Ch 4: Abdominal Wall, Diaphragm, and Lung

Anterior Abdominopelvic Muscles

Rectus abdominus, external oblique, internal oblique, transversus abdominis, and pyramidalis (all are paired muscles except pyramidalis)

Posterior Abdominopelvic Muscles

Psoas, Quadratus lumborum, and iliacus (all are paired muscles)

Anterolateral Abdominal wall location and layers

extends from thoracic cage by diaphragm to the pelvis. the layers are skin, superficial fascia, subcutaneous fascia, and muscles.

Fascia

Is a fibrous tissue between the skin and underlying structures

Layers of fascia

Superficial layer is attached to the skin

Deep layer covers the muscle

What is Aponeuroses

Layers of flat tendinous fibrous sheets that serve as tendons to attach muscles to fixed points. they have minimal blood and nerve supply so its hard to heal itself after injury

Rectus Sheath

Fibrous compartment for rectus abdominis and pyramidalis muscles

Linea Alba

Oriented vertically and courses the length of anterior abdominal wall, separating the bilateral rectus sheaths

Umbilical Ring

Is a defect in linea alba underneath the umbilicus

Umbilicus

Area where all layers of anterolateral abdominal wall fuse (prone to hernia if there’s weakness in the ring)

Inguinal Canal

Formed during fetal development and its the location where structures enter and exit the abdominal cavity (nerves, lymphatics, and blood vessels can run through here).

Congenital hernias can come from here if there is any malformation in fetal development, especially in newborn males, you can see hernias protrude into scrotum from abnormalities in this location

External Inguinal Ring

Exit for spermatic cord (males) and round ligament (females)

Diaphragm

Separates thoracic cavity from abdominal cavity. the convex surface forms floor of thoracic cavity and concave surface forms roof of abdominal cavity

Diaphragmatic Cura

Musculotendinous bands that arise from superior three lumbar vertebrae. the right crus is longer/larger than left and appears as triangular mass anterior to aorta

What are Diaphragmatic Apertures and 3 examples

Opens that permit structures to pass between thorax and abdomen

Caval Hiatus- primarily for IVC

Esophageal- oval opening to the right of the crus for the esophagus

Aortic- in posterior of diaphragm for the aorta

Sternocostal Triangle

Small opening between sternal and costal attachments of the diaphragm and they transmit lymphatic vessels and epigastric vessels

Sonographic Techniques for scanning Abdominal Wall

High frequency linear probe, focal zone placement at area of interest (highly important), standoff device may be beneficial, and light transducer pressure to eliminate distortion of superficial structures

Abscesses

A cavity of pus/dead tissue and an inflammatory response, could be acute (varied shape, may have mass effect) or chronic (result from persistent infection)

Abscess locations

Usually near surgical site or painful area, subphrenic, subhepatic, paracolic gutters, and left perihepatic, perisplenic, and pelvis

Abscess symptoms and treatment

S: pain, swelling, redness, warm to the touch, maybe fever if more advanced

T: antibiotics and often times, incision and drainage and maybe pack it with antibiotics if needed

Abscess Sonographic Appearance

Irregular edges, swelling/edema around the structure itself, complex on the inside (solid and cystic components), may see debris floating, may contain septations, usually good acoustic transmission, and key component is that color doppler may should get peripheral vascularity but not within it

Rectus Sheath Hematoma and clinical presentation

Are associated with muscle trauma that results in hemorrhage (collection of blood underneath skin within the muscle. clinical presentation is pain, palpable mass, decreased hematocrit if severe enough

Rectus Sheath hematoma Sonographic Appearance

Similar to abscess, bloodwork is key (elevated WBC count and decreased hematocrit), mixed echogenicity (starts anechoic and once it starts to coagulate we see more echogenic material and when bleeding stops (basically one big clot) it will be completely echogenic and then as it breaks down it will start to revert to complex with anechoic areas within it until completely dissolves)

Hernias

Protrusion of bowel or fat through an opening in the ventral wall, could be located in umbilical region or inferior lumbar region (spiephelian). always use high frequency linear or curve transducer and utilize Valsalva maneuver and look for abnormalities to find location of hernia for umbilical region.

3 factors aiding in weak abdominal wall/hernia formation

• abnormal collagen metabolism

• pressure overload (exerting a lot of force, heavy weight lifting, straining while using br, or anything with pressure in abdomen)

• natural weak areas where vessels can penetrate abdominal wall

Hernia Complications

Strangulation: Tissue protruding and getting stuck/not being able to return and has pinches blood supply (could result in death of tissue)

Incarceration: tissue is trapped and cannot be pushed back in to normal position

What can a sonographic evaluation of hernia determine

Location, size, and contents of hernia