Variations The number of<unk> l vertebrae to which it is attached varies from four to eight; the number of costal attachments varies; muscle fibers may or may not reach the crest of the ilium. A muscle slip, the axillary arch, varying from 7 to 10 cm in length, and from 5 to 15 mm in breadth, occasionally springs from the upper edge of the<unk><unk>  about the middle of the posterior fold of the axilla, and crosses the axilla in front of the axillary vessels and nerves, to join the under surface of the tendon of the pectoralis major, the coracobrachialis, or the fascia over the biceps brachii. This axillary arch crosses the axillary artery, just above the spot usually selected for the application of a ligature, and may mislead a surgeon. It is present in about 7% of the population and may be easily recognized by the transverse direction of its fibers. Guy et al. extensively described this muscular variant using MRI data and positively correlated its presence with symptoms of neurological impingement. A fibrous slip usually passes from the upper border of the tendon of the<unk><unk> , near its insertion, to the long head of the triceps brachii. This is occasionally muscular, and is the representative of the<unk> epitrochlearis brachii of apes. This muscular form is found in ~5% of humans and is sometimes termed the latissimocondyloideus. The<unk><unk>  crosses the inferior angle of the scapula. A study found that, of 100 cadavers dissected: * 43% had "a substantial amount" of muscular fibers in the<unk><unk>  originating from the scapula. * 36% had few or no muscular fibers, but a "soft fibrous link" between the scapula and the<unk><unk>  * 21% had little or no connecting tissue between the two structures. Triangles * The lateral margin of the<unk><unk>  is separated below from the obliquus externus abdominis by a small triangular interval, the lumbar triangle of Petit, the base of which is formed by the iliac crest, and its floor by the obliquus internus abdominis. * Another triangle is situated behind the scapula. It is bounded above by the trapezius, below by the<unk><unk> , and laterally by the vertebral border of the scapula; the floor is partly formed by the rhomboideus major. If the scapula is drawn forward by folding the arms across the chest, and the trunk bent forward, parts of the sixth and seventh ribs and the interspace between them become subcutaneous and available for auscultation. The space is therefore known as the triangle of auscultation. *The<unk><unk>  can be remembered best for insertion as "A Miss Between Two Majors". As the<unk><unk>  inserts into the floor of the intertubercular groove of the humerus it is surrounded by two major muscles. The teres major inserts medially on the medial lip of the intertubercular groove and the pectoralis major inserts laterally onto the lateral lip. Nerve supply The<unk><unk>  is innervated by the sixth, seventh, and eighth cervical nerves through the thoracodorsal (long subscapular) nerve. Electromyography suggests that it consists of six groups of muscle fibres that can be independently coordinated by the central nervous system.
Latissimus dorsi muscle
Subscapularis muscle
Deltoid muscle
Inferior oblique muscle
Superior oblique muscle
Levator palpebrae superioris muscle
Morcellator
Pulled hamstring