CLAVICAL (THE COLLOR BONE)

CLAVICAL (THE COLLOR BONE)

 

-CLAVICAL (THE COLLOR BONE) is a long bone . It is also known as collor bone/ beauty bone.

-It is the only bone in the body that lies horizontally.

-It is a bone of upper extremity.

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– It has ;

1) Shaft

2) Two ends – lateral and medial.

 

• Side determination

 

√  Lateral End – flat

Medial end – quadrilateral

 

√ Shaft – slightly curved

* Medial 2/3 rd  – convex forwards

* Lateral 1/3 rd – concave forwards.

✓ Clavicle is the only long bone which lies horizontally.

✓ It is the first bone which starts ossifying.

✓ It receives weight of upperlimb  via lateral 1/3 rd through coracoclavicular ligament and transmits to axial skeleton via the medial 2/3 rd.

• Features

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1) Shaft

 

– It is divided into lateral 1/3 rd and medial 2/3 rd.

 

* Lateral 1/3 rd

√ Flattened from above downward

√ 2 borders – Anterior and posterior

 

Anterior – concave forwards

Posterior – convex backwards

 

√ 2 Surfaces – Superior and Inferior

Superior – It is subcutaneous.

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Inferior – Presents an elevation called conoid tubercle and a ridge called trapezoid ridge.

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* Medial 2/3 rd

√ It is rounde

√ 4 surfaces :

Anterior surface – convex forwards

Posterior surface – smooth

Inferior surface – has a rough oval impression at the medial end

Lateral half of the surface has a longitudinal subclavian groove.

There is a nutrient foramen present at the lateral end of the groove.

2) Lateral End / Acromial end

 

– Flattened from above downwards .

– It has a facet that articulates with acromion process of the scapula and form Acromioclavicular joint.

 

3) Medial / Sternal end

 

– It is quadrangular

– Articulates with clavicular notch of manubrium sterni and forms sternoclavicular joint.

 

• Attachments

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1) At Lateral End ;

 

– The margin of articular surface for its Acromioclavicular joint gives attachment to joint Capsule.

 

2) At medial end ;

 

– Margin of articular surface for the sternum gives attachment to ,

(a) Fibrous capsule of sternoclavicular joint

(b) Articular disc ( posterosuperiorly )

(c) Interclavicular ligament ( superiorly )

 

3) Lateral 1/3 rd of shaft

 

(a) Anterior border – it gives origin to deltoid .

(b) Posterior border – It provides insertion to trapezius.

(c) Conoid tubercle and trapezoid ridge – Gives attachment to Conoid and trapezoid parts of coracoclavicular ligament.

 

4) Medial 2/3 rd of shaft

 

(a) Anterior surface : gives origin to pectoralis major

(b) Half of the superior surface : gives origin to Clavicular head of Sternocleidomastoid muscle .

(c) The oval impression on inferior surface ( at the medial end ) : It gives attachment to costoclavicular ligament.

(d) The subclavian groove : It gives insertion to subclavius muscle

(e) Posterior surface close to medial end : it gives attachment to sternohyoid muscle.

(f) Subclavian vessels and cords of brachial plexus passes towards axilla which lies between inferior surface of clavicle and upper surface of 1st rib .

– The nutrient foramen : transmits a branch of suprascapular artery.

 

• Ossification of clavicle

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– It is the first bone to ossify

– It ossifies in membrane ,except for its medial end.

– Ossification starts from 2 primary centres and 1 secondary centre.

 

* Two primary centres :

 

– Appears in shaft

– Between 5th and 6 th week of intrauterine life.

– And fuse about the 45th day..

* The secondary centre

 

– Appears during 15-17 years

– Fuses with shaft during 21-22 years.

 

• Clinical anatomy

1) Clavicle fracture

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– Clavicle is most commanly fractured.

– This fracture can occur by falling on outstretched hand .

– Most common site : junction between two curvatures of the bone.

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2) Cleidocranial dysostosis

– Congenital absence of clavicle or imperfectly developed clavicle in a disease is called as Cleidocranial dysostosis.

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