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Humerus
Humerus - anterior view.png
Position of humerus (shown in red). Anterior view.
Details
Latin Humerus
Identifiers
Gray's p.209
MeSH A02.835.232.087.090.400
TA A02.4.04.001
FMA 13303
Anatomical terms of bone

The humerus (/ˈhjmərəs/, Plural: humeri) is a long bone in the arm or forelimb that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, which consists of the radius and ulna, and consists of three sections. The upper extremity consists of a rounded head, a narrow neck, and two short processes (tubercles, sometimes called tuberosities). Its body is cylindrical in its upper portion, and more prismatic below. The lower extremity consists of 2 epicondyles, 2 processes (trochlea & capitulum), and 3 fossae (radial fossa, coronoid fossa, and olecranon fossa). As well as its true anatomical neck, the constriction below the greater and lesser tubercles of the humerus is referred to as its surgical neck due to its tendency to commonly get fractured, thus often becoming the focus of surgeons.

Structure[edit]

Articulations[edit]

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.

Diagram of the human shoulder joint 
The left shoulder and acromioclavicular joints, and the proper ligaments of the scapula. 
Head of humerus 
The supinator

Nerves[edit]

The axillary nerve is located at the proximal end, against the shoulder girdle. Dislocation of the humerus's 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 at the distal end of the humerus near the elbow is sometimes referred to in popular culture as 'the funny bone'. Striking this nerve can cause a tingling sensation ("funny" feeling), and sometimes a significant amount of pain. It lies posterior to the medial epicondyle, and is easily damaged in elbow injuries.[1]

Horizontal section at the middle of upper arm
Horizontal section of upper arm. 
Humerus 

Function[edit]

Muscular attachment[edit]

The deltoid originates on the lateral third of the clavicle, acromion and the crest of the spine of the scapula. It is inserted on the deltoid tuberosity of the humerus and has several actions including abduction, extension, and circumduction of the shoulder. The supraspinatus also originates on the spine of the scapula. It inserts on the greater tubercle of the humerus, and assists in abduction of the shoulder.

The pectoralis major, teres major, and latissimus dorsi insert at the intertubercular groove of the humerus. They work to adduct and medially, or internally, rotate the humerus.

The infraspinatus and teres minor insert on the greater tubercle, and work to laterally, or externally, rotate the humerus. In contrast, the subscapularis muscle inserts onto the lesser tubercle and works to medially, or internally, rotate the humerus.

The biceps brachii, brachialis, and brachioradialis (which attaches distally) act to flex the elbow. (The biceps do not attach to the humerus.) The triceps brachii and anconeus extend the elbow, and attach to the posterior side of the humerus.

The four muscles of supraspinatus, infraspinatus, teres minor and subscapularis form a musculo-ligamentous girdle called the rotator cuff. This cuff stabilizes the very mobile but inherently unstable glenohumeral joint. The other muscles are used as counterbalances for the actions of lifting/pulling and pressing/pushing.

Left humerus. Anterior view.
Humerus ant (mirroed).png Left humerus - anterior view.png Left humerus - close-up - animation - stop at anterior view.gif HumerusFront.png Human left humerus - anterior view - muscles.svg A. Supraspinatus muscle
B. Latissimus dorsi muscle
C. Pectoralis major muscle
D. Deltoid muscle
E. Brachioradialis
F. Extensor carpi radialis longus muscle
G. Common extensor tendon
H. Subscapularis muscle
I. Teres major muscle
J. Coracobrachialis muscle
K. Brachialis muscle
L. Pronator teres muscle
M. Common flexor tendon


Left humerus. Posterior view.
Humerus post (mirroed).png Left humerus - posterior view.png Left humerus - close-up - animation - stop at posterior view.gif HumerusBack.png Gray208.png


Clinical significance[edit]

Fracture[edit]

Main article: Humerus fracture

Other animals[edit]

Primitive fossil amphibians had little, if any, shaft connecting the upper and lower extremities, making their limbs very short. In most living tetrapods, however, the humerus has a similar form to that of humans. In many reptiles and some primitive mammals, the lower extremity includes a large foramen, or opening, into which nerves and blood vessels pass.[2]

History[edit]

The word "humerus" is derived from Latin: humerus, umerus meaning upper arm, shoulder, and is linguistically related to Gothic ams shoulder and Greek ōmos.[3]

Additional images[edit]

References[edit]

This article incorporates text from a public domain edition of Gray's Anatomy.

  1. ^ "The Humerus". TeachMeAnatomy.net. 
  2. ^ Romer, Alfred Sherwood; Parsons, Thomas S. (1977). The Vertebrate Body. Philadelphia, PA: Holt-Saunders International. pp. 198–199. ISBN 0-03-910284-X. 
  3. ^ Harper, Douglas. "Humerus". Online Etymology Dictionary. Retrieved 6 November 2014. 

Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Humerus — Please support Wikipedia.
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4226 news items

 
SYS-CON Media (press release)
Tue, 03 Mar 2015 01:00:00 -0800

Windhager and Vienna General Hospital have chosen to collaborate with IlluminOss Medical on this important trial for the repair and stabilization of impending and pathologic fractures in the humerus due to metastatic carcinoma," said Robert Rabiner, ...
 
Healio
Fri, 20 Feb 2015 12:39:27 -0800

Eighty-nine patients with proximal humerus fractures underwent 6 weeks of sling immobilization and a home-based program rehabilitation protocol started 2 weeks after injury. The researchers obtained standardized radiographs and CT scans of all injured ...

Medical Daily

Medical Daily
Thu, 05 Mar 2015 10:43:43 -0800

In adults, the arms accounts for 50 percent of bone fractures, according to the infographic, “5 Most Commonly Broken Bones,” by MK Orthopaedics Surgery & Rehabilitation. Typically, the arms break in the humerus of the upper arm, or in the radius of the ...

UPI.com

UPI.com
Wed, 04 Mar 2015 08:06:18 -0800

A more traditional method, relying solely on the circumference of the animal's femur (thigh bone) and humerus (upper arm), put the young dino's weight at almost twice that of the 3-D model's total. But scientists suggest the adolescent dinosaur, who ...

Fairbanks Daily News-Miner

Fairbanks Daily News-Miner
Thu, 05 Mar 2015 00:57:11 -0800

The humerus bone on his left leg split into two parts and then naturally fused back together. He also is missing a bone in one of his paws. And it doesn't slow him down one bit. It was never the plan to keep all these puppies however, so after General ...

Tampabay.com

Tampabay.com
Tue, 03 Mar 2015 17:30:00 -0800

The eagle was found in November with a broken humerus near Tower Lake in Oldsmar. Dr. Peter Black and Dr. Dominique Keller of Busch Gardens repaired the bone in a three-hour surgery and the eagle was taken to the Audubon Center for Birds of Prey, ...

CBS Local

CBS Local
Wed, 04 Mar 2015 05:41:15 -0800

By almost cupping the rim of the rounded head of the humerus at the shoulder, and that of the femur at the hip, the labrum allows for the extraordinary ranges of motion of these “ball and socket” joints while protecting them from dislocation. Ligaments ...
 
SunHerald.com
Tue, 03 Mar 2015 21:03:45 -0800

The rotator cuff is made up of small muscles ending in long, wide tendons that form a "cuff" around the humerus. Along with an excellent illustration, Medline Plus Medical Encyclopedia writes, "There are four muscle tendons that connect to the shoulder ...
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