Scapula

Posterior View

Shoulder girdle & thoracic cage

Definition: scapula is a flat bone that connects the trunk to the upper limb. It is the posterior bone of shoulder girdle. It is also known as shoulder blade.

Shape: triangular in outline.

Site: lies on the postero-lateral aspect of the chest wall extending from the 2nd to 7th rib.

Side determination:

1. Glenoid cavity: is directed laterally & upwards.
2. Spine is directed backwards.
3. Subscapular fossa: is directed fowards.

Posterior, anterior & lateral sides of scapula

General features: It is consist of 2 surfaces, 3 angles, 3 borders, 3 processes

• Surfaces:

Costal (anterior) surface	Dorsal (posterior) surface
- It is directed forwards & medially - Facing the ribs - It carries subscapular fossa	- It is directed backwards & laterally - Palpated from back - Spinous process, divides it into two fossae: infraspinous fossa & supraspinous fossa

• Angles:

Superior angle	Lateral angle (head)	Inferior angle (apex)
- Thin, smooth & rounded - Right angle - Between superior & medial borders - Opposite the 2nd rib	- Thickest part of the bone - Glenoid cavity - Articulate with head of humerus - Supra & infraglenoid tubercles	- Thick & rough - Acute angle - Between medial & lateral borders - Opposite the 7th rib

• Borders:

Superior border	Lateral (axillary) border	Medial (vertebral) border
- Thinnest & shortest - Extend from the superior angle to coracoids process - Near the root of coracoids process, there is suprascapular notch	- Thickest - Extend from the glenoid cavity to the inferior angle - At the upper end, there is infraglenoid tubercle	- Average thickness & longest - Extend from the superior angle to the inferior angle - Presents anterior lip, posterior lip & an intermediate narrow area

• Processes:

Spinous process	Acromion process	Coracoid process
- A triangular plate of bone - Divides the dorsal surface into 2 fossae - It has 2 ends: §  Lateral end- continuous with acromion process §  Medial end- forms the root of the spine - It has 2 surfaces: §  Upper surface §  Lower surface - It has 3 borders: §  Anterior border- attached to scapula §  Posterior border- free, subcutaneous (crest of spine), has upper &lower lips §  Lateral border- free, bounds the spinoglenoid notch	- A projecting forwards from the lateral end of the spine making right angle - It has 2 surfaces: §  Upper surface §  Lower surface - It has 2 borders: §  Medial border- continuous with upper lip of crest of spine, carries small articular facet for articulation with clavicle (acromioclavicular joint) §  Lateral border- continuous with lower lip of the crest of spine at the acromial angle	- A projection from the upper border of the head (glenoid cavity - Directed fowards & slightly laterally - Root of process is related medially to the supraglenoid tubercle & laterally to the suprascapular notch - It has 2 surfaces: §  Upper surface- carries a rough area for muscle attachment §  Lower surface - It has 2 borders: §  Medial border §  Lateral border

Anterior surface of scapula (click at the image to enlarge)

Posterior surface of scapula (click at the image to enlarge)

Lateral border of scapula (click at the image to enlarge)

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Clavicle

Shoulder girdle & thoracic cage

Definition: clavicle is a long bone that connects the trunk with upper limb. It is the anterior bone of shoulder girdle. It is also known as collar bone.

Shape: slender S-shape in appearance. It has double curvature of convex medially and concave laterally.

Functions: it support the shoulder and transmit the upper limb weight to the trunk through the sternum.

Site: lies horizontally at the junction of the front of the chest with front of the neck. Immediately above the first rib. It is subcutaneous throughout its whole extent.

Side determination:

1. Medial end: is bulky and quadrangular.
2. Lateral end: is flattened.
3. Superior surface: is smooth.
4. Inferior Surface: is rough at both ends & a groove for subclavius muscle at its middle third.
5. Anterior Curvature: is convex at its medial two-thirds & concave at its lateral one-third.

Superior surface of the clavicle

Inferior surface of the clavicle

General features: It consists of a shaft and two ends:-

• Shaft:

Lateral one-third	Medial two-thirds
Flattened from above downwards Consists of 2 borders: Anterior border- - It is concave forwards & show a rough area; deltoid tubercle Posterior border- - It is convex backwards Consists of 2 surfaces: Superior surface- - It is subcutaneous & smooth Inferior surface- - It shows 2 rough areas; conoid tubercle & trapezoid ridge	Rounded or quadrangular Consists of 4 surfaces: Anterior surface- - It is rough & convex forwards Posterior surface- - It is smooth & concave backwards Superior surface- - It is subcutaneous & rough on its medial part Inferior surface- - It has rough oval impression medially & subclavian groove in its intermediate third

• Ends:

Lateral end	Medial end
- Known as acromial end - Articulate with acromion process of scapula to form acromioclavicular joint - Flat shape (above downwards)	- Known as sternal end - Articulate with clavicular notch of menubrium -sterni to form sternoclavicular joint - Quadrangular or rounded shape

Acromial end of clavicle

Sternal end of clvicle

Particular features:

A) Muscles attachment:

Region	Specifically	Muscles
Anterior border	Medial third (rounded border)	Pectoralis major muscles
Posterior border	Superiorly, on the medial third	Sternocleidomastoid muscle (clavicular head)
Posterior border	Inferiorly, on the medial third	Sternohyoid muscle
Posterior border	Lateral third	Trapezius muscle
Superior surface & anterior border	Deltoid tubercle, anteriorly on the lateral third	Deltoid muscle
Superior surface	Posteriorly on the lateral third	Trapezius muscle
Inferior surface	Subclavian groove	Subclavius muscle

Superior surface of the clavicle

Inferior surface of the clavicle

B) Ligament Attachment:

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