Neurology: Corticospinal Tracts Overview

Lesions destroy function at the segmental level and interrupt descending motor and ascending sensory tracts.

Acute lesions can follow occlusion of the anterior spinal artery and trauma causing spine fractures.

It causes weakness, wasting, fasciculation of muscles, areflexia of the lower limbs, incontinence, and sensory loss below the lesion.

<p>It is characterized by Brown–Séquard syndrome, with ipsilateral loss of proprioception and upper motor neuron signs, plus contralateral loss of pain and temperature sensation.</p> Signup and view all the answers

<p>It causes weakness, wasting, areflexia of the upper limbs, spastic paraparesis, hyperreflexia, and sensory loss below the lesion.</p> Signup and view all the answers

<p>It causes spastic tetraplegia with hyperreflexia and extensor plantar responses.</p> Signup and view all the answers

<p>Chronic compression is often due to infections, tumors, and prolapsed intervertebral discs.</p> Signup and view all the answers

<p>Multiple sclerosis is the immune disorder commonly linked to these types of lesions.</p> Signup and view all the answers

<p>It contributes descending fibers to the medial vestibulospinal tract, which helps control extensor muscle tone for anti-gravity maintenance of posture.</p> Signup and view all the answers

<p>The medial longitudinal fasciculus links the vestibular nuclei with the oculomotor, trochlear, and abducens nuclei to coordinate head and eye movements.</p> Signup and view all the answers

<p>They influence voluntary movement, reflex activity, and muscle tone while also mediating effects on the circulatory system and breathing.</p> Signup and view all the answers

<p>The corticospinal tract originates in the motor and sensory cortices, descends through the internal capsule and pons, and decussates at the medullary pyramid.</p> Signup and view all the answers

<p>It originates from the red nucleus of the midbrain and is involved in controlling limb flexor muscles.</p> Signup and view all the answers

<p>The tectospinal tract, originating from the contralateral superior colliculus, mediates reflex responses to visual stimuli.</p> Signup and view all the answers

<p>It originates from the ipsilateral lateral vestibular nucleus and facilitates the excitation of limb extensor muscles.</p> Signup and view all the answers

<p>Reticulospinal fibers control the activity of both alpha and gamma motor neurons, thus influencing muscle tone.</p> Signup and view all the answers

<p>Descending spinal tracts are concerned with the control of movement, muscle tone, spinal reflexes, spinal autonomic functions, and the modulation of sensory transmission to higher centers.</p> Signup and view all the answers

<p>The corticospinal tracts are primarily responsible for the control of voluntary, discrete, skilled movements, especially those of the distal parts of the limbs.</p> Signup and view all the answers

<p>Corticospinal tract neurons originate from cell bodies located in the cerebral cortex, particularly in the primary motor cortex of the frontal lobe.</p> Signup and view all the answers

<p>Corticospinal axons traverse the corona radiata and internal capsule to exit the cerebral hemispheres.</p> Signup and view all the answers

<p>In the medulla oblongata, corticospinal fibers form two prominent columns called the pyramids and undergo subtotal decussation.</p> Signup and view all the answers

<p>About 75% to 90% of corticospinal fibers decussate and enter the contralateral lateral corticospinal tract.</p> Signup and view all the answers

<p>Hereditary spastic paraparesis is an inherited degenerative disorder that causes progressive weakness in the legs, leading to marked stiffness of gait.</p> Signup and view all the answers

<p>The corticospinal tract is also known as the pyramidal tract.</p> Signup and view all the answers

<p>It causes spastic paraparesis with hyperreflexia and extensor plantar responses, while sparing sensation and bladder function.</p> Signup and view all the answers

<p>Approximately 55% of corticospinal neurones terminate at cervical levels.</p> Signup and view all the answers

<p>The rubrospinal tract exerts control over the tone of limb flexor muscles, acting excitatory to their motor neurones.</p> Signup and view all the answers

<p>Tectospinal tract fibres predominantly terminate in cervical segments of the spinal cord.</p> Signup and view all the answers

<p>The vestibulospinal tracts originate from the vestibular nuclei in the pons and medulla.</p> Signup and view all the answers

<p>They mediate powerful excitatory effects upon extensor motor neurones.</p> Signup and view all the answers

<p>The tectospinal tract originates from the superior colliculus and mediates reflex movements in response to visual stimuli.</p> Signup and view all the answers

<p>Axons from the red nucleus course ventromedially, cross in the ventral tegmental decussation, and descend to the spinal cord.</p> Signup and view all the answers

A tract in the brainstem that originates from the vestibular nuclei and controls extensor muscle tone for maintaining posture.

