar enlargements show excellent organization of the dorsal, ventral, and lateral horns.
- Sensory tracts to and from the cerebral hemispheres are found in the lateral regions of the spinal cord.
- The spinocerebellar tracts carry proprioceptive information from both the trunk and limbs.
- The dorsal spinocerebellar tract carries proprioceptive information from the lower limb, while the cuneocerebellar tract carries it from the upper limb.
- The spinocerebellar tracts typically terminate in the cerebellum.
- The lateral spinothalamic tract ascends to the cerebellum through the lateral column.
Corticospinal Tract and Motor Function
- The main function of the corticospinal tract is to control voluntary motor function.
- There are two neurons in the corticospinal tract pathway: upper and lower motor neurons.
- Upper motor neurons originate from the motor cortex.
- Lower motor neurons originate from the ventral horn of the spinal cord.
- Clinical presentation of upper motor neuron disease includes spasticity, weakness, and hyperreflexia.
- The dorsal horn has the function of processing sensory information.
- The ventral horn is responsible for innervating skeletal muscles.
- Grey matter is more abundant in regions where spinal nerves exit to the limbs.
Pathways and Impacts on Coordination and Balance
- Descending tracts carry motor information from the brain to the spinal cord and out to the body.
- Primary sensory neurons enter the spinal cord through the dorsal root.
- The dorsal column-medial lemniscus pathway is key for light touch and vibration sensory input.
- The first-order neurons of this pathway synapse on second-order neurons in the medulla.
- Each ascending tract plays a specific role in transmitting sensory information to the brain, including proprioception and pain.
- The right cerebellum controls the left side of the body due to crossovers in the neural pathways.
- Axons of upper motor neurons pass through the brainstem and enter the medulla.
- In the medulla, these axons form the pyramids of the corticospinal tract.
- About 80% of the fibers in the corticospinal tract cross at the decussation of the pyramids before entering the spinal cord.
- Parts of the motor cortex for limb control are organized with specific regions innovating the lower limb versus the upper limb.
Clinical Aspects and Assessments
- Sensory ataxia, characterized by loss of balance and coordination due to poor proprioception input, can be assessed using clinical tests.
- Dorsal column lesions can lead to difficulty in maintaining balance, often evaluated through specific balance tests.
- Clinical evaluation and assessment techniques are fundamental for diagnosing spinal functionality and motor control issues.
Test your knowledge on the ascending and descending tracts of the spinal cord in this quiz. Explore the anatomy of the spinal cord, including its grey and white matter. Learn about the functions and disorders of cerebrospinal fluid and the ventricular system. Join Professor Andrew Dilley for a comprehensive review of these important topics.
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