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    Related Topics

    From Musculoskeletal System

    Hamstrings
    Biceps Femoris, Semitendinosus, Semimembranosus.
    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.
    Clavicle
    Collarbone connecting the arm to the body.
    Vertebral Column
    Spinal column consisting of vertebrae.
    Cervical Vertebrae (C1 - C7)
    Vertebrae in the neck region (C1-C7).
    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.
    Palatine Bones
    Bones forming part of the hard palate and nasal cavity.
    Metacarpals (5 bones)
    5 bones forming the palm of the hand.
    Deltoid
    Shoulder muscle responsible for arm abduction.
    Humerus
    Upper arm bone connecting the shoulder to the elbow.
    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.
    Thoracic Vertebrae (T1 - T12)
    Vertebrae in the upper and mid-back (T1-T12).
    Sartorius
    Longest muscle in the body responsible for hip flexion.
    Pivot Joints
    e.g., atlanto-axial joint
    Temporal Bones
    Bones forming the lower sides of the skull and housing the ears.
    Coccygeus
    Pelvic floor muscle supporting the coccyx.
    Gluteus Maximus
    Largest muscle in the buttocks responsible for hip extension.
    Skull
    Bony structure of the head that encases the brain.
    Ball-and-Socket Joints
    e.g., shoulder, hip
    Saddle Joints
    e.g., thumb joint
    Scapula
    Shoulder blade providing attachment for muscles of the upper limb.
    Phalanges (14 bones)
    14 bones forming the toes.
    Coracoacromial Ligament
    Ligament that connects the acromion to the coracoid process.
    Iliolumbar Ligament
    Ligament connecting the ilium and lumbar vertebrae.
    Symphyses
    Cartilaginous joints where bones are connected by fibrocartilage.

    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 average adult human has 206 bones, but this number can vary slightly due to additional bones in the hands or feet.