1. The Clavicle
a. Anatomy of Clavicle
b. Attachments
c. Ossification
1. Anatomy of Clavicle
a. Shaft
i. Lateral one third
1. Flattened from above-downwards
2. Two borders; anterior & posterior
a. Anterior border, concave forwards
b. Posterior border, convex backwards
3. Two surfaces; superior & inferior
a. Superior surface is subcutaneous
b. Inferior surface has,
i. Elevation called conoid tubercle
ii. Ridge called trapezoid ridge
ii. Medial two third
1. Rounded
2. Four surfaces; anterior, posterior, superior & inferior
a. Anterior surface, convex forwards
b. Posterior surface, smooth
c. Superior surface, rough, in its medial part
d. Inferior surface has,

2. 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-downwards
ii. Bears a facet that articulates with the acromion process of the
scapula to form the acromioclavicular joint

3. 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 determination
i. 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 determination
i. In females, clavicle is;
1. Shorter
2. Lighter
3. Thinner
4. Smoother
5. Less curved, than in males
ii. By (reliable criteria for sexing the clavicle),
1. Midshaft circumference
2. 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

4. 2. Males: lateral end, same level or slightly higher than the medial
end
f. Peculiarities of the Clavicle
i. Only long bone that lies horizontally
ii. Only long bone which ossifies in membrane
iii. Only long bone which has two primary ossification centres
iv. First bone to start ossifying
v. Subcutaneous throughout
vi. Generally, no medullary cavity
vii. Occasionally, pierced by the middle supraclavicular nerve

5. 2. Attachments on the Clavicle
a. 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 capsule
ii. 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 shaft
i. 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. Ossification
a. First bone in the body to ossify

6. b. Ossifies in membrane, except for its medial end
c. Two primary centres
i. Appear in shaft
ii. During 5-6 weeks of intrauterine life
iii. Fuse with each other about the 45th day
d. One secondary centre
i. Appears in medial end
ii. During 15-17 years after birth
iii. Fuses with shaft during 21-22 years
e. Occasionally there may be a secondary ossification centre for the acromial
end also
The Scapula
a. Anatomy of Scapula
b. Attachments
c. 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 surfaces
i. Costal surface (subscapular fossa)
1. Concave forwards
2. Directed anteromedially

7. 3. Marked by three longitudinal ridges
ii. Dorsal surface
1. spine of the scapula is attached
2. spine divides the surface into;
a. smaller supraspinous fossa
b. larger infraspinous fossa
3. the two fossae are connected by the spinoglenoid notch
(situated lateral to the root of the spine)
b. Three borders
i. Superior border
1. Thin
2. Shorter
3. Supraclavicular notch presents (near the root of the coracoid
process)
ii. Lateral border
1. Thick
2. Rod-like
3. 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 border
1. Thin
2. Extends from superior angle to inferior angle

8. c. Three angles
i. Superior angle
1. Covered by trapezius muscle
ii. Inferior angle
1. Covered by latissimus dorsi muscle
2. Moves forward round the chest, when the arm is abducted
iii. Lateral angle (Glenoid angle)
1. Broad
2. 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 processes
i. Spine (spinous process)
1. Triangular plate of bone
2. Has three borders (anterior[root], posterior[crest] & lateral)
3. Crest (posterior border) has a upper lip & a lower lip
4. Has two surfaces, which divides the scapular dorsal surface into
supraspinous & infraspinous fossae
ii. Acromion
1. Two borders; medial & lateral
2. Two surfaces; superior & inferior
3. Facet for the clavicle
iii. Coracoid process
1. Directed forwards & slightly laterally

9. e. Side determination
i. Glenoid angle
1. Broader
2. 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 Scapula
a. 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 fossa
2. superior surface of the spine
iii. Origin of infraspinatus muscle from;
1. medial two-thirds of the infraspinous fossa
2. inferior surface of the spine
iv. Origin of deltoid muscle from;
1. lower lip of the crest
2. lateral border of the acromion (acromial fibres are
multipennate)
v. Insertion of trapezius muscle into;
1. upper lip of crest
2. medial border of the acromion

10. 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 border
2. Into the inferior angle
a. Last five digitations to the inferior angle
vii. Origin of long head & short head of the biceps brachii ;
1. long head arises from supraglenoid tubercle
2. short head arises from the lateral part of the tip of the coracoid
process
viii. Origin of coracobrachialis muscle from the medial part of the tip of
the coracoid process
ix. Insertion of pectoralis minor muscle into;
1. Medial border of the coracoid process
2. 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

11. xvi. Origin of inferior belly of the omohyoid muscle from the medial
border of the suprascapular notch
b. Ligaments
i. Margins of glenoid cavity
1. Capsule of the shoulder joint
2. 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 process
2. To the medial side of the tip of the acromion process
iv. The coracohumeral ligament is attached to the root of the coracoid
process
v. The coracoclavicular ligament is attached