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    Related Topics

    From Musculoskeletal System

    Symphyses
    Cartilaginous joints where bones are connected by fibrocartilage.
    Tarsals (7 bones)
    7 ankle bones.
    Anterior Cruciate Ligament (ACL)
    Knee ligament that stabilizes the joint.
    Anterior Longitudinal Ligament
    Spinal ligament running along the front of the vertebral column.
    Ligamentum Flavum
    Spinal ligament connecting the laminae of adjacent vertebrae.
    Wormian Bones
    Sutural bones in the skull.
    Obliques (External and Internal)
    Muscles responsible for torso rotation.
    Syndesmoses
    Fibrous joints where bones are connected by ligaments.
    Biceps Tendon
    Tendon that attaches the biceps muscle to the bone.
    Levator Ani
    Pelvic floor muscle responsible for lifting the anus.
    Pelvic Floor Muscles
    Muscles that support pelvic organs.
    Temporalis
    Muscle involved in closing the jaw.
    Ball-and-Socket Joints
    e.g., shoulder, hip
    Posterior Longitudinal Ligament
    Spinal ligament running along the back of the vertebral column.
    Hamstrings
    Biceps Femoris, Semitendinosus, Semimembranosus.
    Sutures (in the skull)
    Fibrous joints between skull bones.
    Glenohumeral Ligaments
    Shoulder ligaments that stabilize the shoulder joint.
    Maxillae
    Upper jaw bones that house the teeth and form part of the orbit.
    Sternocleidomastoid
    Muscle that rotates and flexes the neck.
    Deltoid
    Shoulder muscle responsible for arm abduction.
    Fibula
    Smaller bone in the lower leg, located alongside the tibia.
    Rotator Cuff Tendons
    Tendons of the rotator cuff muscles.
    Latissimus Dorsi
    Back muscle responsible for arm adduction and extension.
    Thoracic Cage
    Ribs and sternum forming the protective cage for the heart and lungs.
    Gastrocnemius
    Calf muscle responsible for plantarflexion of the foot.

    Parietal Bones

    Reviewed by our medical team

    Bones forming the sides and roof of the skull.

    1. Overview

    The parietal bones are a pair of large, curved, quadrilateral bones forming a significant portion of the superior and lateral walls of the cranium. These bones are essential components of the neurocranium, enclosing and protecting the brain, particularly the parietal lobes. The right and left parietal bones meet at the top of the skull and contribute to its overall strength and structure.

    2. Location

    The parietal bones are located on the upper lateral sides of the skull:

    • Superiorly: Meet each other at the sagittal suture.

    • Anteriorly: Articulate with the frontal bone at the coronal suture.

    • Posteriorly: Articulate with the occipital bone at the lambdoid suture.

    • Inferiorly: Articulate with the temporal and sphenoid bones at the squamosal and sphenoparietal sutures, respectively.

    3. Structure

    Each parietal bone is thin, flat, and curved, contributing to the cranial vault:

    • External surface: Convex and smooth, provides attachment for the temporalis muscle; marked by parietal eminence (a rounded prominence).

    • Internal surface: Concave and grooved for meningeal vessels, especially the middle meningeal artery.

    • Four borders: Frontal (anterior), occipital (posterior), temporal (inferior), and sagittal (medial).

    • Four angles: Frontal, sphenoidal, occipital, and mastoid angles, which connect with corresponding bones.

    The bone consists of two layers of compact bone (inner and outer tables) with cancellous bone (diploë) in between, providing strength and lightness.

    4. Function

    The parietal bones serve several crucial roles in cranial protection and form:

    • Protect the brain: Enclose the parietal lobes of the brain, shielding them from external trauma.

    • Structural support: Contribute to the cranial vault, maintaining the shape and strength of the skull.

    • Muscle attachment: Provide surfaces for temporalis and other muscles of mastication and facial expression.

    • Formation of sutures: Interlock with surrounding bones to form immovable joints that stabilize the skull.

    5. Physiological role(s)

    Although passive in terms of direct physiological processes, the parietal bones support vital functions by:

    • Enabling cerebral protection: Encase brain tissue, especially the parietal lobes responsible for sensory perception and spatial orientation.

    • Assisting thermoregulation: The scalp and underlying skull dissipate heat produced by brain metabolism.

    • Providing pathways: Grooves on the inner surface house vessels like the middle meningeal artery, essential for cranial perfusion.

    6. Clinical Significance

    Parietal bones are involved in several clinical and surgical conditions:

    • Skull fractures:

      • Parietal bones are commonly fractured in head trauma due to their exposure; may result in epidural hematomas if the middle meningeal artery is torn.

    • Craniotomy procedures:

      • Parietal regions are often accessed surgically to reach underlying brain tissue during tumor resections or hemorrhage evacuation.

    • Hydrocephalus and cranial expansion:

      • In pediatric patients, parietal bones may expand or bulge in conditions like hydrocephalus or craniosynostosis.

    • Parietal foramina anomalies:

      • Small openings near the sagittal suture may transmit emissary veins; enlarged foramina can be associated with syndromes like cleidocranial dysostosis.

    • Decompression surgery:

      • Increased intracranial pressure may require removal of a parietal bone flap (decompressive craniectomy).

    Did you know? Your bones are constantly being broken down and rebuilt — you have a new skeleton every 10 years.