The inferior third of this border is raised into a slight ridge, the medial supracondylar ridge, which became very prominent below; it presents an anterior lip for the origins of the brachialis muscle and the pronator teres muscle, a posterior lip for the medial head of the triceps brachii muscle, and an intermediate ridge for the attachment of the medial intermuscular septum. The Deltoid tuberosity is a roughened surface on the lateral surface of the shaft of the Humerus and acts as the site of insertion of deltoideus muscle. The posterorsuperior part of the shaft has a crest, beginning just below the surgical neck of the humerus and extends till the superior tip of the deltoid tuberosity. This is where the lateral head of triceps brachii  is attached. The radial sulcus, also known as the spiral groove is found on the posterior surface of the shaft and is a shallow oblique groove through which the radial nerve passes along with deep vessels. This is located posteroinferior to the deltoid tuberosity. The inferior boundary of the spiral groove is continuous distally with the lateral border of the shaft. The nutrient foramen of the humerus is located in the anteromedial surface of the humerus. The nutrient arteries enter the humerus through this foramen. Distal humerus
The distal or lower extremity of the humerus is flattened from before backward, and curved slightly forward; it ends below in a broad, articular surface, which is divided into two parts by a slight ridge.
The antero-medial surface, less extensive than the antero-lateral, is directed medialward above, forward and medialward below; its upper part is narrow, and forms the floor of the intertubercular groove which gives insertion to the tendon of the latissimus dorsi muscle; its middle part is slightly rough for the attachment of some of the fibers of the tendon of insertion of the coracobrachialis muscle; its lower part is smooth, concave from above downward, and gives origin to the brachialis muscle. Posterior surface: the area between the medial and lateral borders. The posterior surface appears somewhat twisted, so that its upper part is directed a little medialward, its lower part backward and a little lateralward. Nearly the whole of this surface is covered by the lateral and medial heads of the Triceps brachii, the former arising above, the latter below the radial sulcus.Its three borders are:

Anterior: the anterior border runs from the front of the greater tubercle above to the coronoid fossa below, separating the antero-medial from the antero-lateral surface. Its upper part is a prominent ridge, the crest of the greater tubercle; it serves for the insertion of the tendon of the pectoralis major muscle. About its center it forms the anterior boundary of the deltoid tuberosity, on which the deltoid muscle attaches; below, it is smooth and rounded, affording attachment to the brachialis muscle. Lateral: the lateral border runs from the back part of the greater tubercle to the lateral epicondyle, and separates the anterolateral from the posterior surface.