Editing Humerus (section)

===Upper extremity===
The '''upper''' or '''proximal extremity of the humerus''' consists of the bone's large rounded head joined to the body by a constricted portion called the neck, and two eminences, the greater and lesser tubercles.

====Head====<!-- [[Head of the humerus]] redirects here -->
[[File:Humerus-Head.gif|right|thumb|Head of the humerus]]

The head (''caput humeri''), is nearly hemispherical in form. It is directed upward, medialward, and a little backward, and articulates with the [[glenoid cavity]] of the scapula to form the [[Glenohumeral joint|glenohumeral joint (shoulder joint)]]. The circumference of its articular surface is slightly constricted and is termed the anatomical neck, in contradistinction to a constriction below the tubercles called the surgical neck which is frequently the seat of fracture. Fracture of the anatomical neck rarely occurs.<ref name="Gray's">''[[Gray's Anatomy]]'', see infobox</ref>
The diameter of the humeral head is generally larger in men than in women.

====Anatomical neck====
{{Main|Anatomical neck of the humerus}}
The anatomical neck (''collum anatomicum'') is obliquely directed, forming an obtuse angle with the body. It is most prominent in the lower half of its circumference, while in the upper half, it is represented by a narrow groove separating the head from the tubercles. The line separating the head from the rest of the upper end is called the ''anatomical neck.'' It affords attachment to the articular capsule of the shoulder-joint, and is perforated by numerous vascular [[foramen]]s. Fracture of the anatomical neck rarely occurs.<ref name="Gray's" />

The anatomical neck of the humerus is an indentation distal to the head of the humerus on which the articular capsule attaches.

[[File:Neck-of-Humerus.jpg|none|thumb|400x400px|Anatomical vs surgical neck of humerus]]

====Surgical neck====
{{Main|Surgical neck of the humerus}}
The surgical neck is a narrow area distal to the tubercles that is a common site of fracture.  It makes contact with the [[axillary nerve]] and the [[posterior humeral circumflex artery]].

====Greater tubercle ====
{{Main|Greater tubercle}}
The greater tubercle (''tuberculum majus''; greater tuberosity) is a large, posteriorly placed projection that is placed laterally. The greater tubercle is where ''supraspinatus'', ''infraspinatus'' and ''teres minor'' muscles are attached. The crest of the greater tubercle forms the lateral lip of the bicipital groove and is the site for insertion of ''pectoralis major''.

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&nbsp;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.<ref name="Gray's" />

[[File:Greater-Tubercle-of-Right-Humerus.jpg|none|thumb|400x400px|Greater tubercle of the right humerus]]

[[File:Attachments-of-greater-tubercle.jpg|none|thumb|400x400px|Attachments on the greater tubercle]]

====Lesser tubercle ====
{{Main|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]].<ref name="Gray's" />

[[File:Lesser-Tubercle-of-Right-Humerus.jpg|none|thumb|400x400px|Lesser tubercle of the right humerus]]

[[File:Insertion-of-subscapularis-muscle.jpg|none|thumb|400x400px|Insertion of subscapularis muscle on the lesser tubercle]]

====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. In the fresh state its upper part is covered with a thin layer of cartilage, lined by a prolongation of the [[synovial membrane]] of the shoulder-joint; its lower portion gives insertion to the tendon of the [[latissimus dorsi muscle]]. It is deep and narrow above, and becomes shallow and a little broader as it descends. Its lips are called, respectively, the crests of the greater and lesser tubercles (''bicipital ridges''), and form the upper parts of the anterior and medial borders of the body of the bone.<ref name="Gray's" />
[[File:Bicipital-groove.jpg|none|thumb|400x400px|Bicipital groove]]