IIlustration 7 
Here we see a couple of the essential intrinsic muscles of the pelvis, including unique views of the lateral rotators and a piece of the pelvic floor, the coccygeus. It's true that the six muscles in the butt deep to the gluteus maximus function as lateral rotators of the femur when the pelvis is fixed and the femur movable, but what a limited view of their function! In a four-legged animal, these muscles can be relaxed; in fact, they need to be since the femur moves from extreme flexion to moderate extension. In an upright human, these muscles, along with others like the hamstrings (see below), extend the hip joint to lift the spine skyward, bringing the sacrum and ischial tuberosity closer to the femur.

So let's look as these muscles as hip extensors and pelvic stabilizers, using Grundy's pictures to help us. Taking the left-hand sketch first, we can see how the piriformis (1) and the coccygeus (2) help to bring and keep the sacrum (the very bottom of the spine) close to the femur and the hip bone, respectively. The advantage of the view that we have here is that it is so clear how both of these muscles pull forward on the sacrum, creating a posterior tilt of the pelvis (relative to the femur) and counternutation (extension) in the sacrum (relative to the hip bone). The third muscle in this picture, the obturator internus, also functions to help maintain a posterior tilt of the pelvis, or by extension, prevent an anterior tilt. 

The second side view on the left-hand part of the plate shows another of the lateral rotator group, the obturatur externus. This deep and hard-to-palpate muscle covers the outside of the lower flange of the pelvis, wrapping under the hip joint like a trampoline, curling up behind the femur to attach to the greater trochanter. Considering this muscle in the same light we looked at the first three "lateral rotators," we can see that this one performs the opposite function; draw this origin toward the insertion (assuming the femur is fixed as in standing) and you will get an anterior tilt to the pelvis.

The upper sketch on the right shows us the piriformis running from the top of the trochanter to the lower part of the front of the sacrum, noting again that this is just below the fulcrum of the sacroiliac joint. We can easily imagine that when the spine leans to the left, the bottom of the sacrum and the tailbone, below the fulcrum, would want to move to the right, so that the left piriformis would have to tighten to protect the position of the sacrum. (Note the similarity of this function of the piriformis to the joint-saving function of the rotator cuff muscles of the shoulder.) When the spine returns to upright, then the strain is taken off the piriformis and it can relax again. The problem is that for many of us, there is sufficient imbalance in the spine-from the psoas, iliacus, rib cage imbalance, shoulder malposition, or spinal curvature or rotoscoliosis patterns-to create a constant strain on the sacroiliac joint, and thus a constant state of contraction in the piriformis. Therefore, the piriformis is often the first muscle to get strained and the last to let go as we move into postural balance. And why we can wail on it week after week, and have it come back in the same state on the very next visit.

The last picture shows us the similar stabilizing muscles of the coccygeus and quadratus femoris-two short, strong muscles that essentially recapitulate the journey that the piriformis makes in one leap.

lllustration 8 
Here, Grundy performs a similar operation for the scapula that he did for the pelvis in Illustration 6. Starting from a simple "T" of clay or wood (1), he folds the acromion and scapular spine up and over on the back side and the coracoid process down and forward on the front side (2 and 3). The other corner folds up to form the apex of the scapula (4 and 5). The pictures on the right refine the actions he has performed into the real shape of the scapula. The scapula, of course, is not formulated in this way; it is just a way of seeing the mechanics, but one that illuminates the function of the various parts of the shoulder.

Illustration 9 
In this sketch, Grundy expands the simple mechanics to encompass the entire shoulder. The skeletal structure is depicted as simple wooden blocks, and the individual muscles as simple ropes. In the left-hand picture, we can see the scapula being supported by the trapezius to the outside of the scapula and the levator scapulae to the inside. In the front we see the pectoralis major going out to the arm, with the pectoralis minor underneath going up to the scapula, and the serratus anterior coming around the rib cage.

In the views of the gleno-humeral joint (below), we can see the synergetic actions of the supraspinatus and deltoid in abducting the joint (left picture is more abducted, right picture is less). The supraspinatus is often listed as an assistant or the initiator of abduction, but the situation is a little more complex. The deltoid reaches so far down the humerus that if it contracted by itself to lift the humerus, it would instead slide the head of the humerus up in the shallow glenoid fossa. The supraspinatus, attached very close to the top of the ball, helps the deltoid to do abduction properly by holding the ball down and into the socket. The other muscles of the rotator cuff-the infraspinatus and the subscapularis, in particular-also help to stabilize the ball in the socket during movement.

The practical part of this comes in treating deltoid bursitis, which often comes about when the deltoid has to work too hard because the supraspinatus is not doing its assistant job properly, so that treatment of the supraspinatus can often help take the strain off the deltoid and thus the bursa.

Illustration 10 
Here is another of Grundy's unique "see through" drawings; where else can you see the latissumus from the front? We can see clearly how the latissimus relates to the back of the lower rib cage, and how the tendon twists on its way to its attachment on the front side of the humerus. Grundy also includes the other scapular muscles in this view, so that we can see the supraspinatus and the subscapularis just north and south of the coracoid process, attaching near the ball of the humerus with the joint capsule. 

