Arterial Occlusion Review and Spinal Tract Pathways

Vocabulary flashcards covering the major cerebral and basilar arterial occlusions, clinical presentations, and ascending/descending spinal tract pathways and lesion presentations.

Anterior Cerebral Artery (ACA)

Artery that supplies the portion of the brain that controls the lower body; occlusion results in emotional lability, confusion, amnesia, personality changes, urinary incontinence, and contralateral hemiplegia or hemiparesis greater in the lower than upper extremities.

Middle Cerebral Artery (MCA)

Artery that supplies the portion of the brain that controls the upper body; occlusion results in alterations in communication, cognition, mobility, sensation, contralateral homonymous hemianopia, and contralateral hemiplegia or hemiparesis (motor and sensory loss greater in the face and arm than the leg).

Posterior Cerebral Artery (PCA)

Artery that supplies the occipital lobe, parts of the thalamus, and temporal lobe; occlusion causes hemianesthesia, contralateral hemiplegia (greater in face and upper extremities than lower), cerebellar ataxia, tremor, visual loss (homonymous hemianopia, cortical blindness), receptive aphasia, and memory deficits.

Vertebrobasilar Artery (VBA)

Artery supplying the brain stem, cerebellum, parts of the thalamus, occipital lobe, and temporal lobe; occlusion causes TIAs, upper motor neuron weakness of the face/tongue/throat, loss of vibratory/two-point discrimination/position sense, diplopia, homonymous hemianopia, nausea, vertigo, tinnitus, syncope, dysphagia, and dysarthria.

Complete VBA Blockage

Total occlusion of the vertebrobasilar artery resulting in coma, miotic pupils, decerebrate rigidity, respiratory and circulatory abnormalities, and death.

Internal Carotid Artery (ICA)

Artery that supplies the part of the brain NOT supplied by the VBA; occlusion results in unilateral blindness, severe contralateral hemiplegia and hemianesthesia, and profound aphasia.

Posterior Column

Spinal pathway carrying vibratory sensation, conscious proprioception, 2-point discrimination, and stereognosis; fibers enter and travel up the same side of the spinal cord and cross over at the medulla oblongata (MO).

Fasciculus Gracilis

Posterior column tract responsible for carrying sensory modalities (vibration, conscious proprioception, 2-point discrimination, stereognosis) from the lower body.

Fasciculus Cuneatus

Posterior column tract responsible for carrying sensory modalities (vibration, conscious proprioception, 2-point discrimination, stereognosis) from the upper body.

Lateral Spinothalamic Tract

Lateral column pathway that carries pain and temperature; fibers enter and cross over immediately in the spinal cord, leading to contralateral loss below the lesion if damaged in either the spinal cord or brain.

Ventral Spinothalamic Tract

Anterior column pathway carrying light touch that enters and crosses over immediately in the spinal cord (or after $1$ or $2$ segments); due to dual paths with the posterior column, a lesion in either the spinal cord or brain causes no sensory loss.

Dorsal & Ventral Spinocerebellar Tract

Lateral column tracts carrying unconscious proprioception that enter and travel up the same side of the spinal cord without ever crossing over; a lesion in the spinal cord or brain results in ipsilateral loss below the lesion.

Lateral Corticospinal Tract

Lateral column motor pathway containing $90\%$ of descending motor fibers (assumed affected by lesion) that cross over at the brain and then travel down the same side of the spinal cord.

Ventral Corticospinal Tract

Anterior column motor pathway containing $10\%$ of descending fibers that never cross over.

Motor Pathway Lesion Effects

A lesion in the spinal cord produces motor loss on the same side below the lesion (ipsilateral), whereas a lesion in the brain produces motor loss on the opposite side (contralateral).