| Sibson's muscle | <anatomy> An occasional independent muscular fasciculus between the scalenus anterior and medius, and having the same action and innervation. Synonym: musculus scalenus minimus, Albinus' muscle, Sibson's muscle, smallest scalene muscle. (05 Mar 2000) |
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| skeletal muscle | <anatomy, pathology> A rather non-specific term usually applied to the striated muscle of vertebrates that is under voluntary control. The muscle fibres are syncytial and contain myofibrils, tandem arrays of sarcomeres. (18 Nov 1997) |
| skeletal muscle fibres | Multinucleated contractile cells varying from less than 10 to 100 um in diameter and from less than 1 mm to several centimeters in length; the fibre consists of sarcoplasm and cross-striated myofibrils, which in turn consist of myofilaments; human skeletal muscles are a mixture of red, white, and intermediate type fibre's. (05 Mar 2000) |
| skeletal muscle tissue | <anatomy, pathology> A rather non-specific term usually applied to the striated muscle of vertebrates that is under voluntary control. The muscle fibres are syncytial and contain myofibrils, tandem arrays of sarcomeres. (18 Nov 1997) |
| skeletal muscle ventricle | Autologous skeletal muscle that is wrapped around the heart and electrically stimulated in order to provide mechanical heart assistance. The latissimus dorsi muscle is commonly used to form this ventricle that functions to independently augment cardiac performance by pumping in series with the heart. (12 Dec 1998) |
| skin-muscle reflexes | Superficial or cutaneous reflex's, such as the superficial abdominal reflex's. Synonym: skin reflexes. (05 Mar 2000) |
| slow muscle | <physiology> Striated muscle used for long term activity (e.g. Postural support). Depend therefore on oxidative metabolism and have many mitochondria and abundant myoglobin. (18 Nov 1997) |
| smaller muscle of helix | <anatomy> A band of oblique fibres covering the crus of the helix of the auricle. Synonym: musculus helicis minor, smaller muscle of helix. (05 Mar 2000) |
| smaller pectoral muscle | <anatomy, muscle> Origin, third to fifth ribs at the costochondral articulations; insertion, tip of coracoid process of scapula; action, draws down scapula or raises ribs; nerve supply, medial pectoral nerve. Synonym: musculus pectoralis minor, smaller pectoral muscle. (05 Mar 2000) |
| smaller posterior rectus muscle of head | <anatomy, muscle> Origin, from posterior tubercle of atlas; insertion, medial third of inferior nuchal line of occipital bone; action, rotates head and draws it backward; nerve supply, dorsal branch of first cervical (suboccipital). See: suboccipital muscles. Synonym: musculus rectus capitis posterior minor, musculus rectus capitis posticus minor, smaller posterior rectus muscle of head. (05 Mar 2000) |
| smaller psoas muscle | <anatomy> An inconstant muscle, absent in about 40%; origin, bodies of twelfth thoracic and first lumbar vertebrae and disk between them; insertion, iliopubic eminence via iliopectineal arch (iliac fascia); action, assists in flexion of lumbar spine; nerve supply, lumbar plexus. Synonym: musculus psoas minor, smaller psoas muscle. (05 Mar 2000) |
| smallest scalene muscle | <anatomy> An occasional independent muscular fasciculus between the scalenus anterior and medius, and having the same action and innervation. Synonym: musculus scalenus minimus, Albinus' muscle, Sibson's muscle, smallest scalene muscle. (05 Mar 2000) |
| smooth muscle | <anatomy, pathology, physiology> Muscle tissue in vertebrates made up from long tapering cells that may be anything from 20-500m long. Smooth muscle is generally involuntary and differs from striated muscle in the much higher actin/myosin ratio, the absence of conspicuous sarcomeres and the ability to contract to a much smaller fraction of its resting length. Smooth muscle cells are found particularly in blood vessel walls, surrounding the intestine (particularly the gizzard in birds) and in the uterus. The contractile system and its control resemble those of motile tissue cells (e.g. Fibroblasts, leucocytes) and antibodies against smooth muscle myosin will cross react with myosin from tissue cells, whereas antibodies against skeletal muscle myosin will not. See: dense bodies. (18 Nov 1997) |
| smooth muscle relaxant | An agent, such as an antispasmodic, bronchodilator, or vasodilator, that reduces the tension or tone of smooth (involuntary) muscle. (05 Mar 2000) |
| smooth muscle tissue | <anatomy, pathology, physiology> Muscle tissue in vertebrates made up from long tapering cells that may be anything from 20-500m long. Smooth muscle is generally involuntary and differs from striated muscle in the much higher actin/myosin ratio, the absence of conspicuous sarcomeres and the ability to contract to a much smaller fraction of its resting length. Smooth muscle cells are found particularly in blood vessel walls, surrounding the intestine (particularly the gizzard in birds) and in the uterus. The contractile system and its control resemble those of motile tissue cells (e.g. Fibroblasts, leucocytes) and antibodies against smooth muscle myosin will cross react with myosin from tissue cells, whereas antibodies against skeletal muscle myosin will not. See: dense bodies. (18 Nov 1997) |