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    From Musculoskeletal System

    Humerus
    Upper arm bone connecting the shoulder to the elbow.
    Thoracic Vertebrae (T1 - T12)
    Vertebrae in the upper and mid-back (T1-T12).
    Biceps Brachii
    Muscle responsible for elbow flexion.
    Diaphragm
    Primary muscle for breathing.
    Brachioradialis
    Muscle responsible for forearm flexion.
    Gluteus Maximus
    Largest muscle in the buttocks responsible for hip extension.
    Nasal Bones
    Bones forming the bridge of the nose.
    Ischium
    Part of the pelvis that supports weight while sitting.
    Skull
    Bony structure of the head that encases the brain.
    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.
    Synchondroses
    Cartilaginous joints where bones are connected by hyaline cartilage.
    Hinge Joints
    e.g., elbow, knee
    Sacroiliac Ligaments
    Ligaments connecting the sacrum to the iliac bones.
    Tarsals (7 bones)
    7 ankle bones.
    Gastrocnemius
    Calf muscle responsible for plantarflexion of the foot.
    Scapula
    Shoulder blade providing attachment for muscles of the upper limb.
    Deltoid
    Shoulder muscle responsible for arm abduction.
    Gomphoses
    Fibrous joints where a peg fits into a socket (e.g., teeth in jaw).
    Ellipsoidal (Condyloid) Joints
    e.g., wrist
    Sternum
    Breastbone located in the center of the chest.
    Parietal Bones
    Bones forming the sides and roof of the skull.
    Coccygeus
    Pelvic floor muscle supporting the coccyx.
    Frontal Bone
    Bone forming the forehead and upper part of the orbits.
    Anterior Scalene Muscle
    The anterior scalene muscle is a deep neck muscle that elevates the first rib during inspiration and aids in neck flexion and stability, located between key neurovascular structures.
    Pubis
    Part of the pelvis that joins with the opposite side to form the pubic symphysis.

    Hyoid Bone

    Reviewed by our medical team

    U-shaped bone in the neck that supports the tongue.

    1. Overview

    The hyoid bone is a small, U-shaped bone located in the anterior neck. Uniquely, it is the only bone in the human body that does not articulate directly with any other bone. Instead, it is suspended in place by muscles and ligaments. The hyoid serves as a crucial anchoring structure for the tongue, supports the larynx (voice box), and plays a vital role in swallowing and speech. It is often studied in anatomy due to its functional and forensic significance.

    2. Location

    The hyoid bone is located in the anterior midline of the neck:

    • Superiorly: Lies below the mandible (lower jaw).

    • Inferiorly: Positioned above the thyroid cartilage (Adam's apple).

    • At the level of: Cervical vertebra C3 in a neutral position.

    • Surrounding structures: Connected to the floor of the oral cavity, pharynx, larynx, and epiglottis by muscle and ligament attachments.

    3. Structure

    The hyoid bone has a characteristic horseshoe or U-shape and consists of three parts:

    • Body: The central part, thick and rectangular in shape.

    • Greater horns (cornua): Project posteriorly and laterally from the body; attachment sites for several muscles (e.g., middle constrictor, hyoglossus).

    • Lesser horns (cornua): Small, conical projections superior to the body; serve as attachment points for the stylohyoid ligament.

    The hyoid bone is made of compact bone and has a dense outer cortex with a medullary cavity. It is anchored by the suprahyoid and infrahyoid muscle groups.

    4. Function

    The hyoid bone serves as a dynamic anchor and support for several functions:

    • Supports the tongue: Acts as the base for tongue movement, aiding in speech and swallowing.

    • Assists in swallowing: Serves as a platform for the elevation of the larynx and movement of the pharynx during deglutition.

    • Facilitates speech: Supports vocalization by maintaining airway patency and stabilizing the larynx.

    • Acts as a muscle attachment site: Anchors over a dozen muscles involved in jaw, neck, and throat movement.

    5. Physiological role(s)

    Despite its small size, the hyoid bone plays critical physiological roles:

    • Respiration: Keeps the airway open by supporting the upper respiratory tract and indirectly preventing airway collapse during breathing.

    • Speech modulation: Works with the laryngeal cartilages and vocal cords to modulate pitch and volume.

    • Swallowing reflex: Coordinates with pharyngeal muscles to initiate and complete the swallowing mechanism safely.

    • Muscle coordination: Coordinates movements between the jaw, tongue, and larynx, critical in chewing and phonation.

    6. Clinical Significance

    The hyoid bone is associated with various clinical and forensic considerations:

    • Hyoid fracture:

      • Rare in accidental trauma but may occur in cases of manual strangulation or hanging, making it significant in forensic investigations.

    • Dysphagia (difficulty swallowing):

      • Can result from dysfunction of muscles attached to the hyoid, particularly in neurological or post-surgical conditions.

    • Speech disorders:

      • Abnormal positioning or injury to the hyoid can affect tongue movement and vocal cord tension, impacting speech clarity.

    • Thyroglossal duct cysts:

      • Embryological remnants can form cysts near the hyoid, often requiring surgical excision that includes part of the hyoid bone (Sistrunk procedure).

    • Obstructive sleep apnea:

      • Inferior positioning of the hyoid is sometimes associated with upper airway obstruction, contributing to sleep apnea.

    Did you know? The ischium is the part of the pelvis you sit on.