Abdominal wall, the inguinal canal and hernias Flashcards
What are the two upper horizontal planes for dividing the abdomen?
Transpyloric plane (midway between the jugular notch of the sternum and the pubic symphysis, approximately crossing the L1 vertebra)
Subcostal plane (inferior to 10th costal cartilage, approx L3) are used.
What is the lower horizontal plane for dividing the abdomen?
Transtubercular plane (passing through the tubercles of the iliac crests and the L5 vertebrae)
What defines the left and right vertical planes for dividing the abdomen?
Midclavicular lines (mid-clavicle to midway between ASIS and pubic tubercle)
What are the nine regions of the abdomen?
Hypochondrium: left and right top corners
Epigastric: top centre
Lumbar: left and right middle
Umbilical: middle centre.
Iliac/inguinal: left and right bottom
Pubic/hypogastric: middle bottom
What is the orientation and attachments of the external oblique?
Oriented forwards and downwards - inferomedial
Superiorly: attached to ribs 5-12
Some fibres pass inferiorly to the iliac crest
Some are attached to an aponeurosis - anterior to rectus abdominis, inserting on the midline linea alba.
The inferior border of the aponeurosis of the muscle forms the inguinal ligament.
What innervates the external oblique?
T6/7-T12 thoracic segmental nerves.
What role does the external oblique have?
It increases intra-abdominal pressure and laterally flexes /rotates the trunk.
What is the orientation and attachments of the internal oblique?
Orientation forwards and upwards (superomedial)
Internal oblique arises from the lumbar fascia, the iliac crest and the lateral two thirds or so of the inguinal ligament.
It attaches to the lower three or four ribs (10-12), the linea alba.
It forms the sheath of rectus abdominis (wraps around)
In the inferior part of the abdomen, the internal oblique fibres arch medially from the inguinal ligament and attach to the pubis as part of the conjoint tendon .
What innervates the internal oblique?
T7-T12 thoracic segmental nerves and to some extent the iliohypogastric and ilioinguinal (L1) nerves
What role does the internal oblique have?
It increases intra-abdominal pressure and rotates / laterally flexes the trunk.
What is the orientation and attatchments of the transversus abdominis?
Horizontal orientation run transversely
The fibres arise from the lower six costal cartilages (7-12), the lumbar fascia, the iliac crest and lateral part of the inguinal ligament and to the anterior aponeurosis.
In the superior part of the abdomen, its aponeurosis passes posterior to rectus abdominis to attach to the linea alba.
Inferiorly ,the transversus abdominis aponeurosis lies anterior to rectus abdominis, where it is joined by internal oblique to insert upon the pubis as the conjoint tendon.
What innervates the transersus abdominis?
T8-T12 thoracic segmental nerves and the iliohypogastric and ilioinguinal (L1) nerves
What role does the transversus abdominis have?
It increases intra-abdominal pressure and supports the abdominal viscera
What is the orientation and attatchments of the rectus abdominis?
Long muscles separated by the tendinous linea alba,
The fibres of rectus abdominus are interrupted by three transverse tendinous intersections giving the muscle the so-called ‘six-pack’ appearance.
Attached to the pubic symphysis and pubic crest inferiorly and the xiphisternum and 5 th to 7 th costal cartilages superiorly.
Surrounded by the rectus sheath
The superior ¾ of the muscle is completely enveloped within the rectus sheath, the point at which the rectus sheath becomes deficient posteriorly is called the arcuate line.
What innervates the rectus abdominis?
Innervated by the T7-T12 thoracic segmental nerves
What role does the rectus abdominis have?
It increases intra-abdominal pressure and flexes the trunk.
What is the arcuate line?
The point at which the rectus sheath becomes deficient posteriorly
What arterial supply do the abdominal muscles have?
Anterior: Segmental superior epigastric arteries
‘continuation’ of the segmental ‘thoracic’ ‘intercostal’ supply
Posterior: Segmental from aorta