PLM: PRE-LAB GENERAL MUSCLES
Objective
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Become familiar with the general location of the major muscles.
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Identify and state the general location, structure and function of the 3 types of muscle tissues.
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Explain the system used to name muscles and provide examples.
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Identify and model the actions and function of specified muscles.
Notes: Log into Canvas to Review the 3 General Muscles Over View Video Lectures to complete the Pre-Lab
packet. The Pre-Lab assignment is due at the start of lab.
Introduction
In this laboratory section, we will be reviewing the gross anatomy of muscles. Although there are over 500 muscles in the human body,
most courses require only the major muscles to be committed to memory. In these lab documents, you will study less than 100 of the
most important muscles of the body in detail. To make the learning task more connected with the function of movement, the muscles
are categorized based on their primary role in body movement. In addition, each muscle description includes its location, point of origin,
point of insertion, and primary action. Before you become engaged in learning and identifying the major muscles the initial section of
this laboratory, muscle histology and muscle actions, provides some clues on how muscles are named, which will be a helpful resource.
You will study the muscles through a range of observable and hands on exercises involving the use of human muscle models, virtual
cadaver software on APR, and exploration of a human cadaver from the University of Arizona Willed Body Donation Program.
Muscle Histology
There are three types of muscular tissue: skeletal muscle, smooth muscle, and cardiac muscle. This tissue produces movement
and contraction within the body. Contractile proteins, actin, and myosin, inside muscle fibers are arranged in such a way that they slide
past each other. This shortens (or contracts) the fiber and brings whatever is attached to its ends closer together. In skeletal and
cardiac muscle, the proteins are organized into a visible pattern called striations.
Skeletal Muscle Skeletal muscle is voluntary, meaning we consciously contract these muscles. The muscle fibers are long, slender,
multinucleated, and lie parallel to each other. The contractile proteins are highly organized and clearly visible as striations within the
muscle fiber.
The following are functions of skeletal muscle:
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Pulling on bones to produce movement of the skeleton at the joints
Maintaining posture
Supporting and protecting soft tissues of the abdomen and pelvis
Controlling entrances and exits of the digestive and urinary system
Producing heat to maintain internal body temperature
Serving as a reservoir for amino acids that can be used in times of poor nutrition
Smooth Muscle
Smooth muscle is located in the walls of hollow organs such as the stomach, urinary bladder, and muscular blood vessels (arteries).
For this reason, it is called visceral muscle. The fibers are tapered at each end, (spindle-shaped). They are arranged in an overlapping
pattern like a brick wall to form sheets, layers, and rings of muscle. They have a single nucleus and are involuntary (not under
conscious control). Although actin and myosin are inside each fiber, they are not rigidly organized. Therefore, striations are not visible.
Cardiac Muscle
Cardiac muscle is found only in the heart wall. Contraction of this muscle is responsible for generating the force capable of pumping
blood through our blood vessels. The fibers are branched, have a single nucleus, are striated, and involuntary. A unique feature,
intercalated discs, is found connecting adjacent cells. These structures allow for the rapid communication between adjacent cells that
is necessary for the fibers to contract as a unit.
Muscle Structure
An individual skeletal muscle may be made up of hundreds, or even thousands, of muscle fibers bundled together and wrapped in a
connective tissue covering. Each muscle is surrounded by a connective tissue sheath called the epimysium. Fascia, connective tissue
outside the epimysium, surrounds and separates the muscles.
Muscles Shapes & Naming
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Naming Muscles
Learning the names of almost 100 muscles can be a challenging task. In many anatomy and physiology courses, learning the names of
the muscles and connecting each muscle name with its origin, insertion, and action is often required. The origin refers to the point of
attachment of the muscle tendon to the originating, or immoveable, bone. The insertion is the attachment site of the muscle
tendon to the moveable bone. Because a muscle origin and insertion is the union between tendon and bone, it usually occurs at a
roughened process of the bone, such as a ridge or tubercle. The action is the movement of the bone that occurs during muscle
contraction. Many of the muscles that you will learn in this laboratory are illustrated in Figures on Next Page . Here are some clues
that should help, which explain how muscles are named.
Table1 concepts for general muscles
Character
Description
Location
Muscles could be named after their location. The terms include brachii (arm), femoris
(thigh), pectoralis (chest), gluteus (buttock), and abdominis (abdomen).
