Anterior Abdominal Wall Flashcards
Origin and insertions of external oblique
O- lower 8 ribs
I-Linea alba via rectus sheath, iliac crest, and lower border forms inguinal ligament
Internal oblique O and I
O-Thoracolumbar fascia, iliac crest, lateral two-thirds (2/3) of inguinal ligament
I-Costal margin, linea alba (via rectus sheath), pubic crest + pectineal line (via conjoint tendon)
Transversus abdominis O and I
O- Costal margin, thoracolumbar fascia, iliac crest, lateral one-third (1/3) of inguinal ligament
I- Linea alba (via rectus sheath), pubic crest + pectineal line (via conjoint tendon)
O and I of rectus abdominis
O- Pubic crest
I-Costal cartilages 5, 6, 7
Between which two muscle layers does the neurovascular plane lie
The neurovascular bundle lies between the middle and inner layers of the body wall (internal oblique and transversus abdominis in abdomen; internal and innermost intercostal in thorax)
Nerve supply and actions of the abdominal muscles
Nerve supply – lower 6 thoracic spinal nerves (T7-T12) + iliohypogastric & ilioinguinal (L1) for the fibres of the conjoint tendon (‘inguinal shutter mechanism’)
Actions – move trunk (flexion of trunk, lateral rotation of thoracic region and lateral flexion of trunk), compress abdomen (expiration, evacuation),
support of viscera, control of inguinal shutter mechanism
What is the rectus sheath formed by?
Formed by the aponeuroses of the anterolateral abdominal wall muscles as they insert to the linea alba
Where does linea alba run from/to
Runs from xiphisternum to pubic symphysis
What are the three different cross section levels of the rectus sheath
Above costal margin, below arcuate line, between coastal margin and arcuate line
What is the arrangement of the aponeuroses of the anterolateral abdominal wall muscle at the following levels?
a) above the costal margin b) between the costal margin and the arcuate line
c) below the arcuate line
a) Anterior sheath only (from EO aponeurosis) b) Anterior and posterior sheath (note the splitting of the IO aponeurosis)
c) Anterior sheath only (from all 3 aponeuroses)
What does the rectus sheath contain
Rectus abdominis (+/- pyramidalis) Superior and inferior epigastric vessels
Lower 6 intercostal nerves (T7-T12) and accompanying vessels
In a midline incision (e.g. laparotomy) what layers would be traversed before entering the abdominal cavity?
Skin Superficial fascia (fatty layer of Camper; membranous layer of Scarpa) Linea alba Transversalis fascia Extraperitoneal fat
Parietal peritoneum
What does the inguinal canal contain?
The spermatic cord the male and the round ligament of the uterus in the female
Ilioinguinal nerve
Obliterated remains of the processus vaginalis, which forms the sac of an indirect inguinal hernia
What structures form the anterior wall, posterior wall, roof and floor of the inguinal canal?
Anterior wall - Superficial ring (medially; weak), EO aponeurosis and IO muscle (laterally; strong)
Posterior wall - Conjoint tendon (medially, strong); transversalis fascia and deep ring (laterally; weak)
Roof - Lowermost fibres of IO and TA muscles (insert via conjoint tendon; form ‘inguinal shutter’)
Floor - Inguinal and lacunar ligaments
(Note how the ‘strong’ part of the ant. wall reinforces the ‘weak’ part of the post. wall, & v.v.)
From where are the coverings of the spermatic cord derived?
External spermatic fascia – from EO aponeurosis
Cremasteric fascia – from IO and TA muscles
Internal spermatic fascia – from transversalis fascia