A tract in the brainstem that originates from the reticular formation in the pons and medulla, influencing voluntary movement, muscle tone, and reflex activity. It also plays a role in controlling breathing and blood pressure.

The descending tract from the motor and sensory cortices that controls precise, skilled movements, especially in the hands and feet.

The descending tract from the red nucleus in the midbrain that primarily controls limb flexor muscles.

A descending tract from the superior colliculus that controls reflex responses to visual stimuli, particularly rapid head movements.

The part of the vestibulospinal tract that originates from the lateral vestibular nucleus and primarily excites extensor muscles.

The part of the vestibulospinal tract that originates from the medial vestibular nucleus and is involved in coordinating head and eye movements. It is located in the medial longitudinal fasciculus.

A bundle of fibers that connects the brainstem with the spinal cord, carrying information for various motor functions, including the medial vestibulospinal tract.

Descending tracts of the spinal cord that originate from the cerebral cortex and brainstem, controlling various functions like movement, muscle tone, reflexes, and sensory modulation.

Large nerve cells in the cerebral cortex that are the origin of the corticospinal tracts. They play a crucial role in initiating voluntary movements.

A collection of nerve fibers that connect the cerebral cortex to the spinal cord, transmitting information from the brain to lower regions.

A prominent structure visible on the ventral surface of the medulla oblongata, formed by corticospinal fibers before they cross over.

The process by which a significant portion of the corticospinal fibers cross over to the opposite side of the spinal cord.

A tract located in the lateral part of the spinal cord, containing fibers that have crossed over from the opposite side of the brain.

A tract located on the same side of the brain and spinal cord as its origin, containing a smaller percentage of corticospinal fibers.

A condition characterized by spasticity, increased reflexes, and extensor plantar responses, often caused by damage to the lateral corticospinal tract in the spinal cord, typically affecting the thoracic region.

A part of the central nervous system that primarily coordinates motor functions, including muscle control and movement coordination.

A group of nerve cells located in the ventral horn of the spinal cord that directly innervate and control skeletal muscles.

The movement of a limb, controlled by the nervous system, in response to a stimulus, often visual or auditory.

A lesion in the spinal cord can interrupt descending motor and ascending sensory tracts, leading to specific clinical syndromes based on the affected area.

Damage at the level of the spinal cord segment directly affects the muscles and sensory function in that specific segment.

An acute spinal cord injury, often caused by trauma or a stroke, damages the spinal cord quickly.

Chronic spinal cord damage develops gradually over time, often due to conditions like tumors, infections, or disk herniation.

Multiple sclerosis, an autoimmune disorder, can cause gradual damage to the spinal cord, often leading to subacute or chronic lesions.

A lesion in the lumbosacral spinal cord causes weakness, wasting, and fasciculations in the lower limbs. The lower limbs are also areflexic, meaning reflexes are absent. Additionally, incontinence, sensory loss below the lesion, and sensory ataxia (impaired coordination) are present.

A lesion in the lower cervical spinal cord leads to weakness, wasting, and fasciculations in the upper limbs, along with areflexia. The lower limbs exhibit spastic paraparesis, hyperreflexia, and extensor plantar responses. Additionally, incontinence, sensory loss below the lesion, and sensory ataxia are present.

A Brown-Séquard syndrome is characterized by an ipsilateral loss of proprioception and upper motor neuron signs, such as hemiplegia or monoplegia. Contralaterally, there is a loss of pain and temperature sensation.