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    Related Topics

    From Musculoskeletal System

    Triceps Brachii
    Muscle responsible for elbow extension.
    Palatine Bones
    Bones forming part of the hard palate and nasal cavity.
    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.
    Rotator Cuff Muscles
    Supraspinatus, Infraspinatus, Teres Minor, Subscapularis.
    Brachioradialis
    Muscle responsible for forearm flexion.
    Soleus
    Calf muscle responsible for plantarflexion of the foot.
    Sutures (in the skull)
    Fibrous joints between skull bones.
    Latissimus Dorsi
    Back muscle responsible for arm adduction and extension.
    Synchondroses
    Cartilaginous joints where bones are connected by hyaline cartilage.
    Coccyx
    Tailbone, the remnant of the tail in humans.
    Facial Bones
    Bones forming the structure of the face.
    Vertebral Column
    Spinal column consisting of vertebrae.
    Tarsals (7 bones)
    7 ankle bones.
    Masseter
    Muscle that elevates the mandible.
    Zygomatic Bones
    Cheekbones that form part of the orbit.
    Posterior Cruciate Ligament (PCL)
    Knee ligament that stabilizes the joint.
    Sternocleidomastoid
    Muscle that rotates and flexes the neck.
    Fibula
    Smaller bone in the lower leg, located alongside the tibia.
    Buccinator
    Muscle that helps with chewing and blowing air out.
    Hamstrings
    Biceps Femoris, Semitendinosus, Semimembranosus.
    Saddle Joints
    e.g., thumb joint
    Rotator Cuff Tendons
    Tendons of the rotator cuff muscles.
    Wormian Bones
    Sutural bones in the skull.
    Sacrum
    Triangular bone at the base of the spine.
    Ulna
    Forearm bone on the pinky side.

    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 make up only 15% of your body weight.