_What are the Motions of the Thighs?_ The Thigh performs five kinds of Motions; for it is bent, extended, drawn within side and without, and turn'd round: All these Motions are produc'd by the means of fourteen Muscles, _viz._ three _Flexors_, three _Extensors_, three _Adductors_, three _Abductors_, and two _Obturators_ for the Circular Motion. The _Flexors_ of the Thigh are the _Psoas_, _Iliacus_, and _Pectineus_. The _Psoas_ or _Lumbaris_ is situated inwardly in the _Abdomen_, on the side of the _Vertebra's_. It proceeds from the transverse _Apophyses_ of the two lower _Vertebra's_ of the Back, and of the upper of the Loins, and lying on the inner Face of the _Os Ilion_, sticks to the lesser _Trochanter_ or _Rotator_. The _Iliacus Internus_ hath its Origine in all the Lips of the inner Cavity of the _Os Ilion_, and being joyn'd by a _Tendon_ to the _Lumbaris_, is inserted with it in the lesser _Trochanter_. {49} The _Pectineus_ takes its rise from the fore-part of the _Os Pubis_, and is united before to the Thigh-Bone a little below the lesser _Trochanter_. The _Extensors_ of the Thigh are the _Glutæus Major_, _Medius_, and _Minimus_. The _Glutæus Major_ springs forth out of the lateral part of the _Os Sacrum_, as also the hinder and outer part of the _Os Ilion_ and _Coccyx_, and enters into the Thigh-Bone, four Fingers breadth below the great _Trochanter_ or _Rotator_, being the thickest of all the Muscles of the Body. The _Glutæus Medius_, deducing its Original from the hinder and outward part of the _Os Ilion_, is inserted three Fingers breadth below the great _Trochanter_. The _Glutæus Minimus_ ariseth from the bottom of the Cavity of the _Os Ilion_, and is fasten'd to a small Hole near the great _Trochanter_. The _Adductors_ of the Thigh are the _Triceps Superior, Medius_, and _Inferior_. The _Triceps Superior_ hath its beginning in the top of the _Os Pubis_, and is terminated in the top of a Line, which is on the inside of the Thigh. The _Triceps Medius_ proceeding from the middle of the _Os Pubis_, is inserted in the Thigh-Bone a little lower than the _Triceps Superior_. The _Triceps Inferior_ hath its Source in the bottom of the _Os Pubis_, and is implanted in the Thigh-Bone, a little lower than the _Triceps Medius_. Some Anatomists make only one Muscle of these three, attributing thereto three Originals and three Insertions. These Muscles serve to draw the Thighs one against another. The _Abductors_ of the Thigh are the _Iliacus Externus_, or _Pyriformis_, the _Quadratus_, and the _Gemelli_. {50} The _Pyriformis_ arising from the upper and lateral part of the _Os Sacrum_, and the the _Os Ilion_ cleaves to the Neck of the great _Trochanter_. The _Quadratus_ or square Muscle of the Thigh takes its Origine from the external Prominence of the _Os Ischion_, and adheres to the outward part of the great _Trochanter_.