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    From Musculoskeletal System

    Sartorius
    Longest muscle in the body responsible for hip flexion.
    Masseter
    Muscle that elevates the mandible.
    Coccygeus
    Pelvic floor muscle supporting the coccyx.
    Rotator Cuff Muscles
    Supraspinatus, Infraspinatus, Teres Minor, Subscapularis.
    Phalanges (14 bones)
    14 bones forming the toes.
    Achilles Tendon
    Tendon connecting the calf muscle to the heel bone.
    Wormian Bones
    Sutural bones in the skull.
    Anterior Cruciate Ligament (ACL)
    Knee ligament that stabilizes the joint.
    Acromioclavicular Ligament
    Ligament that connects the acromion to the clavicle.
    Rotator Cuff Tendons
    Tendons of the rotator cuff muscles.
    Obliques (External and Internal)
    Muscles responsible for torso rotation.
    Ball-and-Socket Joints
    e.g., shoulder, hip
    Pectoralis Major
    Chest muscle responsible for shoulder movement.
    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.
    Deltoid
    Shoulder muscle responsible for arm abduction.
    Ellipsoidal (Condyloid) Joints
    e.g., wrist
    Carpals (8 bones)
    8 wrist bones.
    Hamstrings
    Biceps Femoris, Semitendinosus, Semimembranosus.
    Frontal Bone
    Bone forming the forehead and upper part of the orbits.
    Sternocleidomastoid
    Muscle that rotates and flexes the neck.
    Rectus Abdominis
    Abs muscle that flexes the trunk.
    Interspinous Ligament
    Spinal ligament between adjacent vertebral spinous processes.
    Flexor Tendons
    Tendons that help flex the fingers and toes.
    Lacrimal Bones
    Bones forming part of the eye socket and housing the tear ducts.
    Zygomaticus
    Muscle that raises the corners of the mouth.

    Anterior Longitudinal Ligament

    Reviewed by our medical team

    Spinal ligament running along the front of the vertebral column.

    1. Overview

    The Anterior Longitudinal Ligament (ALL) is a strong, broad ligament that runs along the anterior surface of the vertebral bodies in the spine. It plays a crucial role in maintaining vertebral alignment and limiting hyperextension of the vertebral column. The ALL is one of the primary stabilizing ligaments of the spine and extends from the base of the skull to the sacrum. Its integrity is essential for both static posture and dynamic spinal movements.

    2. Location

    The ALL is located along the anterior aspect of the vertebral column, specifically:

    • Superiorly: Begins at the anterior tubercle of the atlas (C1) and the basilar part of the occipital bone of the skull.

    • Inferiorly: Terminates at the anterior surface of the sacrum.

    • It runs continuously along the anterior surfaces of all vertebral bodies and intervertebral discs.

    3. Structure

    The ALL is a dense, fibrous ligament composed primarily of Type I collagen fibers, oriented longitudinally:

    • Width and thickness: It is broader and thicker in the thoracic region and narrower in the cervical and lumbar regions.

    • Attachment: Adheres strongly to the intervertebral discs and vertebral bodies, but less tightly to the periosteum of vertebrae.

    • Three layers:

      • Superficial layer: spans several vertebrae.

      • Intermediate layer: spans 2–3 vertebrae.

      • Deep layer: connects adjacent vertebrae only.

    This layered architecture allows the ALL to resist a range of mechanical stresses along the vertebral column.

    4. Function

    The Anterior Longitudinal Ligament provides multiple biomechanical functions:

    • Limits hyperextension: Prevents excessive backward bending of the spine.

    • Maintains anterior spinal stability: Supports alignment of vertebral bodies during motion and loading.

    • Distributes mechanical stress: Shares the axial load imposed on vertebral bodies and intervertebral discs.

    • Protects intervertebral discs: Limits forward bulging of discs during extension.

    5. Physiological role(s)

    The ALL plays a crucial role in spinal biomechanics and posture:

    • Supports upright posture: Prevents excessive lumbar lordosis or cervical extension while standing or walking.

    • Facilitates segmental motion control: Works with the posterior longitudinal ligament (PLL) to guide and restrict movement.

    • Integrates with spinal biomechanics: Contributes to the complex motion of flexion-extension, lateral bending, and rotation.

    • Assists in spinal proprioception: Contains sensory nerve fibers that contribute to position sense and postural reflexes.

    6. Clinical Significance

    The Anterior Longitudinal Ligament is involved in several spinal conditions and surgical procedures:

    • Hyperextension injuries:

      • Trauma such as whiplash can overstretch or rupture the ALL, leading to instability or anterior disc herniation.

    • Diffuse idiopathic skeletal hyperostosis (DISH):

      • A condition where the ALL becomes ossified, leading to stiffness, limited mobility, and sometimes dysphagia (if cervical spine is involved).

    • Anterior intervertebral disc herniation:

      • Though rare, disc material may protrude anteriorly, resisted or guided by the ALL.

    • Spinal surgery considerations:

      • May be dissected or mobilized during anterior spinal fusion or disc replacement procedures; damage must be minimized to preserve function.

    • Pain and inflammation:

      • Inflammatory conditions (e.g., spondyloarthritis) can affect the ALL and lead to anterior spinal pain or stiffness.

    Did you know? Your bones are constantly being broken down and rebuilt — you have a new skeleton every 10 years.