The Abdomen I

Question 1

Abdomen = part of the trunk between the thorax + pelvis.

What are its superior, inferior, anterolateral borders?

Answer 1

superior = diaphragm

inferior = muscles of the pelvis

anterolaterally = musculoaponeurotic walls

Question 2

What are 2 principle functions of the abdomen?

Answer 2

**protect **+ enclose abdominal contents

**flexibility **= for respiration, posture, locomotion

Question 3

Name the 2 transverse planes + 2 sagittal planes of the abdomen

Answer 3

Transverse:

• subcostal plane (most superior)
• transtubercular plane (most inferior)

Sagittal:

• midclavicular lines (x2)

Question 4

Name the 9 regions of the abdomin, as numbered in this figure.

Answer 4

1. Right hypochondriac
2. Right lumbar
3. Right inguinal
4. Epigaastric
5. Umbilical
6. Hypogastric
7. Left hypochondriac
8. Left lumbar
9. Left inguinal

Question 5

What are the superior and inferior landmarks for the 2 sagittal planes ?

Answer 5

Superior = midclavicular planes; pass approximately 9 cm from the midline

inferior = midinguinal points; midway between the anterior superior iliac spine and the superior edge of the pubic symphysis on each side

Question 6

What are the landmarks for the 2 transverse abdominal planes?

Answer 6

subcostal plane = passes through inferior border of the 10th costal cartilage on each side

transtubercular plane = passes through the iliac tubercles (approx. 5 cm posterior to anterior superior iliac spine) + body of L5

Question 7

Where is the transpyloric plane located?

Answer 7

approximate midpoint between:

superior border of manubrium + superior border of pubic symphysis

(L1 vertebral level)

• comonly transects the pylorus (distal part of stomach)

Question 8

What other important structures are transected by the transpyloric plane?

Answer 8

• fundus of gallbladdar
• neck of pancreas
• origins of superior mesenteric artery & portal vein
• root of transverse mesocolon
• duodenojejunal junction
• hila of kidneys

Question 9

Where does the interspinous plane pass through

Answer 9

anterior superior iliac spine on each side

(easily palpated)

Question 10

Which part of the abdominal wall is NOT musculoaponeurotic?

Answer 10

posterior abdominal wall

(includes lumbar vertebral column)

Question 11

The anterolateral abdominal wall extends

from__________ to ___________?

Answer 11

thoracic cage to the pelvis

Question 12

What are the superior and inferior boundaries of the anterolateral abdominal wall?

Answer 12

superior = 7th - 10th rib cartilages + xiphoid process

inferior = inguinal ligament + superior margins of the anterolateral aspects of the pelvic girdle (iliac crests, pubic crests, + pubic symphysis).

Question 13

Identify the numbered muscles of the anterior abdominal wall:

Answer 13

1. external oblique
2. internal oblique
3. transverse abdominis

Question 14

Identify the fascia in the anterior abdominal wall:

Answer 14

1. Camper fascia (superficial, fatty, subcutaneous)
2. Scarpa fasca (deep, membranous, subcutaneous)
3. a) Superficial Investing (deep) fascia
4. b) Intermediate Investing (deep) fascia
5. c) Deep Investing (deep) fascia
6. Endoabdominal (transversalis) fascia

Question 15

Identify these anterior abdominal wall structures:

Answer 15

1. skin (cut edge)
2. extraperitoneal fat
3. parietal peritoneum

Question 16

In what area is the skin firmly attached to the subcutaneous tissue (in the anterior abdominal wall) ?

Answer 16

at the unbilicus

Question 17

Why is it structurally significant that the muscle fibers of the abdominal walls go in 3 different directions?

Answer 17

b/c the abdomin is a positive pressure area

• higher chance of herniation so intersecting fibers = added strength

Question 18

The subcutaneous tissue over most of the abdominal walls is a major storage site for what?

What happens if there is too much of this substance stored here?

Answer 18

FAT

too much fat** = obesity;** can cause sagging folds “panniculi” (apron)

Question 19

There are some areas of the body that maintain fat storage even during starvation. These areas include…?

