The lesser tubercle of the humerus is the distal skeletal attachment site for the

It has an anterior and posterior face. The greater tubercle serves as attachment site for three of the rotator cuff muscles – supraspinatus, infraspinatus and teres minor – they attach to superior, middle and inferior facets respectively. The lesser tubercle is much smaller, and more medially located on the bone

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.