Which muscle is inserted into the floor of the intertubercular sulcus of the humerus?

Ans. is 'a' i.e., Latissimus dorsi o The shaft of humerus is cylindrical in the upper half and triangular on cross-section in the lower half. The upper part has intertnbercular sulcus {bicipital groove) anteriorly. Bicipital groove contains long head of biceps w ith its synovial sheath and an ascending branch of anterior circumflex humeral artery. Middle third of posterior surface of shaft of the humerus has a spiral groove {radial groove) which contains radial nerve and profunda brachi vessels.o Attachment to shafts are -Insertions of pectoralis major (on lateral lip of bicipital groove), latissimus dorsi (on floor of bicipital groove), teres major (on deltoid tuberosity) and coracobrachialis (medially on mid shaft).Origin of brachialis (anterior surface); Lateral and medial head of triceps (posterior surface); pronater teres (from medial supracondylar ridge); brachioradialis (from lateral supracondylar ridge) and ECRL (from lateral supracondylar ridge).