Deltoid muscle
| Deltoid muscle |
|---|
|
| The deltoid muscle |
| origin |
|
Pars clavicularis : collarbone Pars acromialis : acromion of the shoulder blade Pars spinalis : shoulder blade ( spina scapulae ) |
| approach |
| Humerus ( tuberosity deltoidea humeri ) |
| function |
| Lifting the upper arm |
| Innervation |
| Axillary nerve of the brachial plexus |
| Spinal segments |
| C5, C6 |
The deltoid muscle (from ancient Greek δελτοειδής, "triangular"), also called deltoid or deltoid muscle for short , is a triangular skeletal muscle . It lies like a package over the shoulder joint and gives it support by pressing the head of the humerus into the socket . The deltoid muscle is essential to the contour of the shoulder region and is used to lift the upper arm.
Its fascia is the deltoid fascia .
Shares
The deltoid muscle can be divided into three parts in humans:
- Pars clavicularis (clavicle part; "anterior deltoid muscle")
- Pars acromialis (part of the shoulder height; "middle deltoid")
- Pars spinalis (bone part; "posterior deltoid muscle")
In many mammals, the collarbone is regressed and therefore the pars clavicularis is not developed. In animals without acromion (e.g. horses , real pigs ) the pars acromialis is also missing . The pars spinalis is referred to in veterinary anatomy as the pars scapularis (part of the shoulder blade). Between the acromial and the infraspinatus muscle is dogs and ruminants a bursa , the Bursa subdeltoid .
function
After an initial abduction of the arm by about 10 degrees by the supraspinatus muscle, the deltoideus with its middle fibers (pars acromialis) pulls the arm up to about 60 degrees before it becomes actively insufficient. Now, however, the feathered parts (pars clavicularis and spinalis) reach their required lifting height and can thus abduct and elevate the arm further (lift over 90 degrees). To raise the arm above the horizontal (elevation), however, a rotation of the shoulder blade is necessary, as otherwise the arm will hit the roof of the shoulder. The front fibers also pull the arm forward ( flexion or anteversion) and turn it inwards (medial), while the rear fibers pull the arm backwards ( extension or retroversion) and turn it outwards (laterally).
In quadruped mammals, the muscle acts as a flexor of the shoulder joint .
clinic
The deltoid muscle is used for the intramuscular injection of medication due to its location (great distance from nerves or arteries) . If the axillary nerve is paralyzed , the deltoid muscle, the strongest abductor in the shoulder joint , fails , the supraspinatus muscle can no longer take on the task, and the lifting of the arm is greatly reduced.
Web links
Individual evidence
- ^ Werner Platzer: Pocket Atlas of Anatomy . 11th edition. tape 1 : musculoskeletal system . Georg Thieme Verlag, 2013, ISBN 978-3-13-492011-6 , p. 152 ( google.de ).
- ^ A b Franz-Viktor Salomon: muscle tissue . In: Franz-Viktor Salomon, Hans Geyer, Uwe Gille (Ed.): Anatomy for veterinary medicine . 3. Edition. Enke, Stuttgart 2015, ISBN 978-3-8304-1288-5 , pp. 210 .