Chest Muscles

The thorax is located in the upper region of the trunk, it is defined anteriorly by the sternum, laterally by the ribs and posteriorly by the vertebral column.

The chest muscles are structured in 2 regions:

  • Anterolateral Region
  • coastal region
Anterolateral Region coastal region
Pectoral Major
Pectoral Minor
serratus anterior
subclavian
External Intercostals
Internal Intercostals
Rib Lifters
subcostal
transverse thorax

Anterolateral Region

1. MAJOR CHEST

Músculo Peitoral Maior Medial Insertion : Medial 1/2 of the anterior border of the clavicle, anterior surface of the sternum, external surface of the 1st to 6th costal cartilages and aponeurosis of the external oblique of the abdomen

Lateral Insertion : Crest of the greater tubercle

Innervation : Lateral Pectoral Nerve and Medial Pectoral Nerve (C5 – T1)

Action : Adduction, Medial Rotation, Flexion and Horizontal Flexion of the Shoulder

 

2. MINOR CHEST

I Músculo Peitoral Menor Superior insertion: Coracoid process

Inferior Insertion : External surface of 3rd, 4th and 5th ribs

Innervation : Medial Pectoral Nerve (C8 - T1)

Action :

* Fixed in the Chest : Shoulder Depression and Inferior Rotation of the Scapula

* Fixed on the Scapula : Raises the ribs (inspiratory action)

 

3. SERRATIL ANTERIOR

Upper Portion :
Posterior Insertion : Superior angle of scapula, Músculo Serrátil Anterior
Anterior Insertion : External surface of 1st and 2nd ribs
Average Portion :
Posterior Insertion : Medial border of scapula
Anterior Insertion : External surface of 2nd to 4th ribs

Bottom Portion :
Posterior Insertion : Inferior angle of scapula

Anterior Insertion : External surface of 5th to 9th ribs

Innervation : Long Thoracic Nerve (C5 - C7)

Action :
* Fixed on Scapula : Inspiratory Action
* Fixed in the Ribs : Superior Rotation, Abduction and Depression of the Scapula and Propulsion of the Shoulder
Músculo Subclávio

4. SUBCLAVIO

Lateral Insertion : Lower surface of clavicle

Medial Insertion : 1st rib and costal cartilage

Innervation : Subclavian nerve (C5 – C6)

Action : Depression of the Clavicle and Shoulder

 

coastal region

1. INTERNAL INTERCOSTAL

Superior Insertion : Lower edge of the overlying (upper) rib

Lower Insertion : Upper edge of the infrajacent (lower) rib

Innervation : Corresponding intercostal nerves

Action : Depression of the Ribs (Expiratory Action)

 

2. EXTERNAL INTERCOSTAL

Superior Insertion : Lower edge of the overlying (upper) rib

Lower Insertion : Upper edge of the infrajacent (lower) rib

Innervation : Corresponding intercostal nerves

Action : Raise the Ribs (Inspiratory Action)

The internal and external intercostal muscles cross each other in an “X”. The fibers of the external intercostals run from superior to inferior and from posterior to anterior. The fibers of the internal intercostals run from superior to inferior and from anterior to posterior.

Músculos Intercostais Músculos Intercostais

Músculos Levantadores das Costelas 3. RIB LIFTS

Superior Insertion : Transverse process from 7th cervical to 11th thoracic vertebrae

Inferior Insertion : External surface of 1st to 12th rib

Innervation : Corresponding intercostal nerves

Action : Rib Elevation (Inspiratory Action) and Intercostal Stabilization

 

 

 

 




Músculos Subcostais

4. SUBCOSTAL

Superior Insertion : Inner surface of overlying rib

Inferior Insertion : Inner surface of the 2nd or 3rd rib below

Innervation : Corresponding intercostal nerves

Action : Intercostal Stabilization


 



 

5 Músculo Traverso do Tórax . THORAX TRANSVERSE (STERNUM TRIANGULAR)

Superior Insertion: Inner face of sternum

Inferior Insertion : Inner surface of 2nd to 6th costal cartilages

Innervation : Corresponding intercostal nerves

Action : Stabilization of the anteroinferior part of the thorax

 

 

 

CHEST MUSCLES
Anterior View - Superficial Dissection
 Músculo do Tórax - Vista Superficial
Source: NETTER, Frank H.. Atlas of Human Anatomy. 2nd edition Porto Alegre: Artmed, 2000.
CHEST MUSCLES
Anterior View - Deep Dissection
Músculo do Tórax - Vista Profunda
Source: NETTER, Frank H.. Atlas of Human Anatomy. 2nd edition Porto Alegre: Artmed, 2000.
CHEST MUSCLES
Internal View
Músculo do Tórax - Vista Interna
Source: NETTER, Frank H.. Atlas of Human Anatomy. 2nd edition Porto Alegre: Artmed, 2000.

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