Trunk Muscles

Question 1

Spinal Extensors

Answer 1

• Trunk muscles
• Series of msucles that course vertically on either side of the spines of the vertebrae
• as a group, responsible for extension of the spine

Question 2

Sternocleidomastoid

Answer 2

O. Sternum and clavicle
I. Mastoid process of the temporal bone
A. Rotation of the head, lateral flexion of head and neck

Question 3

Diaphragm

Answer 3

O. Lumbar vertebrae, inferior ribs, xiphoid process
I. Central Tendon
A. Contraction of the diaphragm increases the vertical dimensions of the thorax, used for inspiration

Question 4

Intercostals

Answer 4

External:
O. Rib above
I. Rib below
A. Pull ribs up; assist in inspiration

Internal:
O. Rib above
I. Rib below
A. Pull ribs down; assist in expiration

Question 5

External Abdominal Oblique

Answer 5

O. Outer surface of the ribs
I. Linea alba and bottom free edge of the aponeurosis (inguinal ligament - runs from anterior superior iliac spine to pubic tubercule)
A. Trunk flexion, trunk lateral rotation; increases intra-abdominal pressure

Question 6

Internal Abdominal Oblique

Answer 6

O. Lumbar fascia, parts of the inguinal ligament, iliac crest
I. Linea alba, inferior ribs
A. Trunk flexion, trunk lateral rotation; increases intra-abdominal pressure

Question 7

Transverse Abdominalis

Answer 7

O. Lumbar fascia, parts of the inguinal ligament, iliac crest
I. Linea alba
A. Increase intra-abdominal pressure

Question 8

Rectus Abdominalis

Answer 8

O. Pubis bone
I. Xiphoid process, lower ribs
A. Trunk flexion, increase intra-abdominal pressure

Question 9

Valsalva Effect

Answer 9

• deep breath = lung inflation
• when epiglottis is closed, air is trapped and lungs press against the vertebral column helping to stabilize it
• abdominal/diaphragm contraction applies external pressure to inflated lungs, increasing compression pressure/stabilizing effect
• at the same time, increased pressure reduces and sometimes restrics venous return to the heard and arterial outflow from the heart, and can cause temporary suspension of cerebral blood flow causing dizziness/fainting
• fainting is a physiological safety mechanism to enhance blood flow to the brain by removing gravitational pull on cerebral flow
• switch from vertical to horizontal position should enhance cerebral blood flow