November 11 Lecture - November 11, 2008 Muscles of the...

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November 11, 2008 Muscles of the Trunk Muscles that Make up the Body Wall - Respiratory Diaphragm (Diaphragm) o Sheet of muscle (transverse muscle) that separates the thoracic cavity from the abdominal cavity o Attach to the body wall and around vertebral column o Centre of diaphragm is a leaf-shaped tendon, which serves as anchorage from muscle to contract against o Number of important structures much move through the diaphragm Aorta Inferior vena cava Esophagus Vertebrae Number of nerves o When muscle contracts, thoracic cavities volume is increased, and when diaphragm relaxes, thoracic cavity volume is decreased (increasing pressure in the cavity) Diaphragm contraction will compress abdominal cavity and diaphragm relaxation expands abdominal cavity o Main function: adjust pressure between abdomen and thorax Muscles of the Floor of the Pelvis - Muscles form sheet-like muscular structure (sometimes referred to as pelvic diaphragm) - Whole floor of the pelvis is comprised of muscle known as levator ani, which is further subdivided into iliococcygeus muscle and pubococcygeus muscle o In male, pubococcygeus muscle is attached to prostate gland o In female, pubococcygeus muscle forms sphincter around vagina o Another portion of pubococcygeus muscle entends posteriorly towards the rectum, known as the puborectalis muscle Muscle forms a sling, supporting the rectum and lower end of the large intestine Purpose in forming a sling: holds the lower end of the bowl at right angles to rectum and anal canal. During defecation, muscle must relax in order to allow fecal material to be excreted Muscles of the Perineal Area - Muscles associated with anus and external genitalia - Bulbocavernosus and Ischiocaverosus o In males, makes up the base of the penis o In females, bulbocavernosus surrounds the vagina and forms external vagina sphincter while ischiocavernosus attaches to clitoris at region - External anal sphincter surrounds anal canal and forms external anal sphincter (regulates terminal portion of GI tract) found in BOTH sexes
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Muscles of the Shoulder - Supraspinatus - Infraspinatus - Subscapularis o Located on anterior side of scapula - Tendons radiate outwards and attach to tubercles of humerus (proximal portion) - Fibres arise from flattened surface of the scapula o Supraspinatus: fibres arise from above the spine o Intraspinatus fibres are arising from large area below scapular spine - Teres minor and teres major o Arise from axilary or medial portion of scapula and insert on upper portion of the humerus - Deltoid muscle o Large muscle mass on lateral side of upper arm that extends out over entire shoulder joint (covering all above muscles)
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This note was uploaded on 10/23/2011 for the course BIOL 2125 taught by Professor Dr.park during the Winter '02 term at A.T. Still University.

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November 11 Lecture - November 11, 2008 Muscles of the...

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