. The development of the human body : a manual of human embryology. Embryology; Embryo, Non-Mammalian. 204 THE TRUNK MUSCULATURE The table on page 203 will show the relation of the various trunk muscles to the portions of the myotomes. The intimate association between the pelvic girdle and the axial skeleton brings about extensive modifications of the posterior trunk myotomes. So far as their dorsal portions are concerned probably all these myotomes as far back as the fifth sacral are represented in the sacro-spinalis, but the ventral portions from the first lumbar myotome onward are greatly m
. The development of the human body : a manual of human embryology. Embryology; Embryo, Non-Mammalian. 204 THE TRUNK MUSCULATURE The table on page 203 will show the relation of the various trunk muscles to the portions of the myotomes. The intimate association between the pelvic girdle and the axial skeleton brings about extensive modifications of the posterior trunk myotomes. So far as their dorsal portions are concerned probably all these myotomes as far back as the fifth sacral are represented in the sacro-spinalis, but the ventral portions from the first lumbar myotome onward are greatly modified. The last myotome taking part in the formation of the rectus abdominis is the twelfth thoracic and the last to be represented in the lateral musculature of the. A B Fig. 121.—Perineal Region of Embryos of (A) Two Months and (25) Four to Five Months, showing the Development of the Perineal Muscles. dc, Nervus dorsalis clitoridis; p, pudendal nerve; sa, sphincter ani; sc sphincter cloacae; sv, sphincter vaginse.—{Popowsky.) abdomen is the first lumbar, the ventral portions of the remaining lumbar and of the first and second sacral myotomes either having disappeared or being devoted to the formation of the musculature of the lower limb. The ventral portions of the third and fourth sacral myotomes are represented, however, by the levator ani and coccygeus, and are the last myotomes which persist as muscles in the human body, although traces of still more posterior myotomes are to be found in muscles such as the curvator coccygis sometimes developed in connection with the coccygeal vertebrae. The perineal muscles and the external sphincter ani are also. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original McMurrich, J. Playfair (James Playfair), 1859-1939. Philadelphia : P. Blakiston's son & co.
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Keywords: ., bookautho, bookcentury1900, bookdecade1910, booksubjectembryology
