Questions and Answers
The clavicle has an S-shaped curve that is concave posteriorly in the medial third.
False
The sternal end of the clavicle articulates with the acromion of the scapula at the acromioclavicular joint.
False
The clavicle serves as a stable strut providing maximum freedom of motion for the scapula and free limb.
True
The inferior surface of the clavicle is smooth to allow easy movement against adjacent structures.
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The acromial end of the clavicle is enlarged and triangular.
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The conoid tubercle of the clavicle is located at the sternal end.
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The clavicle consists entirely of compact bone without any trabecular structure.
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The clavicle transmits shocks from the upper limb to the axial skeleton.
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The clavicle forms the bony boundary of the cervico-axillary canal, important for neurovascular protection.
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The clavicle has a medullary cavity that allows for hematopoiesis.
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Study Notes
Clavicle
- Trapezoid line: Attachment point for the lateral part of the coracoclavicular ligament.
- Subclavian groove: Located on the medial third of the clavicle; serves as the attachment for the subclavius muscle.
- Impression for costoclavicular ligament: A rough, oval area providing attachment for the ligament connecting the first rib to the clavicle, which limits shoulder elevation.
Scapula
- Shape: Triangular, flat bone covering the 2nd to 7th ribs on the posterolateral thorax.
- Surfaces:
- Posterior: Convex, divided into supraspinous fossa (smaller) and infraspinous fossa (larger) by the spine of scapula.
- Costal: Concave, forming the large subscapular fossa for muscle attachment.
Landmarks of the Scapula
- Body of scapula: Thin and translucent above and below the spine, with thicker borders, especially laterally.
- Acromion: Flat expansion of the scapular spine, articulates with the clavicle, serving as the shoulder's subcutaneous point.
- Deltoid tubercle: Medial attachment site for the deltoid muscle located on the scapular spine.
- Spine of scapula: Acts as a lever for trapezius muscle alongside the acromion.
- Glenohumeral joint: Positioned inferior to the ac joint; allows for shoulder movement and balance in conjunction with the CC ligament.
- Glenoid cavity: Oval fossa on the scapula that articulates with the head of the humerus, providing a shallow socket.
- Coracoid process: Beak-like projection above the glenoid cavity that supports the CC ligament and resembles a bent finger.
- Borders: The scapula has three borders (medial, lateral, superior) with distinct characteristics,
- Medial border runs parallel to thoracic spine.
- Lateral border is thicker, preventing buckling under stress, and terminates in a robust head.
- Superior border is thin and short, marked by the suprascapular notch.
Function of the Scapula
- Facilitates considerable movement on the thoracic wall at the scapulothoracic joint, enabling upper limb mobility.
Joints
- Sternoclavicular joint: A saddle-type synovial joint functioning like a ball and socket; features an articular disc dividing it into compartments.
- Disc attachments: Strengthened by anterior, posterior sternoclavicular, and interclavicular ligaments.
- Shock absorption: The joint absorbs forces from the upper limb; dislocations are rare, but fractures occur more frequently.
- Articular surfaces: The sternal end of the clavicle articulates with the manubrium of the sternum and the first costal cartilage, both covered with fibrocartilage.
Clavicle Structure
- Shape: S-shaped with convex medial and concave lateral curvatures, enhancing resilience.
- Ends of the clavicle:
- Sternal end: Enlarged and triangular, articulates with the sternum at the SC joint.
- Acromial end: Flat, articulates with the acromion of the scapula at the AC joint.
- Functions:
- Acts as a movable strut supporting the scapula and limb for maximum range of motion.
- Forms a boundary of the cervico-axillary canal, safeguarding neurovascular bundles.
- Transmits shocks from the upper limb to the axial skeleton.
- Composition: Long bone without a medullary cavity; trabecular bone encased in compact bone.
- Surface characteristics:
- Superior surface: Smooth and located beneath skin and platysma muscle.
- Inferior surface: Rough due to ligaments securing it to the first rib and suspending the scapula.
Landmarks of the Clavicle
- Conoid tubercle: Near the acromial end; attaches to the conoid ligament, allowing passive suspension of the upper limb from the clavicle.
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Description
This quiz covers the anatomical features of the clavicle, including the trapezoid line, subclavian groove, and impressions for ligaments. Understanding these structures is crucial for recognizing how they contribute to shoulder stability and function. Test your knowledge on the anatomy and significance of these clavicular attachments.
