Latissimus Dorsi Muscle- An Overview

Introduction

Muscles in the back play an important role in moving the body, bending, rotating the trunk, and standing straight. They also support the spine and become essential for breathing. The latissimus dorsi muscle is one of the muscles located at the back. They are large and flat, covering most of the back region. Due to its broad nature, the muscle has various attachments such as the spine, lower part of the trunk, rib cage, and shoulder blade. This article will discuss the anatomy, functions, associated conditions, and strengthening exercises of latissimus dorsi in detail.

Where Is the Latissimus Dorsi Located?

The Lats muscle is located in the mid-back region. It belongs to the extrinsic muscles of the back, along with levator scapulae(a skeletal muscle present at the back and sides of the neck), trapezius (a superficial back muscle), and rhomboid muscle (rhombus-shaped muscle connected to the shoulder bone).

What Are the Various Attachments of the Latissimus Dorsi Muscle?

The latissimus dorsi muscle originates from various structures, mostly from the vertebrae. The spine is generally composed of three sections such as the

• Cervical portion(neck region),

• Thoracic portion(middle trunk portion),

• Lumbar portion(lower back).

The latissimus dorsi muscle is stretched over eleven vertebrae. The origins of the lats muscle include the six thoracic vertebrae(T7 to T12), five lumbar vertebrae(L1 to L5), lower three to four ribs, bottom of the shoulder bone, thoracolumbar fascia(deep tissue located behind the spinal column), Posterior part of the sacrum(triangular bone located at the base of the spine) and posterior iliac crest. This muscle tapers into a point and inserts over the intertubular groove of the humerus(deep indentation over the upper arm bone just below the shoulder joint). Therefore it gives the appearance of a triangle.

What is the blood supply to the latissimus dorsi muscle?

The latissimus dorsi muscle is primarily supplied by the thoracodorsal artery, part of the terminal branch of the subscapular artery that originates from the axillary region (underarm). This muscle also receives blood supply from

• Lower three intercostal arteries (a group that supplies the area between the ribs).

• Upper three lumbar arteries (arteries located in the lower back region).

What Are the Functions of the Latissimus Dorsi Muscle?

The latissimus dorsi muscle contributes to the movements of the upper back region and arm motion. Through its various attachments, this muscle contributes to multiple functions, such as

• The Latissimus dorsi muscle works along with the teres major muscle (upper limb muscle that attaches to the shoulder bone) and pectoralis major muscle to help bring the arm closer to the body's midline (adduction) and to rotate the upper arm medially.

• With attachment to the teres major muscle, they also help in the extension of the upper arm.

• This muscle helps pull the body weight up by moving the trunk forward and upward with the upper arms fixed overhead, such as doing pull-ups, climbing, or swimming.

• Recent studies have shown its association with the breathing process. They help in enhancing the movement of the trunk during inhalation and exhalation. They function by expanding the ribcage and increasing the circumference of the ribcage during inhalation. They are also active during coughing and sneezing.

• This muscle also helps in the depression of the shoulder by bringing the shoulder down.

• Lateral flexion(side bending).

What Is the Clinical Significance of the Lats Muscle?

• A weak latissimus dorsi muscle can cause movement restrictions while moving the arm away from the body (abduction), side bending with the trunk, and lateral rotation of the trunk. Proper functioning of the lats muscle and its coordination with the teres major and pectoralis major is essential for the appropriate functioning of the upper limb.

• A compromised length and flexibility of the lats muscle can lead to alterations in the movement patterns or posture which can cause lower back pain since it is attached to the spine and the pelvis bone.

• The latissimus dorsi muscle is involved in posterior shoulder dislocation in patients following a seizure or electric shocks.

• Injury to the thoracodorsal nerve is a common complication during surgery in the axillary region. This can result in paralysis of the latissimus dorsi muscle.

• In patients with scoliosis (abnormal curvature in the spine), the lats muscle tends to be tighter on one side.

• In patients with kyphosis (abnormal upper back rounding), the lats muscle tends to be tighter on the front.

What Are the Various Exercises for the Lats Muscle?

Adding the strengthening and stretching exercises of lats muscle in the workout regimen is necessary to build upper body strength, increasing the range of motion and preventing muscle injury. Here are a few recommended stretching and strengthening exercises for lats muscle:

• Active lat stretch: One should begin with the kneeling position, arms extended over the knee, and forearm placed over the floor. Lower the trunk as far as possible and hold the stretch for a few seconds. Relax in the starting position and repeat the exercise ten times.

• Wall press: Stand straight by facing against the wall. Place the palms of both hands over the wall at the height of the hip and bend forward. Hold the position for a minute.

• Downward-facing dog: One should begin with all fours, with the wrist under the shoulder and the knees under the hips. The hip is lifted off from the floor. One should bring the heel towards the floor by keeping the legs straight. Focus on widening the shoulder bone and tightening towards the tailbone. This position is held for ten seconds.

• Pull-ups: pull-ups are one of the effective workouts in strengthening the lats muscle. One can use a chair or a stool under the pull-up bar. With hands over the pull-up bar wider than the shoulder, one should lift their body. And the body is lowered and relaxed. This exercise is repeated eight times.

• Upward-facing dog.

• Cat cow stretch.

• Foam rolling.

Conclusion:

The Lats muscle is one of the core muscles that are necessary for day-to-day activities. They are large and flat muscles located in the mid back region. They have various attachments which contribute to the various body movements. Therefore it is essential to keep the lats muscle strengthened and strong. Exercises such as rows, pull-overs, and pull-ups involving pulling motions can effectively strengthen the Latissimus dorsi muscle.