| Bowman's muscle | <anatomy> The smooth muscle of the ciliary body; it consists of circular fibres (Muller's muscle) and radiating fibres (meridional fibres, or Brucke's muscle); action, in contracting, its diameter is reduced (like a sphincter), reducing tensile (stretching) forces on lens, allowing it to thicken for near vision (accommodation). Synonym: musculus ciliaris, Bowman's muscle, ciliary ligament. (05 Mar 2000) |
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| brachial muscle | <anatomy, muscle> Origin, lower two-thirds of anterior surface of humerus; insertion, coronoid process of ulna; action, flexes elbow; nerve supply, musculocutaneous, usually with a minor contribution from the radial. Synonym: musculus brachialis, brachial muscle. (05 Mar 2000) |
| brachiocephalic muscle | In animals, a compound muscle passing from the brachium or humerus to the head and the dorsal cervical raphe; the clavicular insertion or clavicle subdivides the muscle. Synonym: brachiocephalic muscle. (05 Mar 2000) |
| brachioradial muscle | <anatomy, muscle> Origin, lateral supracondylar ridge of humerus; insertion, front of base of styloid process of radius; action, flexes elbow and assists slightly in supination; nerve supply, (common) radial. Synonym: musculus brachioradialis, brachioradial muscle. (05 Mar 2000) |
| branch of glossopharyngeal nerve to stylopharyngeus muscle | <anatomy> Sole motor branch of the glossopharyngeal nerve to the stylopharyngeus muscle. Synonym: ramus musculi stylopharyngei nervi glossopharyngei. (05 Mar 2000) |
| Braune's muscle | <anatomy> The medial part of the musculus levator ani (pubococcygeus muscle) that passes from the body of the pubis around the anus to form a muscular sling at the level of the anorectal junction; it contracts to increase the perineal flexure during a peristalsis to maintain faecal continence and relaxes to allow defecation. Synonym: musculus puborectalis, Braune's muscle, puborectal muscle. (05 Mar 2000) |
| broadest muscle of back | <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) |
| bronchoesophageal muscle | <anatomy> Muscular fascicles, arising from the wall of the left bronchus, which reinforce the musculature of the oesophagus. Synonym: musculus bronchoesophageus. (05 Mar 2000) |
| Brucke's muscle | <anatomy> The part of the ciliary muscle formed by the meridional fibres. Synonym: Crampton's muscle. (05 Mar 2000) |
| bulbocavernosus muscle | <anatomy> In the male: origin, the perineal membrane fascia on the dorsum of the bulb of the penis; insertion, central tendon of the perineum and the median raphe on the free surface of the bulb; action, constricts bulbous urethra when attempting to expel last drops following urination, or spasmodically with ejaculation to expel semen. In the female: origin, the dorsum of the clitoris, the corpus cavernosum, and the perineal membrane; insertion, central tendon of the perineum; action, acts as a weak sphincter of the vagina; when developed, is a part of "cross-member musculature" of pelvic floor which resists prolapse of pelvic viscera. Nerve supply, pudendal (deep perineal branch). Synonym: musculus bulbospongiosus, musculus bulbocavernosus, musculus ejaculator seminis, musculus sphincter vaginae, sphincter vaginae. (05 Mar 2000) |
| bursa of extensor carpi radialis brevis muscle | <anatomy> The bursa between the tendon of the extensor carpi radialis brevis and the base of the third metacarpal. Synonym: bursa musculi extensoris carpi radialis brevis. (05 Mar 2000) |
| bursa of tensor veli palatini muscle | <anatomy> A small bursa located where the tendon of the tensor passes around the pterygoid hamulus. Synonym: bursa musculi tensoris veli palatini. (05 Mar 2000) |
| bursa of the piriformis muscle | <anatomy> A small bursa located between the tendons of the piriformis and superior gemellus and the femur. Synonym: bursa musculi piriformis. (05 Mar 2000) |
| cardiac muscle | <anatomy> Tissue specialised for contraction. See twitch muscle, catch muscle: Cardiac muscle (heart muscle) is a striated but involuntary muscle responsible for the pumping activity of the vertebrate heart. The individual muscle cells are joined through a junctional complex known as the intercalated disc and are not fused together into multinucleate structures as they are in skeletal muscle. Skeletal muscle is 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. Smooth muscle is 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 (especially the gizzard in birds) and in the uterus. The contractile system and its control resemble those of motile tissue cells (for example 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) |
| cardiac muscle tissue | See: cardiac muscle. (05 Mar 2000) |