CHAPTER 11 Part 1The Muscular System

Copyright © 2007 by John Wiley & Sons, Inc.

Principles ofHuman Anatomy

Eleventh EditionGerard J. Tortora

&

Mark T. Nielsen

11_0111_01

11_0211_02 Arrangement of Fascicles Arrangement is correlated to power & range of

motion A muscle fiber shortens to a length just slightly

greater than that of half it’s resting length Therefore: the longer the fiber the greater its range of

motion Muscle strength is determined by the number of

fibers it contains. Therefore: a short fiber can contract just as forcefully

as a long one.

11_table_01 Parallel vs. Pennate

Usually a muscle either has a small # of long fibers or many short fibers

Parallel muscles usually have good range of motion but not much power.

Pennate muscles usually have a smaller range of motion but have good power.

11_03a11_03a 11_03b11_03b

11_table_02 Origins & Insertions

These both describe muscle attachment points on the bone.

The Origin is where the muscle is attached to the bone that remains stationary when the muscle contracts.

The Insertion is where the muscle is attached to the bone that moves when the muscle contracts.

Muscle Groups

Quadriceps: Rectus femoris Vastus lateralis Vastus medialis Vastus intermedius

The Taylor’s Muscle Sartorius

Longest muscle in the body

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Muscle Groups

Hamstrings Biceps femoris Semitendinosis Semimembranosis

11_22c11_22c

Muscle Groups

Abdominals Rectus abdominis External oblique Internal oblique Transverse abdominis

11_12ab11_12ab

11_12c11_12c 11_12d11_12d

11_12e11_12e 11_12f11_12f

11_12g11_12g 11_13ab11_13ab

Learning Objectives

Understand how fascicle arrangement affects muscle strength & range of motion

Describe the ways in which muscles are named (do this with your cadaver list)

Describe 3 lever systems and give body examples

Which muscles are in the following groups:quadriceps, hamstrings, abdominals