Session 1 - the anterior abdominal wall and hernias Flashcards
How is the abdominal cavity bound posteriorly?
bounded by the lumbar vertebrae and the muscles lying lateral to them (- psoas (and iliacus) and quadratus lumborum)
Which muscles are the most important expiratory muscles in deep, rapid or forced respiration?
the sheet muscles
What are the serratus anterior and the lattisimus dorsi?
Other posterior muscles (although they are more important in thorax anatomy)
Serratus anterior –on the lateral wall of the thorax, with anterior origin and insertion along the medial border of the scapula; acts to pull the scapula forward and around the thorax
Lattisimus dorsi – large triangular muscle of the back, with origin in the thoracolumbar fascia, and insertion into the armpit
What is the anterolateral abdominal wall composed of?
skin, fascia and four pairs of muscles; the external oblique, internal oblique, transversus abdominus and rectus abdominus
Where is the pubic symphysis?
(a secondary cartilaginous joint located) between the left and right pubic bones near the midline of the body. It is located above any external genitalia and in front of the bladder
Where is the pubic tubercle?
just next to the pubic symphysis
a prominent forward-projecting tubercle on the upper border of the medial portion of the superior ramus of the pubis
What does ASIS stand for and where is it?
anterior superior iliac spine
found at the the anterior extremity of the iliac crest of the pelvis
NOTE: it provides attachment for the inguinal ligament, and the sartorius muscle
What is the iliac crest?
the ilium is the largest bone of the pelvis
The crest of the ilium is the superior border of the wing of ilium and the superolateral margin of the greater pelvis.
What s the iliac fossa?
a large, smooth, concave surface on the internal surface of the ilium
What separates the abdominal and the pelvic cavities?
they are continuous, but the pelvic inlet (brim) separates the two
What separates the thoracic and abdominal cavities?
the diaphragm
What are the 4 lines that have to be drawn to split the abdomen into 9 regions?
What vertebral levels are the 2 horizontal lines/planes at?
- 2 mid-clavicular lines (right and left)
- subcostal plane (at L2)
- inter tubercular plane (at L5)
What are the 9 regions of the abdomen?
from right to left
- right hypochondrium/hypochondriac region
- epigastric region
- left hypochondrium/hypochondriac region
- right flank/lumbar region
- umbilical region
- left flank/lumbar region
- right groin/iliac region
- hypogastric/supra pubic region
- left groin/iliac region
What 2 lines are drawn to split the abdomen into 4 quadrants?
saggital plane
trans-umbilical plane
What are the muscles of the anterior abdominal wall?
paired vertical rectus abdominis muscles with rectus sheath
What are the muscles of the lateral abdominal wall?
3 flat sheet muscles:
- external oblique
- internal oblique
- transversus abdominis
What are the muscles of the posterior abdominal wall?
- post vertebral muscles - erector spine group
- psoas (attached to the lower limb)
- quadratus lumborum
- iliacus muscles
How do the 3 flank sheet muscles join at the front anteriorly?
NOTE: they are separate in the flanks
they continue anteriorly as aponeurotic sheaths and contribute to the rectus sheath
What is the function of the 3 flank sheet muscles?
- compress the abdomen and increase intra-abdominal pressure to aid expiration, and evacuation of urine, faeces, parturition (childbirth), heavy lifting
- supports viscera - guards the intestines
- flex and rotate the trunk
What is the external oblique attached to?
- external surface of lower 8th ribs
- it has a free posterior border
- it fans out to attach to xiphoid process, linea alba, pubic crest and the anterior half of the iliac crest
What is the direction of the muscle fibres of the external oblique muscles?
infero-medially
anterior and inferior (downwards and forwards)
What is the inguinal ligament?
a band running from the pubic tubercle to the anterior superior iliac spine
What happens to the external oblique muscles towards the midline?
- the aponeurosis fuses medially with the the rectus sheath
- the lower aponeurotic edge is rolled inwards and forms the inguinal ligament (ASIS to pubic tubercle)
Laterally, what does the internal oblique attach to?
- thoracolumbar fascia
- iliac crest
- inguinal ligament (lateral half)
Medially, what does the internal oblique attach to?
- lower 3 ribs and costal cartilages
- xiphoid process
- rectus sheath
- conjoint tendon
What is the direction of the muscle fibres of the internal oblique muscles?
supero-medially
posterior and inferior (downwards and backwards)
Laterally, what does the tranversus abdominis attach to?
- lower 6 costal cartilages
- thoracolumbar fascia
- iliac crest
- inguinal ligament
Medially, what does the tranversus abdominis attach to?
- xiphoid process
- linea alba (rectus sheath)
- symphysis pubis
- conjoint tendon
What is the direction of the muscle fibres of the tranversus abdominis?
horizontal (like a belt)
Where does the neurovascular plane lie?
between the internal oblique and transversus abdominis muscle layers