Logan Steele
The deltoid muscle is a large, triangular-shaped muscle that forms the rounded contour of the human shoulder. It is a common site for intramuscular injections, including vaccinations. The deltoid muscle is responsible for elevating the arm in the scapular plane and receives blood from the thoracoacromial branch of the axillary artery. The deltoid muscle is divided into three parts: the anterior, or clavicular; lateral, or acromial; and posterior, or spinal. Each of these parts attaches to a different region of the shoulder, with the anterior part attaching to the clavicle, the lateral part attaching to the acromion process, and the posterior part attaching to the spine of the scapula.
| Characteristics | Values |
|---|---|
| Deltoid Muscle Shape | Triangular |
| Deltoid Muscle Name Origin | Named after the Greek letter delta, which is shaped like an equilateral triangle |
| Deltoid Muscle Parts | Anterior or clavicular, lateral or acromial, and posterior or spinal |
| Anterior Deltoid Attachment | Clavicle (collarbone) |
| Lateral Deltoid Attachment | Acromion, a bony knob on the scapula (shoulder blade) |
| Posterior Deltoid Attachment | Spine of the scapula |
| Deltoid Muscle Function | Shoulder abduction, stabilization of the glenohumeral joint, and swinging of the arms when walking |
| Deltoid Muscle Blood Supply | Thoracoacromial branch of the axillary artery |
Explore related products
What You'll Learn
Anterior deltoid
The deltoid muscle is a large, triangular-shaped muscle that forms the rounded contour of the shoulder. It is a powerful muscle that is used in many everyday activities and athletic pursuits. The deltoid is comprised of three distinct sections: the anterior or clavicular part (often referred to as the front deltoid), the intermediate or acromial part (or side deltoid), and the posterior or scapular part (the rear deltoid).
The anterior deltoid is the focus of this discussion. This section of the muscle originates from the superior surface and the anterior border of the lateral third of the clavicle. The anterior fibres arise from the anterior border and upper surface of the lateral third of the clavicle, lying close to the lateral fibres of the pectoralis major muscle. The anterior deltoid is involved in flexion, internal rotation, and horizontal adduction. It works with the pectoralis major to flex the shoulder and arm during walking. The anterior deltoid also internally (medially) rotates the humerus, working in conjunction with the subscapularis, pecs and lats.
The anterior deltoid is involved in abduction of the arm, along with the other sections of the deltoid muscle. When all the fibres contract simultaneously, the deltoid is the prime mover of arm abduction. The anterior and posterior parts of the deltoid also stabilise the arm during abduction, while the lateral segment assists in raising the arm from 15° to 100° degrees.
The deltoid muscle is a key shoulder stabiliser, preventing inferior glenohumeral joint displacement during heavy lifting. The deltoid compensates for weakness in the shoulder due to rotator cuff tears. The deltoid also helps to prevent subluxation or dislocation of the head of the humerus.
Mastering Vaginal Muscle Control: Techniques for Women
You may want to see also
Explore related products
Lateral deltoid
The deltoid muscle is a large, triangular-shaped muscle located in the upper arm and shoulder region. It is responsible for a variety of movements at the shoulder joint, including abduction, flexion, extension, medial rotation, lateral rotation, horizontal flexion, and horizontal extension of the upper arm. The deltoid muscle can be divided into three parts: the anterior, lateral, and posterior.
The lateral deltoid is the middle portion of the deltoid muscle, located between the anterior and posterior heads. It is found directly on top of the shoulder. The lateral deltoid attaches to the acromion process of the scapula, which is the bone that forms the socket of the shoulder joint. The acromion process is a small bony projection located on the lateral edge of the scapula.
When the lateral deltoid contracts independently, it causes the arm to abduct, or move away from the body. This is a crucial movement for activities such as reaching out to the side or lifting and carrying objects. The lateral deltoid works in conjunction with the other parts of the deltoid muscle to produce a variety of movements and provide stability to the shoulder joint.
Additionally, the lateral deltoid plays a role in protecting the shoulder and rotator cuff during activities that require brute strength or force, such as lifting heavy objects or pushing the body up from the ground using the arms. The deltoid muscle as a whole is susceptible to injuries caused by repeated overhead activities, sports injuries, and traumatic events. Therefore, it is important to properly test the function of the deltoid muscle to determine any muscular or nervous injuries accurately.
Head Flexion: What Muscles Are Involved?
You may want to see also
Explore related products
Posterior deltoid
The deltoid muscle is a large, triangular-shaped muscle that forms the rounded contour of the human shoulder. It is comprised of three distinct sections: the anterior or clavicular part (commonly known as the front deltoid), the intermediate or acromial part (known as the side deltoid), and the posterior or scapular part (known as the rear deltoid). The posterior deltoid is the focus of this discussion.
