Anterior abdominal wall

Abdominal walls - AnteriorLateral

Posterior

Anterior abdominal wallThis extends from the thoracic cage to the

pelvis and bounded :–Superiorly • 7th through 10th costal cartilages and and xiphoid process

– Inferiorly • Inguinal ligaments and the pelvic bones.

The wall consists of skin, subcutaneous

tissues (fat), muscles, deep fascia and parietal peritoneum.

Vertebral levels

• T9 – the xiphoid process• L1 trans pyloric plane– Half way between suprasternal notch and pubis or

hand’s breadth from the xiphoid

– Pylorus– Pancreatic neck– Duodenojejunal flexure– Hila of the kidneys– gall bladder fundus

• L3.. Subcostal plane – joining the lowest point of the rib cage- 10th ribs

• L4.. The plane of iliac crest – aortic bifurcation

Surface markings

Spleen9,10,11th ribs 5cm from midlineCupped hand size

Gall bladder Lateral border of rectus abdominisAnd costal margin angle

Fascia• Superficial fascia– superficial fatty layer, Camper's fascia–deeper fibrous layer, Scarpa's fascia.

• Inferiorly Scarpa's fascia blends with the deep fascia of the thigh.

• The transversalis fascia is separated from the parietal peritoneum by a variable layer of fat.

Fascia..

Muscles• 3 Flat Muscles with strong sheet like aponeuroses–External Oblique–Internal Oblique–Transversus Abdominus

• 2 Vertical Muscles–Rectus Abdomius–Pyramidalis

External abdominal oblique (EAO)

• Origin: lateral surfaces of lower (6 -) 8 ribs – 5-8 where it interdigitates with serratus anterior, 9-12 where it interdigitates with latissimus dorsi

• Insertion: anterior half of iliac crest (including anterior superior iliac spine), pubic portion of pecten pubis, body of pubis, linea alba (via rectus sheath)

• Free tendinous inferior margin from anterior superior iliac spine to pubic tubercle (inguinal ligament) sends an expansion to the pecten pubis (lacunar ligament)

• Forms the superficial inguinal ring

Internal abdominal oblique (IAO)

• Origin: anterior layer of the thoracolumbar fascia, anterior 2/3 of iliac crest, iliopectineal arch, inner surface of the lateral half of the inguinal canal

• Insertion: inferior surfaces of 10-12 ribs, rest of fibers miss ribs and insert on linea alba (via rectus sheath), some fibers off inguinal ligament go to body of pubis and pecten pubis (forming the “inframuscular gap” which would be analogous to a middle inguinal ring)

• Above umbilicus, aponeurosis splits to envelope rectus abdominis. Below umbilicus, entire aponeurosis passes anterior to rectus abdominis

• Contributes slips that form cremaster muscle

Transversus abdominis• Origin: inner surfaces of lower 6 costal cartilages,

interdigitating with the origin of the diaphragm, anterior layer of thoracolumbar fascia (aponeurosis coming from lumbar transverse processes) anterior half of iliac crest, and lateral third of inguinal ligament

• Insertion: linea alba• Above umbilicus, aponeurosis passes posterior to

rectus abdominis. Below umbilicus, entire aponeurosis passes anterior to rectus abdominis

• Has a larger “inframuscular” gap than the IAO since its inferior-most fibers do not have such a tight origin insertion curvature near the pubis. Thus, gubernaculum does not pass through the tranversus abdominis muscle.

Rectus abdominis

• Origin: xiphoid process and ventral surface of costal cartilages 5-7

• Insertion: pubic crests and anterior portion of pubic bodies

• Arcuate line is the point at which all flat abdominal muscles pass anterior to rectus abdominis (i.e., epimysium of rectus abdominis in contact with tranversalis fascia)

• No equivalent muscle in the anterior chest wall

• Left and right separated by linea alba• Tendinous intersections

Summury

• Rectus abdominus--vertical midline• Three layers form tube– External oblique (“hands-in-pocket”)– Internal oblique (fibers perpendicular to external)– Transverse abdominus (wraps around)

Rectus sheath

• Above the costal margin External oblique only• Costal margin to halfway between umbilicus

external oblique and split anterior part of the internal oblique. Posterior layer by the split posterior part of IO +Transversus abdominis.

• Below all pass anterior to it. Posterior only tranversalis fascia and peritonium.

Surgical Incisions

• Rich nerve supply to lateral muscles• Segmental to rectus• Blood to rectus from lateral side• Scaring important

Surgical Incisions

• Midline incision– Bloodless field– Good exposure– Superior wide fibres but inferior.

• Paramedian Incision2.5cm lateral and parallel to midline.

Surgical Incisions

• TransrectusNot good

• Subcostal (Kocher)– Right – Billiary surgery– Left – Spleen– Start at midline, 2.5cm bellow costal margin– Rectus is cut, 9th intercostal try to preserve.

Inguinal Canal

4cm , downward and mediallyFrom internal inguinal ring to External iguinal ring

AnteriorExt.Oblique full lengthInt. Oblique lateral one third

Post. Conjoint tendon medially(joined insertion of Int.ob +TransTransversalis fascia lateraly

Roof.Ached fibres of IO and Transversalis