Example: biceps femoris.
Size
Muscles could be names include an adjective describing the relative muscle size. They
include Latin words such as longus (long), brevis (short), maximus (largest), and
minimus (smallest).
Example: gluteus maximus.
Shape
Direction of fibers
Muscles could be named according to their shape. The Latin words that are used include
deltoid (triangular), trapezius (trapezoid), and piriformis (shaped like a pear).
Example: the trapezius is the very large muscle of the back that is in an approximate
shape of a trapezoid.
Muscles could be named according to the direction that their fibers run, usually using the
body mid line as a reference point. The terms include the Latin words rectus (straight,
parallel to midline), transverse (perpendicular to mid line), and oblique (diagonal to mid
line).
Example: rectus abdominis.
Origin
Some muscles associated with the limbs include the Latin term ceps, which means
‘head’ and refers to the head of the muscle, or the origin. Placing a numerical prefix
before this term, such as bi- (two), tri- (three), or quad- (four) identifies the number of
origins of the muscle.
Example: the biceps brachii is a muscle with two origins.
Movement
produced
Location of origin
and insertion
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Muscles could be named according to a general movement they produce during
contraction.
Example: extensor and flexor muscles of the forearm and the adductor muscles of the
leg.
Muscles could be named according to the location of their origin and insertion.
Example: the sternocleidomastoid muscle has origins on the sternum (sterno) and
clavicle (cleido) and inserts on the mastoid process of the temporal bone.
Take a moment to locate at least one muscle that serves as an example for each naming concept in Table 1.
Note: Terms with an * (on this page only) are of interest but not required on the Muscles Terms List.
Figure 1 human muscles, anterior view.
Terms List: General Muscles Terms
Histology
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striations
myofibers
intercalated discs
uninucleate
multinucleate
skeletal muscle
cardiac muscle
smooth muscle
Functional Classifications
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agonist
antagonist
fixator
synergist
Actions
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extension
flexion
dorsiflexion
plantar flexion
abduction
adduction
circumduction
hyperextension
inversion
eversion
pronation
supination
elevation
depression
protraction
retraction
rotation
STUDENT NAME: ____________________
LAB TA: ________________
PRE – LAB WORKSHEET
SKELETAL MUSCLE
SMOOTH MUSCLE
CARDIAC MUSCLE
Label: nuclei, striations, fibers
Label: nuclei & muscle cells
Label: nuclei, Striations, intercalated
disks
FILL OUT THE CHART
Skeletal
Striation (Y/N)
Nuclei per Cell
Intercalated Discs
Voluntary or Involuntary
LABEL THE DIAGRAM
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Smooth
Cardiac
FILL OUT THE TABLE & LABEL DIAGRAM
Classification
Description/Definition
Agonist
Antagonist
Fixator
Synergist
FILL OUT THE MISSING INFORMATION ON THE TABLE BELOW
Muscle Actions
Description/Definition
Extension
Movement that decreases the angle of a joint
Dorsiflexion
Movement of the ankle that increases the joint angle
and curls the toes.
Abduction
Movement of a body part towards the midline.
Circumduction
Movement that increases the joint angle beyond 180⁰
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Muscle Actions
Description/Definition
Inversion
Foot movement in which the plantar regions faces
laterally.
Pronation
A rotational movement of the forearm that turns the
palm so that it faces upward or forward.
Elevation
Movement in the inferior direction.
Protraction
Movement in the posterior direction.
Rotation
Muscle Names: Match the muscle with how it is named. Multiple letters may be used.
_____ Orbicularis oris
A.
Action of the muscle
_____ Rhomboideus major
B.
Shape of the muscle
_____ Digastric
C.
Relative size of the muscle
_____ Trapezius
D.
Number of origins
_____ Rectus abdominus
E.
Location on bone/body
_____ Levator scapulae
F.
Direction muscle fibers run
_____ Sternohyoid
_____ Subscapularis
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_____ Gluteus maximus
A.
Action of the muscle
_____ Biceps femoris
B.
Shape of the muscle
_____ Deltoid
C.
Relative size of the muscle
_____ Supinator
D.
Number of origins
_____ Extensor carpi ulnaris
E.
Location on bone/body
_____ Palmaris longus
F.
Location of origin and/or insertion
_____ Soleus
_____ Adductor brevis
Name the Actions
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