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    From Musculoskeletal System

    Gastrocnemius
    Calf muscle responsible for plantarflexion of the foot.
    Lumbar Vertebrae (L1 - L5)
    Vertebrae in the lower back (L1-L5).
    Saddle Joints
    e.g., thumb joint
    Pivot Joints
    e.g., atlanto-axial joint
    Parietal Bones
    Bones forming the sides and roof of the skull.
    Brachioradialis
    Muscle responsible for forearm flexion.
    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.
    Facial Bones
    Bones forming the structure of the face.
    Tarsals (7 bones)
    7 ankle bones.
    Acromioclavicular Joint
    The acromioclavicular joint connects the clavicle and scapula at the top of the shoulder, enabling smooth scapular motion and stability during arm movements.
    Cervical Vertebrae (C1 - C7)
    Vertebrae in the neck region (C1-C7).
    Anterior Cruciate Ligament (ACL)
    Knee ligament that stabilizes the joint.
    Quadriceps
    Rectus Femoris, Vastus Medialis, Vastus Lateralis, Vastus Intermedius.
    Levator Ani
    Pelvic floor muscle responsible for lifting the anus.
    Quadriceps Tendon
    Tendon that connects the quadriceps to the patella.
    Patellar Tendon
    Tendon connecting the patella to the tibia.
    Buccinator
    Muscle that helps with chewing and blowing air out.
    Cranial Bones
    Bones of the skull that protect the brain.
    Coracoacromial Ligament
    Ligament that connects the acromion to the coracoid process.
    Scapula
    Shoulder blade providing attachment for muscles of the upper limb.
    Iliolumbar Ligament
    Ligament connecting the ilium and lumbar vertebrae.
    Gluteus Maximus
    Largest muscle in the buttocks responsible for hip extension.
    Lateral Collateral Ligament (LCL)
    Knee ligament that stabilizes the outer knee.
    Metatarsals (5 bones)
    5 bones forming the mid-foot.
    Achilles Tendon
    Tendon connecting the calf muscle to the heel bone.

    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 adult human body contains around 60,000 miles of blood vessels.