1.3 Osteology and Arthrology of the Pectoral Guide

Question 1

Sternoclavicular joint Type

Answer 1

• Synovial saddle

- Functions as a ball-and-socket

Question 2

Articulating surfaces of SC joint

Answer 2

• Sternal end of clavicle

- Manubrium of sternum and 1st costal cartilage

Question 3

Attachment for fibrous layer of capsule for SC joint

Answer 3

Margins of the articular surfaces

Question 4

Synovial membrane of SC joint

Answer 4

Lines internal surfaces of fibrous layer

Question 5

Describe the articular disc of SC joint

Answer 5

Divides SC joint into 2 compartments

Question 6

Attachments for articular disc of SC joint

Answer 6

Attached to anterior and posterior SC ligaments and interclavicular ligament

Question 7

Function of articular disc of SC joint

Answer 7

Reason for great strength of this joint

Question 8

Ligaments for SC joint

Answer 8

Anterior SC ligament
Strengthens capsule anteriorly
Posterior SC ligament
Strengthens capsule posteriorly
Interclavicular ligament
Strengthens capsule superiorly
Costoclavicular ligament
Anchors inferior surface of sternal end of clavicle to 1st rib/cartilage
Limits elevation of pectoral girdle

Question 9

Anterior SC ligament

Answer 9

Strengthens capsule anteriorly

Question 10

Posterior SC ligament

Answer 10

Strengthens capsule posteriorly

Question 11

Interclavicular ligament

Answer 11

Strengthens capsule superiorly

Question 12

Costoclavicular ligament

Answer 12

• Anchors inferior surface of sternal end of clavicle to 1st rib/cartilage
• Limits elevation of pectoral girdle

Question 13

Mobility of SC joint

Answer 13

Very mobile despite its strength

Question 14

Movements of SC joint

Answer 14

• Allows movements of pectoral girdle and upper limb
• Clavicle raised to 60-degrees in full elevation of upper limb
• SC joint can be moved anteriorly/posteriorly over a 25-30 degree range

Question 15

Acromioclavicular joint Type

Answer 15

Synovial plane

Question 16

Articulating surfaces of AC joint

Answer 16

Acromial end of clavicle

Acromion

Question 17

What covers the articulating surfaces of the AC joint?

Answer 17

Fibrocartilage

Question 18

What separates the articulating surfaces of AC joint?

Answer 18

Incomplete wedge-shaped articular disc

Question 19

Describe the joint capsule for AC joint

Answer 19

• Sleeve-like

- Relatively loose fibrous layer

Question 20

Describe the synovial membrane of AC joint

Answer 20

Lines internal surface of fibrous layer of capsule

Question 21

How strong is the capsule of the AC joint?

Answer 21

• Relatively weak

- Strengthened superiorly by fibers of trapezius

Question 22

Ligaments of the AC joint

Answer 22

• AC ligament
• Coracoclavicular ligament
• Conoid ligament
• Trapezoid ligament

Question 23

AC ligament
From acromion to clavicle
Strengthens AC joint superiorly
Keeps acromion from driving under clavicle even when joint is separated
Coracoclavicular ligament
Extra-articular
Anchors clavicle to coracoid process of scapula
Provides means for scapula and upper limb to passively hang from clavicle
Conoid ligament
Apex (narrow) attached to root of coracoid process
Base (wide) attached to conoid tubercle on inferior surface of clavicle
Trapezoid ligament
Nearly horizontal
Attached to superior surface of coracoid process
Extends laterally and posteriorly to trapezoid line on inferior clavicle

Answer 23

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