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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.

322 news items

Bleacher Report

Bleacher Report
Thu, 31 Jul 2014 23:28:16 -0700

For example, a dislocated shoulder involves the bone of the upper arm, the humerus, falling out of the shoulder socket. The very serious dislocated knee occurs when a hit forces the tibia, or shin bone, to move out of alignment with the thigh's femur ...
 
FiveThirtyEight
Fri, 01 Aug 2014 08:33:45 -0700

There were approximately 529,000 fractures to the femur, tibia and fibula compared with 231,000 fractures of the humerus, radius and ulna. chalabi-datalab-bonafide-2. But you asked specifically how many other kids were breaking bones. Does the fact ...
 
BBC Sport
Thu, 31 Jul 2014 16:01:08 -0700

In March 2010 he was practising for a diving show in Philippines when the 7m platform he was on collapsed and he fell into a 3m cement hole next to the pool. He suffered a broken arm [humerus], a broken wrist, a broken back, broken legs and head injuries.
 
Petersburg Pilot
Thu, 31 Jul 2014 15:18:45 -0700

The fully flexible model shows the scapula, clavicle, and a portion of humerus and joint ligaments. Models of knee and hip joints are on order, Ellie van Swearingen, department head, told the PMC board during a meeting July 24. The models make it ...

Toledo Blade

Toledo Blade
Wed, 30 Jul 2014 21:14:51 -0700

In Toledo Municipal Court, he faces a number of misdemeanor charges, including cruelty to animals, for allegedly shooting the dog in the 900 block of Clark Street. The bullet struck the dog's right humerus bone and ricocheted down to the radius ...
 
SB Nation
Thu, 31 Jul 2014 10:45:26 -0700

Healthy rotator cuff muscles will activate with every shoulder motion to keep the head of the humerus within the shoulder joint capsule. In addition to stability, the rotator cuff is also an important component of the pitching motion. The muscles of ...
 
Huffington Post
Thu, 31 Jul 2014 06:46:45 -0700

Turns out you might need to repeat kindergarten: Some of the most basic things you learned your first time through aren't actually true. Being a kid is basically living a lie. Sometimes, it doesn't take long to debunk the myths you're told: Santa Claus ...
 
Scranton Times-Tribune
Wed, 30 Jul 2014 21:41:15 -0700

An ankle injury sidelined him in 2012 and a fracture to his humerus last season put him on the shelf for a month. But his fiery spirit had earned him the respect of his teammates. He was a captain and despite being hurt, he never missed attending a ...
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