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Flashcards in Abdomen Deck (17)
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Fascia of anterolateral abdominal wall
Superficial to deep layers

Subcutaneous tissue
Superficial fatty layer
Deep membranous later


Three flat muscles of the abdomen

External oblique
Internal oblique
Transversus abdominis


What do all three flat muscles of the abdomen end and are like

End anteriorly in a strong sheet like aponeurosis
Forms the rectus sheath


What are the two vertical muscles of the abdomen

Rectus abdominis
Pyramidalis (not highlighted)


External oblique

Origin - external surfaces of 5-12 ribs

Insertion - linea alba, pubic tubercle and anterior half of iliac crest

Innervation - thoraco- abdominal nerves and subcostal nerve (anterior rami of t7-t11)

Action - compress and support abdominal viscera; flex and rotate trunk


Internal oblique

Origin - Thoracolumbar fascia anterior two thirds of iliac crest and connective tissue deep to inguinal ligament

Insertion - inferior borders of 10-12 ribs linea alba and pubis via conjoint tendon

Innervation - thoraco-abdominal nerves (anterior rami of t7-t11) and subcostal nerve

Action - compress and support abdominal viscera flex and rotate trunk


Transversus abdominis

Origin - internal surfaces of 7-12 costal cartilages thoraco-lumbar fascia iliac crest and connective tissue deep to inguinal ligament

Insertion - linea alba with aponeurosis of internal oblique pubic crest and pubis via conjoint tendon

Innervation - thoracic-abdominal nerves (anterior rami of t7-t11) subcostal and first lumbar

Action - compresses and supports abdominal viscera


Rectus abdominis

Origin - pubic symphysis and Pubic crest

Insertion - xiphoid process and 5-7 costal cartilages

Innervation - thoracic-abdominal and subcostal nerves (anterior rami of t7-t12 spinal nerves)

Actions - flexes trunk (lumbar vertebrae) and compresses abdominal viscera stabilizes and controls tilt of pelvis


Functions of abdominal muscles

Form a strong expandable support for this region
Protect the abdominal viscera from injury
Compress the abdominal viscera to maintain or increase intra-abdominal pressure.
Produce force required for defecation pee vomit and childbirth
Produce anterior and lateral flexion and rotation of the trunk and help maintain posture



A dome shaped musculotendinous partition separating the thoracic and abdominal cavities
Chief muscle for inspiration
Forms convex floor of the thoracic cavity

Descends during inspiration


Three parts of diaphragm

Sternal part
- two muscular slips that attach to the posterior aspect of the xiphoid process of the sternum

Costal part
- consisting of wide muscular slips that attach to the internal surfaces of the inferior six costal cartilages and their adjoining ribs on each side forms the dome of the diaphragm

Lumbar part
- arising from two aponeurotic arches the medial and lateral arcuate ligaments and the three superior lumbar vertebrae


The posterior abdominal wall is composed mainly of

Five lumbar vertebrae and associated IV discs
Posterior abdominal wall muscles psoas quadratus lumborum iliacus transversus abdominis and internal and external oblique muscles
Lumbar plexus composed of the anterior rami of lumbar spinal nerves
Fascia including thoracolumbar fascia
Diaphragm contributing to the superior part of the posterior wall
Fat nerves vessels and lymph nodes


What are the posterior abdominal wall muscles

Psoas major
Quadratus lumborum


Psoas major

Superior - transverse processes of lumbar vertebrae: sides of bodies of t12 -s1 vertebrae and inervening IV discs

Inferior - by a strong tendon to lesser trochanter of femur

Innervation - lumbar plexus via anterior branches of nerves L2-L4

Action - acting inferiorly with iliacus flexes thigh; acting superiorly flexes vertebral column laterally to balance the trunk : when sitting acts inferiorly with iliacus to flex trunk



Superior - superior two thirds of Iliac fossa ala of sacrum and anterior sacro-iliac ligaments

Inferior - lesser trochanter of femur and shaft inferior to it and to psoas major tendon

Innervation - femoral nerve L2-L4

Action - flexes thigh and stabilizes hip joint acts with psoas major


Quadratus lumborum

Superior - medial half of inferior border of 12 rib and tips of lumbar transverse processes

Inferior - iliolumbar ligament and internal lip of iliac crest

Innervation - anterior branches of t12 and l1-l4

Actions - extends and laterally flexes vertebral column fixes 12 rib during inspiration


What are the three largest branches of the lumbar plexus

Obturator nerve (L2-L4)

Femoral nerve (L2-L4)

Lumbosacral trunk (L4, L5)