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    Related Topics

    From Musculoskeletal System

    Symphyses
    Cartilaginous joints where bones are connected by fibrocartilage.
    Hyoid Bone
    U-shaped bone in the neck that supports the tongue.
    Metacarpals (5 bones)
    5 bones forming the palm of the hand.
    Diaphragm
    Primary muscle for breathing.
    Masseter
    Muscle that elevates the mandible.
    Flexor and Extensor Groups
    Muscles responsible for flexing and extending the hand and wrist.
    Glenohumeral Ligaments
    Shoulder ligaments that stabilize the shoulder joint.
    Tibia
    Shin bone, the larger bone in the lower leg.
    Facial Bones
    Bones forming the structure of the face.
    Medial Collateral Ligament (MCL)
    Knee ligament that stabilizes the inner knee.
    Lumbar Vertebrae (L1 - L5)
    Vertebrae in the lower back (L1-L5).
    Brachioradialis
    Muscle responsible for forearm flexion.
    Coracoacromial Ligament
    Ligament that connects the acromion to the coracoid process.
    Sacroiliac Ligaments
    Ligaments connecting the sacrum to the iliac bones.
    Cranial Bones
    Bones of the skull that protect the brain.
    Hinge Joints
    e.g., elbow, knee
    Inferior Nasal Conchae
    Bones inside the nasal cavity that filter and humidify air.
    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.
    Triceps Brachii
    Muscle responsible for elbow extension.
    Wormian Bones
    Sutural bones in the skull.
    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.
    Achilles Tendon
    Tendon connecting the calf muscle to the heel bone.
    Hamstrings
    Biceps Femoris, Semitendinosus, Semimembranosus.
    Ulna
    Forearm bone on the pinky side.
    Radius
    Forearm bone on the thumb side.

    Sternum

    Reviewed by our medical team

    Breastbone located in the center of the chest.

    1. Overview

    The sternum, or breastbone, is a flat, elongated bone located in the center of the anterior thoracic wall. It forms the anterior portion of the rib cage and provides protection to vital thoracic organs, including the heart and major blood vessels. The sternum also serves as an essential anchor point for ribs and clavicles.

    2. Location

    The sternum is situated in the midline of the anterior thorax:

    • Anterior to: The heart, great vessels, and upper mediastinum.

    • Medial to: The ribs and costal cartilages.

    • Superiorly: Articulates with the clavicles and the first pair of ribs.

    • Inferiorly: Ends just above the xiphoid process and costal arch.

    3. Structure

    The sternum is a flat bone composed of three parts:

    • Manubrium:

      • Uppermost, triangular portion.

      • Articulates with the clavicles (at the sternoclavicular joints) and first two pairs of ribs.

      • Features include the jugular (suprasternal) notch and clavicular notches.

    • Body (gladiolus):

      • Longest central portion of the sternum.

      • Articulates with costal cartilages of ribs 2 to 7.

      • Connected to the manubrium at the sternal angle (Angle of Louis), a key clinical landmark.

    • Xiphoid process:

      • Small, cartilaginous projection at birth that ossifies with age.

      • May vary in shape and size; serves as an attachment for muscles like the diaphragm and rectus abdominis.

    The sternum has an internal spongy bone structure with a thin layer of compact bone externally and is rich in red bone marrow.

    4. Function

    The sternum performs several structural and protective roles:

    • Protects thoracic organs: Shields the heart, great vessels, and part of the lungs from trauma.

    • Attachment point: Provides anchorage for ribs (via costal cartilages) and clavicles, maintaining the structural integrity of the thoracic cage.

    • Supports respiration: Moves slightly during breathing, facilitating thoracic expansion and contraction.

    • Muscle origin: Serves as an attachment site for the pectoralis major, sternocleidomastoid, sternohyoid, and other muscles.

    5. Physiological role(s)

    Though primarily structural, the sternum contributes to physiological processes:

    • Hematopoiesis: Contains red bone marrow, especially in the manubrium and body, active in producing blood cells.

    • Landmark for procedures: Used for sternal puncture or bone marrow biopsy in adults.

    • Postural alignment: Acts as a central anchor for rib movements and spinal posture in the thoracic region.

    6. Clinical Significance

    The sternum plays a role in various clinical and surgical contexts:

    • Sternal fractures:

      • Often due to blunt trauma (e.g., motor vehicle collisions); can injure underlying heart or great vessels.

    • Sternal angle (Angle of Louis):

      • Important landmark for rib counting and auscultation; marks the level of the 2nd rib and bifurcation of the trachea.

    • Sternal puncture:

      • Used to access bone marrow in diagnostics for leukemia, lymphoma, or anemia.

    • Mediastinal surgery:

      • The sternum is often divided (median sternotomy) to access the heart and lungs in procedures like open-heart surgery.

    • Xiphoid process issues:

      • Can cause xiphodynia—pain or discomfort from inflammation or trauma.

    • Congenital anomalies:

      • Includes cleft sternum or pectus carinatum/excavatum, which may require surgical correction for functional or cosmetic reasons.

    Did you know? Bones are responsible for protecting organs like the brain, heart, and lungs.