A humerus fracture can be classified by the location of the humerus

Humerus

The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....

 involved: the upper end, the shaft, or the lower end.

Certain lesions are commonly associated with fracture

Fracture

A fracture is the separation of an object or material into two, or more, pieces under the action of stress.The word fracture is often applied to bones of living creatures , or to crystals or crystalline materials, such as gemstones or metal...

s to specific areas of the humerus. At the upper end, the surgical neck of the humerus

Surgical neck of the humerus

The surgical neck of the humerus is a constriction below the tubercles of the greater tubercle and lesser tubercle.It is much more frequently fractured than the anatomical neck of the humerus. A fracture in this area is most likely to cause damage to the axillary nerve...

 and anatomical neck of humerus

Anatomical neck of humerus

The anatomical neck of the humerus is obliquely directed, forming an obtuse angle with the body.It is best marked in the lower half of its circumference; in the upper half it is represented by a narrow groove separating the head from the tubercles....

 can both be involved, though fractures of the surgical neck are more common. The axillary nerve

Axillary nerve

The axillary nerve or the circumflex nerve is a nerve of the human body, that comes off the of the brachial plexus at the level of the axilla and carries nerve fibers from C5 and C6...

 can be damaged in fractures of this type. Mid-shaft fractures may damage the radial nerve

Radial nerve

The radial nerve is a nerve in the human body that supplies the upper limb. It supplies the medial and lateral heads of the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial compartment of the forearm and the associated joints and overlying skin.It...

, which traverses the lateral aspect of the humerus closely associated with the radial groove. The median nerve

Median nerve

The median nerve is a nerve in humans and other animals. It is in the upper limb. It is one of the five main nerves originating from the brachial plexus....

 is vulnerable to damage in the supracondylar area, and the ulnar nerve

Ulnar nerve

In human anatomy, the ulnar nerve is a nerve which runs near the ulna bone. The ulnar collateral ligament of elbow joint is in relation with the ulnar nerve. The nerve is the largest unprotected nerve in the human body , so injury is common...

 is vulnerable near the medial epicondyle

Medial epicondyle of the humerus

The medial epicondyle of the humerus, larger and more prominent than the lateral epicondyle, is directed a little backward. In birds, where the arm is somewhat rotated compared to other tetrapods, it is called ventral epicondyle of the humerus....

, around which it curves to enter the forearm.