the thorax) subserve respiration (muscles of respiration, including intercostal muscles). The Muscles of the Trunk The muscles of the trunk include back, thoracic, and abdominal muscles as well as diaphragm The Back _ Segmental muscles of the back: m. erector spinae _ Muscles encroaching on the back: mm. trapezius, rhomboideus major and minor, together with levator scapulae (shoulder girdle muscle) and latissimus dorsi (muscle of the upper extremity) The Thoracic Wall _ Intercostal muscles (external, internal, intimi)—inspiration, expiration; scalenus muscles—inspiration _ Muscles encroaching on the trunk: m. serratus anterior—abduction of the arm, auxiliary muscle of respiration; m. pectoralis major—adduction, internal rotation of the upper arm, auxiliary muscle of respiration; sternocleidomastoid muscle, also auxiliary muscle of respiration. The Abdominal Wall Muscles: m. rectus abdominis, external and internal oblique muscles, mm. transversus abdominis, psoas major, and quadratus lumborum— rotation, flexion, lateral inclination of the trunk, compression of the abdomen. The Diaphragm The most important muscle of respiration (contraction—inspiration, relaxation—expiration). The Pelvic Floor Levator ani muscle—forms the pelvic diaphragm; m. transversus perinei profundus—forms the urogenital diaphragm; medial part of the levator ani (puborectalis), m. sphincter ani externus—voluntary constriction of the anus; m. sphincter urethrae—voluntary constriction of the urethra. 4 The Locomotor System (Musculoskeletal System) Vegetativ nerv sistemasining organizm ichki muhiti doimiyligini saqlashda ishtiroki ayniqsa muhim ahamiyatga ega. a Chunonchi, masalan, havo haroratining ko’tarilishi, ter ajralishining kuchayishi, shuningdek periferik qon tomirlar sistemasining kengayishi hisobiga issiqlik ajratish bilan o’tadi. Bularning hammasi tana xaroratini doimiy darajada tutib turish imkonini beradi va organizmning issiqlab ketishiga to’siqlik qiladi. Ko’p qon yo’qotish xollarida yurak ritmining tezlashuvi kuzatiladi, tomirlar torayadi va umumiy qon aylanishi doirasiga to’qimalar va organlardan normal qon aylanishni ta`minlaydigan taloqdagi depolangan qon otilib chiqadi.
