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    From Musculoskeletal System

    Parietal Bones
    Bones forming the sides and roof of the skull.
    Pivot Joints
    e.g., atlanto-axial joint
    Tibia
    Shin bone, the larger bone in the lower leg.
    Soleus
    Calf muscle responsible for plantarflexion of the foot.
    Sesamoid Bones
    e.g., patella, some found in hands/feet.
    Obliques (External and Internal)
    Muscles responsible for torso rotation.
    Iliolumbar Ligament
    Ligament connecting the ilium and lumbar vertebrae.
    Carpals (8 bones)
    8 wrist bones.
    Medial Collateral Ligament (MCL)
    Knee ligament that stabilizes the inner knee.
    Quadriceps Tendon
    Tendon that connects the quadriceps to the patella.
    Achilles Tendon
    Tendon connecting the calf muscle to the heel bone.
    Anterior Longitudinal Ligament
    Spinal ligament running along the front of the vertebral column.
    Facial Bones
    Bones forming the structure of the face.
    Thoracic Cage
    Ribs and sternum forming the protective cage for the heart and lungs.
    Cervical Vertebrae (C1 - C7)
    Vertebrae in the neck region (C1-C7).
    Syndesmoses
    Fibrous joints where bones are connected by ligaments.
    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.
    Buccinator
    Muscle that helps with chewing and blowing air out.
    Interspinous Ligament
    Spinal ligament between adjacent vertebral spinous processes.
    Frontal Bone
    Bone forming the forehead and upper part of the orbits.
    Palatine Bones
    Bones forming part of the hard palate and nasal cavity.
    Triceps Brachii
    Muscle responsible for elbow extension.
    Phalanges (14 bones)
    14 bones forming the toes.
    Hyoid Bone
    U-shaped bone in the neck that supports the tongue.
    Ethmoid Bone
    Bone forming part of the nasal cavity and the orbit.

    Coracoacromial Ligament

    Reviewed by our medical team

    Ligament that connects the acromion to the coracoid process.

    1. Overview

    The coracoacromial ligament is a strong, triangular band of connective tissue located in the shoulder. It connects the coracoid process to the acromion, both of which are projections of the scapula. This ligament forms part of the coracoacromial arch, a protective arch over the head of the humerus, preventing its upward displacement. Although it does not directly stabilize the glenohumeral joint, it plays a crucial role in maintaining the structural integrity of the shoulder and preventing impingement.

    2. Location

    The coracoacromial ligament is found in the superior aspect of the shoulder, forming a roof over the glenohumeral joint:

    • Proximally: Attaches to the lateral border of the coracoid process.

    • Distally: Inserts onto the medial border of the acromion process.

    • Orientation: Extends obliquely over the head of the humerus, forming a protective arch along with the acromion and coracoid process.

    3. Structure

    The coracoacromial ligament is composed of dense regular connective tissue and has the following structural characteristics:

    • Shape: Flat and triangular, with a broad base at the acromion and an apex at the coracoid process.

    • Fibers: Run obliquely, blending with the deep fascia of the shoulder and sometimes with the deltoid or trapezius muscle fascia.

    • Coracoacromial arch: Along with the acromion and coracoid process, it forms a bony-ligamentous arch over the humeral head.

    4. Function

    The coracoacromial ligament serves important mechanical and protective functions:

    • Prevents superior dislocation: Acts as a barrier to upward displacement of the humeral head during shoulder movements.

    • Supports the coracoacromial arch: Maintains the integrity of the arch, which protects the rotator cuff and glenohumeral joint from direct trauma.

    • Limits excessive motion: Assists in restricting superior translation of the humerus.

    5. Physiological role(s)

    Though not a dynamic stabilizer, the coracoacromial ligament has several physiological roles:

    • Passive restraint: Provides a static check-rein to upward movement of the humeral head, especially during deltoid contraction.

    • Force redirection: Helps distribute forces exerted by surrounding muscles and tendons over the superior shoulder.

    • Anatomical roof: Forms a part of the shoulder's subacromial space, influencing the biomechanics of the rotator cuff tendons and bursa.

    6. Clinical Significance

    The coracoacromial ligament is implicated in various shoulder pathologies, particularly in impingement syndromes:

    • Subacromial impingement syndrome:

      • The coracoacromial arch can impinge on the supraspinatus tendon or subacromial bursa during arm elevation, causing pain and reduced mobility.

      • Thickening or ossification of the ligament may contribute to narrowing of the subacromial space.

    • Rotator cuff tears:

      • Chronic impingement against the ligament can cause wear and eventual tearing of the supraspinatus tendon.

    • Coracoacromial ligament release:

      • In severe or recurrent impingement cases, partial resection of the ligament may be performed surgically to decompress the subacromial space.

    • Shoulder instability evaluation:

      • Though it does not directly stabilize the glenohumeral joint, an intact coracoacromial arch is a secondary restraint to superior translation in the event of rotator cuff failure.

    Did you know? Bones in the feet form arches that provide balance and flexibility.