The Anterior Abdominal Wall Flashcards
The anterior abdominal wall can be divided into…
… anterolateral and posterior sections
Functions of the AAW
- Support, protection, anti-gravity maintenance
- Assists in forceful expiration by pushing the abdominal viscera upwards.
- Is involved in any action (coughing, vomiting, defecation) that increases intra-abdominal pressure.
The anterolateral abdominal wall consists of four main layers (external to internal)…
Skin Superficial fascia Muscles Associated fascia Parietal peritoneum
Superior borders of the AAW
Costal cartilages 7-12
Xiphoid process
Level of 10th cartilage, L3
Inferior borders of the AAW
Pubic bones and iliac crests at L4
Umbilicus
The abdominal quadrants are formed by…
… two intersecting lines at the umbilicus, running from the xiphoid process to the pubic symphysis and across the umbilicus
What are the planes of the abdominal regions?
- 2 Mid-clavicular planes (vertical)
- Transpyloric plane (horizontal)
- Intertubercular plane (horizontal)
The transpyloric plane is found…
…halfway between the jugular notch and pubic symphysis, above the umbilicus.
The intertubercular plane is formed by…
The tubercles of the iliac crests
The filled urinary bladdder lies in…
The hypogastric region
The cutaneous nerves of the AAW are derived from…
…the ventral rami of T7 through L1.
Direction of the cutaneous nerves of the AAW
They pass inferiomedially in plane between the transverse and internal oblique muscles
Layers of the abdominal wall from superficial to deep:
- Skin
- Superficial fascia
- Deep superficial fascia
- Muscles
- Transversalis fascia
- Extraperitoneal fat (extraperitoneal fascia)
- Peritoneum
How many muscles make up the AAW?
5 - TIRE P(ump)
Superficial fascia above the umbilicus
It is a single sheet of connective tissue, continuous with the superficial fascia in other regions of the body.
Superficial fascia below the umbilicus
It is divided into two layers; the fatty superficial layer (Camper’s fascia) and the membranous deep layer (Scarpa’s fascia).
The muscles of the anterolateral abdominal wall can be divided into
two main groups: flat and vertical
In the anteromedial aspect of the abdominal wall, each flat muscle forms an…
…aponeurosis (a broad, flat tendon), which covers the vertical rectus abdominis muscle.
The linea alba is formed by…
…the aponeuroses of all the flat muscles becoming entwined in the midline to form a fibrous structure
Properties of external oblique
- The largest and most superficial flat
- ## Its fibres run inferomedially (pocket)
Origin and insertion of external oblique
Originates from ribs 5-12, and inserts into the iliac crest and pubic tubercle.
Innervation of the abdominal muscles
Thoracoabdominal nerves (T7-T11) and subcostal nerve (T12), except pyramidalis that’s just subcostal
Properties of Internal Oblique
- lies deep to the external oblique
- smaller and thinner in structure
- fibres running superomedially (inverted pocket).
Origin and insertion of internal oblique
Originates from the inguinal ligament, iliac crest and lumbodorsal fascia, and inserts into ribs 10-12.
Transversus abdominis properties
- Deepest of the flat muscles
- Transversely running fibres.
Deep to the transversus abdominis muscle is…
… a well-formed layer of fascia, known as the transversalis fascia.
Origin and insertion of transversus abdominis muscle
Originates from the inguinal ligament, costal cartilages 7-12, the iliac crest and thoracolumbar fascia. Inserts into the conjoint tendon, xiphoid process, linea alba and the pubic crest.
Origin and insertion of rectus abdominis
Originates from the crest of the pubis, before inserting into the xiphoid process of the sternum and the costal cartilage of ribs 5-7
Location of pyramidalis
Superficial and inferior to the rectus abdominis.
Apex and base of pyramidalis
Base - on the pubis bone
Apex - attached to the linea alba.
The anterior wall of the rectus sheath is formed by…
…the aponeuroses of the external oblique, and of half of the internal oblique.
The posterior wall of the rectus sheath is formed by…
…the aponeuroses of half the internal oblique and of the transversus abdominis.
At what point of the AAW is there no rectus sheath?
Approximately midway between the umbilicus and the pubic symphysis, where all the aponeuroses move to the anterior wall of the rectus sheath.
At this point, there is no posterior wall to the sheath; the rectus abdominis is in direct contact with the transversalis fascia.
The demarcation point where the posterior layer of the rectus sheath ends is called…
…the arcuate line.
Arterial supply above the umbilicus
Superior and inferior epigastric Musculophrenic Subcostal Lumbar 1-4 Posterior intercostal
Arterial supply below the umbilicus
Superficial epigastric
Superficial circumflex iliac
Superficial external pudendal
Below the umbilicus, the superficial veins of the AAW drain into…
…the femoral venous system via the great saphenous
Above the umbilicus, the superficial veins of the AAW drain into…
…the azygous venous system