We also see teres major coming from the bottom of the scapula and accompanying the latissimus to the humerus to form the back side of the armpit. These two muscles need to be able to let go and stretch when the arm is lifted above the head. When this movement is restricted, a host of other shoulder problems and pains will follow. To assure that they are free, put a loose fist on the back side of the armpit and pin these two muscles against the ribs. You can do this side-lying (on one side) or sitting (on both). Now, while you keep the latissimus and teres pinned, have your client abduct his or her elbow out and up, like the wings of a large bird. As they approach or pass horizontal, you will feel the stretch under your arm, and they will feel it, too. Of course, you are staying still and they are doing the moving, so they can control the degree and speed of the stretch. After a few passes, have them abduct their arm without your hands on them, and you will both be rewarded with a very light and moveable arm.

Illustration 11 
Here, Grundy isolates the forearm pronators, and shows how they work to bring the radius across and around the ulna. When you put your hand in front of you and pronate and supinate your hand rapidly, it's hard to convince yourself that it really is only the radius that is moving relative to the other arm bones. Put your other hand under your arm near the elbow and do the movement again. Now you can clearly feel that the ulna stays still while the radius moves around it. Move up toward the wrist, staying in contact with the ulna as you continue to rotate the lower arm, and you may be more convinced.

Here we see the pronator quadratus at the distal end of the arm, and the pronator teres reaching down from the humerus to pull the radius over. Both muscles act on both ends of the joint, where the radius touches the ulna near the elbow and near the wrist. In fact, the interosseous membrane (not pictured) could be considered as part of the joint, joining the two synovia at either end.

Illustration 12 
Taking on the same area in a more mechanical way, here we see the radius parsed out in more detail. With simple blocks of wood, Grundy shows how the two muscles work to fold the radius over the ulna in pronation (1-5). This time he adds the biceps tendon, showing how it gets wound around the radius like a string around a top during pronation, so that it can spin the "top" of the radius into supination. Hold your biceps while actively supinating and feel it tense, and watch the "mouse" go up and down your arm. This extra-strong supinator goes to work when you are putting in a screw (and sometimes you wish you had a similar one for pronation if you have to get it out again).

In 6-9, Grundy "carves" a little more detail into the shape of the radius, first by showing the sickle-shaped arc of the bone in general (8). In 9, he goes further, showing how the bone is thicker on the inside near the radial head, to provide a strong attachment for the biceps tendon, but that this reverses toward the wrist end of the bone, to provide a strong attachment point for the pronator teres. The resultant bone (10) that we have been looking at for years is now suddenly full of new meaning.

Illustration 13 
Turning now to the legs, we begin with a Grundy view of the hamstrings. Most anatomy texts content themselves with a posterior view of the hamstrings. The oblique and sideways view that Grundy shows us, with only the hamstrings shown, demonstrate their role in stabilizing the pelvis on the legs, as many other books do. But this one also clearly shows the short head of the biceps, running from the linea aspera on the back of the femur down to the fibular head. You can reach this essential part of the hamstrings by finding the lateral tendon of the hamstrings above the knee in back, and slipping in laterally to this tendon just behind the iliotibial tract and the vastus lateralis.

Illustration 14 
Oh, those adductors! They are difficult to understand in terms of function, and difficult to find in terms of palpation, but let's see what Grundy has to say about them. The picture on the left shows the complex "mainsail" shape of the adductor magnus, and makes clear its role in stabilizing the pelvis on the leg. The adductor magnus has two lower attachments. One is on the medial femoral epicondyle, which you can feel if you slide your thumb down the inside of your thigh until you run into the bone just above the knee. The other lower attachment runs along the outer edge of the linea aspera, completely covered by the hamstrings. The upper attachment runs along the ramus of the ischium and pubis, a sharp edge of bone that can be felt on either side of the perineum. The middle sketch simplifies the shape of the adductor magnus, showing the twist in the muscle between the linea aspera attachment and the pelvic attachment. 

The right-hand picture shows the entire complex of inner-thigh and inner-pelvic muscles. Most superficial on the inner thigh are the three muscles of the pes anserinus, running up from below the knee-from front to back, the sartorius, gracilis and the semitendinosus. In front of the sartorius are the quadriceps group, including the rectus femoris. To the far right of the picture, the tensor fasciae latae, deprived of its fascial extension of the iliotibial tract, flies free. Between the sartorius and the gracilis, we see the bouquet of (from front to back) the iliacus, psoas major, pectineus and adductor longus (which is the tendon you can always feel, and frequently see, when you sit cross-legged). Behind the gracilis is the adductor magnus we looked at in the left-hand picture.

If you put your left hand on the inside of the left thigh (when the client is side-lying, for instance), you can see from this picture that your thumb will fall on the sartorius, your index finger on the adductor longus, your middle finger on the gracilis, your ring finger on the adductor magnus, and your little finger on the hamstrings. This little mnemonic can at least give us some orientation in this complicated area.

Continue