The Obturator Externus ariseth from the outward Circumference of the same Hole of one Ischion, and is terminated in the side of the other near the great Trochanter.
What are the Motions of the Leg, and what are its Muscles?
The Leg is mov'd four several ways, that is to say, it is bent, extended, and drawn inward and outward, by the means of eleven Muscles viz. three Flexors, four Extensors, two Adductors and two Abductors.
The three Flexors of the Leg are the Biceps, the Semi-nervosus, and the Semi-membranosus.
The Biceps hath two Heads, the longer whereof cometh out of the bottom of the Prominence
of the Ischion, and the other from the middle and exterior part of the Femur, and is terminated in the outward and upper part of the Epiphysis of the Perone or Fibula.
The Semi-nervosus hath its Origine in the Knob of the Ischion, and is join'd backward to the top of the Epiphysis of the Tibia. These three Muscles are plac'd in the back-part of the Thigh below the Buttocks.
The four Extensors of the Leg are the Rectus, the Vastus Internus, the Vastus Externus, and the Crureus.
The Rectus or streight Muscle of the Leg takes its rise from the fore-part and the bottom of the Ilion, and descends in a right Line: It covers with its Tendon, which is common to the three following, the whole Knee-Pan, and adheres to the top of the Tibia, on the fore-part.
The Vastus Internus, being situated on the inside of the Thigh, hath its beginning in the top of the Thigh inwardly, and a little below the lesser Trochanter or Rotator: Afterward it is ty'd to the Tibia by a large Tendon, common thereto with the preceeding.