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    Related Topics

    From Musculoskeletal System

    Gliding (Plane) Joints
    e.g., between carpals
    Masseter
    Muscle that elevates the mandible.
    Inferior Nasal Conchae
    Bones inside the nasal cavity that filter and humidify air.
    Biceps Brachii
    Muscle responsible for elbow flexion.
    Scapula
    Shoulder blade providing attachment for muscles of the upper limb.
    Hamstrings
    Biceps Femoris, Semitendinosus, Semimembranosus.
    Ethmoid Bone
    Bone forming part of the nasal cavity and the orbit.
    Ischium
    Part of the pelvis that supports weight while sitting.
    Cranial Bones
    Bones of the skull that protect the brain.
    Pubis
    Part of the pelvis that joins with the opposite side to form the pubic symphysis.
    Zygomatic Bones
    Cheekbones that form part of the orbit.
    Metacarpals (5 bones)
    5 bones forming the palm of the hand.
    Lacrimal Bones
    Bones forming part of the eye socket and housing the tear ducts.
    Hinge Joints
    e.g., elbow, knee
    Deltoid
    Shoulder muscle responsible for arm abduction.
    Radius
    Forearm bone on the thumb side.
    Ellipsoidal (Condyloid) Joints
    e.g., wrist
    Sphenoid Bone
    Bone forming part of the base of the skull and sides of the orbits.
    Humerus
    Upper arm bone connecting the shoulder to the elbow.
    Sacrum
    Triangular bone at the base of the spine.
    Ribs (12 Pairs)
    12 pairs of bones that form the sides of the thoracic cage.
    Palatine Bones
    Bones forming part of the hard palate and nasal cavity.
    Skull
    Bony structure of the head that encases the brain.
    Clavicle
    Collarbone connecting the arm to the body.
    Vertebral Column
    Spinal column consisting of vertebrae.

    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? The clavicle is the only bone in the body that connects the arm to the body trunk.