Podcast
Questions and Answers
Which muscle stabilizes the clavicle by pulling it downwards?
Which muscle stabilizes the clavicle by pulling it downwards?
What is the primary action of the serratus anterior muscle?
What is the primary action of the serratus anterior muscle?
Which muscle, when stiff, can contribute to a rounded or forward shoulder posture?
Which muscle, when stiff, can contribute to a rounded or forward shoulder posture?
The sternocostal portion of the pectoralis major originates from which structure?
The sternocostal portion of the pectoralis major originates from which structure?
Signup and view all the answers
Which of the following muscles aids in expiration by pulling the thorax downwards?
Which of the following muscles aids in expiration by pulling the thorax downwards?
Signup and view all the answers
Which muscle originates from the internal surface of the sternum and inserts on the cartilage of ribs 2-6?
Which muscle originates from the internal surface of the sternum and inserts on the cartilage of ribs 2-6?
Signup and view all the answers
Which muscle group elevates the thorax, aiding in inspiration?
Which muscle group elevates the thorax, aiding in inspiration?
Signup and view all the answers
Where do the Levatores Costarum Longi muscles originate?
Where do the Levatores Costarum Longi muscles originate?
Signup and view all the answers
Flashcards are hidden until you start studying
Study Notes
Superficial Muscles of the Thorax
- Subclavius: Located beneath the clavicle, originates from the 1st rib and inserts on the lower surface of the clavicle. It stabilizes the clavicle by pulling it downwards.
- Serratus Anterior: Large muscle fibers located on the lateral aspect of ribs 1-9. Originates from the external surface of ribs 1-9 and inserts at the medial border of the scapula. Contraction pulls the medial margin of the scapula forward, helping to flex the arm.
- Pectoralis Minor: Located anterior to the serratus anterior, originates from the external surface of ribs 3-5. Inserts at the coracoid process of the scapula. Contraction pulls the shoulder down and medially. Stiffness in this muscle can cause forward shoulder posture.
- Pectoralis Major: Divided into three parts: Clavicular, Sternocostal, and Abdominal. All parts originate from different areas (clavicle, sternum/costal cartilage, abdominal muscles respectively) and insert at the crest of the greater tubercle of the humerus.
Deep Muscles of the Thorax
- Subcostal Muscles: Located on the inside of the thorax. Originate from the lower rib and insert on the upper rib. Contraction pulls the thorax downwards, aiding in expiration.
- Transverse Thoracis Muscle: Originates from the internal surface of the sternum, xiphoid process, and cartilage of ribs 4-7. Inserts at the cartilage of ribs 2-6. Also aids in pulling the chest downwards for expiration.
- Internal Intercostal Muscles: Located between the ribs. Originate from the lower rib and insert into the upper rib. Contraction pulls the chest down for expiration.
- External Intercostal Muscles: Located superficially to the internal intercostal muscles. Originate from the upper rib and insert at the lower rib. Contraction elevates the thorax, aiding in inspiration by expanding the thoracic cavity.
- Levatores Costarum Muscles: Tiny muscles on the back. Divided into two groups:
- Levatores Costarum Breves: Short levatores costarum, originate from the transverse process of C7 to T11, and insert one rib below.
- Levatores Costarum Longi: Longer muscles, originate from T8-T11, and insert two ribs below, skipping one rib. Contraction of both groups pulls the thorax up to aid inspiration.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge on the superficial muscles of the thorax, including the Subclavius, Serratus Anterior, Pectoralis Minor, and Pectoralis Major. Learn about their origins, insertions, and functions to deepen your understanding of thoracic anatomy.
