| Muscles in the Pectoral
Region |
|
| Pectoralis Major (1) |
|
Origin |
- Medial half of the clavicle
- Anterior surface of the sternum
- First six costal cartilages
|
| |
| Insertion |
- External oblique.
- Lip of bicipital (intertubacular) groove of humerus
|
| |
| Actions |
- Adduction of the extended limb
- Medial rotator of the arm
- Flexion of the upper limb (Clavicular portion)
- Depression of the arm and shoulder (sternocostal
head)
- Elavation of the ribs (used in artificial respiration)
|
Innervation
- Medial pectoral nerve
- Lateral pectoral nerve
|
Identify muscles 2 and 3
|
| |
|
| Pectoralis minor (2) |
|
|
Origin
- 3 rd -5 th ribs
- fascia covering the intercostal muscles
Insertion
- Coracoid process of the scapula
- Rarely the tendon of insertion passes upwards to blend with the coracohumeral
ligament
Innervation
- Medial pectoral nerve(from the medial cord of the brachial plexus)
Actions
- Depresses the point of the shoulder
- With the serratus anterior, it draws the scapula forwards round the
thoracic wall
|
| |
|
| Serratus anterior
(3) |
 |
Origin |
| Upper 8 sibs anterolaterally |
| |
| Insertion |
- First slip: inferior angle of scapula
- Next three: medial border of the scapula
- Last four: inferior angle of scapula
|
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| Innervation |
- Long thoracic nerve (C5,C6 C7)
|
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| Actions |
- Protraction of the scapula
- Lateral rotation of the scapula
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|
| Subclavius |
 |
Origin
- Junction of the first rib and its costal cartilage
|
| |
Insertion
- Inferior aspect of clavicle (Area
marked [C])
|
| |
Innervation
- Upper trunk of brachial plexus (C5, C6)
|
| |
| Actions
- Depresses lateral part of clavicle
Note:
The subclavius acts as a buffer between a fractured clavicle and
subclavian artery |
| |
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