Thoracic Wall And Abdominal Region Quiz!

Explanation
The pectoralis major muscle is indeed a powerful adductor and medial rotator of the arm. This means that it is responsible for bringing the arm closer to the body and rotating it inward. This muscle is located in the chest region and plays an important role in various arm movements, such as hugging, pushing, and throwing. Therefore, the statement "Pectoralis major muscle is the powerful adductor & medial rotator of the arm" is true.

Explanation
The trapezius muscle is a large muscle that extends from the back of the neck to the upper back and shoulders. It attaches the pectoral girdle, which includes the collarbone and shoulder blade, to the cranium (skull) and vertebral column (spine). This attachment allows the trapezius muscle to play a key role in stabilizing and moving the shoulder blades and upper back. Therefore, the statement that the trapezius muscle attaches the pectoral girdle to the cranium and vertebral column is true.

Explanation
The statement is false because the rhomboid major muscle is not part of the intermediate group of muscles of the extrinsic back muscles. Instead, it is classified as one of the deep muscles of the back. The intermediate group includes muscles such as the serratus posterior superior and inferior, while the deep muscles include muscles such as the rhomboid major and minor.

Explanation
The statement is false because the intercostal veins actually lie most superior in the costal grooves, not most inferior. They accompany the intercostal arteries and nerves, but their position is different from what is stated in the question.

Explanation
The statement is false because the inferior thoracic aperture is actually bounded posterolaterally by the 11th and 12th ribs. The costal margins, which are formed by the joined costal cartilages of ribs 7-10, do not contribute to the boundary of the inferior thoracic aperture.

Explanation
The anterolateral abdominal wall muscles, such as the external oblique, internal oblique, and transversus abdominis, are involved in expiration rather than inspiration. These muscles contract during expiration to increase intra-abdominal pressure, which helps to push air out of the lungs. Therefore, the statement that anterolateral abdominal wall muscles help in inspiration is incorrect.

Explanation
In lactating women, the dominant component of the female breast is glandular tissue. This is because glandular tissue is responsible for producing and secreting milk. During lactation, the breasts undergo changes to support milk production, and the glandular tissue increases in size and activity. This allows for the production and release of milk to nourish the baby. Therefore, it is true that in lactating women, the dominant component of the female breast is glandular tissue.

Explanation
The erector spinae muscles are a group of muscles located on either side of the vertebral column. They play a major role in extending and straightening the back, which is an important function of the vertebral column. Therefore, it is correct to say that the erector spinae muscles are the chief extensors of the vertebral column.