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Ironically, the old name for quadratus plantae was exor digitorum accessorius, which I believe was a better name. It told us of its simple yet profound contribution to the FDL. Quadratus plantae: Cool! 14. ADDUCTOR MAGNUS I believe the adductor magnus is the most underappreciated muscle in the human body. As its name implies, it is a tremendously large muscle. Yet, the immenseness of its size cannot be appreciated from super cial anterior or super cial posterior views because it is deep from both perspectives. It can be viewed as a shelf that the more anterior muscles of the adductor group sit on, and it can be viewed as a shelf that the medial hamstrings sit on. To understand this muscle you must either look at a medial view of the thigh, wherein at least a small amount of it is super cial and shows, or even better, look at deeper views from the anterior or posterior perspective. But being large is not enough to qualify it to be on our list of cool muscles. So why do I include adductor magnus here? One reason is that it has a twist in its bers, similar to the latissimus dorsi and the levator scapulae. But even more fascinating is that it is a transitional muscle between the medial and posterior compartments of the thigh. The adductor magnus has two heads. The anterior head is innervated by the obturator nerve, as are the majority of the adductor muscles. But the posterior head is innervated by the sciatic nerve, as are the hamstrings. And the posterior head attaches proximally onto the ischial tuberosity (like the hamstrings), and extends the thigh at the hip joint (like the hamstrings). For these reasons, the adductor magnus is often referred to as the fourth hamstring, although this designation should really be applied only to its posterior head. An immense adductor muscle that has a twist and is an honorary member of the hamstring group . . . that is cool! 15. GLUTEUS MEDIUS While we are in the region of the hip joint, let's discuss the gluteus medius for a moment. I like to call the gluteus medius the deltoid of the hip. This is because, like the deltoid, the gluteus medius has anterior, middle, and posterior bers. And these bers act upon the thigh at the hip joint in the same manner that the deltoid acts upon the arm at the shoulder joint. Like the anterior deltoid, the anterior gluteus medius exes, abducts, and medially rotates. Like the middle deltoid, the middle gluteus medius effectively does pure abduction. And like the posterior deltoid, the posterior gluteus medius extends, abducts, and laterally rotates. (By the way, the gluteus minimus could be similarly described.) But another fascinating aspect of the gluteus medius is that its major function is its reverse-action/closed-chain pull upon the pelvic bone toward depression. A pull toward pelvic depression acts to stabilize the pelvis by preventing the opposite-side pelvic bone from depressing when the opposite- side foot leaves the ground during its swing phase of the gait cycle (walking). Weakness of the gluteus medius causes a dysfunction when walking, known as Trendelenburg gait Neutral postion Hip abductor musculature Hip adductor musculature Depression of the right pelvis (and elevation of the left pelvis) A C B Gluteus medius: The deltoid of the hip. a) Gluteus medius. b) Closed-chain motion of the pelvis at the hip joint by the gluteus medius. a b 15 (a falling of the pelvis toward the swing-leg side, similar to how models walk). It could be noted that the reverse/closed-chain function of the deltoid at the shoulder joint is also important because it acts to stabilize (and/or downwardly rotate) the L i s te n to T h e A B M P Po d c a s t a t a b m p.co m /p o d c a s t s o r w h e reve r yo u a cce s s yo u r favo r i te p o d c a s t s 103 Gluteus medius Piriformis