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    Related Topics

    From Musculoskeletal System

    Extensor Tendons
    Tendons that help extend the fingers and toes.
    Rectus Abdominis
    Abs muscle that flexes the trunk.
    Adductors
    Muscles that bring the thighs toward the midline.
    Obliques (External and Internal)
    Muscles responsible for torso rotation.
    Symphyses
    Cartilaginous joints where bones are connected by fibrocartilage.
    Posterior Cruciate Ligament (PCL)
    Knee ligament that stabilizes the joint.
    Ligamentum Flavum
    Spinal ligament connecting the laminae of adjacent vertebrae.
    Syndesmoses
    Fibrous joints where bones are connected by ligaments.
    Sartorius
    Longest muscle in the body responsible for hip flexion.
    Anterior Cruciate Ligament (ACL)
    Knee ligament that stabilizes the joint.
    Rotator Cuff Muscles
    Supraspinatus, Infraspinatus, Teres Minor, Subscapularis.
    Occipital Bone
    Bone forming the back and base of the skull.
    Coracoacromial Ligament
    Ligament that connects the acromion to the coracoid process.
    Thoracic Cage
    Ribs and sternum forming the protective cage for the heart and lungs.
    Anterior Scalene Muscle
    The anterior scalene muscle is a deep neck muscle that elevates the first rib during inspiration and aids in neck flexion and stability, located between key neurovascular structures.
    Abductor Digiti Minimi Muscle
    The abductor digiti minimi muscle is a hypothenar muscle that abducts and flexes the little finger, aiding grip and precision in hand movements.
    Metatarsals (5 bones)
    5 bones forming the mid-foot.
    Fibula
    Smaller bone in the lower leg, located alongside the tibia.
    Ball-and-Socket Joints
    e.g., shoulder, hip
    Vomer Bone
    Bone forming the nasal septum.
    Facial Bones
    Bones forming the structure of the face.
    Gliding (Plane) Joints
    e.g., between carpals
    Annular Ligament
    The annular ligament is a strong fibrous band encircling the head of the radius, stabilizing the proximal radioulnar joint and allowing smooth rotation of the forearm.
    Humerus
    Upper arm bone connecting the shoulder to the elbow.
    Interspinous Ligament
    Spinal ligament between adjacent vertebral spinous processes.

    Latissimus Dorsi

    Reviewed by our medical team

    Back muscle responsible for arm adduction and extension.

    1. Overview

    The latissimus dorsi is a large, flat, triangular muscle located in the lower back. Commonly referred to as the "lats," it is one of the broadest muscles in the human body. This powerful muscle plays a central role in upper limb movement, particularly in actions involving pulling, extension, and internal rotation of the shoulder. It also contributes to posture and trunk stabilization.

    2. Location

    The latissimus dorsi is located in the posterior thoracic and lumbar regions of the body:

    • Origin:

      • Spinous processes of T7–T12 vertebrae

      • Thoracolumbar fascia

      • Iliac crest (posterior part)

      • Inferior 3 to 4 ribs

      • (Sometimes) the inferior angle of the scapula

    • Insertion:

      • Floor of the intertubercular sulcus (bicipital groove) of the humerus

    • Superficial to: Deeper muscles of the back such as the erector spinae

    3. Structure

    The latissimus dorsi is a broad, fan-shaped muscle with a wide origin and a narrow tendon of insertion:

    • Shape: Triangular and sheet-like

    • Fibers: Run superolaterally from the spine and lower back to converge into a tendon that passes anterior to the shoulder joint

    • Innervation: Thoracodorsal nerve (C6, C7, C8), a branch of the posterior cord of the brachial plexus

    • Blood supply: Thoracodorsal artery (a branch of the subscapular artery)

    4. Function

    The latissimus dorsi is involved in several key movements of the upper limb:

    • Extension of the shoulder: Moves the arm backward

    • Adduction of the arm: Brings the arm toward the body's midline

    • Internal (medial) rotation of the humerus: Rotates the arm inward

    • Assists in respiration: Acts as an accessory muscle in forceful expiration (e.g., coughing or heavy breathing)

    5. Physiological role(s)

    In addition to movement, the latissimus dorsi supports various physiological functions:

    • Postural support: Helps stabilize the spine and pelvis during dynamic upper limb movements

    • Trunk motion: Assists in lateral flexion and rotation of the trunk when the arm is fixed

    • Force generation: Critical for pulling motions such as climbing, swimming, and rowing

    • Muscle synergy: Works with the teres major, pectoralis major, and rotator cuff muscles to coordinate shoulder movements

    6. Clinical Significance

    The latissimus dorsi is clinically relevant in musculoskeletal health, injury, and reconstructive surgery:

    • Muscle strain or tear:

      • Can occur during sports involving sudden pulling motions (e.g., gymnastics, rock climbing); leads to pain and weakness in shoulder extension

    • Thoracodorsal nerve injury:

      • May occur during axillary surgery or trauma, resulting in weakness of shoulder adduction and extension

    • Myofascial pain syndrome:

      • Trigger points in the latissimus can refer pain to the mid-back or posterior shoulder area

    • Reconstructive surgery:

      • The muscle is commonly used in flap procedures, such as latissimus dorsi flap for breast reconstruction after mastectomy

    • Posture and imbalance:

      • Overactivation or tightness can contribute to shoulder internal rotation and poor posture, often seen in athletes with repetitive pulling tasks

    Did you know? The smallest joint in the body is the stapes in the ear.