Pectoral Girdle

Question 1

classify the sternoclavicular joint

Answer 1

functionally a ball and socket

synovial complex multiracial saddle joint

Question 2

nerve supply to the sternoclavicular joint

Answer 2

medial supraclavicular nerve (C3 & 4)

nerve to subclavicus (C5 &C6)

Question 3

classify the acromioclavicular joint

Answer 3

synovial (despite being coated in fibrocartilage) complex, multiaxial, plane joint

Question 4

neve supply to the acromioclavicular joint

Answer 4

lateral supraclavicular
lateral pectoral
suprascapular
axillary nerve

C4, 5, 6

Question 5

Stabilising factors of the sternoclavicular joint

Answer 5

shape and extent of the articular surfaces
surrounding musculature
strength and integrity of ligament s - particularly costoclavicular ligamnet (primary stabiliser)

Question 6

Stabilising factors of acromioclavicular joint

Answer 6

coracoclavicular ligament

trapezius and deltoid as they cross the joint line

Question 7

Describe shape of the intraarticular disc of the sternoclavicular joint

Answer 7

complete fibrocartilagenous disc

flat and round - thinner centrally
may be perforated to allow communicationn between the two joint cavities

Question 8

Describe attachments of the intraarticular disc of the sternoclavicular joint

Answer 8

joint capsule infront and behind

firmly to upper border of medial end of clavicle (superiorly)

firmly to the 1st CC (inferiorly)

Question 9

Describe functions of the intraarticular disc of the sternoclavicular joint

Answer 9

provides cushioning

compensates for inconcruency

allows increased ROM by acting as a mobile joint surface

aids stability due to the ligamentous attachments - particularly superiomedial displacement of clavicle

Question 10

Describe shape of the intraarticular disc of the acromioclavicular joint

Answer 10

wedge shaped

partially dividing the joint cavity

Question 11

Describe attachments of the intraarticular disc of the acromioclavicular joint

Answer 11

upper inner capsule

extends down between the two articular surfaces

Question 12

Describe function of the intraarticular disc of the acromioclavicular joint

Answer 12

improves incongruence and some shock absorption

not present in everyone

Question 13

what is the function of the pectoral girdle?

Answer 13

weight of UL transferred to the scapular from the humerus, from the scapular to the clavicle, and from the clavicle to the trunk via the sternoclavicular joint.

Question 14

Describe the concavoconvex rule

Answer 14

imb with concave joint surface glides in the SAME direction as the direction of the limb
i.e. if the surface is concave, the limb will glide forwards and move forwards.

The limb with the convex joint surface glides in the OPPOSITE direction to the movement of the limb.
i.e. if the surface is convex, the limb will glide forwards and move backwards

Question 15

Describe the structure of the sternoclavicular joint capsule

Answer 15

strong and fibrous
forms a sleeve around the joint

strong anteriorly, posteriorly and superiorly

weak inferiorly

Question 16

Describe the attachments of the sternoclavicular joint capsule

Answer 16

articular margins of clavicle and sternum

extends inferiorly to upper surface of 1st CC

Question 17

How is the sternoclavicular joint capsule strong?

Answer 17

reinforced by:

• anterior sternoclavicular ligamnet (anteriorly)
• posterior sternoclavicular ligmanet (posteriorly)
• interclavicular ligament (superiorly

weak inferiorly - where it passes between the clavicle and the 1st CC

Question 18

Describe the synovial membrane of the sternoclavicular joint

Answer 18

lines each compartment

loose laterally where it is reflected from articular margin of medial end of clavicle to margins of disc

medially attaches to margins of disc and articular margin of sternum

Question 19

Describe the structure of the acromioclavicular joint capsule

Answer 19

relatively loose, fibrous capsule
- made of strong coarse fibres - run in parallel fasiculi

thickest and strongest superiorly

Question 20

How is the acromioclaviclular joint capsule strengthened?

Answer 20

reinforced by trapezius - superiorly

by superior and inferior acromioclavicular lgiaments

Question 21

Describe the synovial membrane of the acromioclavicular joint?

Answer 21

lines the inner surface, attaches to the articular margins

Question 22

what are the 3 articulating surfaces of the sternoclavicular joint

Answer 22

medial end of clavicle
superolateral angle of manubrium sterni
adjacent part of 1st CC

Question 23

describe the articulating surfaces of the sternoclavicular joint

Answer 23

Clavicle - coated in fibrocartilage

• convex superoinferiorly
• concave anteroposteriorly

Sternum - coated in hyaline cartilige

• concave superioinferiorly
• convex anteroposteriorly

congruency improved by fibrocartiliagenous disc

clavicular surface larger so projects above the manubrium

Question 24

Why is the sternoclavicular joint incongruent?

Answer 24

due to the reciprocally concavoconvex surfaces - with different radii

i.e. the clavicular curvature is greater than the sternal curvature

Question 25

Describe the articular surface of the acromioclavicular joint?

Answer 25

slightly convex facet on lateral end of clavicle - facing posteriolaterally slightly concave facet on anteromedial acromion - faces anteromedially clavicle overrides acromion - therefore acromion displaced down in clavicle dislocation BOTH SURFACES COATED IN FIBROCARTILIGE