The humerus ( , Plural: humeri ) is a long bone in the arm or forearm that extends from the shoulder to the elbow. It connects the scapula and the two forearm bones, fingers and ulna, and consists of three parts. The upper extremity of humeral consists of a round head, narrow neck, and two short processes (tubercle, sometimes called tuberosity). Her body is cylindrical at the top, and more prismatic below. The lower limb consists of 2 epicondyles, 2 processes (trochlea & capitulum), and 3 fossae (radial fossa, coronoid fossa, and olecranon fossa). As well as a true anatomical neck, narrowing under a smaller and smaller tubercle of the humerus is referred to as surgical neck because of its tendency to fracture, which is often the focus of the surgeon.
Video Humerus
Etymology
The word "humerus" comes from the Latin: humerus, umerus which means upper arm, shoulder, and linguistically related to Gothic ams shoulders and Greek ? mos .
Maps Humerus
Structure
Articulation
On the shoulders, the humeral head articulates with the glenoid fossa of the scapula. Furthermore, at the elbow, the humerus capitulum articulates with the head of the fingers, and the humerus trochlea articulates with a notch of troklear ulna.
Nerves
The axillary nerve is located at the proximal end, against the shoulder girdle. Dislocation of the glenohumeral joint of the humerus, has the potential to injure the axillary nerve or axillary artery. The signs and symptoms of this dislocation include loss of normal shoulder contour and palpable depression under the acromion.
Radial nerves follow the humerus closely. In the humerus midshaft, the radial nerve runs from the posterior to the anterior aspect of the bone in the spiral groove . Humerus fractures in this region may cause radial nerve injury.
The ulnar nerve is located at the distal end of the humerus near the elbow. When attacked, it can cause different sensations of tingling, and sometimes a large amount of pain. Sometimes popularly called 'funny bones', perhaps because of this sensation ("funny" feeling), as well as the fact that the bone name is a 'funny' homophone. It lies posterior to the medial epicondyle, and is easily damaged by elbow injury.
Function
Muscle ties
Deltoid is derived from the lateral third of the clavicle, acromion and spinal apex of the scapula. It is inserted in the humerus deltoid tuberosity and has several actions including abduction, extension, and shoulder circumduction. Supraspinatus also comes from the spine of the scapula. It inserts on a larger tuberkul of the humerus, and aids the kidnapping of the shoulder.
Pectoralis major, teres major, and latisimus dorsi insert on the intertubercular groove of the humerus. They work to add and medial, or internally, rotate the humerus.
The infraspinatus and teres are small inserts on larger tubercles, and work for lateral, or external, twisting the humerus. Instead, the subscapular muscles insert into the lower tubercle and work to medial, or internally, rotate the humerus.
Brachii, brachialis, and brachioradialis brains (which attach to the distal) act to flex the elbow. (Biceps do not stick to the humerus.) Tricep brachii and anconeus extend the elbow, and attach to the posterior side of the humerus.
The four supraspinatus, infraspinatus, teres minor and subscapularis muscles form a corset of muskulo-ligaments called rotator cuff. This cuff stabilizes the highly mobile glenohumeral joints but is inherently unstable. Other muscles are used as a counterweight for lifting/pulling and pushing/pushing action.
Other animals
The amphibian primitive fossils have little, if any, axis connecting the upper and lower extremities, making their limbs very short. In most living tetrapods, however, the humerus has a form similar to humans; connecting their extremities. In many reptiles and some primitive mammals, the lower extremities include large foramen, or opening, which allows the nerves and blood vessels to pass through.
Additional images
Ossification
The top Accompany the axis in the 20th year. Parts that make up the top - Head Start from the first year, larger tubercle Starts from year 3, smaller tubercle Starts from the fifth year.
Bottom end shaft Accompany the shaft in 16 to 17 years. The parts that make up the lower end are - The lateral capitulum and flanges of trochlea Sers from the 2nd year, The medial trochlea section starts from the 10th year, the lateral epicondyle begins from the 12th year and the medial epicondyle begins from the sixth year.
See also
- Humerus Fracture
References
- This article combines text in the public domain of page 209 of the 20th edition of Gray's Anatomy (1918)
External links
- Ã, "Humerus". New International Encyclopedia . 1905.
Source of the article : Wikipedia
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