Download Muscle Rules Maniken Clay Build Directions

Muscle Rules – Maniken Build Directions
*Anything in this packet is fair game for assessments.
1. Review the terms ventral and dorsal. Locate the ventral and dorsal side on the arm of the maniken and feel
for the radial groove on the ventral side of the humerus.
2. Locate the ventral side and use a pencil to place a dot on the lateral and medial side of the radial groove
(about halfway up the humerus).
3. Locate the ulna just below the fold of the elbow. Observe the hollowed out area in the antecubital region.
Place a pencil dot above this area.
4. These dots each represent an attachment point for a muscle. Students should note that there are at least
two attachments (in this case three) and the muscle will cross a joint at the elbow. This represents: Rule
#1: Muscles must have at least two attachments and must cross at least one joint.
5. Build the brachialis muscle on the ventral forearm of the Maniken®.
6. Using terra cotta clay, form two balls about the diameter of a nickel.
7. Rolling the clay between the tabletop and a palm, roll each ball into a long carrot. The total length of the
carrots should stretch from the humeral attachment to the ulnar attachment. Encourage students to keep
rolling if the carrot is too short or pinch some off if the carrot is too long.
8. Bring the fat part of the carrots together, leaving the tops free (rabbit ears).
9. Attach the two free ends to the humeral attachments. Place the combined fat end across the elbow and
attach the end to the ulnar attachment. Pinch off any extra clay. Use your thumb to press the clay muscle
onto the arm. Remember, all of the muscles in the room do not have to look identical.
10. Pull your forearm towards your heart and watch the position of your fingers. You should notice that your
index finger and thumb are closer together at the start, but pull away from one another as you move your
arm closer to your chest. This represents Rule #2: Muscles always “pull” and get shorter.
11. Recognize that the ulnar attachment is being pulled (and moved forward), while the humeral attachment
stays stationary.
12. The attachment that moves is known as the insertion of the muscle. The insertion is usually the distal
attachment. The attachment that does not move and pulls the other attachment toward it is referred to as
the origin. The origin is usually the proximal attachment. This represents Rule #3: The attachment that
moves is known as the insertion and the attachment that remains stationary is known as the origin.
13. Extend your arms out in front of your body. This angle as 180°.
14. Show the movement of the muscle you have built. This time you should pay attention to what happens to
the angle when the muscle shortens. Notice that the angle decreases. What do we call motion at a joint
that decreases the angle between articulating bones? Remember, we call this movement flexion and thus
a muscle such as this is referred to as a flexor.
15. The Brachialis muscle you have built have the following properties:
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Origin = halfway down the humerus (both medial and lateral of the radial groove)
Insertion = proximal ulna
Action = flexes elbow
16. If muscles can only be pulled, then how does a flexed arm go back to being straight? Another muscle must
pull to get the arm back to 180°.
17. What do we call motion at a joint that increases the angle between articulating bones. We call this
movement extension and thus a muscle that controls this movement is referred to as an extensor. This
represents Rule #4: Muscles that decrease the angle between ventral surfaces of the body are
known as flexors. Muscles that increase the angle between ventral surfaces of the body are known
as extensors.
18. Now create an extensor, the triceps medial head, on the maniken arm.
19. Place a pencil dot halfway up the dorsal side of the humerus. Place another dot just distal of the elbow
onto the ulna. This is a good place to review Rule #1.
20. Using terra cotta clay, form a ball the diameter of a nickel. Roll the ball into an even tube. Again, check to
make sure this tube reaches from attachment to attachment.
21. Attach the ends of the clay tube to dots on the humerus and on the ulna. Since the back of the humerus is
flat, the muscle shapes to the bone and is also flat. They should use their thumbs to flatten the clay.
Remove any clay that makes its way to the ventral side.
22. This triceps brachii muscle is an extensor since the angle increases during motion.
23. The triceps brachii is an extensor with the following properties:
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Origin = proximal half of dorsal humerus
Insertion = distal of elbow on the ulna
Action = extends elbow
24. Flexors are on the ventral side of the body and extensors are located dorsally.
25. For smooth movements to occur, can both extensors and flexors be contracting at the same time? No
because when the flexors are pulling, the extensors are relaxing. The represents Rule #5: Muscles work
in opposing pairs.
26. Think back to your pencil fascicles. All of the muscle fibers are parallel and can “pull” in the same direction.
Use a pencil or a wire tool to add striations to the clay muscles you have built. These striations run in the direction
in which the muscle moves which represents Rule #6: Muscle striations point to the attachments and show
the direction of pull.