Muscular System
Chapter 11 – Lecture Notes
to accompany
Anatomy and Physiology: From Science to Life
textbook by
Gail Jenkins, Christopher Kemnitz, Gerard Tortora
1
Chapter Overview
11.1 Physiology of Movement
11.2 Naming Skeletal Muscles
11.3 Muscles of Head
11.4 Muscles of Neck
11.5 Muscles of Torso
11.6 Muscles of Pelvic Floor
11.7 Muscles of Thorax, Pectoral Girdle and
Movement of Upper Limb
11.8 Muscles of Vertebral Column
11.9 Muscle of Pelvic Girdle and Movement of
Lower Limb
2
Essential Terms
muscular system
 voluntarily controlled skeletal tissues of body
bilateral
 occurring on both sides of body
lever
 rigid structure that moves around a fixed point called
a fulcrum
effort
 force that causes movement
load
 resistance to movement
3
Introduction



Almost 700 individual skeletal muscles
primary function is to produce
movements of body parts
also function to stabilize bones
4
Concept 11.1
Physiology of Movement
5
Physiology of Movement
skeletal muscles that produce movements do
so by exerting force on tendons of articulating
bones
during muscle contraction one bone is pulled
toward another
origin




end of muscle at stationary bone
insertion


end of muscle at movable bone
body


fleshy part of bone between tendons
6
Lever Systems and Leverage
bones act as levers
joints are the fulcrums
levers can operate



at a mechanical advantage


at a mechanical disadvantage



when a smaller effort can move a heavier load
when a larger effort moves lighter load
position of effort, load, and fulcrum on lever
determine mechanical advantage or
disadvantage
7
Effects of Fascicle Arrangement
fibers within a fascicle are parallel
fascicles are arranged in one of five patterns








parallel
fusiform (like a cigar)
circular
triangular
pennate (like a feather)
fascicular arrangement affects muscle’s power
and range of motion
8
Fascicular Arrangement
range of motion

measure in degrees of a circle through which
bones of a joint can be moved
longer and more parallel the fibers



power




greater range of motion
depends on total cross-sectional area
thicker muscles have more power
fascicular arrangement is a compromise of
range of motion and power
9
Figure 11.1
10
Coordination within Muscle Groups
prime mover or agonist


antagonist


muscle that opposes the desired action, stretching
and yielding to movement of prime mover
fixator




muscle that causes a desired action
stabilizes the prime mover increasing efficiency
several for some movements
muscles can generally switch roles depending
on movement
11
Figure 11.13ab
12
Figure 11.13cd
13
Concept 11.2
Naming Skeletal Muscles
14
Naming Skeletal Muscles
Most skeletal muscle names contain
combinations of word roots for their features

1.
2.
3.
4.
5.
6.
7.
pattern of muscle’s fascicles
size
shape
action
number of origins
location of muscle
sites of origin and insertion
15
Table 11.2 pt 1
16
Table 11.2 pt 2
17
Figure 11.2a
18
Figure 11.2b
19
Concept 11.3
Muscles of the Head
20
Muscles of the Facial Expression




muscles lie within layers of superficial fascia
originate on fascia or on bones of skull
insert into skin or other muscles rather than
bones
move skin rather than a joint in contraction
21
Figure 11.3ab
22
Figure 11.3c
23
Table 11.3 pt 1
24
Table 11.3 pt 2
25
Muscles of the Eyeball Movement
extrinsic

originate outside the eyeball
in the orbit
insert on outer surface of eyeball in various
directions



intrinsic

originate and insert entirely within eyeball
move structures inside the eyeball




iris
lens
26
Figure 11.4a
27
Figure 11.4b
28
Table 11.4
29
Muscles that Move the Mandible




also called muscles of mastication
involved in chewing
assist in speech
also protract the mandible
30
Figure 11.5
31
Table 11.5
32
Muscles That Move the Tongue
extrinsic



originate outside the tongue and insert into it
move entire tongue in various directions
intrinsic



originate and insert within the tongue
alter shape of tongue
33
Figure 11.6
34
Table 11.6
35
Concept 11.4
Muscles of the Neck
36
Muscles of the Anterior Neck
suprahyoid muscles


superior to hyoid bone
infrahyoid muscles


inferior to hyoid bone
37
Figure 11.7ab
38
Figure 11.7cd
39
Table 11.7
40
Muscles That Move the Head
41
Figure 11.8
42
Table 11.8
43
Concept 11.5
Muscles of the Torso
44
Muscles that Act on Abdominal Wall
Functions

contain and protect the abdominal viscera

flex, laterally flex, and rotate vertebral column
at intervertebral joinings

compress abdomen during forced exhalation

produce force of

defecation

urination

childbirth
45
Figure 11.9ab
46
Figure 11.9c
47
Table 11.9
48
Muscles Used in Breathing



diaphragm
external intercostal
internal intercostal
49
Figure 11.10ab
50
Figure 11.10c
51
Figure 11.10d
52
Table 11.10
53
Concept 11.6
Muscles of the Pelvic Floor
54
Muscles of the Pelvic Floor


pelvic diaphragm group
levator ani group
55
Figure 11.11
56
Table 11.11
57
Muscles of the Perineum
two layers

deep



assist in urination in males and females
ejaculation in males
superficial



help maintain erection of penis in males and
clitoris in females
facilitate ejaculation in males
58
Figure 11.12
59