Answer 19

• face
• bottocks

*fun facts from Dr. Ray :)*

Question 20

1. Inferior to the umbilicus, the deepest part of the subcutaneous tissue is reinforced by which types of fibers?
2. What are the two layers of subcutaneous tissue here?

Answer 20

1. many elastic and collagen fibers
2. • Camper fascia = superficial fatty layer
     - Scarpa fascia = deep membranous layer

Question 21

The membranous layer (Scarpa fascia) continues inferiorly into the ___________.

Answer 21

perineal region as the superficial perineal fascia (Colles fascia)

*NOT into the thighs (fascia lata)*

Question 22

What is the clinical significance of the membranous Scarpa fascia being sufficiently complete ?

Answer 22

Significant because:

fluids** escaping from a ruptured vessel or urethra (blood and/or urine) may **accumulate deep to it

Question 23

The superficial, intermediate, and deep layers of investing fascia cover____________ ?

Answer 23

the external aspects of the three muscle layers of the anterolateral abdominal wall + their aponeuroses (flat expanded tendons)

Question 24

The endoabdominal fascia (membranous sheet of varying thickness) lines the __________?

Answer 24

the internal aspect of the abdominal wall

Question 25

The portion of fascia lining the **deep surface of the transverse abdominal muscle** and its aponeurosis is called...?

Answer 25

"transversalis fascia" | (relatively firm)

Question 26

The portion of fascia **lining the abdominal cavity** is called...?

Answer 26

"parietal peritoneum" (internal to transversalis fascia; separated by extraperitoneal fat)

Question 27

What is the clinical significance of fascia and fascial spaces of abdominal wall?

Answer 27

**1. potential space** b/t membranous layer of subcutaneous tissue + deep fascia (covering rectus abdominis + external oblique m.) ** fluid may accumulate** - cannot spread inferiorly into the thigh because the _membranous layer fuses with the deep fascia of the thigh_ (fascia lata) 2. helps **protect against contamination **therefore, during surgeries, entry into the periotoneal cavity is aoided as much as possible.

Question 28

Why is the **potential (or fat-filled) space** b/t the endoabdominal fascia of special importance in surgery?

Answer 28

**it can be opened during surgery** - access structures on/in anterior aspect of posterior abdominal wall without entering the peritoneal sac - minimize risk of contamination - **Space of Bogros** = b/t transversalis fascia + parietal peritoneum; anterolateral part of potential space used for placing prostheses (ex. when repairing inguinal hernias);

Question 29

How many bilaterally paired muscles are there in the anterolateral abdominal wall?

Answer 29

**5 muscles** - 3 flat (external oblique, internal oblique, and transverse abdominal) - 2 verticle (rectus abdominis, pyrimidalis)

Question 30

The fibers of which 3 abdominal muscles are blended together for increased strength?

Answer 30

external oblique internal oblique transverse abdominal

Question 31

External Obliques

Answer 31

**origin:** External surfaces of 5th - 12th ribs **insertion:** Linea alba, pubic tubercle + anterior half of iliac crest **innervation:** Thoracoabdominal nerves (T7 - T11) + subcostal nerve * - largest, most superficial* * - run inferomedially* * - left superficial become right deep; Right superficial become left deep @ linea alba* * - continued anteromedially as aponeurosis*

Question 32

The 3 flat muscles continue anteromedially as....?

Answer 32

**aponeuroses** | (strong, sheet-like)

Question 33

At what point do the aponeuroses form the tough, aponeurotic, tendinous rectus sheath?

Answer 33

- between the **midclavicular line** and the **midline** (medially) - at the **spinoumbilical line;** running from umbilicus to anterior superior iliac spine (inferiorly) * most become continuous with tendinous fibers of the contralateral internal oblique*

Question 34

**Linea alba**

Answer 34

- interweaved aponeuroses form a midline raphe - extends from xiphoid process to the pubic symphysis

Question 35

1. Which aponeuroses interweave together to form the linea alba? 2. What is this sheath called? 3. Which anterior abdominal muscles are enclosed in this sheath?

