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The latissimus dorsi muscle, commonly referred to as the 'lats', is a large, flat muscle in the lower posterior thorax that stretches across the back, behind the arm. It is one of the largest muscles in the back and is responsible for several functions, including upper extremity movement and respiratory functions. The latissimus dorsi muscle is also associated with various injuries and conditions, such as chronic shoulder and back pain, and is an important source of muscle for breast reconstruction surgery.
| Characteristics | Values |
|---|---|
| Common name | Latissimus dorsi muscle |
| Colloquial name | Lats |
| Location | Lower posterior thorax |
| Function | Upper extremity movement, accessory respiratory muscle |
| Innervation | Thoracodorsal nerve (C6-C8), a branch of the brachial plexus |
| Blood supply | Thoracodorsal artery, perforating arteries of the 9th-11th posterior intercostal arteries, 1st-3rd lumbar arteries |
| Attachments | Vertebral part, Costal part, spinous processes of vertebrae T7-L5, thoracolumbar fascia, posterior iliac crest, ribs, inferior angle of the scapula |
| Related muscles | Teres major, pectoralis major |
| Injuries | Muscle pulls, strains, tears, sports injuries (golf, baseball, swimming, etc.), chronic shoulder and back pain |
| Treatment | Rest, ice, compression, elevation, NSAIDs, physical therapy |
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What You'll Learn
Location
The latissimus dorsi muscle, commonly referred to as the 'lats', is a large, flat muscle located in the lower posterior thorax, spanning the lumbar and lower thoracic regions of the back. It stretches across the lower two-thirds of the trunk, covering the serratus posterior muscles.
The latissimus dorsi muscle is attached to the spine, connecting to the lumbar and thoracic vertebrae, with its fibres converging towards the proximal humerus. The muscle originates from several locations, including the spinous processes of vertebrae T7-L5, the thoracolumbar fascia, posterior iliac crest, lower ribs, and the inferior angle of the scapula.
The latissimus dorsi muscle is closely related to the teres major muscle embryologically, as they both originate from the pre-muscle sheath of the arm. The latissimus dorsi spreads across the posterior aspect of the thorax and trunk, while the teres major develops within the limb bud. During embryonic development, the fibres of the latissimus dorsi reach the iliac crest when the embryo is at least 20 mm long.
The latissimus dorsi muscle is also associated with the auscultation triangle, an anatomical landmark. The triangle is bordered by the trapezius muscle superiorly, the medial border of the scapula medially, and the latissimus dorsi muscle itself inferiorly. When the arms are folded across the chest and the trunk is bent forward, the lower pulmonary lobes become accessible for auscultation of respiratory sounds using a stethoscope.
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Function
The latissimus dorsi muscle, commonly referred to as the 'lats', is a large, flat muscle that covers the majority of the lower posterior thorax. It is one of the largest muscles of the back, stretching across the lower posterior thorax and wrapping around the sides of the body, behind the arms.
The primary function of the latissimus dorsi is in upper extremity movement. It is responsible for extension, adduction, transverse extension (also known as horizontal abduction or horizontal extension), flexion from an extended position, and internal rotation of the shoulder joint. The muscle also plays a role in the extension and lateral flexion of the lumbar spine.
The latissimus dorsi works in collaboration with the teres major and pectoralis major muscles to perform actions of the upper extremity. Together, these muscles adduct, medially rotate, and extend the arm at the glenohumeral joint. The latissimus dorsi is also active in the extension of the humerus. This extension is strongest when the motion is started from a position of partial flexion or abduction.
The latissimus dorsi is also implicated in respiratory functions. It is considered a respiratory accessory muscle, assisting in forceful respiratory functions such as coughing and sneezing. During a cough or sneeze, the muscle can be felt pressing forcibly inward, as it acts to compress the thorax and abdomen. It also assists in the breathing process by enhancing the movements of the trunk during inhalation and exhalation. The muscle lifts and expands the circumference of the rib cage during inhalation, which may increase the volume of air that enters the lungs. During exhalation, it helps decrease the circumference of the trunk, which may result in squeezing more air out.
The latissimus dorsi is a climbing muscle, a rowing muscle, and a swimming muscle. When the arms are in a fixed overhead position, it pulls the trunk upward and forward, as in climbing or performing a chin-up. It is also active in moving the trunk forward and upward when the upper extremities are fixed, as in walking with crutches.
