LABORATORY FIVE
The Skeletal Muscle System:
Anatomy
Organization & Terminology
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Endomysium: Around each
muscle cell (fiber)
Muscle fiber – Notice the
peripheral nuclei
Microscopic view of a skeletal
muscle
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Striations (dark and light
bands)
Sarcoplasm and sarcolemma
Myofibril (contractile organelle
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Motor Unit & Neuromuscular Junction
• Motor Unit: motor neuron +
muscle fibers it innervates
(stimulates)
• Neuromuscular junction: the
point of communication
between a motor nerve and a
skeletal muscle fiber
• Motor end plate: the contact
surface on sarcolemma
• Motor Neuron:
– Myelinated axon
– Axon terminal
– Schwann cells
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Skeletal muscles Contraction
In order for contraction of a
muscle to cause
movement, there are
attachment sites on two
different bones:
Origin: Less movable
attachment
Insertion: More movable
attachment
Action: Moves insertion
toward origin
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Muscle Action and Origin/Insertion
• You need to learn the action of muscles listed on
the provided handout – use flash cards or
highlight them in your textbook
• For muscles with more than one listed action,
learn the action that pertains to the joint within
parenthesis
• Origin & insertion are extra credit learning
material. Learn all muscles Origin and Insertion,
not just the muscles listed on the provided sheet
• Both origin/insertion and action questions will be
just a written question not on the model
Identification of Human Skeletal Muscles
•Mostly superficial muscles and only a
few deep muscles
•ID some attachments by name
•ID muscles that work the head, neck,
shoulder, anterior & posterior trunk,
elbow, wrist, hip, knee, and ankle
•View superficial muscles on leg and arm
models (do not take them apart)
•Flexors: anterior view
•Extensors: posterior view
•View deep muscles on the torso model
and on the head, neck, and shoulder
models
•Right side superficial muscles
•Left side deep muscles
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Head & Trunk Muscles Not
Shown in your Textbook
• Head
• Epicranius: frontalis, occipitalis, galea aponeurotica
• Anterior Trunk
• External and internal intercoastals
• Posterior trunk
• Splenius, rhomboid & erector spinae: Look on the left side of
the model where trapezius & latissimus dorsi are removed
• Ligamentum Nuchae (medial posterior neck)
• Dorsal lumbar Fascia
• Supra & infraspinatus
• Teres Major: inferior to infraspinatus
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Trunk
(aponeurosis)
Transversus
abdominis can
only be
viewed
internally
Quadriceps Group
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Hamstring Group
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Prioritize studying for Lab 5
• Name of muscles – most questions
– ALL of the muscles included in the handout are
assigned for identification purposes
• Gross and microscopic view of skeletal muscle
• Assigned muscle actions (provided handout)
– e.g.: Name the muscle that extends elbow: triceps
brachii
• Origin & insertion of all muscles in your handout
(extra credit)
Grades for First Practicum
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Answer key is posted on the cabinet
Grades “A”, “B”, “C”: Congratulations!
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Grade “D” in lab, and “C” or better in lecture
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Continue doing what you’re doing
Help your classmates get better
Tell them your learning strategy
Make sure you get a grade “C” or better on the lecture portion of the course
Read ahead, get yourself familiarized with the upcoming lab
Visit the last hour of other labs with instructors’ permission
Attend open lab regularly
Do all your lab quizzes
Make sure you turn in all your completed lab assignments on time
Do all the extra credit assignments
Make sure you do well on the lecture portion of the course
Grade “F”
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This should be a wake up call for you
What you have been doing is not working for you
Change your learning strategy
Talk to your classmates who have been successful on the first practicum
Form study groups
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