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Show 1^87.] ANATOMY OF HYDROMYS. 57 This represents the intercolumnar fascia of human anatomy. From the lower border of the combined internal oblique and transversalis a number of muscular fibres pass on to the same process and surround it as a series of rings nearly to its lower end. There is a large erector penis overlying the crus of either side, but no transversus perinei. The bulbus urethrae is double, and each half is overlaid by a muscular sheet which joins its fellow of the opposite side in a raphe on the lower surface of the penis ; posteriorly the two halves unite behind the rectum, round which tube they form a kind of sling. In the angle between this last muscle (accelerator urinae) and erector penis lies Cowper's gland. The psoas and iliacus muscles are both large and differ in no respect from the normal. There is no psoas parvus. Rectus abdominis is attached to the second rib. Muscles of the Lower Extremity.-The exterior of the buttock is covered by a large sheet of muscle arising from (1) crest of ilium, (2) under the anterior superior spine of the ilium, (3) by means of an aponeurosis from all the vertebrae from the last lumbar to the last sacral inclusive. It is inserted into (1) the third trochanter at the middle of the femur; (2) the larger part into the fascia on the outer side of the thigh and leg and the upper part of the patella. As there is no separate tensor vaginae femoris or sartorius, this muscular sheet would appear to represent these two in fusion with gluteus maximus. Gluteus medius is very large ; its anterior fibres are inserted into the outer edge of the great trochanter, its posterior into the femur inferior and anterior to this process. Gluteus minimus arises from the concavity of the ilium, and is inserted by tendon into the upper part of tbe great trochanter. There is no separate or intrapelvic pyriformis; part of the fibres of the gluteus minimus arising from the edge of the sacrum close to the sacro-sciatic foramen appear to represent this muscle. Biceps is very large, and arises (1) superficially from the upper caudal vertebrae by fascia ; (2) deeper, from the tuberosity of the ischium. The two parts unite, and are inserted (1) by fascia into the outer part of the patella; (2) by tendon into the process near the head of the fibula; (3) by fascia into the whole of the front of the leg as far down as the back of the heel. Thus the entire of the thigh and leg below gluteus maximus is covered by this large muscular sheet. Semitendinosus is single-headed and arises from the tuberosity and adjacent portion of the ischium; it is inserted into the crest of the tibia below the gracilis. Semimembranosus, which is very much smaller than either of the other hamstring muscles, is inserted into the upper part of the posterior aspect of the internal condyle of the femur. Rectus femoris has a single tendon with a double attachment, viz. under the acetabulum and to the margin of the ilium. There is a scansorius arising from the entire of the anterior edge of the ileum. Pectineus consists of two distinct parts-(1) Internal, which is thin and arises from the inner part of the linea ileo-pectinea, some of its fibres underlying the outermost of gracilis ; this portion is inserted |
