LINGUIST 3F03 Lecture Notes - Lecture 8: Intercostal Muscle, Thoracic Cavity, Accessory Muscle
27 Nov 2018
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Document Summary
Sternal head, costal head, vertebral head - diaphragm muscle: only the origin is different. The primary muscle of inspiration is the diaphragm, the dividing line between the thorax and the abdomen. The bers of the diaphragm pull on the central tendon, resulting in the downward motion of the diaphragm during inspiration. This movement expands the lungs in the vertical dimension. Accessory muscles of thorax and neck help to promote inspiration: elevate the rib cage, expand the rib cage. A person can survive on diaphragmatic support without accessory muscles: quiet inspiration (tidal respiration) - only need diaphragm, forced inspiration - need accessory muscles. Anterior thoracic muscles of inspiration: external intercostal (main contributor to the anterior-posterior volume change of the thoracic cavity) More towards the front of the cavity: internal intercostal (interchondral (part between the cartilages - sternum meets the bony part of the ribs) portion)
