| semisextile | <astronomy> An aspect of the planets when they are distant from each other the twelfth part of a circle, or thirty degrees. Source: Websters Dictionary (01 Mar 1998) |
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| semispinal | Half spinal; denoting muscles attached in part to the spinous processes of the vertebrae. (05 Mar 2000) |
| semispinal muscle | <anatomy> The most superficial layer of the three layers of the transversospinal muscle; comprised of semispinalis capitis, semispinalis cervicis, and semispinalis thoracis muscles. Synonym: musculus semispinalis, semispinal muscle. (05 Mar 2000) |
| semispinal muscle of head | <anatomy, muscle> Origin, transverse processes of five or six upper thoracic and articular processes of four lower cervical vertebrae; insertion, occipital bone between superior and inferior nuchal lines; action, rotates head and draws it backward; nerve supply, dorsal primary rami of cervical spinal nerves. Synonym: musculus semispinalis capitis, musculus complexus, semispinal muscle of head. (05 Mar 2000) |
| semispinal muscle of neck | <anatomy> Continuous with musculus semispinalis thoracis; origin, transverse processes of second to fifth thoracic vertebrae; insertion, spinous processes of axis and third to fifth cervical vertebrae; action, extends cervical spine; nerve supply, dorsal primary rami of cervical and thoracic spinal nerves. Synonym: musculus semispinalis cervicis, musculus semispinalis colli, semispinal muscle of neck. (05 Mar 2000) |
| semispinal muscle of thorax | <anatomy, muscle> Origin, transverse processes of fifth to eleventh thoracic vertebrae; insertion, spinous processes of first four thoracic and fifth and seventh cervical vertebrae; action, extends vertebral column; nerve supply, dorsal primary rami of cervical and thoracic spinal nerves. Synonym: musculus semispinalis thoracis, musculus semispinalis dorsi, semispinal muscle of thorax. (05 Mar 2000) |
| semispinalis capitis | <anatomy, muscle> Origin, transverse processes of five or six upper thoracic and articular processes of four lower cervical vertebrae; insertion, occipital bone between superior and inferior nuchal lines; action, rotates head and draws it backward; nerve supply, dorsal primary rami of cervical spinal nerves. Synonym: musculus semispinalis capitis, musculus complexus, semispinal muscle of head. (05 Mar 2000) |
| semispinalis cervicis muscle | <anatomy> Continuous with musculus semispinalis thoracis; origin, transverse processes of second to fifth thoracic vertebrae; insertion, spinous processes of axis and third to fifth cervical vertebrae; action, extends cervical spine; nerve supply, dorsal primary rami of cervical and thoracic spinal nerves. Synonym: musculus semispinalis cervicis, musculus semispinalis colli, semispinal muscle of neck. (05 Mar 2000) |
| semispinalis muscle | <anatomy> The most superficial layer of the three layers of the transversospinal muscle; comprised of semispinalis capitis, semispinalis cervicis, and semispinalis thoracis muscles. Synonym: musculus semispinalis, semispinal muscle. (05 Mar 2000) |
| semispinalis thoracis | <anatomy, muscle> Origin, transverse processes of fifth to eleventh thoracic vertebrae; insertion, spinous processes of first four thoracic and fifth and seventh cervical vertebrae; action, extends vertebral column; nerve supply, dorsal primary rami of cervical and thoracic spinal nerves. Synonym: musculus semispinalis thoracis, musculus semispinalis dorsi, semispinal muscle of thorax. (05 Mar 2000) |
| Semisulcospina | A genus of operculate snails (family Pleuroceriidae, subclass Prosobranchiata). An oriental form, Semisulcospina libertina, is the first intermediate host of a number of trematodes, including Paragonimus westermani. Origin: semi-+ L. Sulcus, a furrow + spina, thorn, spine (05 Mar 2000) |
| semisulcus | A slight groove on the edge of a bone or other structure, which, uniting with a similar groove on the corresponding adjoining structure, forms a complete sulcus. (05 Mar 2000) |
| semisulfur mustard | 2-(2-chloroethylthio)ethanol An antineoplastic agent. Synonym: mustard chlorohydrin, semisulfur mustard. (05 Mar 2000) |
| semisupination | The attitude or assumption of a partly supine position. (05 Mar 2000) |
| semisupine | Denoting semisupination. (05 Mar 2000) |