Clavicle

introduction ,osteology,myology and clinical anatomy on clavicle

1. CLAVICLE Dr. Sharlin. BPT, PgD in Biomechanics and kinesiology in sports

2. Clavicle is also called collar bone / Beauty bone Supports the shoulder so that the arm can swing clearly away from the trunk. The clavicle transmits the weight of the limb to the sternum. Parts Of Clavicle Cylindrical part – shaft 2 ends – Medial end - Lateral end

3. Side Determination : The lateral end is flat, and the medial end is large and quadrilateral. The shaft is slightly curved, so that it is convexforwards in its medial two-thirds, and concaveforwards in its lateral one-third. The inferior surface is grooved longitudinally in its middle one-third.

4. Peculiarities of the Clavicle It is the only long bone that lies horizontally. It is subcutaneous throughout. It is the first bone to start ossifying.(5 th – 6 th week of gestation) It is the only long bone which ossifies in membrane. It is the only long bone which has two primary centres of ossification.

5. 6. There is no medullary cavity. 7. It is occasionally pierced by the middle supraclavicular nerve. 8. It receives weight of upper limb via lateral one-third through coracoclavicular ligament and transmits weight of upper limb to the axial skeletal via medial two-third part

6. OSTEOLOGY

7. SHAFT: The shaft is divided into 1. Lateral one-third 2. Medial two-third The lateral one-third flattened from abovedownwards. It has two borders : Anterior – Concave forward Posterior – Convex Backward It has two surfaces : Superior – Subcutaneous Inferior – Conoid tubercle and trapezoid ridge

8. Medial two-third: Shaft is rounded It has four surfaces: Anterior surface - convex forwards. Posterior surface - smooth. Superior surface - rough in its medial part. Inferior surface - rough oval impression at the medial end. lateral half of this surface has a longitudinal subclasubclavian groove.The nutrient foramen lies at the lateral end of the groove.

9. Clavicle Ends: 1. Lateral or acromial (Greek peak of shoulder) end 2. Medial or Sternal end Lateral/Acromial end: flattened from above downwards. It bears a facet that articulates with the acromion process of the scapula to form the acromioclavicular joint.

10. Medial / Sternal end: It is quadrangular andarticulates with the clavicular notch of the manubrium sterni to form the sternoclavicular joint. The articular surface extends to the inferior aspect,for articulation with the first costal cartilage.

11. MYOLOGY

12. At the lateral end, the margin of the articular surface for its acromioclavicular joint gives attachment to a. The joint capsule. At the medial end, the margin of the articular surface for the sternum gives attachment to: a. Fibrous capsule of sternoclavicular joint all around b. Articular disc postero -superiorly. c. Interclavicular ligament superiorly.

13. Lateral one-third of shaft a. The anterior border gives origin to the deltoid
b. The posterior border provides insertion to thetrapezius. c. The conoid tubercle and trapezoid ridge giveattachment to the conoidandtrapezoid parts of thecoracoclaaicular ligament

14. Medial two-thirds of the shaft. a. Most of the anterior surface gives origin to the pectoralis major b. Half of the rough superior surface gives origin to theclavicular head of the sternocleidomastoid. c. The oval impression on the inferior surface at the medial end gives attachment to the costoclaaicularligament.

15. d. The subclavian groove gives insertion to the subclavius muscle. E. The margins of the groove give
attachment to the clavipectoral fascia F. The posterior surface close to medial end gives origin to sternohyoid muscle

16. G. The subclavian vessels and cords of brachial plexus pass towards the axilla lying between the inferiorsurface of the clavicle and upper surface of firstrib. Subclavius muscle acts as a cushion.The nutrient foramen transmits a branch of thesuprascapular artery.

17. Clinical Anatomy

18. The clavicle is commonly fractured by falling on the outstretched hand (indirect violence). Themost common site of fracture is the junctionbetween the two curvatures of the bone, which is the weakest point. The lateral fragment is displaced downwards by the weight of the limbas trapezius muscle alone is unable to support theweight of upper limb

19. The clavicles may be congenitally absent, or imperfectly developed in a disease called cleidocranial dysostosis . In this condition, the shoulders droop, and can be approximated anteriorly in front of the chest