Anterior abdominal wall Flashcards
Origin of external oblique
Arise just lateral to the anterior extremities of the lower eight ribs. Upper four interdigitate with serratus anterior. Lower four interdigitate with lat dorsi.
Insertion of external oblique
Inserts to the outer half of the iliac crest, inguinal ligament, pubic tubercle, the aponeurosis of the rectus sheath and linea alba, and xiphisternum
Borders of external oblique
Three borders; a posterior muscular, and an upper and lower aponeurotic. The first two lie free. The latter is rolled.
Arterial supply of external oblique
Check: Branches of superior and inferior epigastric, superficial epigastric, the lumbar and deep circumflex arteries, superficial circumflex iliac arteries, ascending branch of deep circumflex artery
Borders of lumbar triangle of petit
Anterior border is the posterior margin of external oblique
Posterior border is the anterior margin of lat dorsi
Base is the iliac crest
Floor is the internal oblique
What artery is at risk in a gridiron incision?
The ascending branch of the deep circumflex iliac artery
What planes divide the abdomen into nine regions?
Left and right midclavicular lines: extend down to midinguinal points
Intertubercular plane: runs between the tubercles of the iliac crests
Transpyloric plane: found midway between the jugular notch and the top of the pubic symphysis. Some clinicians use the supcostal plane, a little lower.
Name the nine abdominal regions
Three rows from superior to inferior:
Left and right hypochondral and epigastric
Left and right lumbar and umbilical
Left and right iliac and hypogastric or suprapubic
Innervation of external oblique
Lateral cutaneous branches of the lower intercostal and subcostal nerves (T7-12)
What are the attachments and significance of the upper border of the external oblique aponeurosis
Runs free from the fifth rib to the xiphisternum. Is the only structure in the anterior rectus sheath above the costal margin.
Innervation of internal oblique
Lower intercostal and subcostal nerves (T7-12) and iliohypogastric and ilioinguinal nerves (L1). The lowest fibres are innervated by L1 which is hence responsible for the integrity of the inguinal canal
Innervation of transversus abdomens
Lower intercostal and subcostal nerves (T7-12) and iliohypogastric and ilioinguinal nerves (L1). The lowest fibres are innervated by L1 which is hence responsible for the integrity of the inguinal canal
Innervation of pyrimidalis
Subcostal nerve T12
Origin and insertion of the inguinal ligament of Poupart
ASIS to pubic tubercle
What happens to the inguinal ligament when the thigh is extended?
The fascia lata pulls the ligament downward in a genlt convexity
What abdominal muscles arise from which part of the inguinal ligament?
The edge of the ligament is inrolled. The internal oblique and transverses muscles arise from the lateral part of this gutter
Describe the relations of the superficial inguinal ring
V shaped gap above and lateral to the pubic tubercle. The gap extends down to the pubic crest, medial to the tubercle. The aponeurosis is attached to the medial part of the pubic crest, beside the pubic symphysis.
Describe the relations and give the eponym of the lacunar ligament
Gimbernat
Arises from the medial end of the inguianl ligament and extends backwards to the pectineal line
What are the intercrural fibres?
Found at the apex of the superficial inguinal ring, fibres running at right angles to those of the aponeurosis. These blend and prevent the crura from separating.
Where does the reflected part of the inguinal ligament run?
From the pubic tubercle, fibres running upwards and medially behind the spermatic cord to interdigitate in the linea alba
Origin of internal oblique muscle
Lumbar fascia, anterior two thirds of iliac crest and lateral two thirds of inguinal ligament
Insertion of internal oblique muscle
Costal margin, aponeurosis of rectus sheath (both ant and post), conjoint tendon to pubic crest and pectineal line.
The anterior configuration changes at the conjoint tendon
A free lower border arches over the spermatic cord - laterally in front of the cord, medially behind the cord
Origin of transversus abdominus
Costal margin (from inside each costal cartilage, interdigitating with the costal origins of the diaphragm), lumbar fascia of quadrates lumborum,internal lip of iliac crest, the fascia over iliacus, and the lateral half of inguinal ligament deep to OM
Insertion of transverses abdominus
Aponeurosis of post rectus sheath above arcuate line, and ant rectus sheath below arcuate line, fusing behind IOM fibres then together forming the conjoint tendon to pubic crest and pectineal line
Origin of rectus abdominus
Two heads per belly; medial from pubic crest and lateral from pubic symphysis.
