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    Related Topics

    From Musculoskeletal System

    Wormian Bones
    Sutural bones in the skull.
    Ethmoid Bone
    Bone forming part of the nasal cavity and the orbit.
    Biceps Brachii
    Muscle responsible for elbow flexion.
    Occipital Bone
    Bone forming the back and base of the skull.
    Ischium
    Part of the pelvis that supports weight while sitting.
    Ellipsoidal (Condyloid) Joints
    e.g., wrist
    Glenohumeral Ligaments
    Shoulder ligaments that stabilize the shoulder joint.
    Tibialis Anterior
    Muscle that dorsiflexes and inverts the foot.
    Zygomaticus
    Muscle that raises the corners of the mouth.
    Nasal Bones
    Bones forming the bridge of the nose.
    Pelvic Floor Muscles
    Muscles that support pelvic organs.
    Posterior Longitudinal Ligament
    Spinal ligament running along the back of the vertebral column.
    Triceps Brachii
    Muscle responsible for elbow extension.
    Sutures (in the skull)
    Fibrous joints between skull bones.
    Trapezius
    Muscle responsible for moving, rotating, and stabilizing the scapula.
    Metacarpals (5 bones)
    5 bones forming the palm of the hand.
    Deltoid
    Shoulder muscle responsible for arm abduction.
    Phalanges (14 bones)
    14 bones forming the toes.
    Sesamoid Bones
    e.g., patella, some found in hands/feet.
    Pectoralis Major
    Chest muscle responsible for shoulder movement.
    Palatine Bones
    Bones forming part of the hard palate and nasal cavity.
    Achilles Tendon
    Tendon connecting the calf muscle to the heel bone.
    Obliques (External and Internal)
    Muscles responsible for torso rotation.
    Hamstrings
    Biceps Femoris, Semitendinosus, Semimembranosus.
    Ligamentum Flavum
    Spinal ligament connecting the laminae of adjacent vertebrae.

    Lacrimal Bones

    Reviewed by our medical team

    Bones forming part of the eye socket and housing the tear ducts.

    1. Overview

    The lacrimal bones are a pair of small, thin bones located in the anterior part of the medial wall of each orbit. Despite being the smallest bones of the face, they play a crucial role in forming the lacrimal fossa, which supports the lacrimal sac involved in tear drainage. These bones are part of the facial skeleton and contribute to both the orbital and nasal regions.

    2. Location

    Lacrimal bones are found in the medial walls of the eye sockets (orbits):

    • Anterior to: The ethmoid bone.

    • Posterior to: The frontal process of the maxilla.

    • Superiorly: Articulates with the frontal bone.

    • Inferiorly: Related to the nasolacrimal canal which continues into the inferior nasal meatus.

    3. Structure

    Each lacrimal bone is a small, rectangular, and fragile structure composed of two surfaces and four borders:

    • Lateral (orbital) surface: Faces the orbit; features the lacrimal groove, which helps form the lacrimal fossa for the lacrimal sac.

    • Medial (nasal) surface: Faces the nasal cavity and articulates with the ethmoid bone.

    • Lacrimal crest: A vertical ridge that divides the orbital surface and contributes to the formation of the lacrimal sac fossa.

    • Nasolacrimal canal: Formed in conjunction with the maxilla, this canal transmits the nasolacrimal duct that drains tears into the nasal cavity.

    • Articulations: Each lacrimal bone articulates with four bones — frontal, maxilla, ethmoid, and inferior nasal concha.

    4. Function

    The primary functions of the lacrimal bones include:

    • Support for tear drainage: Form part of the lacrimal apparatus by contributing to the lacrimal fossa, which houses the lacrimal sac.

    • Orbital structure: Help form the medial wall of the orbit, maintaining its integrity and protecting the eye.

    • Nasal communication: Assist in channeling tears from the lacrimal sac to the inferior nasal meatus via the nasolacrimal duct.

    5. Physiological role(s)

    Though small, the lacrimal bones support vital physiological functions:

    • Tear drainage: Indirectly participate in the lacrimal apparatus function by providing structural support for tear collection and flow into the nasal cavity.

    • Ocular protection: As part of the orbit, they help shield the eye from trauma and support adjacent soft tissues.

    • Sinus and nasal drainage: Contribute to drainage dynamics by connecting the orbital and nasal regions through the lacrimal pathway.

    6. Clinical Significance

    The lacrimal bones are associated with several clinical and surgical concerns:

    • Nasolacrimal duct obstruction (NLDO):

      • Blockage of the duct passing through the nasolacrimal canal can result in epiphora (tear overflow), often requiring surgical intervention like dacryocystorhinostomy (DCR).

    • Orbital fractures:

      • Due to their fragility, lacrimal bones may be fractured in cases of blunt facial trauma, sometimes affecting tear drainage or causing orbital complications.

    • Dacryocystitis:

      • Infection of the lacrimal sac, often secondary to obstruction, can involve the lacrimal bone region and cause painful swelling near the inner corner of the eye.

    • Surgical relevance:

      • Surgeries involving the orbit or nasolacrimal system (e.g., endoscopic DCR) must navigate around or through the lacrimal bone.

    Did you know? The smallest bone in the human body is the stapes (in the ear), measuring just 0.1 inches.