| musculus interosseus plantaris | <anatomy> Three intrinsic muscles of foot; origin, the medial side of the third, fourth, and fifth metatarsal bones; insertion, corresponding side of proximal phalanx of the same toes; action, adducts three lateral toes; nerve supply, lateral plantar. Synonym: musculus interosseus plantaris. (05 Mar 2000) |
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| musculus interosseus volaris | <anatomy> Three muscles in the hand; origin, first: ulnar side of second metacarpal; second and third: radial sides of fourth and fifth metacarpals; insertion, first: into ulnar side of index; second and third: into radial sides of ring and little fingers; action, adducts fingers toward axis of middle finger; nerve supply, ulnar. See: flexor pollicis brevis muscle. Synonym: musculus interosseus palmaris, musculus interosseus volaris. (05 Mar 2000) |
| musculus interspinalis cervicis | Origin, tubercle of spinous process of cervical vertebra; insertion, tubercle of spinous process of next superior vertebra; action, extends the neck; nerve supply, dorsal rami of cervical nerves. Synonym: musculus interspinalis cervicis, cervical interspinal muscle. (05 Mar 2000) |
| musculus interspinalis lumborum | Origin, superior margin of lumbar spinous process; insertion, inferior margin of next superior spinous process; action, extends lumbar vertebrae; nerve supply, dorsal primary rami of lumbar spinal nerves. Synonym: musculus interspinalis lumborum, lumbar interspinal muscle. (05 Mar 2000) |
| musculus interspinalis thoracis | Often poorly developed or absent muscles between spinous process of thoracic vertebrae; action, extends thoracic vertebrae; nerve supply, dorsal primary rami of thoracic nerves. Synonym: musculus interspinalis thoracis, thoracic interspinal muscle. (05 Mar 2000) |
| musculus intertragicus | An occasional muscle on the cranial surface of the auricle spanning the antitragohelicine fissure. Synonym: musculus incisurae helicis, musculus intertragicus. (05 Mar 2000) |
| musculus ischiocavernosus | <anatomy, muscle> Origin, ramus of ischium; insertion, corpus cavernosum penis (or clitoridis); action, compresses the crus of the penis (or clitoris) forcing blood in its sinuses into the distal part of the corpus cavernosum; nerve supply, perineal. Synonym: musculus ischiocavernosus, musculus erector clitoridis, musculus erector penis. (05 Mar 2000) |
| musculus ischiococcygeus | <anatomy, muscle> Origin, spine of ischium and sacrospinous ligament; insertion, sides of lower part of sacrum and upper part of coccyx; action, assists in support of pelvic floor, especially when intra-abdominal pressures increase; nerve supply, third and fourth sacral. Synonym: musculus coccygeus, coccygeal muscle, musculus ischiococcygeus. (05 Mar 2000) |
| musculus keratopharyngeus | See: middle constrictor muscle of pharynx. (05 Mar 2000) |
| musculus laryngopharyngeus | Origin, outer surfaces of thyroid (thyropharyngeal part) and cricoid (cricopharyngeal part, musculus cricopharyngeus; superior or upper oesophageal sphincter muscle) cartilages; insertion, pharyngeal raphe in the posterior portion of wall of pharynx; action, narrows lower part of pharynx in swallowing, the cricopharyngeal part has a sphincteric function for the oesophagus, allowing some voluntary control of eructation and reflux; nerve supply, pharyngeal plexus. Synonym: musculus constrictor pharyngis inferior, cricopharyngeus muscle, laryngopharyngeus, musculus laryngopharyngeus. (05 Mar 2000) |
| musculus latissimus dorsi | <anatomy, muscle> Origin, spinous processes of lower five or six thoracic and the lumbar vertebrae, median ridge of sacrum, and outer lip of iliac crest; insertion, with teres major into posterior lip of bicipital groove of humerus; action, adducts arm, rotates it medially, and extends it; nerve supply, thoracodorsal. Synonym: musculus latissimus dorsi, broadest muscle of back. (05 Mar 2000) |
| musculus levator alae nasi | Portion of musculus levator labii superioris alaeque nasi muscle inserting into wing of nose. (05 Mar 2000) |
| musculus levator anguli oris | <anatomy, muscle> Origin, canine fossa of maxilla; insertion, orbicularis oris and skin at angle of mouth; action, raises angle of mouth; nerve supply, facial. Synonym: musculus levator anguli oris, musculus caninus, musculus triangularis labii superioris. (05 Mar 2000) |
| musculus levator anguli scapulae | <anatomy, muscle> Origin, from posterior tubercles of transverse processes of four upper cervical vertebrae; insertion, into superior angle of scapula; action, raises the scapula; nerve supply, dorsal scapular nerve. Synonym: musculus levator scapulae, elevator muscle of scapula, musculus levator anguli scapulae. (05 Mar 2000) |
| musculus levator ani | <anatomy> Formed by pubococcygeus and iliococcygeus muscles; origin, posterior body of pubis, tendinous arch of the levator ani, and spine of ischium; insertion, anococcygeal ligament, sides of the lower part of the sacrum and of coccyx; action, resists prolapsing forces and draws the anus upward following defecation; supports the pelvic viscera; nerve supply, nerve to levator ani (fourth sacral spinal nerve). Synonym: musculus levator ani, elevator muscle of anus. (05 Mar 2000) |