Insertion of rectus abdominus
Most to 5th, 6th, 7th costal cartilages (= EOM), some to medial inferior costal margin (i.e. lower border of 7th costal cartilage = IOM, and the xiphisternal fibres of the diaphragm = int oblique)
Action of rectus abdominus
Flexes trunk, aids forced expiration and increases IAP
Action of external and internal oblique muscles
Support, expiration, raises IAP and with muscles of opposite side abducts and rotates trunk
Action of transversus abdominus
Support, expiration, conjoint tendon supports inguinal canal
Action of pyrimidalis
Reinforces rectus sheath
Origin of pyrimidalis
Pubic crest, anterior to origin of rectus abdominus, but posterior to RA’s sheath.
Insertion of pyrimidalis
Lower linea alba, approx 4cm or 1.5inch above its origin
Body of rectus abdominus
The two bellies lie edge to edge below the arcuate line. Separated by the linea alba above the arcuate line. Three tendinous intersections - umbilicus, xiphisternum, and one between these two. Sometimes also found below the umbilicus. Intersections are superficial only - do not involve the posterior sheath.
Linea alba origin and insertion
From xiphoid process to pubic symphysis. Lower portion very narrow. Broadens from just below the umbilicus.
Which muscles form what parts of the rectus sheath?
EOM anterior, TAM posterior, IOM splits around. Below the arcuate line all pass anteriorly. Here TAM and IOM fuse completely, EOM only fuses in the midline.
What is the semilunar line?
A shallow and bloodless groove running from the pubic tubercle to the costal margin (at the transpyloric plane), formed by the splitting of IOM aponeurosis around RA
Describe the nerve supply to rectus and its sheath
Posterior intercostal nerves T7-11 pass between TAM and IOM and enter the sheath and enter the midline of the rectus by piercing the posterior layer of IO aponeurosis.. They pass through the anterior sheath to become the anterior cutaneous nerves.
T7 runs up, T8 transverse, the rest obliquely downwards
How do cutaneous nerves to the lateral abdominal wall arise?
Posterior intercostal nerves T7-11 run between IOM and TAM. Before reaching the sheath they give off lateral cutaneous branches which pierce IOM and EOM to the skin and supply EOM also.
What does the subcostal nerve supply?
T12 subcostal supplies Ant Abd Wall, RAM, PM, and has a lateral cutaneous branch to the buttock
Describe the vascular supply to the anterior abdominal wall
Superior epigastric artery passes through the diaphragm to anastomose with inf epigastric artery within rectus abdominus. Inferior epigastric arises from the external iliac artery at the inguinal ligament, passes behind the conjoint tendon and enters RA via the arcuate line. The deep circumflex iliac artery arises from ext iliac, runs laterally to ASIS between TAM and iliac fascia, and anastomoses with iliolumbar and gluteal arteries. At the ASIS it gives off an ascending branch which enters the NV plan to anastomose with IEA and lumbar arteries.
Lumbar arteries supply the anterolatereal abdominal wall but do not reach the rectus sheath.
Describe the venous drainage of the anterior abdominal wall
Veins accompany arteries
Describe the lymphatic drainage of the abdominal wall
Superficial lymph drainage in quadrants to the pectoral group of axillary nodes above and the superficial inguinal below. Deep is into extra peritoneal tissue then above to mediastinal and below to external iliac and para-aortic
What are the four actions of the abdominal muscles?
- Move the trunk - ant and wall is the flexor of the vertebral column but not TAM
- Depress the ribs for expiration - recti and obliques, not TAM
- Compress the abdomen EOM, IOM, and aided strongly by TAM
- Support the viscera
EOM and IOM but not transversus are abductors and rotators of the trunk - L) EOM works with R) IOM and vice versa. Needed for one armed movements e.g. tennis.
What are the contents of the rectus sheath?
Rectus abdominus
Pyramidalis
The ends of the lower six thoracic nerves and their accompanying posterior intercostal vessels
How else may the arcuate line be known?
The semicircular line of Douglas dammit
How does the diaphragm overcome being weaker than the abdominal wall?
Closure of the glottis =/- closure of the mouth and nasopharynx
How do you test the anterior abdominal wall?
Test RA by lying on back and raising head without using the arms. No specific tests for the others.
