Bone:Clavicle, scapula and humerus:Bony features

**Clavicle** is a paired horizontal long bone that serves as a strut between the scapula and the sternum and is a component of the pectorial girdle.

Its medial end is rounded and convex forward.

* has a facet for the articulation with the sternum and the first costal cartilage.
* rough area inferiorly for attachment of the costoclavicular ligament.

At its middle third, the shaft, a subclavian groove on the shaft provide attachment of the subclavius and clavipectoral fascia.

The lateral end is flat and curves back to articulate with the scapula.

* inferior surface has a rough ridge called the trapezoid line and further medially is a small rounded projection called conoid tubercule.

**Scapula** is a paired flat triangular bone situated on the posterior aspect of the thorax, forming the second part of the pectorial girdle. It has a thicker lateral border with a thinner "blade like" body.

It consists of 2 surfaces (front/dorsal), 3 borders (superior/medial/lateral) and 3 angles (lateral/inferior/superior).

Two surface:

* Front surface: broad concavity called subscapular fossa for attachment of the subscapularis.
* Back surface: a bony spine separate it into supraspinous and infraspinous fossa.
	+ The spine extends laterally and sloping upwards to the acromion. The acromion is the lateral rectangular projection from the spine and curves towards and upwards to articulate with the clavicle and overhang the glenoid cavity.
	+ A dip in the spine, is the suprascapular notch (which house the suprascapular nerve and vessels).

Border

* Superior border: from superior angle to the base of the coracoid process, an upward projecting bend finger-like bony structure.
* Medial border: the longest border and extents from superior angle to inferior angle.
* Lateral border: thick bony border and extends from the lower margin of glenoid cavity to the inferior angle. Beneath the glenoid fossa is a rough impression called infraglenoid tubercle.

Angles

* Lateral angle: a broadened cup of glenoid fossa on a narrow neck. The superior aspect of the fossa is the coracoid process. A tubercle at the upper glenoid is called supraglenoid tubercle.
* Superior angle: the superior border meets the medial border and is covered by trapezius
* Inferior angle: the lateral border meets the medial border and is covered by lattissimus dorsi

   **Humerus** is the long bone of the arm which articulates with the scapula at the glenoid fossa.

* Proximal end:
	+ convex articular surface called head of the humerus, covered with hyaline cartilage.
	+ The articular margin is the anatomical neck.
	+ Two bony prominence lie in the anterior aspect termed lesser and greater tubercle. The lesser tubercle projects forwards and continue downwards as the medial border of the bicipital sulcus. The greater tubercle projects laterally and has three facets for insertion of the rotator cuff muscles.
* Shaft:
	+ the middle portion of the humerus. Triangular in cross-section.
	+ deltoid tuberosity forms a V-shaped prominent ridge on the middle lateral aspect of the shaft.
* Distal end:
	+ radial groove extends distally
	+ lateral supracondylar ridge connects with the lateral epicondyle.
	+ medial supracondylar ridge connects with the prominent medial epicondyle.
	+ Articular surface of the elbow joint between the epicondyles, covered with hyaline cartilage.
		- Capitulum - projects forwards and inferiorly for radial articulation
		- Trochlea - sharp ridge curving from the front to back for ulnar articulation
		- Two anterior fossa above the trochlea and capitulum are shallow coronoid fossa and radial fossa
		- One posterior fossa is olecranon fossa.