The Claviclea. Anatomy of Clavicleb. Attachmentsc. Ossification

1. Anatomy of Claviclea. Shaft

i. Lateral one third1. Flattened from above-downwards2. Two borders; anterior & posterior

a. Anterior border, concave forwardsb. Posterior border, convex backwards

3. Two surfaces; superior & inferiora. Superior surface is subcutaneousb. Inferior surface has,

i. Elevation called conoid tubercleii. Ridge called trapezoid ridge

ii. Medial two third1. Rounded2. Four surfaces; anterior, posterior, superior &

inferiora. Anterior surface, convex forwardsb. Posterior surface, smoothc. Superior surface, rough, in its medial partd. Inferior surface has,

i. rough oval impression, at the medial end

ii. longitudinal subclavian groove, at the lateral half

iii. nutrient foramen, at the lateral end of the groove (it transmits a branch of suprascapular artery)

b. Lateral end (acromial end)

i. Flattened from above-downwardsii. Bears a facet that articulates with the acromion

process of the scapula to form the acromioclavicular joint

c. Medial end (sternal end)i. Quadrangular (quadrilateral)

ii. articulates with the manubrium sterni to form the sternoclavicular joint

iii. articular surface extends to inferior aspect, to articulate with the first costal cartilage

d. Side determinationi. Ends: lateral, flattened & medial, quadrilateral

ii. Curves: convex forwards, medial 2/3 & concave forwards, lateral 1/3

iii. Trapezoid ridge: inferior surface is grooved longitudinally, in medial 1/3

e. Sex determinationi. In females, clavicle is;

1. Shorter2. Lighter3. Thinner4. Smoother5. Less curved, than in males

ii. By (reliable criteria for sexing the clavicle),1. Midshaft circumference2. Weight of the clavicle

iii. Position of the lateral end, relative to the medial end,

1. Females: lateral end little below to the medial end

2. Males: lateral end, same level or slightly higher than the medial end

f. Peculiarities of the Claviclei. Only long bone that lies horizontally

ii. Only long bone which ossifies in membraneiii. Only long bone which has two primary ossification

centres

iv. First bone to start ossifyingv. Subcutaneous throughout

vi. Generally, no medullary cavityvii. Occasionally, pierced by the middle supraclavicular

nerve

2. Attachments on the Claviclea. Lateral end (at the margin of the articular surface for

the acromioclavicular joint)i. Joint capsule

b. Medial end (at the margin of the articular surface for the sternoclavicular joint)

i. Joint capsuleii. Articular disc (posterosuperiorly)

iii. Interclavicular ligament (superiorly)c. Lateral one third of shaft

i. Origin of deltoid muscle (anterior border)ii. Insertion of trapezius muscle (posterior border)

iii. Conoid & trapezoid parts of the coracoclavicular ligament (at conoid tubercle & trapezoid ridge)

d. Medial two thirds of shafti. Origin of pectoralis major muscle (anterior

surface)ii. Origin of clavicular head of the

sternocleidomastoid muscle (rough superior surface)

iii. Costoclavicular ligament (oval impression on the inferior surface)

iv. Insertion of subclavius muscle (subclavian groove)v. Clavipectoral fascia (margins of the subclavian

groove)

3. Ossificationa. First bone in the body to ossifyb. Ossifies in membrane, except for its medial endc. Two primary centres

i. Appear in shaftii. During 5-6 weeks of intrauterine life

iii. Fuse with each other about the 45th day

d. One secondary centrei. Appears in medial end

ii. During 15-17 years after birthiii. Fuses with shaft during 21-22 years

e. Occasionally there may be a secondary ossification centre for the acromial end also

The Scapulaa. Anatomy of Scapulab. Attachmentsc. Ossification

1. Anatomy of Scapula Flat bone Placed on the posterolateral aspect of the thoracic

cage Has 2 surfaces, 3 borders, 3 angles & 3 processes

a. Two surfacesi. Costal surface (subscapular fossa)

