This patient’s ependymoma was located in the tapered caudal endof the spinal cord, which is supplied by branches of the aorta andspinal arteries. Ependymomas in this region are particularlyvulnerable to vessel damage due to higher mobility andvascularization, and movement can lead to vessel rupture andhemorrhage, as occurs in this case. In this case, the patientsuffered from a sudden onset of symptoms, presumably followinghemorrhage. Answer the following questions regarding the loss ofmotor and sensory function observed.

Justify the patient’s sudden onset of lower limbparalysis by answering the following questions:

a. Using words and/or drawings, be sure todescribe the structure of the corticospinal pathway. Identify thelocation of the upper and lower somatic motor neurons, decussation,and white matter tracts in the spinal cord. Then, describe how thepatient’s ependymoma and subsequent hemorrhage impactedexcitability of somatic neurons in this pathway.

b. Justify the patient’s paralysis in bothlower limbs. Describe how changes in excitability in lower motorneurons leads to changes in excitability in a skeletal muscle fiber(cell). In your answer, be sure to briefly describe the structureand function of the neuromuscular junction (NMJ), identifying anymembranebound proteins and the sequence of events required forskeletal muscle excitation and subsequent force generation. Statehow ependymoma hemorrhage changes graded and action potentials in askeletal muscle fiber (cell), the concentration of intracellularcalcium, and cross-bridge formation in the muscle.