Logo

    Related Topics

    From Musculoskeletal System

    Glenohumeral Ligaments
    Shoulder ligaments that stabilize the shoulder joint.
    Inferior Nasal Conchae
    Bones inside the nasal cavity that filter and humidify air.
    Ethmoid Bone
    Bone forming part of the nasal cavity and the orbit.
    Fibula
    Smaller bone in the lower leg, located alongside the tibia.
    Frontal Bone
    Bone forming the forehead and upper part of the orbits.
    Diaphragm
    Primary muscle for breathing.
    Lacrimal Bones
    Bones forming part of the eye socket and housing the tear ducts.
    Facial Bones
    Bones forming the structure of the face.
    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.
    Acetabulum
    The acetabulum is the pelvic socket that connects with the femoral head to form the hip joint, vital for stability, movement, and weight-bearing.
    Femur
    Thigh bone, the longest and strongest bone in the body.
    Maxillae
    Upper jaw bones that house the teeth and form part of the orbit.
    Hamstrings
    Biceps Femoris, Semitendinosus, Semimembranosus.
    Acromioclavicular Joint
    The acromioclavicular joint connects the clavicle and scapula at the top of the shoulder, enabling smooth scapular motion and stability during arm movements.
    Ilium
    Uppermost and largest part of the hip bone.
    Lateral Collateral Ligament (LCL)
    Knee ligament that stabilizes the outer knee.
    Cranial Bones
    Bones of the skull that protect the brain.
    Cervical Vertebrae (C1 - C7)
    Vertebrae in the neck region (C1-C7).
    Sacrum
    Triangular bone at the base of the spine.
    Patella
    Knee cap, protecting the knee joint.
    Parietal Bones
    Bones forming the sides and roof of the skull.
    Mandible
    Lower jawbone that houses the teeth.
    Coccygeus
    Pelvic floor muscle supporting the coccyx.
    Masseter
    Muscle that elevates the mandible.
    Synchondroses
    Cartilaginous joints where bones are connected by hyaline cartilage.

    Rectus Abdominis

    Reviewed by our medical team

    Abs muscle that flexes the trunk.

    1. Overview

    The rectus abdominis is a long, flat, paired muscle that runs vertically along the anterior abdominal wall. Commonly referred to as the “six-pack” muscle due to its segmented appearance, it plays a major role in flexing the trunk, stabilizing the pelvis, and increasing intra-abdominal pressure. It is a key muscle in core strength and postural stability.

    2. Location

    The rectus abdominis is located in the midline of the anterior abdominal wall:

    • Extends from: The pubic symphysis and pubic crest (inferiorly) to the xiphoid process and costal cartilages of ribs 5–7 (superiorly).

    • Medially: Meets its contralateral counterpart at the linea alba.

    • Enclosed within: The rectus sheath, formed by the aponeuroses of the external oblique, internal oblique, and transversus abdominis muscles.

    3. Structure

    The rectus abdominis is a strap-like, segmented muscle divided horizontally by fibrous bands called tendinous intersections:

    • Shape: Long, vertical, and narrow, running parallel to the midline.

    • Tendinous intersections: Transverse fibrous bands that give rise to the “six-pack” appearance; typically three per side.

    • Linea alba: A fibrous midline seam that separates the left and right rectus muscles.

    • Innervation: Supplied by lower thoracoabdominal nerves (T7–T12).

    • Blood supply: Primarily from the superior and inferior epigastric arteries.

    4. Function

    The rectus abdominis performs several key musculoskeletal functions:

    • Trunk flexion: Flexes the vertebral column, particularly during activities like sit-ups or bending forward.

    • Posterior pelvic tilt: Stabilizes the pelvis by preventing anterior tilt, especially during leg raises.

    • Assists in forced expiration: Helps in expelling air by depressing the ribs and compressing the abdomen.

    • Contributes to abdominal compression: Works with other abdominal muscles to compress the abdominal cavity during defecation, childbirth, and lifting.

    5. Physiological role(s)

    Beyond mechanical movement, the rectus abdominis supports important physiological processes:

    • Core stability: Provides stability to the trunk, supporting the spine and preventing injury during dynamic movement.

    • Intra-abdominal pressure regulation: Works with the diaphragm and pelvic floor to maintain pressure needed for urination, defecation, and parturition.

    • Breathing support: Acts as an accessory muscle of respiration during forceful exhalation (e.g., coughing, blowing).

    • Spinal health: Protects the lumbar spine by resisting excessive extension and rotation.

    6. Clinical Significance

    The rectus abdominis is clinically significant in several conditions:

    • Muscle strain:

      • Common in athletes, especially during activities involving sudden trunk flexion or rotation.

    • Diastasis recti:

      • Separation of the rectus abdominis along the linea alba, often seen postpartum or in individuals with significant abdominal distension.

    • Hernias:

      • Weakness in the anterior abdominal wall near the rectus sheath may lead to epigastric or umbilical hernias.

    • Surgical relevance:

      • The rectus sheath is often incised in abdominal surgeries; care must be taken to avoid damaging underlying structures.

    • Cosmetic and functional rehabilitation:

      • Targeted in physical therapy and fitness programs for strengthening, posture correction, and aesthetic training (e.g., six-pack formation).

    Did you know? Your thumb has two phalanges, whereas other fingers have three.