Muscles of the thoracic wall
After going through this study unit you will be able to:
- Identify and name the intrinsic and extrinsic muscles of the thoracic wall.
- Describe their attachment points and innervation patterns.
- Understand the anatomic relations between the muscles.
The muscles of the thoracic wall are defined as muscles attached to the bony framework of the thoracic cage. They maintain the stability of the thoracic wall, and play a role in respiration. The muscles of the thoracic wall are divided into two groups: intrinsic and extrinsic.
The intrinsic muscles of the thoracic wall originate and insert onto the thoracic cage and contribute to its structure. This group of muscles generally work together to facilitate breathing movements through the elevation and depression of the rib cage and are therefore also known as the muscles of respiration. Intrinsic muscles of the thoracic wall include the: serratus posterior, levatores costarum, intercostal, subcostal and transversus thoracis muscles, as well as the variably present sternalis muscle.
The extrinsic muscles of the thoracic wall usually have one attachment to the thoracic cage and are functionally related to the neck, abdomen, back and/or upper limbs. Although these muscles can be classified as thoracic muscles and are involved in movement of the rib cage for respiration, their primary functions relate to movement of the pectoral girdle and/or the arm and are therefore also known as the anterior axioappendicular muscles. As a secondary function these muscles contribute to movements during breathing and include the subclavius, pectoralis major and minor muscles as well as the inferior portion of the serratus anterior muscle.
The following video will introduce you to the anterior trunk muscles in general, with an emphasis on a few specific muscle groups of the thoracic wall.
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Revise the anatomy and relations of the extrinsic and intrinsic muscles of the thoracic wall with our galleries below.
|Intrinsic muscles||Serratus posterior muscles (superior, inferior)
Levatores costarum muscles
Intercostal muscles (external, internal, innermost)
Transversus thoracis muscles
Intrinsic muscles: Intercostal nerves
Extrinsic muscles: Subclavian nerve medial and lateral pectoral nerves, long thoracic nerve, anterior rami of cervical spinal nerves C3-C8
Intrinisc muscles: Accessory respiratory muscles, support and stabilize thoracic cage
Primary role: Pectoralis major (Flex, adduct and internally rotate arm) subclavius (stabilize and depress clavicle) pectoralis minor and serratus anterior (rotate and stabilize scapula)
Secondary role: Accessory respiratory muscles