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    Related Topics

    From Musculoskeletal System

    Sternocleidomastoid
    Muscle that rotates and flexes the neck.
    Gomphoses
    Fibrous joints where a peg fits into a socket (e.g., teeth in jaw).
    Zygomatic Bones
    Cheekbones that form part of the orbit.
    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.
    Gliding (Plane) Joints
    e.g., between carpals
    Lumbar Vertebrae (L1 - L5)
    Vertebrae in the lower back (L1-L5).
    Radius
    Forearm bone on the thumb side.
    Tarsals (7 bones)
    7 ankle bones.
    Buccinator
    Muscle that helps with chewing and blowing air out.
    Palatine Bones
    Bones forming part of the hard palate and nasal cavity.
    Occipital Bone
    Bone forming the back and base of the skull.
    Rotator Cuff Muscles
    Supraspinatus, Infraspinatus, Teres Minor, Subscapularis.
    Maxillae
    Upper jaw bones that house the teeth and form part of the orbit.
    Glenohumeral Ligaments
    Shoulder ligaments that stabilize the shoulder joint.
    Wormian Bones
    Sutural bones in the skull.
    Sternum
    Breastbone located in the center of the chest.
    Mandible
    Lower jawbone that houses the teeth.
    Sacrum
    Triangular bone at the base of the spine.
    Medial Collateral Ligament (MCL)
    Knee ligament that stabilizes the inner knee.
    Cranial Bones
    Bones of the skull that protect the brain.
    Humerus
    Upper arm bone connecting the shoulder to the elbow.
    Thoracic Vertebrae (T1 - T12)
    Vertebrae in the upper and mid-back (T1-T12).
    Extensor Tendons
    Tendons that help extend the fingers and toes.
    Patellar Tendon
    Tendon connecting the patella to the tibia.
    Achilles Tendon
    Tendon connecting the calf muscle to the heel bone.

    Ribs (12 Pairs)

    Reviewed by our medical team

    12 pairs of bones that form the sides of the thoracic cage.

    1. Overview

    The ribs are a set of 12 paired flat bones that form the rib cage (thoracic cage), an essential part of the axial skeleton. These bones articulate with the thoracic vertebrae and curve around the chest to protect vital organs such as the heart and lungs. They also assist in respiration and provide attachment points for muscles involved in breathing and trunk movement.

    2. Location

    The ribs are located in the thoracic region of the trunk:

    • Posteriorly: Articulate with the thoracic vertebrae (T1–T12).

    • Anteriorly: Most connect to the sternum directly or indirectly via costal cartilage (except ribs 11 and 12).

    • Lateral to: The vertebral column and thoracic organs.

    3. Structure

    Each rib is a curved, flat bone with a bony posterior portion and a cartilaginous anterior end. Ribs are classified into three groups:

    • True ribs (1–7): Directly attach to the sternum via individual costal cartilages.

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

    • Floating ribs (11–12): Do not connect to the sternum at all; their anterior ends are free.

    Each rib typically has the following features:

    • Head: Articulates with the vertebral bodies (usually two adjacent vertebrae).

    • Neck: Connects the head with the body.

    • Tubercle: Articulates with the transverse process of the corresponding vertebra.

    • Angle: The point where the rib curves sharply forward.

    • Body (shaft): Main portion of the rib; thin and curved.

    • Costal groove: Located on the inner surface of the rib; protects the intercostal vessels and nerve.

    4. Function

    The ribs serve several important mechanical and structural roles:

    • Protect thoracic organs: Encase and shield the heart, lungs, and major vessels from trauma.

    • Assist in respiration: Elevate and expand during inhalation; depress during exhalation, aiding in ventilation.

    • Support muscular attachment: Serve as origin/insertion sites for intercostal muscles, diaphragm, pectorals, serratus anterior, and abdominal muscles.

    • Contribute to thoracic rigidity: Maintain thoracic shape and resist external pressure during breathing.

    5. Physiological role(s)

    Beyond structure, the ribs play a role in broader physiological systems:

    • Respiratory mechanics: Facilitate lung expansion by increasing thoracic volume during inspiration.

    • Neurovascular conduit: House and protect intercostal nerves, arteries, and veins within the costal grooves.

    • Support cardiovascular function: By maintaining intrathoracic pressure, ribs indirectly assist in venous return.

    • Postural stability: Interact with vertebrae and sternum to maintain upright posture and trunk stability.

    6. Clinical Significance

    Rib injuries and abnormalities are commonly encountered in clinical settings:

    • Rib fractures:

      • Often due to trauma (e.g., falls, car accidents); most common in ribs 5–9.

      • Painful with breathing; may risk puncturing lungs or damaging intercostal vessels.

    • Flail chest:

      • Occurs when multiple consecutive ribs are fractured in two or more places, causing a free-floating segment that moves paradoxically during breathing.

    • Costochondritis:

      • Inflammation of costal cartilage, typically affecting ribs 2–5; presents as localized anterior chest pain.

    • Thoracic outlet syndrome:

      • May result from compression of neurovascular structures between the first rib and clavicle.

    • Congenital anomalies:

      • Includes cervical ribs (extra rib above the first rib), which can compress neurovascular structures and cause symptoms.

    • Surgical relevance:

      • Rib resections may be performed for thoracic access or tumor removal; care must be taken to avoid damaging the intercostal bundle.

    Did you know? Your hand has 5 metacarpal bones.