Anatomically speaking, the arm refers only to the humerus and only that portion of the arm supported by this solitary bone
. The brachium
refers to the segment of the arm that runs along the humerus. It is a straight bone running from the shoulder
to the elbow
The humerus is comprised of a single bone, with a head, a shaft, and an end. It is the longest bone within the upper extremity. The proximal head neatly meets with the glenoid cavity and the shaft draws down toward the distal end.
The distal end of the bone is structured to accept the two bones
associated with the forearm. An indented groove obviates the neck which underscores the head of the bone. The obvious constricure below the head is a very common site for arm bone fractures
The large knob which is on the lateral proximal end of the humerus is called the greater tubercle. The lesser tubercle is just slightly smaller and anterior to the greater tubercle and is noted by the intertubercular groove. This groove serves the tendon which belongs to the long head of the biceps brachii
Along the lateral mid-region of the humerus lies a roughened surface which serves as the deltoid tuberosity where the deltoid muscle is then attached.
Nutrient foramina are the various small opening throughout the bones of the body. This is to permit the passage of nutrients through the bones. The distal end of the humerus contains two articular surfaces on the humeral condyle.
The lateral rounded section that conjoins the radius
is the capitulum. There is then a portion represented medially that acts like a pulley and is known as the trochlea and conjoins with the ulna
The lateral and medial epicondyles are located on either side and above the condyles.
The ulna nerve
passes through the ulna sulcus which is protected by the large medial epicondyle. This is commonly called the funny bone due to the strange sensation often associated with meeting it with sudden stimuli.
The distinct depression
above trochlea is the coronoid fossa and is positioned on the anterior surface. On the distal posterior surface the depression
known as the olecranon fossa is positioned. Both of the fossas are designed to be inclined to work directly with the movements of the ulna when the forearm moves.