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Humerus
Humerus - anterior view.png
Position of humerus (shown in red). Anterior view.
Illu upper extremity.jpg
Latin Humerus
Gray's p.209
MeSH Humerus
TA A02.4.04.001
FMA FMA:13303
Anatomical terms of bone

The humerus (/ˈhjmərəs/; ME from Latin humerus, umerus upper arm, shoulder; cf. Gothic ams shoulder, Greek ōmos. Plural: humeri) is a long bone in the arm or forelimb that runs from the shoulder to the elbow.

Anatomically, in modern humans, it connects the scapula and the lower arm (consisting 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 Gray207.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

In 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]

Additional images[edit]

References[edit]

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

  1. ^ http://teachmeanatomy.net/upper-limb-2/bones/the-humerus/
  2. ^ Romer, Alfred Sherwood; Parsons, Thomas S. (1977). The Vertebrate Body. Philadelphia, PA: Holt-Saunders International. pp. 198–199. ISBN 0-03-910284-X. 

External links[edit]


Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Humerus — Please support Wikipedia.
This page uses Creative Commons Licensed content from Wikipedia. A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia.

210 news items

My New Orleans

My New Orleans
Fri, 29 Aug 2014 09:41:15 -0700

An audible sudden 'crack' often signals a spiral like break of a humerus under tremendous pressure from powerful and opposing torques,” adds Dr. Edmunds. “The sharp points of the fractured humerus can damage the radial or median nerves causing a ...
 
WBIR-TV
Sat, 30 Aug 2014 20:00:00 -0700

Cecere said, "He had a broken humerus, a broken wing." Leader spent the past two-and-a-half years in rehabilitation to gain enough strength to fly again. Eagle releases honors Sen. Howard Baker Jr. Sen. Howard Baker Junior (Photo: Evan Johnson).

Irish Independent

Irish Independent
Sun, 31 Aug 2014 18:30:00 -0700

Having reviewed the video evidence at length, I would say that the surgeon in question was lucky not to have a dislocated shoulder, fractured collarbone or an unfunny fracture of his humerus bone. It was certainly no Ronaldo-type dive. The relationship ...

CarAdvice

CarAdvice
Mon, 01 Sep 2014 04:48:45 -0700

What do you do when you get in the driver's seat of a new car for the first time? Make sure you're comfortable, right? Wrong. There's a process you need to follow to ensure you're in the best position to control the car, and stay as safe as you can in ...
 
Buffalo News
Fri, 29 Aug 2014 21:30:00 -0700

Rotator cuffs: These are a group of four muscles and tendons that form a “cuff” around the top of the upper arm bone, or humerus. They stabilize the shoulder and hold the bones together, while allowing the lifting of the arm. Rotator cuffs can be ...
 
Vibe
Fri, 29 Aug 2014 06:41:15 -0700

It's not "Black Ice" or even "Cell Therapy" for Goodie Mob brethren Cee-Lo Green & Big Gipp but "Shine Like Gold" still proves that the ATL legends can give people another hit whenever they want. In the humerus clip, the two of them pay tribute to the ...

The Guardian

The Guardian
Thu, 28 Aug 2014 08:11:15 -0700

“It is something that I will take massive pride in doing,” he added, screaming, as another meaty FA apparatchik snapped a wide elasticated cotton band embroidered with an England crest around his humerus. “As a kid I always loved watching a big England ...
 
Perth Now
Sun, 31 Aug 2014 07:03:45 -0700

After the MRI Ms Johnson complained of constant pain before her left shoulder swelled and it became obvious something was wrong. Later X-rays confirmed a fracture to her left humerus. Ms McClafferty said her mother had no pre-existing injuries aside ...
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