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    From Musculoskeletal System

    Buccinator
    Muscle that helps with chewing and blowing air out.
    Wormian Bones
    Sutural bones in the skull.
    Coccyx
    Tailbone, the remnant of the tail in humans.
    Ischium
    Part of the pelvis that supports weight while sitting.
    Femur
    Thigh bone, the longest and strongest bone in the body.
    Trapezius
    Muscle responsible for moving, rotating, and stabilizing the scapula.
    Coccygeus
    Pelvic floor muscle supporting the coccyx.
    Gliding (Plane) Joints
    e.g., between carpals
    Saddle Joints
    e.g., thumb joint
    Lumbar Vertebrae (L1 - L5)
    Vertebrae in the lower back (L1-L5).
    Facial Bones
    Bones forming the structure of the face.
    Tibialis Anterior
    Muscle that dorsiflexes and inverts the foot.
    Acromioclavicular Ligament
    Ligament that connects the acromion to the clavicle.
    Pectoralis Major
    Chest muscle responsible for shoulder movement.
    Ellipsoidal (Condyloid) Joints
    e.g., wrist
    Quadriceps Tendon
    Tendon that connects the quadriceps to the patella.
    Vertebral Column
    Spinal column consisting of vertebrae.
    Sphenoid Bone
    Bone forming part of the base of the skull and sides of the orbits.
    Phalanges (14 bones)
    14 bones forming the toes.
    Extensor Tendons
    Tendons that help extend the fingers and toes.
    Parietal Bones
    Bones forming the sides and roof of the skull.
    Metatarsals (5 bones)
    5 bones forming the mid-foot.
    Sacroiliac Ligaments
    Ligaments connecting the sacrum to the iliac bones.
    Triceps Brachii
    Muscle responsible for elbow extension.
    Posterior Cruciate Ligament (PCL)
    Knee ligament that stabilizes the joint.

    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 ilium is the largest part of the hip bone.