anatomy 8.1

What bones make up the pectoral girdle?

Left and right clavicles and left and right scapulae.

What is the main function of the pectoral girdle?

It articulates with the trunk, supports the upper limbs, and provides attachment sites for muscles.

How does the pectoral girdle increase upper limb mobility?

The scapula moves freely over the thorax. The shoulder joint has a shallow cavity, allowing a wide range of motion.

Why can the scapula move freely?

It is not directly attached to the axial skeleton.

What is another name for the clavicle?

Collarbone.

What is the shape of the clavicle?

S-shaped.

The clavicle extends between which two bones?

The manubrium of the sternum and the acromion of the scapula.

What is the only direct connection between the pectoral girdle and the axial skeleton?

The clavicle.

What is the medial end of the clavicle called?

The sternal end.

The sternal end of the clavicle articulates with what structure?

The manubrium of the sternum.

What joint is formed by the sternal end of the clavicle?

Sternoclavicular joint.

What is the lateral end of the clavicle called?

The acromial end.

The acromial end of the clavicle articulates with what structure?

The acromion of the scapula.

What joint is formed by the acromial end of the clavicle?

Acromioclavicular joint.

Which surface of the clavicle is smooth?

Superior surface.

Which surface of the clavicle contains grooves and ridges for muscle and ligament attachment?

Inferior surface.

What is the conoid tubercle?

A rough projection on the inferior surface near the acromial end where the coracoclavicular ligament attaches.

What is the costal tuberosity?

A prominence near the sternal end where the costoclavicular ligament attaches.

Learning Strategy: How can you recognize the acromial end of the clavicle?

It is flattened and resembles the acromion of the scapula.

Describe the scapula.

A broad, flat, triangular bone.

What is the spine of the scapula?

A ridge on the posterior surface of the scapula.

The spine of the scapula continues into what structure?

The acromion.

What is the acromion?

A flattened posterior projection that forms the tip of the shoulder.

What does the acromion articulate with?

The acromial end of the clavicle.

What is the coracoid process?

A smaller, anterior projection of the scapula for muscle and ligament attachment.

Name the three borders of the scapula.

Superior border, medial (vertebral) border, and lateral (axillary) border.

What passes through the suprascapular notch?

The suprascapular nerve.

Name the three angles of the scapula.

Superior angle, inferior angle, and lateral angle.

What is the glenoid cavity (glenoid fossa)?

A shallow socket on the lateral angle that articulates with the humerus.

What bone articulates with the glenoid cavity?

The humerus.

What is the supraglenoid tubercle?

A muscle attachment site above the glenoid cavity.

What is the infraglenoid tubercle?

A muscle attachment site below the glenoid cavity.

What is the subscapular fossa?

The broad, slightly concave anterior surface of the scapula where the subscapularis muscle attaches.

What are the supraspinous and infraspinous fossae?

Depressions on the posterior scapula above and below the spine that serve as attachment sites for the supraspinatus and infraspinatus muscles.

Why are clavicle fractures common?

The clavicle's S-shape makes it poor at resisting stress. Falls or direct blows often fracture the middle of the bone, and posterior fractures can damage the nearby subclavian artery and vein.