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    Related Topics

    From Musculoskeletal System

    Hyoid Bone
    U-shaped bone in the neck that supports the tongue.
    Sesamoid Bones
    e.g., patella, some found in hands/feet.
    Obliques (External and Internal)
    Muscles responsible for torso rotation.
    Occipital Bone
    Bone forming the back and base of the skull.
    Sutures (in the skull)
    Fibrous joints between skull bones.
    Frontal Bone
    Bone forming the forehead and upper part of the orbits.
    Temporal Bones
    Bones forming the lower sides of the skull and housing the ears.
    Patella
    Knee cap, protecting the knee joint.
    Acromioclavicular Ligament
    Ligament that connects the acromion to the clavicle.
    Rectus Abdominis
    Abs muscle that flexes the trunk.
    Sternum
    Breastbone located in the center of the chest.
    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.
    Quadriceps
    Rectus Femoris, Vastus Medialis, Vastus Lateralis, Vastus Intermedius.
    Posterior Longitudinal Ligament
    Spinal ligament running along the back of the vertebral column.
    Tibialis Anterior
    Muscle that dorsiflexes and inverts the foot.
    Ball-and-Socket Joints
    e.g., shoulder, hip
    Tibia
    Shin bone, the larger bone in the lower leg.
    Saddle Joints
    e.g., thumb joint
    Metatarsals (5 bones)
    5 bones forming the mid-foot.
    Thoracic Vertebrae (T1 - T12)
    Vertebrae in the upper and mid-back (T1-T12).
    Sternocleidomastoid
    Muscle that rotates and flexes the neck.
    Syndesmoses
    Fibrous joints where bones are connected by ligaments.
    Sphenoid Bone
    Bone forming part of the base of the skull and sides of the orbits.
    Scapula
    Shoulder blade providing attachment for muscles of the upper limb.
    Gomphoses
    Fibrous joints where a peg fits into a socket (e.g., teeth in jaw).

    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? Ligaments hold bones together and are tough yet flexible.