humerus
| Bone: Humerus |
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| Upper extremity |
| Gray's |
subject #51 209 |
| MeSH |
Humerus |
The humerus is a long bone in the arm or fore-legs (animals) that runs from the shoulder to the elbow. On a skeleton, it fits between the scapula and the radius and ulna. It consists of the following three sections:
- Upper extremity of humerus
- Body of humerus
- Lower extremity of humerus
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Contents
- 1 Articulations
- 2 Muscle attachments
- 3 Actions
- 4 Clinical Considerations
- 5 Popular Culture
- 6 Additional images
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Articulations
The bursa lies between the scapula and the chest wall, and allows the scapula to move over the chest wall. Movements of the shoulder are actually often combined movements of the gleno-humeral joint as well as movement of the scapula on the chest wall.
The distal end of the humerus (at the elbow) creates a hinge joint with the ulna, allowing only flexion and extension. This happens on the trochlea of the humerus. Two pits at this end of the humerus (the coronoid fossa and the olecranon fossa) allow the ulna room to move, but prevent it from over-flexing/extending.
There is also a pivot joint between the capitulum (sometimes called the capitellum) of the humerus, and the head of the radius. This allows the hand to pronate and supinate (turn to face downwards or upwards).
Muscle attachments
A variety of muscles attach to the humerus. These enable movement at the elbow and at the shoulder.
The rotator cuff muscles attach at the proximal humerus, and can rotate and abduct the arm at the shoulder.
Some of the forearm muscles, (such as pronator teres, and the flexors and extensors of the wrist) also attach to the distal humerus.
| Muscle |
Attachment |
| Extensor carpi radialis brevis muscle |
lateral epicondyle |
| Extensor carpi ulnaris muscle |
lateral epicondyle (and also to the posterior border of the ulna |
| Extensor digiti minimi muscle |
lateral epicondyle |
| Extensor digitorum muscle |
lateral epicondyle |
| Supinator muscle |
lateral epicondyle (and also to the radial collateral ligament, annular ligament, the supinator fossa, and the crest of the ulna ) |
| Flexor carpi radialis muscle |
medial epicondyle |
| Flexor carpi ulnaris muscle, its humeral head |
medial epicondyle |
| Flexor digitorum superficialis muscle, its humeroulnar head |
medial epicondyle (and also to the ulnar collateral ligament and the coronoid process of the ulna ) |
| Palmaris longus muscle |
medial epicondyle |
| Pronator teres muscle |
medial epicondyle (and also to the coronoid process of the ulna) |
| Latissimus dorsi muscle |
intertubercular groove, floor of the |
| Pectoralis major muscle |
intertubercular groove, lateral lip |
| Teres major muscle |
intertubercular groove, medial lip |
| Infraspinatus muscle |
greater tubercle, middle facet |
| Supraspinatus muscle |
greater tubercle, superior facet |
| Teres minor muscle |
greater tubercle, inferior facet |
| Subscapularis muscle |
lesser tubercle |
| Anconeus muscle |
olecranon, lateral surface (and also to the superior part of the posterior surface of the ulna) |
| Brachioradialis muscle |
lateral supracondylar ridge, proximal two-thirds of the |
| Coracobrachialis muscle |
medial humerus, middle third of the |
| Extensor carpi radialis longus muscle |
lateral supracondylar ridge |
| Deltoid muscle |
deltoid tuberosity |
Actions
- Deltoid has a variety of actions on the top of the arm.
- Pectoralis major, teres major and latissimus dorsi, which all insert at the intertubercular groove of the humerus, adduct and medially rotate the humerus.
- Biceps brachii, brachialis, coracobrachialis, and brachioradialis (which attaches very distally), act to flex the elbow. Biceps however does not attach to the humerus.
- Triceps brachii and anconeus extend the elbow, and attach to the posterior side of the humerus.
Clinical Considerations
The most common type of shoulder (glenohumeral joint) dislocation is an anterior or inferior dislocation of the humerus. This dislocation has the potential to injure the axillary nerve or axillary artery. Signs and symptoms of this dislocation are: a loss of the normal contour of the shoulder, a depression under the acromion that you can feel, and being able to feel the head of humerus in the axilla (armpit).
Popular Culture
Since 'Humerus' is the homonym of 'humorous', the bone is almost always referred to in popular culture as 'the funny bone'. This may also be a consequence of the ulnar nerve lying very close to the bone, which thus produces a 'funny' (though actually rather unpleasant) feeling when knocked. However, to hit one's funny bone is not a literal expression; the phrase refers to something that strikes someone as extremely humorous.
Additional images
Diagram of the human shoulder joint
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Humerus (right) - anterior view
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Humerus (right) - posterior view
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Left humerus. Anterior view.
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Left humerus. Posterior view.
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The left shoulder and acromioclavicular joints, and the proper ligaments of the scapula.
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Cross-section through the middle of upper arm.
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This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.
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v • d • e
Bones of upper limbs |
| pectoral girdle, clavicle: conoid tubercle - trapezoid line - costal tuberosity - subclavian groove
scapula: spine of scapula - suprascapular notch - acromion - glenoid cavity - glenoidal labrum - coracoid process
fossae (subscapular, supraspinatous, infraspinatous) borders (superior, lateral/axillary, medial/vertebral) angles (superior, inferior, lateral) tubercles (infraglenoid, supraglenoid)
humerus: upper extremity - necks (anatomical, surgical) - tubercles (greater, lesser) - intertubercular groove
body - radial sulcus - deltoid tuberosity
lower extremity - capitulum - trochlea - epicondyles (lateral, medial) - supracondylar ridges (lateral, medial) - fossae (radial, coronoid, olecranon)
ulna: upper extremity (olecranon, coronoid process, tuberosity, radial notch, semilunar notch) - body of ulna - lower extremity (styloid process)
radius: upper extremity (tuberosity) - body - lower extremity (ulnar notch, styloid process)
carpus: scaphoid - lunate - triquetral - pisiform - trapezium - trapezoid - capitate - hamate (hamulus)
metacarpus: 1st metacarpal - 2nd - 3rd - 4th - 5th
phalanges of the hand
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Search Term: "Humerus"
Categories: Skeletal system | Upper limb anatomy |
