| OCR Text |
Show 1885.] MYOLOGY OF THE WATER-OPOSSUM. 21 A thin sheet of muscular fibres passes from basioccipital to great cornu of hyoid and pharynx, and a deeper set pass to side of tongue, side of hyoid, and pharynx. Constrictor muscles form one sheet. Scalenus posticus.-Arises by muscular fibres from third rib, interdigitating with serratus magnus. It passes forwards to he inserted by a small tendon into second cervical transverse process. It is closely connected with following muscle. Scalenus anticus.-Arises from upper surface of first rib and is inserted by small tendons into second to sixth cervical transverse processes. Irachelo-mastoid.-Arises from all cervical transverse processes ; inserted into mastoid just behind cleido-mastoid. Tendinous intersection at its anterior fourth. Complexus.-Arises from transverse processes as low as fourth dorsal ; inserted into occiput. Tendinous intersection at its middle. Splenius.-Arises from spinous processes of all cervical and first two dorsal vertebrae. Inserted into, occipital crest and mastoid process under cover of trapezius and cleido-occipital. Its posterior fibres are continuous with serratus posticus superior. Muscles of Trunk. External oblique.-Arises by fleshy digitations from outer surfaces of third to thirteenth rib. Inserted into linea alba, tips and outer border of marsupial bone, and tendon, extending from anterior superior iliac spine to pubes just behind origin of pectineus. Internal oblique.-Very thin ventrally, thicker dorsally\ Arises from lumbar fascia and anterior part of iliac crest. Inserted into lower few ribs, becoming merged with lower interccstals, and into outer border of marsupial bone. Tendinous intersections continue the lower two ribs in this muscle for a short distance. Transversalis.--Consists of very thin fibres. Separated from last muscle by intercostal nerves. Pyramidalis.-Completely overlies rectus abdominis. Arises from inner border of marsupial bone by muscular fibres, and by tendinous fibres from its tip. The posterior fibres pass transversely inwards to linea alba, the upper fibres obliquely forwards, and those from tip of marsupial bone directly forwards to blend with rectus. Rectus abdominis.-Arises from inner border of marsupial bone. Fibres pass directly forwards and are inserted into first rib close to sternum, and to sternum in first intercostal space. Only one intersection was noticed situated at level of ensiform appendix. Serratus posticus superior.-Arises by fascia from all dorsal spinous processes excepting the last one. Inserted into third to twelfth ribs. Its anterior fibres are connected with splenius. Serratus posticus inferior.-Arises by tendinous fibres from eleventh to thirteenth dorsal vertebrae and from lumbar vertebrae behind this. Inserted into tenth to thirteenth ribs. Its fibres overlie serratus superior and are continuous behind with internal oblique. |
