KIN 100 - Muscles of the Abdominal Wall (lecture 15) Flashcards
What is the abdominal wall subdivided into
- the anterior wall
- right and left lateral walls
- posterior wall
Describe the anterolateral wall and what is it’s function
The boundary between anterior and lateral wall
- Muscles work together to compress and support the abdominal organs
How many pairs of muscles are located in the anterolateral abdominal wall
4; 3 pairs of flat muscles and 1 pair of vertical muscles
What are the three pairs of flat muscles of the anterolateral abdominal wall (from superficial to deep)
- External oblique
- Internal oblique
- Transversus abdominus
What is the pair of vertical muscles in the anterolateral abdominal wall
Rectus abdominus
Describe the fibre direction of the external oblique
“anteroinferior” and “hands in pocket”
What structure forms the inguinal ligament
The inferior edge of the aponeurosis of external oblique
Describe the fibre direction of the transversus abdominus
horizontal
Describe the fibre direction of the internal oblique
“anterosuperior”
Where do all muscles of the anterolateral abdominal wall meet in the midline
linea alba
What are the functions of all the muscles of the anterolateral abdominal wall
- compress and support the abdominal viscera
- Flex and rotate the trunk
Describe the rectus abdominus
a bilateral muscle that runs vertically between the ribs and the pubic symphysis
- 6 pack
- left and right muscles separated by linea alba
Describe how the aponeuroses is formed
aponeuroses of the external oblique crosses the midline and blend with the fibres of the contralateral internal oblique aponeuroses
The aponeuroses form a sheath around the rectus abdominus muscle
Describe the diaphragm
A domed muscle that separates the thorax from the abdomen
Diaphragm attachment
attached to the periphery to the margins of the thoracic cage and the superior lumbar vertabrae
What do the muscle fibers of the diaphragm converge to form
the central tendon (supports the weight of the heart)
What are the three openings in the diaphragm
- Caval opening for the inferior vena cava at the level of T8
- Esophageal hiatus for the esophagus at the level of T10
- Aortic hiatus for the aorta at the level of T12
How many ligaments can be seen from the inferior view of the diaphragm
5 :
midline median arcuate ligament
bilateral medial arcuate ligaments
bilateral lateral arcuate ligaments
Midline median arcuate ligament
arches over the abdominal aorta and forms the aoritc hiatus
Bilateral medial arcuate
arch over the psoas major muscles
Bilateral lateral arcuate ligaments
arch over the quadratus lumborum muscles
What are the 3 pairs of muscles located in the posterior abdominal wall
- Psoas major
- Iliacus
- Quadratus lumborum
Psoas major
Proximal attachment: Lateral aspect of lumbar vertebrae
Distal attachment: Lesser trochanter of femur
Actions:
- Thigh flexion
- Trunk flexion (when contracting bilaterally)
- Trunk lateral flexion (when contracting unilaterally)
Iliacus
Proximal attachment: iliac fossa
Distal attachment: Lesser trochanter of femur
Action: Thigh flexion
Quadratus lumborum
Proximal attachment: 12th rib and transverse process of lumbar vertebrae
Distal attachment: Iliac crest
Actions:
- Trunk extension (when contracting bilaterally)
- Trunk lateral flexion (when contracting unilaterally)
Describe how the lumbar plexus is formed
Lumbar spinal nerves (L1-L5) exit the intervertebral foramina and their interior rami of plexus of nerves within the psoas major muscle
What are the terminal branches of the lumbar plexus
- Femoral nerve
- Obturator nerve
- Lumbosacral trunk
