The Pectoral Girdle

Question 1

The Pectoral Girdle consists of?

Answer 1

The clavicle and scapula

Question 2

What joint links the free limb to the axial skeleton?

Answer 2

The sternocalvicular joint

Question 3

Why are muscles required to stabilise the shoulder joint?

Answer 3

Because as the shoulder joint is extremely mobile, it has sacrificed stability, which needs to be overcome with muscles

Question 4

How are movements in the pectoral girdle classified?

Answer 4

By the movement of the scapula

Question 5

Superior rotation

Answer 5

Glenoid points superiorly

Question 6

Whats another name for the forearm?

Answer 6

‘Anti-brachium’

Question 7

Clavicle functions?

Answer 7

• To act as a strut to stop muscles attached to the scapula pulling it into the thorax.
• acts as an attachment point for muscles

Question 8

Where is the weak point of the clavicle?

Answer 8

2/3 medially, 1/3 laterally. Here there is no muscles attached, so force of the free limb is transmitted to this area, making in a common place of breaking

Question 9

The two roughened areas of the clavicle are, and what is their purpose?

Answer 9

1) Coracoclavicular area
2) Costoclavicular area
This allows for attachments of two ligaments that stabilise the clavicle

Question 10

What is the purpose of having a mobile scapula?

Answer 10

For the hands. These need to be extremely sensitive and mobile with the environment

Question 11

What are the borders of the scapula?

Answer 11

Medial, lateral and superior

Question 12

What processes of the scapula are?

Answer 12

spinous, acromion and coracoid

Question 13

What are the four fossas of the scapula?

Answer 13

Subscapula, supraspinous, infraspinous and glenoid

Question 14

There is a groove in the middle of the clavicle, what is this called and what is it for?

Answer 14

Subclavian groove, for the subclavian muscle to run through

Question 15

What does the clavicle articulate with?

Answer 15

The acromion process of the scapula, and the manubrium of the sternum

Question 16

What are the four important joints of the pectoral girdle?

Answer 16

1) Sternoclavicular (synovial)
2) Acromioclavicular (synovial)
3) Shoulder joint
4) Scapula-thoracic (conceptual)

Question 17

scapulothoracic joint

Answer 17

scapulothoracic join conceptual joint where scapula moves along the thoracic wall

Question 18

What are the main stabilisers of the Sternoclavicular joint?

Answer 18

Anterior and posterior sternoclavicular ligaments
costoclavicular ligament
interclavicular ligament

Question 19

Is posterior or anterior sternoclavicular ligament stronger?

Answer 19

Posterior is significantly stronger as there is a need to protect the posterior arteries that run behind the clavicle

Question 20

Purpose of interclavicular ligament

Answer 20

Runs along the jugular notch, that supports the superior aspect of the SC joint. This is the only joint between the two sides, and means that the SC joints can’t be seperated

Question 21

O and I of subclavius muscle. Purpose

Answer 21

O= first rib and costicartilage
I= subclavian groove
Acts as a brace to oppose any upwards tension of on the clavicle

Question 22

What supports the inferior part of the clavicle?

Answer 22

The costoclavicular ligament

Question 23

Main stabilisers of the acromioclavicular joint?

Answer 23

acromioclavicular ligament
Coracoclavicular ligament (conoid + trapezoid)

Question 24

What is special about the coracoclavicular ligament of the acromioclavicular joint?

Answer 24

Muscles like trapezoid attach and pull clavicle upwards. The CC ligament apposes this, and allows for the limb to be passively hanging with low energy expenditure

Question 25

What is the purpose of ‘stabilising muscles’?

Answer 25

When stimulated, these muscles do not move but inside contract to stabilise the joint. this is especially important for highly mobile joints

Question 26

Trapezius

O? I? Nerve? Action?

Answer 26

O= skull -T12
I= anatomical horseshoe
Nerve= accessory nerve
Action= retracts, elevates and depresses scapula

Question 27

Levator Scapulae

O? I? Nerve? Action?

Answer 27

O= transverse process of upper cervical 
I= superior angle of scapula
Nerve= dorsal scapula nerve
Action= elevate and internally rotates scapula

Question 28

Rhomboid Min & Maj

O? I? Nerve? Action?

Answer 28

O= spinous process 
I= medial border of scapula
Nerve= dorsal scapula nerve
Action= retracts, elevates and inferiorly rotates scapula
can act as a stabiliser.

Question 29

Latissimus Dorsi

O? I? Nerve? Action?

Answer 29

O= T7 - sacrum
I= anterior humerus
Nerve= Thoracodorsal nerve
Action= adducts, internally rotates humerus

Question 30

Pectoralis Major
O=
I=

Answer 30

O= clavicular and sternocostal
I= anterior humerus
Nerve= lateral and medial pectoral nerve
Action= Adducts and internally rotates humerus

Question 31

Pectoralis minor

O? I? Nerve? Action?

Answer 31

O= ribs (3-5)
I= coracoid
Nerve= medial pectoral nerve
Action= depresses and protracts scapula

Question 32

What is a good landmark of pec minor and pecmajor

Answer 32

The medial pectoral nerve runs through pec minor (innervates it) to pec major. therefore this connecting nerve can be a useful landmark

Question 33

What is saturday night palsy?

Answer 33

When you full asleep with your arm full abducted, the neurovascular bundle is stretched and compressed under the coracoid process. This can cause numbness in the morning.

Question 34

What part of Pectoralis Major is often damaged?

Answer 34

The sternocostal head. with excessive load, (excessive gymming) this can rupture.

Question 35

Serratus anterior

O? I? Nerve? Action?

Answer 35

O= lateral anterior surface of ribs
I=medialborder of scapula
Nerve= Long thoracic nerve
Action= Protracts, depresses (and some lower fibres sup rotate) scapula

Question 36

What is clinically important about the long thoracic nerve (supples serratus anterior)

Answer 36

It runs along top of serratus, with a axillary lymph node. during a maesectomy, you can damage this nerve, leading to a winged scapula.