Chest and Abdominal Wall

Question 1

External Intercostals

Answer 1

O: Run between contiguous ribs from tubercles to costochondral junctions
N: Thoracic VPR
A: 1. Elevate ribs for inspiration
2. Maintain rigidity of chest wall with pressure and volume changes

Question 2

Internal Intercostals

Answer 2

O: Run between contiguous ribs from sternum to angles
N: Thoracic VPR
A: Maintain rigidity of chest wall with pressure and volume changes

Question 3

External Abdominal Oblique

Answer 3

O: Lower 8 ribs, interdigitating with serratus anterior and latissimus doors
I: 1. From lower 2 ribs to anterior 1/2 of outer lip of iliac crest
2. Remaining fibers end in aponeurosis of external abdominal oblique
N: 1. Thoracoabdominal nerves (T7-T11 VPR)
2. Subcostal nerve
A: 1. Support and compress abdominal viscera
2. Assist in forceful expiration
3. BILATERALLY: Flex vertebral column
4. LATERAL FIBERS:
a. Bilaterally: Posteriorly rotate pelvis
b. Unilaterally: Laterally flex vertebral column
5. ANTERIOR FIBERS:
a. Unilaterally: Flex and contralaterally rotate vertebral column
** Activity of oblique abdominals with their crisscrossing struts enhance stability in the lumbar spine **

Question 4

Internal Abdominal Oblique

Answer 4

O: 1. Lateral 2/3 of inguinal ligament
2. Anterior 2/3 of iliac crest (intermediate lip)
3. Lateral Raphe of TLF
I: 1. Posterior fibers to lower 3 or 4 ribs
2. Lower fibers from inguinal ligament to pubic crest
3. Remaining fibers end in aponeurosis of internal oblique
N: 1. Thoracoabdominal Nerves (T6-T12 VPR)
2. L1 VPR
A: 1. Support and compress abdominal viscera
2. Assist in forceful expiration
3. BILATERALLY: Upper fibers flex vertebral column
4. UNILATERALLY: Upper fibers laterally flex and rotate vertebral column to SAME SIDE
** Activity of oblique abdominals with their crisscrossing struts enhance stability in the lumbar spine **
** May act in FEEDFORWARD manner with transverses abdomens to help stabilize lumbar spine **

Question 5

Transversus Abdominis

Answer 5

O: 1. Lateral 2/3 inguinal ligament
2. Anterior 2/3 of iliac crest (inner lip)
3. Middle layer of TLF
4. Internal aspects of lower 6 costal cartilages, interdigitating with the diaphragm
I: 1. Almost all fibers end in aponeurosis
2. Lower fibers of which attach to pubic crest
3. Remaining fibers end in linea alba
4. Upper fibers may extend across midline to be continued with fibers of contralateral transversus
N: 1. Thoracoabdominal Nerve (T7-T12 VPR)
2. L1 VPR
A: 1. Support and compress abdominal viscera
2. Assist in forced inspiration, acting to DECREASE infrasternal angle
** May act in FEEDFORWARD manner with internal abdominal oblique to help stabilize lumbar spine **

Question 6

Rectus Abdominus

Answer 6

O: 1. Pubic crest
2. Pubic symphysis
I: 1. Costal cartilages of ribs 5-7
2. Xiphoid
N: Thoracoabdominal Nerve (Anterior Rami of T6-T12 spinal nerves)
A; 1. Flexes vertebral column
2. FIXED THORAX: Posteriorly rotate pelvis