1. The Skeletal Muscle System: Anatomy
LABORATORY FIVE
The Skeletal Muscle System: Anatomy
Next week, cadavers will be available for those who are interested. It’s optional.11/11/2018

2. Organization & Terminology
Endomysium: Around each muscle cell (fiber)
Muscle fiber – Notice the peripheral nuclei
Microscopic view of a skeletal muscle
Striations (dark and light bands)
Sarcoplasm and sarcolemma
Myofibril (contractile organelle
A (Dark) bands: correspond to length of myosin (thick) filaments
I (Light) bands: actin (thin) only
Z line: anchor for actin; separates sarcomeres
H zone: center of A band; no actin
M line: Narrow region at center of H zone; anchor for myosin
Epimysium: A thicker coat of dense CT
Perimysium: collagenous fiber membrane
Endomysium: areolar CT

3. 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
If you pick up a piece of paper, you don’t need to activate a lot of motor units, but for picking up a heavy object, you plan ahead to employ all of these motor units and use more muscles; therefore, more strength.
Some muscles are controlled by a few neurons and some muscles by only one neuron.

4. 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

5. 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

6. 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
Many students are confused about flexors versus extensors of the forearm because the figure in their book shows an arm that is missing some fingers.

7. Head & Trunk Muscles Not Shown in your Textbook
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
Splenius & Erector Spinae: Look on the left side of the models where Trapezius & Latissimus dorsi are removed

8. Trunk Transversus abdominis can only be viewed internally
(aponeurosis)
Transverse abdominis is the first muscle to be used during starvation and it is not replaceable, not mitotic cells…
Transversus abdominis can only be viewed internally

9. Quadriceps Group

10. Hamstring Group

11. 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)

12. Grades for First Practicum
Answer key is posted on the cabinet
Grades “A”, “B”, “C”: Congratulations!
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
Grade “D” in lab, and “C” or better in lecture
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”
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