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Injuries
The latissimus dorsi muscle can be injured due to overuse, poor posture, or poor form during sports and exercise. The pain may manifest in several places, including the shoulder blade, upper and lower back, arms, or fingers. The pain will worsen when reaching forward, extending the arms, or reaching overhead.
Common exercises that engage the latissimus dorsi and may lead to injury include weightlifting, pull-ups, and bench presses. Specific sports that can increase the risk of injury include golf, baseball, skiing, rowing, tennis, and swimming.
If the latissimus dorsi is injured, an individual may feel pain across their entire back, shoulders, and scapula. In some cases, the pain may radiate to the inside of the upper arms and down to the fingers. Treatment for an injured latissimus dorsi includes rest, ice, compression, and elevation. Non-steroidal anti-inflammatory medication (NSAIDs) may also be recommended if the pain or swelling is severe.
In rare cases, the latissimus dorsi muscle can tear, which is more likely to occur in professional athletes such as water skiers, golfers, baseball pitchers, rock climbers, and gymnasts. Surgery may be considered if the injury is severe and limits the individual's physical performance.
To prevent injuries, it is important to maintain good posture and avoid slouching. Staying hydrated by drinking plenty of water, especially before and after exercising, is also recommended.
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Exercises
The latissimus dorsi muscle, or 'lats' as it is commonly referred to, is one of the largest muscles in the back. It is a climbing, rowing, and swimming muscle, and it is innervated by the thoracodorsal nerve. The latissimus dorsi muscle is responsible for extension, adduction, transverse extension, flexion from an extended position, and internal rotation of the shoulder joint.
- Weightlifting
- Pull-ups
- Pull-downs
- Bent-over rows
- One-arm dumbbell rows
- Seated rows using a resistance band
- Barbell rows
- Straight-arm pulls
- Renegade rows
- Bench presses
It is important to note that exercises involving pulling or rowing motions are particularly effective in working the latissimus dorsi muscles. Additionally, heavier weights can be used for latissimus dorsi exercises as they are the largest muscles in the back. However, it is crucial to maintain proper form during exercises to avoid injury to the latissimus dorsi muscle.
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Innervation
The latissimus dorsi muscle, commonly referred to as the 'lats', is a large, flat muscle that covers the lower posterior thorax, extending to the sides and behind the arm. It is innervated by the sixth, seventh, and eighth cervical nerves, also known as the thoracodorsal nerve (C6-C8), which is a branch of the brachial plexus. This nerve originates from the posterior cord of the brachial plexus and enters the muscle on its deep surface.
The latissimus dorsi muscle receives blood flow from the thoracodorsal branch of the subscapular artery, which is a continuation of the axillary artery. In addition to the thoracodorsal artery, the latissimus dorsi muscle is supplied by perforating arteries arising from the posterior intercostal arteries and lumbar arteries.
The thoracodorsal nerve plays a crucial role in carrying innervation to the latissimus dorsi muscle, enabling it to perform various functions. This muscle is responsible for upper extremity movements, including adduction, extension, and internal rotation of the arm at the glenohumeral joint. It also assists in respiratory functions, such as coughing and sneezing, and plays a role in climbing, rowing, and swimming movements.
The latissimus dorsi muscle is closely associated with the teres major and pectoralis major muscles. These three muscles work together to depress the arm and perform actions of the upper extremity. They collaborate to adduct, extend, and medially rotate the arm, with the latissimus dorsi and teres major muscles also contributing to the extension of the humerus.
The proper functioning and coordination of the latissimus dorsi muscle with the teres major and pectoralis major muscles are vital for smooth and fluid upper extremity movements. Any alterations in the length or stiffness of this muscle can impact movement patterns and postures, potentially exacerbating low back pain.
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Frequently asked questions
The latissimus dorsi muscle, commonly referred to as the "lats", is a large, flat muscle on the back that stretches to the sides and behind the arm.
The latissimus dorsi is located in the lower posterior thorax, covering the serratus posterior muscles.
The primary function of the latissimus dorsi is in upper extremity movement. It is also a respiratory accessory muscle, assisting in breathing by expanding the rib cage during inhalation and helping to squeeze air out during exhalation.
The latissimus dorsi muscle can be injured due to overuse, poor posture, or improper form during sports and exercise. Common exercises that engage this muscle include weightlifting, pull-ups, and bench presses. Specific sports that can increase the risk of injury include golf, baseball, skiing, rowing, tennis, and
An individual with a latissimus dorsi injury may experience pain across their back, shoulders, and scapula. The pain may also radiate to the inside of the upper arms and down to the fingers.
