Triceps BrachiiThe triceps brachii is the primary extensor of theforearm (the antagonist of the biceps brachii) (fig. 1-29).It originates at two points on the humerus and one on thescapula. These three heads join to form the large muscleon the posterior surface of the upper arm. The point ofinsertion is the olecranon process of the ulna.Latissimus DorsiThe latissimus dorsi is a broad, flat muscle thatcovers approximately one-third of the back on eachside (figs. 1-28 and 1-29). It rotates the arm inward anddraws the arm down and back. It originates from theupper thoracic vertebrae to the sacrum and theposterior portion of the crest of the ilium. Its fibersconverge to form a flat tendon that has its insertion inthe humerus.GluteusThe gluteus (maximus, minimus (not shown), andmedius) are the large muscles of the buttocks, whichextend and laterally rotate the thigh, as well as abductand medially rotate it (fig. 1-29). They arise from theilium, the posterior surface of the lower sacrum, andthe side of the coccyx. Their points of insertion includethe greater trochanter and the gluteal tuberosity of thefemur. The gluteus maximus is the site of choice forintramuscular injections.1-21HM3F0129STERNOCLEIDO-MASTOIDDELTOIDTRICEPSBRACHIIGRACILISGASTROCNEMIUSSOLEUSVASTUSLATERALISSARTORIUSLATISSIMUSDORSITRAPEZIUSGLUTEUSMEDIUSGLUTEUSMAXIMUSBICEPSFEMORISDELTOIDTEMPORALISFigure 1-29.—Posterior view of superficial skeletal muscles.
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business