The posterior deltoid, or rear deltoid, is a key shoulder stabiliser. It works with the latissimus dorsi to extend the arm during walking or ambulation. This muscle also helps with many pulling movements and stabilises the shoulder joints. It externally rotates the shoulders and extends the humerus behind the body, as in the action of pulling a lawnmower cord or bringing the arm backward when walking. Rowing and pull-up exercises are great for strengthening the posterior deltoid.
The posterior deltoid is also involved in abduction of the arm. When all three parts of the deltoid contract simultaneously, the muscle assists in abducting the arm past 15 degrees. The posterior deltoid, along with the anterior deltoid, stabilises the arm during abduction, while the lateral segment assists in raising the arm from 15 to 100 degrees.
The deltoid muscle as a whole receives its blood supply from the thoracoacromial branch of the axillary artery, which originates from the second part of the axillary artery. The deltoid also receives minor contributions from the posterior humeral circumflex and profunda brachii arteries. The anterior and posterior branches of the axillary nerve innervate the deltoid.
Building a Bigger Chest: Strategies for Maximum Muscle Growth
You may want to see also
Explore related products
Deltoid tuberosity
The deltoid muscle is a large triangular-shaped muscle that forms the rounded contour of the human shoulder. It is comprised of three distinct portions: the anterior or clavicular part (commonly known as the front delt), the posterior or scapular part (commonly known as the rear delt), and the intermediate or acromial part (known as the side delt).
The deltoid muscle attaches to the deltoid tuberosity, which is a rough, triangular prominence found at the middle third of the anterolateral surface of the humerus. The deltoid tuberosity serves as the distal attachment site for the deltoid muscle. It is a prominent feature in less than 10% of people and is vulnerable to avulsion fractures.
The deltoid muscle is responsible for elevating the arm in the scapular plane and is the prime mover of arm abduction along the frontal plane when all its fibres contract simultaneously. The anterior deltoid works with the pectoralis major to flex the arm during walking, while the posterior deltoid works with the latissimus dorsi to extend the arm. The deltoid also acts as a shoulder stabilizer, preventing inferior glenohumeral joint displacement during heavy lifting.
The deltoid muscle is a common site for intramuscular injections and is susceptible to various pathologies, including tears, fatty atrophy, and enthesopathy. Deltoid tears are often associated with rotator cuff tears and can lead to functional disfunction of the shoulder complex.
Shrinking Muscles: Strategies to Reduce Muscle Size
You may want to see also
Explore related products
Shoulder stabilisation
The deltoid muscle is a large, triangular-shaped muscle that forms the rounded contour of the human shoulder. It is also known as the 'common shoulder muscle'. It is comprised of three distinct sections: the anterior or clavicular part (commonly known as the front deltoid), the intermediate or acromial part (or side deltoid), and the posterior or scapular part (or rear deltoid).
The deltoid muscle is a key shoulder stabilizer. It is responsible for elevating the arm in the scapular plane, and its contraction also elevates the humeral head. The muscle's primary function is shoulder abduction, and it also contributes to the stabilization of the glenohumeral joint. When the three parts of the deltoid contract simultaneously, it results in abduction of the shoulder when the arm is already held at 15 degrees of abduction. The anterior deltoid works with the pectoralis major to flex the arm when walking, while the posterior deltoid works with the latissimus dorsi to extend the arm during ambulation.
The deltoid is a very powerful muscle and is used in many everyday activities, such as putting clothes on a line, carrying shopping bags, or washing hair. It is also used in athletic activities such as netball, swimming, and water polo. It is a common site for intramuscular injections, including vaccinations.
The deltoid muscle is innervated by the axillary nerve, which may be injured during shoulder surgery, resulting in disastrous functional consequences. Deltoid muscle tears are unusual but are frequently related to traumatic shoulder dislocation or massive rotator cuff tears.
Muscle Protein: What's the Deal?
You may want to see also
Frequently asked questions
The deltoid muscle is a large, triangular-shaped muscle that forms the rounded contour of the human shoulder.
The deltoid muscle is attached by tendons to the skeleton at the clavicle (collarbone), scapula (shoulder blade), and humerus (upper arm bone).
The deltoid muscle can be divided into three parts: the anterior or clavicular, the lateral or acromial, and the posterior or spinal.
The deltoid originates from the scapular spine, superior acromial surface, and lateral third of the clavicle.
The main function of the deltoid muscle is to produce shoulder abduction, or the movement of the arm away from the body. It also contributes to the stabilization of the glenohumeral joint.
