Abducts the arm at the glenohumeral shoulder joint. The medial head of the Triceps brachii arises from inferior two-thirds of the humerus to insert, along with the other two heads of the triceps, on the olecranon of the ulna. The long head of the Triceps brachii is one of three heads that make up the muscle. It descends between teres minor and major, dividing the wedge-shaped interval between them and the humerus into triangular and quadrangular spaces.
The lateral head of the Triceps brachii, one of three heads of the muscle, originates from the humerus, superior to the radial groove to insert on the olecranon process. If any of the deltoid muscles are sprained or injured in any way, this variation can cause the pain, spasming, decreased or altered sensation, or sometimes a lack of blood supply.
As mentioned earlier, the deltoid muscle plays a large role in the gross movements of the arm. Each head of the deltoid muscle also plays a role in the stabilization of the glenohumeral joint which serves to improve the smoothness and overall quality of arm movement. The glenohumeral joint, consisting of the scapula and humerus, relies on upper arm musculature for stabilization and overall maintenance of the joint integrity.
The deltoid is a muscle, with motor function as its sole and primary job. Motor function which the deltoid is responsible for includes shoulder abduction, shoulder flexion, and shoulder extension which allows the shoulder to stay at its resting position while also giving the option of backward movement. The motions enabled by the deltoid muscle play a large role in the overall use of the arm in daily tasks. The deltoid muscle serves no sensory function, though nerves and arteries which run through it allow for its oxygenation and movement.
Therefore, severe injury to the deltoid muscle may indirectly cause injury to the underlying nerves and arteries which run through or are adjacent to the deltoid. Conditions associated with the deltoid often are related to injury of the deltoid muscle or adjacent muscles with similar functions.
Muscles in the upper arm region include the supraspinatus, infraspinatus, teres minor, and subscapularis together known as the rotator cuff. The most common injury to this group of muscles as a whole is a rotator cuff tear.
This may place undue mechanical stress on the deltoid muscle, which can cause a muscle sprain if it continues over a long period of time. More specific to the deltoid muscle is its integration within the entire arm, as this plays a role in surgical approaches.
Due to the frontal placement of the anterior head of the deltoid, this muscle is an important consideration when surgeons choose an approach which involves access through the front of the arm. Surgeries such as open capsular reconstructions for frontal shoulder instability, shoulder replacement surgeries, biceps tendon repairs, and rotator cuff repair surgeries all may utilize the deltopectoral approach.
The deltopectoral approach uses fibers and anatomical landmarks from the deltoid and pectoralis major muscles to guide surgical incisions. Both frontal and side approaches to surgery include the splitting of deltoid muscle fibers followed by fibers being sewn back together. Any of these approaches which include the splitting of the deltoid fibers can result in injury to the deltoid muscle. This may require some rehabilitation to the deltoid muscle along with the typical rehabilitation course specific to the surgical procedure.
Due to the placement of the axillary nerve immediately below the deltoid muscle, the nerve supply to the deltoid and other upper arm muscles may also be impacted through surgery or traumatic injuries. This nerve loss can result in a partial or complete loss of motor function to the deltoid muscle, along with the other muscles the axillary nerve supplies. Motor loss would also be accompanied by loss of sensation to the deltoid muscle, depending on the severity of the nerve loss.
The cephalic vein runs adjacent to the deltoid muscle and assists with circulation and fluid management. An injury of any kind to the cephalic vein can result in fluid buildup to the upper arm. If not addressed immediately and properly, fluid buildup can lead to a host of other complications, including skin changes, loss of blood flow, nerve damage, loss of muscle strength, and more. Rehabilitation of the deltoid muscle looks much the same as rehabilitation of most large muscles of the arm. If someone has surgery on the deltoid muscle or even an injury which requires extensive rehabilitation, treatment of the deltoid will typically follow a specific protocol.
This protocol will vary slightly based on the injury which occurred and whether surgery was performed. Most protocols require an individual to wear a brace which immobilizes the arm for two to three weeks. While the arm is immobilized, an occupational or physical therapist will provide either active or passive motion to the joints below the upper arm.
The deltoid muscle is constructed with three main sets of fibers: anterior, middle, and posterior. These fibers are connected by a very thick tendon and are anchored into a V-shaped channel. This channel housed in the shaft of the humerus bone in the arm. The deltoid muscle is responsible for the brunt of all arm rotation and allows a person to keep carried objects at a safer distance from the body. It is also tasked with stopping dislocation and injury to the humerus when carrying heavy loads.
One of the most common injuries to the deltoid muscle is a deltoid strain. Deltoid strain is characterized by sudden and sharp pain where injured, intense soreness and pain when lifting the arm out from the side of the body, and tenderness and swelling caused by and located at the deltoid muscle. The supraspinatus muscle is a rotator cuff muscle located in the shoulder, specifically in the supraspinatus fossa, a concave depression in the rear….
The quadratus plantae is a muscle in the foot that extends from the anterior front of the calcaneus heel bone to the tendons of the digitorum…. The deltoid has three distinct functions that correspond to the three bands of muscle fibers. Contraction of the anterior fibers flexes and medially rotates the arm by pulling the humerus towards the clavicle. Flexion and medial rotation of the arm moves the arm anteriorly, as in reaching forward or throwing a ball underhand.
The lateral fibers abduct the arm by pulling the humerus toward the acromion. Abduction of the arm results in the arm moving away from the body, as in reaching out to the side.
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