How are cardiac muscle cells arranged?

How are cardiac muscle cells arranged?

• A. In parallel sheets attached to the fibrous skeleton
• B. In spiral bundles attached to the fibrous skeleton
• C. In random bundles with no pattern
• D. In circular layers around the chamber interior

Answer: (B)

The heart muscle is organized into spiral (helical) bundles that wrap around the chambers, not into parallel sheets, random patterns, or circular rings. This spiral arrangement allows the myocardium to twist as it contracts, producing a wringing motion that efficiently squeezes blood from the chamber toward the outflow tract. The fibrous skeleton provides anchor points for these muscle bundles and helps maintain the shape and integrity of the valves while insulating the atrial and ventricular conduction. If the fibers were arranged in parallel sheets or purely circular layers, the contraction would be less efficient at propelling blood and maintaining chamber geometry.

The heart muscle is organized into spiral (helical) bundles that wrap around the chambers, not into parallel sheets, random patterns, or circular rings. This spiral arrangement allows the myocardium to twist as it contracts, producing a wringing motion that efficiently squeezes blood from the chamber toward the outflow tract.

The fibrous skeleton provides anchor points for these muscle bundles and helps maintain the shape and integrity of the valves while insulating the atrial and ventricular conduction. If the fibers were arranged in parallel sheets or purely circular layers, the contraction would be less efficient at propelling blood and maintaining chamber geometry.