Answer 35

1. aponeurosis fibers interweave from: - right + left sides - superficial + intermediate; intermediate + deep layers 2. "rectus sheath" 3. contains the **rectus abdominis + pyramidalis**

Question 36

External Oblique Aponeurosis

Answer 36

Inferior attachment = **pubic crest** (medial to pubic tubercle) inferior margin = **inguinal ligament** (thickened fibrous band; free posterior edge spanning b/t anterior superior iliac spine + pubic tubercle)

Question 37

**Inguinal Ligament**

Answer 37

- continuous inferiorly w. deep fascia of thigh - acts as a *retinaculum* (retaining band) for structures passing deep to it (iliopsoas muscle + femoral vessels + nerve) ***\*most herniations happen here = weak area\****

Question 38

**Internal Oblique Muscle**

Answer 38

**Origin:** Thoracolumbar fascia, anterior two-thirds of iliac crest + lateral half of inguinal ligament **Insertion**: Inferior borders of 10th - 12th ribs, linea alba + pecten pubis via conjoint tendon **Innervation:** Thoracoabdominal nerves (anterior rami of T7-T12 nerves) + first lumbar nerves **Main action:** Compress + support abdominal viscera; flex + rotate trunk * - deep to extrenal; superficial to transversus* * - run anterosuperiorly*

Question 39

**Transversus Abdominis muscles**

Answer 39

**Origin:** Internal surfaces of 7th - 12th costal cartilages, thoracolumbar fascia, iliac crest + lateral third of inguinal ligament **Insertion:** Linea alba w. aponeurosis of internal oblique, pubic crest + pecten pubis via conjoint tendon **Innervation:** Thoracoabdominal nerves (anterior rami of T7-T12 nerves) first lumbar nerves **Main action:** Compresses + supports abdominal viscera * - run transverly* * - deep to internal obliques*

Question 40

**Rectus Abdominis** (characteristics)

Answer 40

- long, broad, strap-like muscle (broad + thin _superiorly_; narrow + thick _inferiorly_) - principal vertical muscle of anterior abdominal wall - paired rectus muscles; separated by the linea alba; lie close together inferiorly - Most of rectus abdominis is enclosed in rectus sheath - anchored transversely by attach. to anterior layer of the rectus sheath (three or more **tendinous intersections**) - sometimes herniation may occur; connection not strong

Question 41

The connecting inersection of the **rectus abdominis** usually occur at which locations?

Answer 41

- level of xiphoid process - umbilicus - halfway between these two

Question 42

Rectus Abdominis Muscle

Answer 42

**Origin:** Pubic symphysis and pubic crest **Insertion:** Xiphoid process and 5th - 7th costal cartilages **Innervation:** Thoracoabdominal nerves (anterior rami of T7-T12 nerves) **Main action:** Flexes trunk (lumbar vertebrae) + compresses abdominal viscera; stabilizes and controls tilt of pelvis **(balancing pelvis)**

Question 43

**Pyramidalis muscle**

Answer 43

**- absent in approximately 20% of people** - small, triangular muscle - lies anterior to inferior rectus abdominis - attaches to anterior surface of pubis + anterior pubic ligament - ends in **linea alba** - **tenses linea alba** (when present)

Question 44

Rectus Sheath

Answer 44

- strong, incomplete fibrous compartment of **rectus abdominis + pyramidalis muscles** - formed by decussation + interweaving of aponeuroses of flat ab. muscles

Question 45

Rectus Sheath: Layers + make-up

Answer 45

- **external oblique** aponeurosis contributes to **anterior wall of sheath** throughout its length - superior **2/3 of internal oblique** aponeurosis splits into 2 layers (laminae) at the lateral border of rectus abdominis; *one passes anterior, the other passes posterior* - **anterior lamina** joins aponeurosis of **external oblique** = ***anterior layer of sheath*** - **posterior lamina** joins aponeurosis of the **transverse abdominal** = ***posterior layer of sheath*** - approx. 1/3 of distance fr. umbilicus to pubic crest --\> **aponeuroses of 3 flat muscles** pass anterior to rectus abdominis = ***anterior layer of sheath*** * \*(fibers of anterior + posterior layers of sheath interlace @ anterior median line = linea alba)* * \*\*(only thin transversalis fascia left to cover rectus abdominis posteriorly)*

Question 46

Why is the posterior layer of the rectus sheath deficient superior to the costal margin?

