Latissimus Dorsi Definition

The latissimus dorsi muscle is a plain, wing-like muscle that originates in the lower thoracic vertebrae, lower ribs, scapula, and iliac crest, as well as connects to or inserts into a groove in the upper arm bone (humerus). The shoulder joint may be extended, adducted, abducted (brought away from the body), and flexed. It also helps with sideways bending and lumbar spine extension (straightening) (lateral flexion).

Latissimus Dorsi Location

The latissimus dorsi is located in the middle of the back. It’s easy to see one side of the muscle if you think of the spine as the base of a triangle and the humeral connection as the apex of that triangle. Although this muscle is an individual muscle divided into right as well as left segments, it has a triangular or wing-like shape on the opposite side of the body. Each triangle’s upper sides intersect the scapulae, or shoulder blades’ bottom sections.

Although the latissimus dorsi muscle is the biggest in the human body, it is not the strongest. due to its thin thickness of less than one centimetre. Because a person can function properly without it, this muscle is often employed in reconstructive surgery to heal major wounds or replace damaged tissue.

Latissimus Dorsi Function

We need to understand the latissimus dorsi muscle’s genesis and insertion while looking at its function. All muscles have one or more points of origin and insert into one or more other points. The origin is a non-moving, stationary location. The insertion points are places where you can move about. This indicates that movement is always in the direction of the insertion point toward the origin. The genesis and implantation of the Latissimus dorsi are explained in further detail below.

This muscle is not self-contained. The shoulders and arms are moved by a variety of muscles. The pectoralis major, latissimus dorsi, trapezius, serratus anterior, and deltoid muscles are among them. The rotator cuff is another key muscle group. The rotator cuff is made up of four muscles: the supraspinatus, infraspinatus, teres minor, and subscapularis. They arise from the scapula and insert at the humerus, much as the latissimus dorsi. To provide a broad range of mobility in the upper extremities, all of these muscles function together or against one another.

The latissimus dorsi muscle has several origins, the majority of which are found in the vertebrae. These are the sources:

• 7–12th thoracic vertebrae
• 1 to 5 lumbar vertebrae.
• The shoulder blade’s bottom angle (scapula)
• 3–4 ribs from the bottom
• The iliac crest on the back of the leg
• Posterior sacrum  

The intertubercular groove near the apex of the humerus is the single insertion point. In the figure below, you can see where this groove is positioned. This implies that when it contracts, it pulls the upper arm towards the position of the hip and back. Due to the fact that the wing-shaped muscle is located at the base of the shoulder blades, it also aids in the stabilisation of these movable bones.

The function of the latissimus dorsi is commonly characterised as that of a climbing muscle, although it also plays a role in rowing, specific swimming strokes, and holding an axe while rising and lowering it high over the head.

When we exhale, this muscle also performs a little function. As you cough, you’ll sense the wing-shaped muscles on either side of your back contract. It helps to force the air out of the lungs by shrinking the thoracic space when it contracts.

Despite the fact that this muscle seems to have numerous functions, it is not insignificant. When muscles from various parts of the body are needed to close large wounds, such as surgical free flaps, the latissimus dorsi is an excellent option. According to one tiny piece of research, even when this muscle is entirely destroyed, most patients have minimal trouble moving their shoulders and may resume their previous activities without difficulty.

Latissimus Dorsi Movements

The activity of the latissimus dorsi is strongly reliant on the actions of other muscles. We’ve also discovered that without this specific muscle, mobility is generally compromised.

Other muscles work together as agonist and antagonist sets to give the shoulder a wide range of motion. An agonist muscle provides the force required to complete a motion and must constrict (shorten) or loosen up in order to do so (lengthen). The agonist is also known as the prime mover, since they are the ones who create the force. The antagonist muscle operates in the opposite direction to the agonist muscle.

As a result, these muscles must act in tandem. The antagonist relaxes when the agonist contracts, and vice versa. Antagonists maintain the position of their body component. The biceps and triceps are examples of antagonist and agonist muscle groups. In the illustration, you will observe how one loosens as well as the other tightens to move the elbow joint.

Another muscle type is the synergist, which assists the agonist. It has the ability to both stabilise the joint and lower the amount of energy required for the agonist to function. The synergist will contract if the agonist contracts. The latissimus dorsi may sometimes serve as a synergist.

Adduction and Abduction

Adduction is the downward movement that occurs when you create the symbol T using your hands and body and then return one or both hands back to your sides from a horizontal posture. The pectoralis major, latissimus dorsi, and teres major are the principal arm adductor agonists. The deltoid, trapezius, and supraspinatus muscles all perform antagonist motions.

In abduction, you extend your arms away from your sides. The latissimus dorsi becomes an antagonist rather than an agonist in this action, and the deltoid muscles become major movers.

Extension

Shoulder hyperextension is when your arm is at your side and is swung backward from the shoulder. Shoulder extension is the process of returning your arm to a more neutral posture after it has been swung forward from the shoulder. The latissimus dorsi isn’t engaged in hyperextension, and it only has a modest influence on returning a flexed shoulder back to neutral.

