Muscles of the Abdomen and Pelvis Flashcards
What are the anterolateral abdominal walls?
the space between the rib cage and pelvis, closed by the skin, fascia and four pairs of muscles
What are the muscles of the anterolateral abdominal walls?
rectus abdominis
external oblique
internal oblique
transverse abdominis
The four pairs of muscles of the anterolateral abdominal walls acting bilaterally together does what? What does it aid?
compress the abdomen to aid in: defecation, urination, forced exhalation and childbirth
What is the origin of the rectus abdominis muscle
pubic crest and pubic symphysis
What is the insertion of the rectus abdominis
5-7 costal cartilages and xiphoid process
Where are the tendinous intersections of the rectus abdominis located?
one at level of naval
one near xiphoid process
one between the two above
sometimes at level of umbilicus
What is the rectus sheath
encloses the rectus abdominis, formed by the aponeuroses of the other three muscles
The right and left rectus sheath meet at the anterior midline to form what?
linea alba, from xiphoid process to pubic symthisys
Does the linea alba include the umbilicus ?
yes
What movements does the rectus abdominis produce acting bilaterally?
flexes spine, antagonizes erector spinae
What is the reverse muscle action of the rectus abdominis?
flexes pelvis on the spine
What is the superficial muscle of the abdomen?
external oblique
What direction do the muscle fibres of external oblique run?
inferiorly, anteriorly, medially
What is the origin of the external oblique
ribs 5-12
What is the insertion of the external oblique
iliac crest and linea alba
the aponeurosis of the external oblique forms what layer of the rectus sheath?
anterior layer, right and left muscles fuse @ linea alba
What forms the inguinal ligament?
the aponeurosis of the external oblique, ‘jumping’ between ASIS and pubic tubercle
What movement does the external oblique do acting bilaterally?
flexion of spine
What movement does the external oblique do acting unilaterally?
lateral flexion of spine, rotation of spine
What is the intermediate muscle of the abdomen?
internal oblique
What direction does the muscle fibres of the internal oblique run?
superiorly, anteriorly, medially
the fascicles of the internal oblique extend at what angle to external oblique?
right angle
What is the origin of the internal oblique muscles
iliac crest, inguinal ligament, thoracolumbar fascia
What is the insertion of the internal oblique muscle
costal cartliages of ribs 7-10, linea alba
The aponeurosis of the internal oblique contributes to what layers of the rectus sheath?
anterior and posterior because its splits into two layers
The aponeuroses of right and left internal oblique fuse where?
linea alba
What movements does the internal oblique produce acting bilaterally
flexion of spine
What movements does the internal oblique produce acting unilaterally
lateral flexion of spine, rotation of spine
What is the deep muscle of the abdomen?
transversus abdominis
What direction does the muscle fibres of the transversus abdominis run?
transversly around the abdominal walls
What are the actions of the transversus abdominis
compression of abdominal walls, rotation of spine
What is the origin of the transversus abdominis
iliac crest, inguinal ligament, lumbar fascia, costal cartilages 5-10
What is the insertion of the transversus abdominis
xiphoid process, linea alba, pubis
The aponeurosis of the transversus abdominis for what layer of the rectus sheath
posterior layer
What is the inguinal canal? Where is it located?
oblique passageway in the anterior abdominal wall located superior and parallel to the medial half of the inguinal ligament
What is the length of the inguinal canal
4-5cm
Where does the inguinal canal originate
deep inguinal ring
Where does the inguinal canal end?
superficial inguinal ring
What is the deep inguinal ring?
an opening in the aponeurosis of the transverse abdominis muscle
What is the superficial inguinal ring?
an opening in the aponeurosis of the external oblique muscle
What are the differences between the inguinal canal in men vs women?
in men contains spermatic cord
in women contains round ligament of uterus
What is the posterior abdominal wall composed of?
lumbar vertabrae, hip bone, psoas major, iliacus, quadratus lumborum
What is the origin of the quadratus lumborum
iliac crest and iliolumbar ligmanet
What is the insertion of the quadratus lumbrum
12th rib and TP of L1-L4
What are the bilateral actions of the the quadratus lumborum?
- pulls 12th rib down during forced exhalation
- fixes 12th rib to prevent excessive elevation during forced inhalation
- extensor of spine
what are the unilateral actions of the quadratus lumborum?
lateral flexion of the spine
What is the innervation of the quadratus lumborum?
thoracic spinal nerve T12 and lumbar spinal nerves L1-L3
The muscles of the pelvic floor are also called:
pelvic diaphragm
The pelvic diaphragm stretches from:
pubis to coccyx
What is the largest and most important muscle of the pelvic floor
levator ani
What are the three parts of the levator ani?
puborectalis
iliococcygeus
pubococcgeus
True or false: the levator ani supports the pelvic viscera
true
The levator ani acting in conjunction with the diaphragm to increase intra-abdominal pressure is useful for:
coughing forced exhalation vomiting urination defecation
What muscle functions as the internal sphincter for the anus?
levator ani
What are the two muscles of the pelvic floor?
levator ani
ischiococcygeus
What are the piercings of the pelvic diaphragm?
anal canal, urethra in both sexes
vagina in female
True or false: females pelvic diaphragm is stronger than mens
false: females pelvic diaphragm is weaker than mens due to the piercing of the vagina
What is the perineum
diamond shaped area closing the pelvic cavity
What are the two triangles of the perineum? What divides them?
urogenital triangle
anal triangle
divided by a line between the two ischial tuberosities
Describe the urogenital triangle
anterior portion of the perineum, sphincter for urethra, plays a roll in process of erection and ejaculation, contributes to intercourse
Describe the anal triangle
posterior portion of the perineum, includes the external anal sphincter for voluntary control of defecation