C13: Abdominal Wall

Question 1

what are some indications for an Abdo wall US?

Answer 1

• palpable mass (from abdo, or wall?)
• surgical wound assessment
• trauma
• findins on other DI tests

+ us a high frequency probe

Question 2

what is a standoff pad? why is it used

Answer 2

• gel like pad to increase the distance b/w the probe and the abdo wall…
• used to minimize the main bang artifact

Question 3

what are the 3 layers of the abdo wall

Answer 3

• epidermis
• subcutaneous tissue (fat)
• muscle

Question 4

how does the epidermis appear on US and how thick should it be

Answer 4

• echogenic

- 1-4 mm thick

Question 5

how does the subcutaneous tissue (fat) appear on US and how thick should it be

Answer 5

• variable thickness

- variable echogenicity but usually less echogenic than muscle

Question 6

what factor influences the echogencity of fat

Answer 6

water content…. more water makes it appear more echogenic because water and fat dont mix so you end up with multiple interfaces which appear bright

Question 7

describe the rectus abdominis (RA).

where is it located? where does it originate and where does it insert

Answer 7

• paired, located midline and anterior on the abdo wall (most anterior muscles of the abdo)
• separated by the lines alba
• originates at pubic symphysis and pubic crest and inserts into the xiphoid process and costal cartilage

Question 8

what is the rectus sheath?

what is it made out of

Answer 8

• sheath that encloses the RA muscles

- formed by the aponeuroses of the internal, external and transverse abdominus

Question 9

where do the 3 tendinous insertions of the RA muscle attach?

what is there function

Answer 9

• to the rectus sheath anteriorly… b/w the xiphoid and inferior to the umbilicus
• allow for localization of hematomas

Question 10

what is an aponeuroses?

Answer 10

-flat sheet of fibrous c-tissue that serves as a tendon to attach muscle to fixed points

Question 11

describe the line alba

what forms this structure?

what artifact does it commonly cause

Answer 11

• fibrous band that extends from the xiphoid to the pubic symphysis
• wider above the belly button and appear echogenic on US

+formed by the aponeuroses of the 3 lateral abdo muscles

-refractive duplication artifact

Question 12

what is the arcuate line

Answer 12

• a point b/w the umbilicus and the pubic symphysis where the posterior part of the rectus sheath passes in front of the rectus muscle….

… now theres only c-tissue located anteriorly

Question 13

describe the external oblique muscles, where do they originate and insert.
how do they run?

Answer 13

• outer layer of muscle on the anterolateral abdo wall
• originate from the outer surface of the lower 8 ribs
• run diagonally and insert into the xiphoid, linea alba, pubic bones and anterior iliac crest

Question 14

describe the internal oblique muscles, where do they originate and insert.
how do they run?

Answer 14

• deep to the external obliques… run 90 degrees to the externals
• originate from the lumbar fascia, anterior iliac crest and inguinal ligament
• insert into the lower 3 ribs, xiphoid, linea alba and pubic symphysis

Question 15

describe the tranversus abdominis muscles, where do they originate and insert.
how do they run?

Answer 15

• deep to the internal obliques…. run horizontally
• originate from the lower 6 ribs, lumbar fascia, iliac crest and inguinal ligament
• insert into the xiphoid, linea alba and pubic symphysis

Question 16

whats the US appearance of muscle tissue

Answer 16

• hypoechoic to sonolucent (anechoic)
• specular reflectors
• striated appearance in SAG…. speckled in TRX

Question 17

what are the 3 muscles of the posterior abdo wall

Answer 17

1. Psoas major
2. Quadratus lumborum
3. iliacus

Question 18

describe the psoas major muscles, where do they originate and insert.
how do they appear on US?

Answer 18

• fan shaped muscles
• originate from the side walls of the vertebral column
• insert into the lesser trochanters of the femurs
• look hypoechoic

Question 19

describe the quadratus lumborum muscles, where do they originate and insert.

Answer 19

• posterolateral to the psoas muscles and directly posterior to the kidneys… flat muscle
• originate at the iliac crest
• insert into the 12th rib and upper4 lumbar vertebra

Question 20

where do the iliacus muscles originate and insert?

Answer 20

-originate at the iliac fossa, sacrum and SI joints

Question 21

what is the inguinal canal?

how does it run in the body

Answer 21

-a slit like passage way thats obliquely oriented tunnel that runs inferior and medial in the body

Question 22

what are the 2 openings of the inguinal canal and where are they located

Answer 22

1. Deep inguinal ring/internal ring

• opening at the superior end of the canal
• located b/w the anterior superior iliac spine and pubic symphysis

2. Superficial inguinal ring/external ring
   - opening at the inferior end of the canal that goes through the external oblique aponeurosis

Question 23

which opening of the inguinal canal is a defect of the transversalis fascia?

Answer 23

deep inguinal ring

Question 24

the inguinal canal contains which structures and its walls are formed by which structures?

Answer 24

-contain spermatic cord (M) and round ligament (W)

Anterior wall:
-formed by aponeuroses of external obliques

Posterior wall:
- formed by transversalis fascia

Question 25

describe the diaphragm… what is it made of

Answer 25

• dome shaped partition separating the thorax from the abdo

- made of muscle and tendon… active muscle of respiration

Question 26

where does the diaphragm originate

Answer 26

at the periphery of the thoracic cage w/ 3 groups of muscle fibres….

1. lumbar spine (crura)
2. lower sternum
3. lower 6 ribs

Question 27

what structure joins midline to form the arcuate line

Answer 27

lumbar spine/crura

Question 28

which crus of the diaphragm is longer and broader

Answer 28

R

Question 29

where do the 3 muscles fibres of the diaphragm insert and what do they form

Answer 29

-insert radially and from a central tendon

Question 30

describe the relationship of the crura to the celiac axis and IVC

Answer 30

• above the level of the celiac axis its anterior to the AO…at the celiac axis its lateral to the AO
• posterior to IVC

Question 31

SEE questions 1-7 about the pleural space

Answer 31

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