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    Related Topics

    From Musculoskeletal System

    Quadriceps
    Rectus Femoris, Vastus Medialis, Vastus Lateralis, Vastus Intermedius.
    Femur
    Thigh bone, the longest and strongest bone in the body.
    Gliding (Plane) Joints
    e.g., between carpals
    Hamstrings
    Biceps Femoris, Semitendinosus, Semimembranosus.
    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.
    Parietal Bones
    Bones forming the sides and roof of the skull.
    Ethmoid Bone
    Bone forming part of the nasal cavity and the orbit.
    Gluteus Maximus
    Largest muscle in the buttocks responsible for hip extension.
    Sternum
    Breastbone located in the center of the chest.
    Zygomatic Bones
    Cheekbones that form part of the orbit.
    Wormian Bones
    Sutural bones in the skull.
    Fibula
    Smaller bone in the lower leg, located alongside the tibia.
    Mandible
    Lower jawbone that houses the teeth.
    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.
    Anterior Longitudinal Ligament
    Spinal ligament running along the front of the vertebral column.
    Tibia
    Shin bone, the larger bone in the lower leg.
    Maxillae
    Upper jaw bones that house the teeth and form part of the orbit.
    Inferior Nasal Conchae
    Bones inside the nasal cavity that filter and humidify air.
    Ribs (12 Pairs)
    12 pairs of bones that form the sides of the thoracic cage.
    Biceps Tendon
    Tendon that attaches the biceps muscle to the bone.
    Symphyses
    Cartilaginous joints where bones are connected by fibrocartilage.
    Synchondroses
    Cartilaginous joints where bones are connected by hyaline cartilage.
    Carpals (8 bones)
    8 wrist bones.
    Coracoacromial Ligament
    Ligament that connects the acromion to the coracoid process.
    Buccinator
    Muscle that helps with chewing and blowing air out.

    Thoracic Cage

    Reviewed by our medical team

    Ribs and sternum forming the protective cage for the heart and lungs.

    1. Overview

    The thoracic cage, commonly known as the rib cage, is a bony and cartilaginous structure that surrounds the thoracic cavity. It provides protection for vital thoracic organs such as the heart and lungs, supports the upper body, and plays a critical role in respiration. Composed primarily of ribs, the sternum, and thoracic vertebrae, the thoracic cage is both strong and flexible, allowing it to withstand internal and external forces while permitting expansion and contraction during breathing.

    2. Location

    The thoracic cage is located in the upper part of the trunk:

    • Superiorly: Bounded by the thoracic inlet (above the first rib and manubrium).

    • Inferiorly: Ends at the costal margin and diaphragm (separating it from the abdominal cavity).

    • Anteriorly: Formed by the sternum and costal cartilages.

    • Posteriorly: Bounded by the thoracic vertebrae.

    3. Structure

    The thoracic cage consists of 37 bones and supporting cartilage:

    • 12 pairs of ribs (24 bones):

      • True ribs (1–7): Attach directly to the sternum via costal cartilage.

      • False ribs (8–10): Indirectly attach to the sternum via cartilage of the rib above.

      • Floating ribs (11–12): Do not connect to the sternum at all.

    • Sternum (1 bone): Consists of the manubrium, body, and xiphoid process.

    • 12 thoracic vertebrae: Posteriorly anchor each rib via costovertebral and costotransverse joints.

    • Costal cartilages: Hyaline cartilage connecting anterior ends of ribs to the sternum or each other.

    4. Function

    The thoracic cage serves multiple essential functions:

    • Protects vital organs: Shields the heart, lungs, great vessels, and upper abdominal organs like the liver and spleen.

    • Supports respiration: Expands and contracts during breathing to aid in air exchange via diaphragm and intercostal muscle movements.

    • Structural support: Serves as an anchor for the upper limbs and muscles of the back, chest, and neck.

    • Shock absorption: The flexible ribs and cartilages help absorb and dissipate mechanical forces from impacts.

    5. Physiological role(s)

    In addition to its structural contributions, the thoracic cage plays key physiological roles:

    • Ventilation mechanism: Acts as a dynamic structure that changes volume to facilitate pulmonary ventilation through rib elevation and depression.

    • Muscle integration: Provides attachment for respiratory muscles (intercostals, diaphragm, serratus posterior) and accessory muscles (scalenes, sternocleidomastoid).

    • Lymphatic and vascular flow: Movements of the thoracic cage assist circulation of blood and lymph in the thoracic region.

    6. Clinical Significance

    Disorders and injuries involving the thoracic cage can impair breathing and organ function:

    • Rib fractures:

      • Most common thoracic injury; may lead to pain, pneumothorax, or hemothorax if sharp rib edges puncture lung tissue.

    • Flail chest:

      • Occurs when multiple adjacent ribs are fractured in more than one place, resulting in a free-floating chest wall segment that moves paradoxically during breathing.

    • Costochondritis:

      • Inflammation of the costal cartilage, typically causing chest wall pain; often mistaken for cardiac pain.

    • Pectus deformities:

      • Conditions like pectus excavatum (sunken chest) and pectus carinatum (protruding sternum) may affect cardiopulmonary function or require surgical correction.

    • Thoracic outlet syndrome:

      • Compression of nerves or vessels between the first rib and clavicle, leading to neurovascular symptoms in the upper limb.

    • Osteoporosis-related fractures:

      • Weakening of thoracic vertebrae or ribs can result in compression fractures, especially in the elderly.

    Did you know? Ligaments hold bones together and are tough yet flexible.