Humerus


Humerus
Bone: Humerus
Illu upper extremity.jpg
Upper extremity
HumerusFront.png
Gray's subject #51 209
MeSH Humerus

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

Anatomically, 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.

Contents

Muscles attached to the humerus

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, coracobrachialis, and brachioradialis (which attaches distally) act to flex the elbow. (The biceps, however, does 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.

Humerus - superior epiphysis
Humerus - inferior epiphysis

Articulations

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 olecranon process of the ulna.

Nerves

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.

In other animals

Primitive fossil amphibians had little, if any, shaft connecting the upper and lower extremities, making their limbs very short. In most living vertebrates, 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.[1]

Additional images

Diagram of the human shoulder joint  
Human arm bones diagram  
Humerus (right) - anterior view  
Humerus (right) - posterior view  
Left humerus. Anterior view.  
Left humerus. Posterior view.  
Left humerus with muscle attachments. Anterior view.  
Left humerus with muscle attachments. Posterior view.  
The left shoulder and acromioclavicular joints, and the proper ligaments of the scapula.  
Cross-section through the middle of upper arm.  
The Supinator.  
Head of humerus.
Head of humerus.  

References

  1. ^ Romer, Alfred Sherwood; Parsons, Thomas S. (1977). The Vertebrate Body. Philadelphia, PA: Holt-Saunders International. pp. 198–199. ISBN 0-03-910284-X. 

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.


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Look at other dictionaries:

  • humérus — [ ymerys ] n. m. • XVIe; lat. humerus « épaule » ♦ Os long constituant le squelette du bras, de l épaule au coude. Saillies de l extrémité supérieure (⇒ trochin, trochiter) , inférieure (⇒ condyle, épicondyle, trochlée) de l humérus. Tête de l… …   Encyclopédie Universelle

  • humerus — HÚMERUS s.n. Os lung, pereche, cuprins între umăr şi cot, formând scheletul braţului. – Din fr. humérus, lat. humerus. Trimis de gall, 13.09.2007. Sursa: DEX 98  húmerus s. n., pl. húmeruşi Trimis de siveco, 10.08.2004. Sursa: Dicţionar… …   Dicționar Român

  • Humerus — Humérus 1:tête de l humérus 2:sillon intertuberculaire 3:tubercule majeur 4:tubercule mineur 5:crête du tubercule mineur 6:crête du tubercule majeur 7:tubérosité deltoïdienne 8:crête supracondylaire latérale 9:fosse radiale 10:épicondyle latéral… …   Wikipédia en Français

  • Humerus — Hu me*rus, n.; pl. {Humeri}. [L.] (Anat.) (a) The bone of the brachium, or upper part of the arm or fore limb. (b) The part of the limb containing the humerus; the brachium. [1913 Webster] …   The Collaborative International Dictionary of English

  • humerus — [hyo͞o′mər əs] n. pl. humeri [hyo͞o′mərī] [L humerus, umerus, the shoulder, upper arm < IE * om(e)sos, the shoulder > Sans áṃsa , Gr ōmos] the bone of the upper arm or forelimb, extending from the shoulder to the elbow: see SKELETON …   English World dictionary

  • Humĕrus — (lat.), 1) Schulter, Schulterblatt; 2) Oberarm, Oberarmbein. Daher humerāils (humerarius), was sich auf die Schulter od. auf den Oberarm bezieht; daher H. arteria, H. vena, Armarterie, Armvene (s. b.) …   Pierer's Universal-Lexikon

  • Humĕrus — (lat.), der Oberarm, s. Arm …   Meyers Großes Konversations-Lexikon

  • Humerus —   [lateinisch] der, /...ri, der Oberarmknochen (Arm) …   Universal-Lexikon

  • Humerus — Humerus, Oberarmknochen ⇒ Stylopodium …   Deutsch wörterbuch der biologie

  • humerus — 1706, bone of the upper arm, originally (14c.) shoulder, a misspelled borrowing of L. umerus shoulder, from PIE *om(e)so (Cf. Skt. amsah, Gk. omos, O.N. ass, Goth. ams shoulder ) …   Etymology dictionary

  • humerus — ► NOUN (pl. humeri) Anatomy ▪ the bone of the upper arm or forelimb, between the shoulder and the elbow. DERIVATIVES humeral adjective. ORIGIN Latin, shoulder …   English terms dictionary


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