Answer 46

because the *transverse abdominal muscle pass internal to the costal cartilages* and the *internal oblique attaches to the costal margin...* ## Footnote **...rectus abdominis lies directly on the thoracic wall**

Question 47

What are the major functions & actions of the anterolateral abdominal muscles?

Answer 47

→Form a strong expandable support for the anterolateral abdominal wall. →Protect the abdominal viscera from injury. →Compress the abdominal contents to maintain or increase the intra-abdominal pressure and, in so doing, oppose the diaphragm (increased intra-abdominal pressure facilitates expulsion). →Move the trunk and help maintain posture.

Question 48

What is important to consider when palpating the anterolateral abdominal walls?

Answer 48

- use **_warm hands_** (cold hands=anterolateral ab. muscles tense=*guarding*) - **_guarding:_** reflexive muscular rigidity that cannot be willfully suppressed ***--\> sign of abdominal organ inflammation*** ***--\> involuntary muscular spasms attempt to protect viscera fr. pressure (painful when abdominal infection is present)***

Question 49

Palpation of abdominal viscera is performed with the patient in what position? Why?

Answer 49

**1. supine position** with **thighs and knees semiflexed** - adequate relaxation of the anterolateral abdominal wall 2. **upper limbs at the sides** +** **putting a **pillow under the knees ** - relax the anterolateral abdominal muscles

Question 50

With a patient is supine with ab. muscles relaxed, what motion stimulates the **superficial abdominal reflex**?

Answer 50

** quickly stroking horizontally** (lateral to medial) toward the umbilicus - * Usually, contraction of the abdominal muscles is felt* * - injury to the abdominal skin results in a **rapid reflex contraction** of the abdominal muscles.*

Question 51

What underlies the linea alba at the umbilicus? What was the function of this structure?

Answer 51

**umbilical ring** - fetal umbilical vessels passed to/from umbilical cord and placenta * All layers of anterolateral abdominal wall fuse at the umbilicus.* * (Cannot distinguish b/t different fibers)*

Question 52

Why is a prominent abdomen normal in infants and young children?

Answer 52

- their gastrointestinal tracts contain **considerable amounts of air** - their **anterolateral abdominal cavities are enlarging** and their **abdominal muscles are gaining strength** - have a **relatively large liver **

Question 53

What may be a sign of increased intra-abdominal pressure?

Answer 53

Eversion of the umbilicus ## Footnote *- usually resulting from ascites (serous fluid accumulation) or a large mass (tumor; enlarged organ) *

Question 54

Tumors and organomegaly can produce...?

Answer 54

abdominal enlargement

Question 55

What is the clinical significance of being able to palpate the spleen?

Answer 55

it means it is already pathology (3x larger than normal) \*cannot palpate a normal spleen\*

Question 56

Most abdominal hernias occur in what areas?

Answer 56

inguinal region umbilical region epigastric region

Question 57

What type of hernia is common in newborns? What causes this?

Answer 57

**Umbilical hernias ** ***(Herniation occurs through the umbilical ring)*** - anterior abdominal wall is relatively weak in umbilical ring (esp. in low-birth-weight infants)

Question 58

Who will be most likely to experience **aquired umbilical hernias**? What occurs in this type of hernia?

Answer 58

**women** + **obese people** - extraperitoneal fat and/or peritoneum protrude into the hernial sac

Question 59

Which parts of the abdominal muscles are more likely to herniate?

