The greater tubercle is just lateral to the anatomical neck. Its upper surface is rounded and marked by three flat impressions: the highest of these gives insertion to the supraspinatus muscle; the middle to the infraspinatus muscle; the lowest one, and the body of the bone for about 2.5 cm. below it, to the teres minor muscle. The lateral surface of the greater tubercle is convex, rough, and continuous with the lateral surface of the body. Lesser tubercle
The lesser tubercle (tuberculum minus; lesser tuberosity) is smaller, anterolaterally placed to the head of the humerus. The lesser tubercle provides insertion to subscapularis muscle. Both these tubercles are found in the proximal part of the shaft. The crest of the lesser tubercle forms the medial lip of the bicipital groove and is the site for insertion of teres major and latissimus dorsi muscles. The lesser tuberosity, is more prominent than the greater: it is situated in front, and is directed medialward and forward. Above and in front it presents an impression for the insertion of the tendon of the subscapularis muscle. Bicipital groove
The tubercles are separated from each other by a deep groove, the bicipital groove (intertubercular groove; bicipital sulcus), which lodges the long tendon of the biceps brachii muscle and transmits a branch of the anterior humeral circumflex artery to the shoulder-joint. It runs obliquely downward, and ends near the junction of the upper with the middle third of the bone.
The medial border is thicker, of greater length, and consequently more prominent, than the lateral.The grooved portion of the articular surface fits accurately within the semilunar notch of the ulna; it is broader and deeper on the posterior than on the anterior aspect of the bone, and is inclined obliquely downward and forward toward the medial side. Articulations
At the shoulder, the head of the humerus articulates with the glenoid fossa of the scapula. More distally, at the elbow, the capitulum of the humerus articulates with the head of the radius, and the trochlea of the humerus articulates with the trochlear notch of the ulna. Nerves
The axillary nerve is located at the proximal end, against the shoulder girdle. Dislocation of the humeruss glenohumeral joint has the potential to injure the axillary nerve or the axillary artery. Signs and symptoms of this dislocation include a loss of the normal shoulder contour and a palpable depression under the acromion. The radial nerve follows the humerus closely. At the midshaft of the humerus, the radial nerve travels from the posterior to the anterior aspect of the bone in the spiral groove. A fracture of the humerus in this region can result in radial nerve injury. The ulnar nerve lies at the distal end of the humerus near the elbow. When struck, it can cause a distinct tingling sensation, and sometimes a significant amount of pain.