Excerpted from Muscle, The Gripping Story of Strength and Movement, Chapter One, Discovery and Description
Length determines the name for some muscles. Thumb in Latin is pollux, and it has two muscles that fold (flex) the thumb across the palm— the flexor pollicis longus and flexor pollicis brevis. Size matters too. I am guessing that you are presently sitting on your gluteus maximus muscles. (Gluteus comes from Greek gloutos, buttock.)
Between the gluteus maximus and the pelvis are the gluteus medius and gluteus minimus muscles. And smack against the backof the hip joint is a matched pair of small muscles, the superior and inferior gemelli— twins. In the abdominal wall, alignment is everything. The rectus (straight) abdominis (the highly valued “six-pack”) runs longitudinally, while the obliquus externus abdominis and transversus abdominis run their separate routes.
Other muscles resemble geometric shapes and are so named.
There are three “quadratus” (square) muscles. One is in the foot,
one is deep in the forearm, and the other crosses the hip joint. The
rhomboid major and minor are parallelogram-shaped muscles that
attach on the thoracic spine and the shoulder blade; and the deltoid,
crossing over the top of the shoulder, is the shape of the Greek letter
Δ. The serratus anterior has a jagged origin from multiple ribs on
the front of the chest, and the gracilis is indeed slender or gracile— a
long, thin muscle on the inner thigh.
Several muscles’ names describe their action. The cremaster (a
muscle that lifts the testicle) derives its name from the Greek verb
for “I hang,” and the levator scapulae raises the shoulder blade.
A few muscles’ names simply identify their origins and insertions.
For instance, the sternocleidomastoid is the strappy muscle on the
side of the neck that turns your head to the side. One end attaches
on the breastbone (sterno) and collarbone (clavicle, cleido) and the
other end fastens to the mastoid process of the skull, which is palpable
just behind the earlobe.
Some muscles received names of objects they resemble. Piriformis, a hip muscle, is pear-shaped. The deep calf muscle, the soleus, is sandal-shaped. Overlying it is the bulgy gastrocnemius, literally the belly of the leg. In each palm and sole are four worm-shaped muscles, lumbricales manus and lumbricales pedis, respectively. The Latin name for earthworm is Lumbricus.
My favorite muscle name is sartorius, which applies to the longest muscle in the body. It starts high on the pelvic rim, crosses the front of the thigh, and finishes on the inside of the leg just below the knee. Contracting the sartorius on both sides causes the hips to flex, the thighs to rotate outward, and the knees to flex, resulting in the owner ending up in a cross- leg sitting position. This is the position that tailors traditionally assumed when working on garments in their laps. Sartor in Latin means tailor, hence sartorius’s name.
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