Anatomy Test 7 (Actions)

How do muscle contractions work (What attachments are moving)?

Insertions move towards origins

What is the action of the rectus abdominis?

It flexes the vertebral column (especially the lumbar portion), and compresses the abdomen to aid in defecation, urination, forced inhalation, and childbirth. It also flexes the pelvis on the vertebral column

What is the action of the external abdominal oblique?

Acting together (bilaterally), they compress the abdomen and flex the vertebral column

Acting singly (unilaterally), it laterally flexes the vertebral column, especially the lumbar portion, and it rotates the vertebral column

What is the action of the internal abdominal oblique?

Acting together (bilaterally), they compress the abdomen and flex the vertebral column

Acting singly (unilaterally), it laterally flexes the vertebral column, especially the lumbar portion, and it rotates the vertebral column

What is the action of the transverse abdominis?

It compresses the abdomen

What is the action of the quadratus lumborum?

Acting together (bilaterally), they pull the 12th ribs inferiorly during forced exhalation, they fix the 12th ribs to prevent their elevation during deep inhalation, and they help extend the lumbar portion of the vertebral column

Acting singly (unilaterally), it laterally flexes the vertebral column, especially the lumbar portion. And it elevates the hip bone on one side

What is the action of the iliocostalis muscle group?

Acting together, the muscles of each region (cervical, thoracic, and lumbar) extend and maintain the erect posture of the vertebral column of their respective regions 

Acting singly, they laterally flex the vertebral column of their respective regions to the same side as the contracting muscle

What is the action of the longissimus capitis?

Acting together, both the longissimus capitis muscles extend the head

Acting singly, it rotates the head to the same side as the contracting muscle and extend the vertebral column

What is the action of the longissimus colli and longissimus thoracis?

Acting together, the longissimus colli and both longissimus thoracis muscles extend the vertebral column of their respective regions

Acting singly, they laterally flex the vertebral column of their respective regions

What is the action of the spinalis capitis?

It extends the head

What is the action of the spinalis colli and the spinalis thoracis?

Acting together, muscles of each region (cervical and thoracic) extend the vertebral column of their respective regions

What is the action of the multifidus?

Acting together, they extend the vertebral column

Acting singly, they weakly laterally flex the vertebral column and weakly rotate the vertebral column to the opposite side of the contracting muscles. They also play a role in stability and proprioception

What is the action of the rotatores?

Acting together, they weakly extend the vertebral column

Acting singly, they weakly rotate the vertebral column to the side of the opposite contracting muscle. They also play a role in stability and proprioception

What is the action of the scalenus anterior?

Acting together, the right and left scalenus anterior and scalenus medius muscles elevate the ribs during deep inhalation

What is the action of the scalenus medius?

Acting together, they flex the cervical vertebrae

Acting singly, they laterally flex and slightly rotate the cervical vertebrae

What is the action of the scalenus posterior?

Acting together, the right and left scalenus posterior elevate the second ribs during deep inhalation, and they flex the cervical vertebrae

Acting singly, they laterally flex and slightly rotate the cervical vertebrae

What is the reverse muscle action of the rectus abdominis?

Laying down and pulling knees toward the stomach

What happens when the right internal abdominal oblique contracts singly?

It causes lateral bending of the trunk to the right and twisting of the vertebral column to the right

What happens when the right external abdominal oblique is contracted singly?

It causes rotation to the left because origins are moving to insertion and it causes lateral bending to the right

What is the common action for all the muscles of the anteroabdominal wall?

Flexion of the vertebral column

What happens if the left internal abdominal oblique and the right external abdominal oblique were to contract at the same time?

It would cause twisting of the trunk to the left