HHSC 105 Chapter 11 Axial Muscles: (Relevant) What did you learn & Content Review

The unilateral contraction of which muscle causes lateral flexion of the neck and rotation of the head to the opposite side?

The sternocleidomastoid causes lateral flexion of the neck and rotation of the head to the opposite side.

What structures form the rectus sheaths and how do the left and right rectus sheaths relate to the linea alba

Each rectus sheath is formed from the aponeuroses of the external oblique, internal oblique, and transversus abdominis muscles. The linea alba serves as a connecting region between the left and right rectus sheaths.

Describe the erector spinae, and briefly discuss their function

The erector spinae is the largest muscle mass in the back. The muscles of the erector spinae consist of three groups of muscles: iliocostalis (located laterally), longissimus (located intermedially) and spinalis (located medially). The muscles of the erector spinae are used to maintain posture and help us stand erect.

What is the effect of contracting the abdominal oblique muscles?

The external and internal oblique muscles laterally flex the vertebral column (bend the body laterally) and rotate the vertebral column to the opposite side, if they contract unilaterally. If these muscles bilaterally contract, they compress the abdominal wall and flex the vertebral column

Compare the functions of the external intercostals and the internal intercostals.

The external intercostal muscles elevate the ribs during inhalation. The internal intercostals depress the ribs, but only during a forced exhalation; an normal exhalation takes no active muscular effort.

Describe the functions of the thoracic diaphragm

The muscle fibers of the diaphragm converge toward a central tendon, a strong aponeurosis that functions as the insertion tendon for all peripheral muscle fibers of the diaphragm. When the diaphragm contracts, the central tendon is pulled inferiorly toward the abdominal cavity, which increases the vertical dimensions of the thoracic cavity.

Identify the muscle of respiration that partitions the thoracic and abdominopelvic cavities. What is the name of the structure to which all fibers of this muscle converge?

The muscle of respiration that separates the thoracic and abdominal cavities is the diaphragm. The structure to which all diaphragm muscle fibers converge is called the central tendon.

Identify the muscles of the abdominal wall

The muscles of the abdominal wall include: the external oblique, internal oblique, transversus abdominis, and rectus abdominis.