| intercostal muscles | Respiratory muscles that arise from the lower border of one rib and insert into the upper border of the adjoining rib, and contract during inspiration or respiration. (12 Dec 1998) |
|---|---|
| intermediate layer of the transversospinalis muscles | <anatomy, muscle> Origin, from the sacrum, sacroiliac ligament, mamillary processes of the lumbar vertebrae, transverse processes of thoracic vertebrae, and articular processes of last four cervical vertebrae; insertion, into the spinous processes of all the vertebrae up to and including the axis; action, rotates vertebral column; nerve supply, dorsal primary rami of spinal nerves. Synonym: musculus multifidus, intermediate layer of the transversospinalis muscles, musculus multifidus spinae. (05 Mar 2000) |
| interosseous muscles | Muscles which arise from and run between the long (metacarpal and metatarsal) bones of the hand and foot, extending to and producing movement of the digits. See: dorsal interosseous muscles of foot, dorsal interosseous muscles of hand, palmar interosseous muscle, plantar interosseous muscle. Synonym: musculi interossei. (05 Mar 2000) |
| interspinales muscles | The paired muscles between spinous processes of adjacent vertebrae; subdivided into cervical, thoracic, and lumbar muscles. Synonym: musculi interspinales, interspinal muscles. (05 Mar 2000) |
| interspinal muscles | The paired muscles between spinous processes of adjacent vertebrae; subdivided into cervical, thoracic, and lumbar muscles. Synonym: musculi interspinales, interspinal muscles. (05 Mar 2000) |
| intertransversarii muscles | The paired muscles between transverse processes of adjacent vertebrae; there are anterior and posterior muscles in the cervical region; lateral and medial muscles in the lumbar region; and single muscles in the thoracic region. Synonym: musculi intertransversarii, intertransverse muscles. (05 Mar 2000) |
| intertransverse muscles | The paired muscles between transverse processes of adjacent vertebrae; there are anterior and posterior muscles in the cervical region; lateral and medial muscles in the lumbar region; and single muscles in the thoracic region. Synonym: musculi intertransversarii, intertransverse muscles. (05 Mar 2000) |
| intrinsic muscles | Muscles fully contained (origin, belly, and insertion) within the structure under consideration. For example, the interossei and lumbrical muscles are intrinsic muscles of the hand. (05 Mar 2000) |
| intrinsic muscles of foot | Muscles fully contained (origin, belly, insertion) in the foot and toes. These muscles are arranged in four layers and all are innervated by the plantar branches of the tibial nerve. Although they may be capable of producing the actions described under their individual entries, as a group the primary function of the intrinsic muscles of the foot is to provide dynamic support of the longitudinal arch of the foot, resisting the forces which act momentarily to spread the arch during walking and running. (05 Mar 2000) |
| involuntary muscles | Muscle's not ordinarily under control of the will; except in the case of the heart, they are smooth (nonstriated) muscle's, innervated by the autonomic nervous system. (05 Mar 2000) |
| ocular muscles | The voluntary muscles which control eye movement (27 Sep 1997) |
| oculomotor muscles | Muscles of the eye that include musculi bulbi (extraocular), musculus orbicularis oculi (eyelids), and musculus orbitalis. These control the eye and surrounding structures. (12 Dec 1998) |
| Oehl's muscles | Strands of muscle fibres in the chordae tendineae of the left atrioventricular valve. (05 Mar 2000) |
| tendon sheath of abductor pollicis longus and extensor pollicis brevis muscles | The synovial sheath lining the compartment of the extensor retinaculum that contains the abductor pollicis longus and extensor pollicis brevis tendons. Synonym: vagina tendinum musculorum abductoris longi et extensoris brevis pollicis. (05 Mar 2000) |
| tendon sheath of extensor carpi radialis muscles | The synovial sheath lining the compartment of the extensor retinaculum containing the tendons of the extensor carpi radialis longus and brevis muscles. Synonym: vagina tendinum musculorum extensorum carpi radialium. (05 Mar 2000) |