1. Concave forwards2. Directed anteromedially3. Marked by three longitudinal ridges

ii. Dorsal surface1. spine of the scapula is attached2. spine divides the surface into;

a. smaller supraspinous fossab. larger infraspinous fossa

3. the two fossae are connected by the spinoglenoid notch (situated lateral to the root of the spine)

b. Three bordersi. Superior border

1. Thin2. Shorter

3. Supraclavicular notch presents (near the root of the coracoid process)

ii. Lateral border1. Thick2. Rod-like3. Acts as a lever for the action of the serratus

anterior muscle in overhead abduction of the arm

4. Infraglenoid tubercle presents (at the upper end)

5. There is a rough stripe on the dorsal surface along the border (origin of teres major & teres minor muscles)

iii. Medial border1. Thin2. Extends from superior angle to inferior angle

c. Three anglesi. Superior angle

1. Covered by trapezius muscleii. Inferior angle

1. Covered by latissimus dorsi muscle2. Moves forward round the chest, when the arm

is abductediii. Lateral angle (Glenoid angle)

1. Broad2. Bears the glenoid fossa (glenoid cavity), which

is directed forwards, laterally & slightly upwards

3. Supraglenoid tubercle presents (superior to the glenoid fossa)

4. Infraglenoid tubercle presents (inferior to the glenoid fossa)

d. Three processesi. Spine (spinous process)

1. Triangular plate of bone2. Has three borders (anterior[root],

posterior[crest] & lateral)3. Crest (posterior border) has a upper lip & a

lower lip4. Has two surfaces, which divides the scapular

dorsal surface into supraspinous & infraspinous fossae

ii. Acromion1. Two borders; medial & lateral2. Two surfaces; superior & inferior3. Facet for the clavicle

iii. Coracoid process1. Directed forwards & slightly laterally

e. Side determinationi. Glenoid angle

1. Broader2. Bears the glenoid fossa

ii. Presence of spine (posterior)iii. Presence of thickest border (laterally)iv. Convexity of dorsal surface & concavity of costal

surface

2. Attachments on the Scapulaa. Muscles

i. Origin of multipennate subscapularis muscle from the medial two-thirds of the subscapular fossa (costal surface)

ii. Origin of supraspinatus muscle from;1. medial two-thirds of the supraspinous fossa2. superior surface of the spine

iii. Origin of infraspinatus muscle from;1. medial two-thirds of the infraspinous fossa2. inferior surface of the spine

iv. Origin of deltoid muscle from;1. lower lip of the crest2. lateral border of the acromion (acromial fibres

are multipennate)v. Insertion of trapezius muscle into;

1. upper lip of crest2. medial border of the acromion

vi. Insertion of serratus anterior ;1. Along the medial border of the costal surface

a. First digitations, from superior angle to root of spine

b. Next two digitations to the medial border2. Into the inferior angle

a. Last five digitations to the inferior anglevii. Origin of long head & short head of the biceps

brachii ;1. long head arises from supraglenoid tubercle2. short head arises from the lateral part of the tip

of the coracoid processviii. Origin of coracobrachialis muscle from the medial

part of the tip of the coracoid processix. Insertion of pectoralis minor muscle into;

1. Medial border of the coracoid process2. Superior surface of the coracoid process

x. Origin of long head of the triceps from the Infraglenoid tubercle

xi. Origin of teres minor muscle from the upper two-thirds of the rough strip on the dorsal surface along the lateral border

xii. Origin of teres major muscle from the lower one-thirds of the rough strip on the dorsal aspect of the lateral border

xiii. Insertion of levator scapulae muscle along the dorsal aspect of the medial border, from the superior angle to the root of the spine

xiv. Insertion of rhomboideus minor muscle into the medial border (dorsal aspect) medial to the root of the spine

xv. Insertion of rhomboideus major muscle into the medial border (dorsal aspect) between the root of spine & inferior angle

xvi. Origin of inferior belly of the omohyoid muscle from the medial border of the suprascapular notch

b. Ligamentsi. Margins of glenoid cavity

1. Capsule of the shoulder joint2. Glenoidal labrum

ii. Margins of the facet on the medial aspect of the acromion give attachment to the capsule of the acromioclavicular joint

iii. The coracoacromial ligament is attached;1. To the lateral borders of the coracoid process2. To the medial side of the tip of the acromion

processiv. The coracohumeral ligament is attached to the root

of the coracoid processv. The coracoclavicular ligament is attached