Answer 59

_**- the lines where abdominal aponeuroses interlace** _ (ocassionally have gaps; ex. *midline*, *transition fr. aponeurosis to r.sheath*) - gaps can be **congenital** due to stresses of obisity + aging OR consequences of surgery or trauma

Question 60

epigastric hernia

Answer 60

occurs in midline b/t xiphoid process + umbilicus (through linea alba) ## Footnote *(usually problems with muscle fibers at this site = hernia)*

Question 61

Spigelian hernias

Answer 61

**occur along semilunar lines** - hernial sac = (peritoneum) covered w. skin + fatty subcutaneous tissue - usually people more than 40 years - usually associated with obesity

Question 62

What parts of the **Thoracoabdominal nerves** supply the anterior abdominal wall?

Answer 62

distal, abdominal parts of the **anterior rami of T7 - T11**

Question 63

Which **lateral (thoracic) cutaneous branches** supply the anterior abdominal wall?

Answer 63

from the thoracic spinal nerves **T7 - T9 or T10**

Question 64

Subcostal nerve

Answer 64

large **anterior ramus** of spinal nerve **T12**

Question 65

**Iliohypogastric** and **ilioinguinal nerves**

Answer 65

**terminal branches** of the **anterior ramus** of spinal nerve **L1**

Question 66

Which nerves approach the abdominal musculature separately to provide the **multi-segmental innervation** of the abdominal muscles?

Answer 66

inferior thoracic **spinal nerves (T7 - T12)** **+** **iliohypogastric and ilioinguinal nerves (L1)**

Question 67

Inferior thoracic spinal nerves (T7 - T12) + the iliohypogastric and ilioinguinal nerves (L1) run **oblique but mostly horizontal.** What are they susceptable to?

Answer 67

**injury in surgical incisions** or from **trauma at any level** of the abdominal wall

Question 68

Injury to the inferior thoracic or iliohypogastric and ilioinguinal nerves may result in what? What does this predispose a person to if it occurs in the **inguinal region**?

Answer 68

- weakening of the muscles - predisposed to inguinal hernia

Question 69

When it is possible, how are abdominal inscisions made? What 2 things are considered in these incisions?

Answer 69

Made to follow the cleavage lines **(Langer lines)** in the skin _insicions chosen for:_ 1. adequate exposure 2. best possibly cosmetic effect

Question 70

The location of an incision in abdominal surgery depends on...? What is considered to accomodate these desired outcomes?

Answer 70

- the type of operation - location of the organ(s) the surgeon wants to reach - bony or cartilaginous boundaries - avoidance of (especially motor) nerves - maintenance of blood supply - minimizing injury to muscles + fascia of the wall - aiming for favorable healing **surgeon must consider _direction of the muscle fibers_ + _location of aponeuroses and nerves_**

Question 71

What are 2 types of **high-risk** incisions?

Answer 71

**pararectus** and **inguinal** incisions

Question 72

Pararectus incisions

Answer 72

**along the lateral border of the rectus sheath ** - undesirable b/c likely to cut the nerve supply to the rectus abdominis - blood supply from inferior epigastric artery also may be compromised

Question 73

Inguinal incisions

Answer 73

**for repairing hernias** - may injure the ilioinguinal nerve directly; may be inadvertently included in the suture during closure of the incision

Question 74

Incisional Hernia

Answer 74

**protrusion of omentum** (a fold of peritoneum) **or an organ through a surgical incision** - can result if muscular + aponeurotic layers of abdomen do not heal properly

Question 75

What factors can predispose a patient to an incisional hernia?

Answer 75

- advanced age - debility of patient - obesity - post-op. wound infection

Question 76

**Endoscopic (Minimally Invasive) Surgery**

Answer 76

**tiny perforations of the abdominal wall allow the entry of remotely operated instruments** - replaces larger conventional incisions - many abdominopelvic surgical procedures can be done this way - potential for *nerve injury*, *incisional hernia*, or *contamination* through the open wound + the t*ime required for healing* are **minimized** * \* surgeons should know both methods, as resources might not be available\**