Attaching the elastic muscle cords

Each of the elastic muscle cords ("muscles") in your kit connects to two attachment sites (an origin and an insertion) and represents a line of action for a muscle. To attach a muscle, you just need to know how to attach each end of the cord ends to one of the three possible attachment site types: a quadriceps tendon clip, an attachment site/hole on the surface of a bone, and an attachment site/hole in a cross-section plate. The instructions below are the same whether the muscle end you're attaching is of the thinner, elastic cord type or the thicker, inelastic cord type.

Materials needed

IfTo you'reattach attachingmost aof musclethe to a bone,muscles, you'll need the forceps, located at the bottom left corner of Parts Plate A.

The forceps should be attached to the bottom left corner of Parts Plate A in your kit.

Before you attach any muscles, be sure that you understand the muscle color and labeling scheme used in your kit. This will help you easily identify each muscle, its attachment sites, and its corresponding compartment.

Attaching a muscle to a quadriceps tendon clip

The first muscle attachment type is to a quadriceps tendon clip. Each of the four quadriceps muscles has a yellow tendon clip, one for each of the four quadriceps tendons (wide yellow straps). These clips have attachment sites for one or up to three cords (one site for rectus femoris and up to three sites for the vasti muscles). Each clip is labeled with the corresponding quadriceps attachment site (REF-B, VAI-E, VAL-D, VAM-D). If you're attaching a muscle to one of the quadriceps tendon clips, attach it first to the clip before attaching it to the cross-section plate or to the surface of a bone.

The quadriceps tendon clips (the yellow plastic pieces indicated by circles) connect the quadriceps elastic muscle cords to the quadriceps tendons (yellow straps). One of the clips (for vastus intermedius) is mostly obscured in the photo above by another clip directly anterior to it (middle clip in the photo, for rectus femoris).

To attach a muscle to a quadriceps tendon clip, insert the end of the cord with a shorter "tail" (cord after the knot) into the hole and pull the cord into the slot to lock the knot in place, as shown in the video below. When inserting the cord into the clip, be sure that you insert the cord through the labeled side first (you should see the clip label as you're inserting the cord). If one end of the cord has a longer "tail" than the other (the bit of cord after the knot), attach the end with the shorter tail to the clip.

Video showing how to attach an elastic muscle to a quadriceps tendon clip. The first half of the video shows steps from a front view of the clip; the second half of the video shows the same steps from a side view of the clip.

Attaching a muscle to a bone

The second attachment type is to the surface of a bone. These are the keyhole-shaped holes (with accompanying labels) that you see all over the surface of the bones of your knee kit.

Photo of an example of an attachment site on the surface of a bone with an elastic muscle cord attached, showing label printed in the surface

Inside each of these keyholes is a hook that catches the knot of a cord and holds it in place as long as the cord is pulled within the normal action range of the corresponding muscle. This means that for all of the motion simulations you perform, the cords will stay attached even though they are simply hooked into place. If you're attaching a muscle between the surface of a bone and a cross-section plate, attach it first to the bone before attaching it to the cross-section plate. If you're attaching a muscle between the surface of a bone and a quadriceps clip, attach it first to the quadriceps clip before attaching it to the bone.

To attach an elastic cord to an attachment site on a bone's surface, push the knot's cord into the hole using forceps and then pull the cord through the slit of the keyhole to pull the knot into the internal hook, as shown in the video below. If one end of the cord has a longer "tail" than the other (the bit of cord after the knot), attach the end with the shorter tail to the bone.

Video attaching an elastic muscle cord to a bone surface attachment site using forceps.

Attaching a muscle to a cross-section plate

The third and last attachment type is toa cross-section plate (either the superior or inferior cross-section plates.one). The cross-section plates have the same keyhole-shaped holes as the surface of the bones, each located within the indentation of the corresponding muscle.

Photo of cross-section plate showing the holes and their labels

Attaching a muscle to a cross-section plate is easier than attaching it to the other two attachment types. For this reason, whenever you're attaching a muscle,muscle that connects to the cross-section plate, attach it to the cross-section plate last; that is, attach it to a quadriceps tendon clip or to the surface of bone and then attach it to athe cross-section plate. To attach a muscle to a cross-section plate, thread the cord and knot through the hole and then slide the cord into the keyhole slit to secure the knot in place, as shown in the video below. If one end of the cord has a longer "tail" than the other (the bit of cord after the knot), attach the end with the longer tail to the cross-section plate.

Video showing how to attach an elastic muscle to a cross-section plate. Insert the cord first through the labeled side and then pull the cord into the slit from the opposite side to secure the knot in place.