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Pennate or Parallel?

by Greg Crowther


This call-and-response song, written for BBIO 352, outlines the fundamental distinction between muscle fibers oriented parallel to the muscle's line of action and muscle fibers oriented at an angle to it. As is often true in muscle physiology, there is a trade-off between how quickly a muscle can shorten and how much force it can exert.

While not a parody, this song is somewhat reminiscent of "Thank You (Falettinme Be Mice Elf Agin)" by Sly and the Family Stone.


Pennate or parallel: (Pennate or parallel:)
Tension versus speed. (Tension versus speed.)
Each one does something well. (Each one does something well.)
What does each joint need? (What does each joint need?)

Fibers in parallel (Fibers in parallel)
Have more change in length. (Have more change in length.)
Pennate, as you can tell, (Pennate, as you can tell,)
Maximize their strength. (Maximize their strength.)

Pennate or parallel! (Pennate or parallel!)
Pennate or parallel! (Pennate or parallel!)
Pennate or parallel! (Pennate or parallel!)
Pennate or parallel! (Pennate or parallel!)

Other Files

sheet music (with melody play-back)

Lesson Plan

Songs like this one can be used during class meetings and/or in homework assignments. Either way, the song will be most impactful if students DO something with it, as opposed to just listening.

An initial, simple follow-up activity could be to answer the study questions below. A more extensive interaction with the song might entail (A) learning to sing it, using an audio file and/or sheet music as a guide, and/or (B) illustrating it with pictures, bodily poses, and/or bodily movements. The latter activity could begin with students identifying the most important or most challenging content of the song, and deciding how to illustrate that particular content.

Study Questions

(1) Think of the muscle that a crab uses to close its claw. Based on its function, is this muscle likely to have paralel muscle fibers, or pennate ones?

(2) Picture each of the following human muscles based on diagrams or laboratory models. State whether each is paralell, pennate, or neither. (a) Biceps brachii. (b) Gastrocnemius. (c) Orbicularis oculi. (d) Rectus abdominus. (e) Rectus femoris. (f) Sartorius.

(Answers may be found on the answers page.)