In transverse extension, the latissimus dorsi, in conjunction with the posterior deltoid muscle, becomes the major mover, similar to when you extend your shoulders and elbows back while doing paddling activities. Transverse extension is antagonistic to the anterior deltoid muscles, pectoralis major, and biceps.

Internal Rotation

Fold one arm, holding the elbow near to your side, and thrust your hand straight to engage the shoulder’s internal or medial rotation. Now cross your lower arm over your abdomen and to the other side of your body. Is there any mobility in your shoulder? The internal rotation of this joint is causing you discomfort. The pectoralis major, latissimus dorsi, and anterior deltoid muscles are the key agonists for internal rotation. The teres minor, infraspinatus, and posterior deltoid muscles are antagonists.

Trunk Movement

The latissimus dorsi has a minor involvement in trunk movements. This is regulated mostly by the erector spinae and abdominal muscles. While it acts as the principal mover while the trunk is kept upright (extension), it acts as an antagonist when the trunk is bent forward (flexion) (flexion). It functions in synergy with the neck turning and lateral flexion to the side.

Pelvic Movement

Because the latissimus dorsi inserts at the pelvic iliac crest, it functions in conjunction with the front (forward) and lateral (to the side) pelvic tilts. While the latissimus dorsi becomes hyperactive as a result of poor posture, it may cause the hip to protrude forward – or to one side if just a small portion of the muscle is affected.

Scapular Movement

Finally, the latissimus dorsi serves as a synergist for the shoulder blades, especially as a neutralising synergist or stabiliser. This thin sheet of muscle keeps both scapulae steady during movement since it covers the lowest regions of both. The latissimus dorsi’s horizontal sheet barely touches the base of the shoulder blades.

Latissimus Dorsi Pain

One probable cause of lower back discomfort is a reduced, tight latissimus dorsi muscle that pushes on the spine and pelvis. Long-term shortening may cause persistent back ache because the body tries to counteract by swivelling the pelvis and altering the way a person moves.

These balancing impacts have the potential to result in lifelong harm. Without initially heating up the muscle, a rapid shoulder movement results in a latissimus dorsi strain, which must be managed with calm and repeated, brief applications of ice. Try some of the exercises farther down to avoid more latissimus dorsi strain.

Muscle tears in the latissimus dorsi are uncommon, but they are almost always associated with certain athletic activities. Rock climbers, rodeo steer wrestlers, golfers, skiers, body builders, baseball players, tennis players, gymnastics, volleyball players, and basketball athletes have latissimus dorsi tears, according to the linked source. A majority of these exercises include severe movement of the upper arm with trunk rotation.

Despite this, since the muscle is so big and covers so many areas, it is difficult to detect an injury to it. The latissimus dorsi muscle may cause pain in the back, behind the shoulders, between the shoulder blades, and even in the fingers. To see whether an injury to this muscle is causing pain, the individual should raise his or her arms over his or her head, toss a ball, or extend his or her arms forward at shoulder height.

Latissimus Dorsi Exercises

Exercises for the latissimus dorsi will only be effective if the muscle is gradually warmed up beforehand, using the proper technique and posture.

The latissimus dorsi side stretch should be the first step in your routine. Imagine a cable linked to the top of your head, pushing you up to your full height. Your hips should be relaxed and your back should be straight. Your feet should be spaced apart slightly. Lean to one side and lift both arms over your head until you feel a stretch in your upper back. Hold for 10 seconds before gently returning to the starting position. Rep, this time bending to the other side. Stretch each side at least fifteen times on each side, progressively increasing the sideward movement without discomfort.

The back bow, the next latissimus dorsi stretch, needs you to lie on your stomach. Forward-stretch your arms and point your toes. Bring your shoulders and lower limbs up using just your back muscles. The idea is to resemble Superman or Supergirl as they soar over the sky. Hold it for as long as you can without feeling any discomfort, then gently return to your normal posture. rep a total of 10 times.

The pelvic raise is the third latissimus dorsi muscle exercise. Pull your belly in and turn on your back, pressing your lower back into the floor. Bend your knees and place your feet flat on the floor with your arms at your sides. Slowly lift the pelvis up using your back muscles, hold this position without pain, and gently lower the pelvis back to the floor. Repeat at least ten times, moving slowly each time.

Regular latissimus dorsi stretch exercises help to prevent back discomfort by allowing this muscle to stretch as well as relax. It’s just as vital to return to your original posture slowly and gently as it is to stretch.

References

• Di Giacomo G, Pouliant N, Costantini N, de Valta A. (2008) Atlas of Functional Shoulder Anatomy. New York, Springer-Verlag.
• Jeno SH, Varacallo M. Anatomy, Back, Latissimus Dorsi. [Updated 2019 Apr 5]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK448120/
• Laitung JK, Peck F. Shoulder function following the loss of the latissimus dorsi muscle. Br J Plast Surg. 1985;38(3):375‐379. doi:10.1016/0007-1226(85)90245-0