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    Related Topics

    From Musculoskeletal System

    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.
    Flexor Tendons
    Tendons that help flex the fingers and toes.
    Pectoralis Major
    Chest muscle responsible for shoulder movement.
    Acromioclavicular Ligament
    Ligament that connects the acromion to the clavicle.
    Coccygeus
    Pelvic floor muscle supporting the coccyx.
    Sesamoid Bones
    e.g., patella, some found in hands/feet.
    Patellar Tendon
    Tendon connecting the patella to the tibia.
    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.
    Zygomatic Bones
    Cheekbones that form part of the orbit.
    Inferior Nasal Conchae
    Bones inside the nasal cavity that filter and humidify air.
    Flexor and Extensor Groups
    Muscles responsible for flexing and extending the hand and wrist.
    Obliques (External and Internal)
    Muscles responsible for torso rotation.
    Coccyx
    Tailbone, the remnant of the tail in humans.
    Quadriceps
    Rectus Femoris, Vastus Medialis, Vastus Lateralis, Vastus Intermedius.
    Lateral Collateral Ligament (LCL)
    Knee ligament that stabilizes the outer knee.
    Posterior Longitudinal Ligament
    Spinal ligament running along the back of the vertebral column.
    Biceps Tendon
    Tendon that attaches the biceps muscle to the bone.
    Triceps Brachii
    Muscle responsible for elbow extension.
    Medial Collateral Ligament (MCL)
    Knee ligament that stabilizes the inner knee.
    Temporalis
    Muscle involved in closing the jaw.
    Tibialis Anterior
    Muscle that dorsiflexes and inverts the foot.
    Palatine Bones
    Bones forming part of the hard palate and nasal cavity.
    Ischium
    Part of the pelvis that supports weight while sitting.
    Sphenoid Bone
    Bone forming part of the base of the skull and sides of the orbits.
    Tarsals (7 bones)
    7 ankle bones.

    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? Each human hand has 27 bones.