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Gemellus Muscles: Superior & Inferior

Instructor: Artem Cheprasov
This lesson goes over a pair of muscles called gemellus superior and gemellus inferior. You'll learn about their origins, insertions, vascular supply, innervation, and actions.

Gemelli

Let's start this science lesson with a bit of astrology and grammar. Are you a Gemini? If so, you might as well be a Gemelli, not a Gemeni.

You probably know that Gemini are astrological twins. The word Gemini comes to us from ''geminus,'' which means twin in Latin, while ''gemeni'' means twins. The diminutive of ''geminus'' is ''gemellus.'' So, ''gemelli'' refers to twins as well.

And so this lesson is going to be about the so-called twin muscles known as gemellus superior and gemellus inferior.

Origin & Insertion

These might as well be fraternal twins as opposed to identical twins because they are not exactly the same (as you're about to learn).

Gemellus superior is smaller than gemellus inferior and might even be absent in some people. Gemellus superior originates from the dorsal aspect of the ischial spine. What does this mean? When we say dorsal, we are referring to the back or toward the back. The ischial spine is a triangular protrusion, sort of like a spine bone might have, of the ischium. The ischium is one part of the pelvic bone.

Gemellus superior inserts on the medial surface of the greater trochanter. When we say medial, we are referring to the side that is closest to the midline of the person. So it's the ''inner'' side of something. The greater trochanter is a prominent bony projection on the femur (the thigh bone).

The gemellus inferior muscle originates from the upper portion of the lateral surface of the ischial tuberosity. When we say lateral, we are referring to something that is opposite of medial. So it's toward the side as opposed to toward the midline. The ischial tuberosity is a portion of the ischium that you sit on. The gemellus inferior inserts onto the medial surface of the greater trochanter, just like the gemellus superior.

The gemellus superior (in red) and the gemellus inferior (below it).
The gemellus superior (in red) and the gemellus inferior (below it).

Blood Supply, Innervation, & Actions

Gemellus superior is supplied with blood by the inferior gluteal and internal pudendal arteries, while gemellus inferior is supplied with blood by the medial circumflex femoral artery.

Gemellus superior is innervated by the nerve to obturator internus, which is formed from portions of the L5, S1, and S2 spinal nerves. Gemellus inferior is innervated by the nerve to quadratus femoris, which is composed of portions of L4, L5, and S1.

Both gemellus superior and gemellus inferior act to perform the following functions:

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