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عجميّة أبو َمها

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- Dr Al - Muhtaseb

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Refer to Snell for clinical notes (as the doctor said in his first lecture O_O)

and to the slides for illustrations.

This sheet is about abdomen, there are anterior and posterior abdominal

walls

The posterior abdominal wall is formed by the lower five lumbar

vertebrae, bones and muscles originating from the back, but today we will

talk about the anterior abdominal wall.

Let’s have some definitions (you can skip)

- Aponeurosis (many aponeuroses): flattened tendon serves as

attachment to flat muscles -either origin or insertion-.

- Viscera: the internal organs in a body cavity

- the difference between the visceral peritoneum and the

parietal peritoneum?

the parietal peritoneum: covering the abdominal cavity. we

can’t reach any organ in the abdomen without incising the

parietal peritoneum.

the visceral peritoneum: adherent to the viscera (the organs),

the viscera cover the abdominal cavity

(parietal peritoneum is then the membrane which covers the

abdominal viscera While the visceral peritoneum is adherent to

the viscera.

Let’s start…

Abdomen: is the region of the trunk that lies between the diaphragm

above and the inlet of the pelvis below

- ABOVE, it is formed by the diaphragm which separates the

abdominal cavity and the thoracic cavity,

The diaphragm has right and left domes (also known as cupolae).

We should know what is found above the right cupola and what is

below it

Below the right cupola, we find the liver, usually pushes the

right cupola upward until it reaches the 5th intercoastal

space

Above in the chest, the base of right pleura

Above the left cupola, we find the left pleura of lung

Below the left cupola, we find the spleen

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- BELOW, no separation here, the abdominal cavity is continuous

with the pelvic cavity through the pelvic inlet, until reaching the

iliac crest, the line between the left and right iliac tubercles

separates abdomen and pelvis

There are some structures that are found in both the abdomen and

pelvis (such as descending colon, rectum and anal canal, they all

start at abdomen and ends at pelvis)

We conclude that the abdomen is not separated from pelvis, but

then, a boundary between them is formed by the iliac crest

Borders

- Superiorly (Anterior Border):

lower Costal cartilages

(7-12 ribs, remember that both 11 and 12 have no coastal

cartilages)

Xiphoid process (at the end of sternum)

- Inferiorly (Anterior Border):

Pubic bone -symphysis pubis-

iliac crest

(at the Level of L4.)

- Umbilicus:

an important landmark, (Level of intervertebral disc L3-L4)

Areas of the abdomen

There are many organs (viscera) in the abdomen, like those of the

digestive system, in order to locate each organ; the abdominal area

is divided into four quadrants, formed by two intersecting lines

(Vertical & Horizontal Intersect at umbilicus):

1) Upper left

2) Upper right

3) Lower left

4) Lower right

This has a great clinical importance, (doctors usually use these anatomical

terms) let’s have some examples,

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1) if a patient complains of severe pain in his lower right quadrant,

one of the most common, possible diagnoses is acute appendicitis,

because appendix is found there (the right iliac fossa) … and when

doctors make sure by blood tests, surgeons will hence perform

appendectomy to relieve pain.

(differential diagnoses: ascending colon and cecum too)

2) If a 40-year old woman feels pain in the right upper quadrant, her

doctor will think of cholecystitis… because the upper right

quadrant is where the gall bladder exists

(liver too)

But the four quadrants method is outdated, and there is a new, more

accurate method which is known as “the nine areas”.

The abdomen is divided into 9 regions by four imaginary planes/ lines

Two Vertical Planes: (left and right Midclavicular planes)

They extend from the midpoint of each clavicle, to the midpoint between

pubic symphysis and anterior superior iliac spine (midinguinal point)

Two Horizontal Planes:

Upper Subcostal plane:

- this plane lies at the level of L3

- Joins the lower end of costal cartilage on each side, (Below the

costal cartilage, more precisely, below the costal cartilage number

9.)

Lower Intertubercular plane: At the level of L5 vertebra, between the two

right and left iliac tubercles of the hip bone.

The names of the regions:

i. First row:

o Right hypochondriac region (below ribs/ the costal cartilage)

you find:

the right lobe of the liver

the gall bladder.

o Left hypochondriac region (below ribs/ the costal cartilage),

you find:

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the spleen. (the spleen is a reservoir of blood, any trauma

can cause bleeding).

o Epigastric region (above the stomach), you find:

the stomach

the left lobe of the liver .

ii. Second row:

o Umbilical region (in the middle, around the umbilicus), the

small intestines are deep to it

o Right lumbar region (ascending colon).

o Left lumbar region (descending colon).

(The kidneys lie in the posterior part of the right and left lateral lumbers)

iii. Third row:

o The suprapubic/ the hypogastric region (below the stomach) :

it is where we find the urinary bladder and urethra.

o Right iliac (inguinal) region (where you find the cecum and the

appendix)

o Left iliac (inguinal) region - Related to the inguinal canal (the

spermatic cord in males and ovaries in females)

NOTES:

you have to be able to differentiate between appendicitis

and menstrual pain in females

The appendicitis` pain starts around the umbilicus, because

there is a dermatome around it, then the pain moves to the

lower right of the abdomen.

Another clinical application: inguinal hernia might take place

here

Anterior abdominal wall

What are the Layers of Anterior Abdominal Wall?

(skin/ superficial fascia -subdermal- / (deep fascia) /transversalis

fascia/ extraperitoneal/ parietal peritoneum -simple squamous

epithelial layer-

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These layers are very important, surgeons!

1. Skin

2. Superficial Fascia :

o Above the umbilicus (one fatty layer). Scarp's fascia.

o Below the umbilicus two layers (fatty and membranous layers)

I. Camper's fascia - fatty superficial layer.

In males’ scrotum, the continuation of this camper’s layer

is a muscle that is called dartos muscle under the skin

meaning that the abdominal wall descends to the

perineum.

II. Scarpa's fascia - deep membranous layer, it attaches to

the fascia lata below the inguinal ligament in the lower

limb. It is continuous into the perineum, it attaches to

the pubic arch at both sides, and posteriorly to the

perineal body.

Attachment of scarpa’s fascia=

Inf: Fascia lata

Sides: Pubic arch

Post: Perineal body

(The membranous fascial layer in the scrotum, has an

extension called COLLE`S FASCIA.)

What is the perineal body?

o It is a fibrous structure anterior to anus (between the anal

orifice and the symphysis pubis anteriorly??).

Clinical point on the scarp`s fascia: rupture of penile urethra leads to

extravasations of urine:

- Around scrotum and penis

- Around perineum

- lower abdomen (below the umbilicus, where membranous layer

is found)

- above the fascia lata. LUCKILY, this happens because of the

continuous scarp’s fascia attachment, if not attached, the urine

would possibly reach the lower limb…

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3. Deep fascia:

- a layer of connective tissue covering the muscles,

- it is very thin, and may be absent in some people, especially in

women, because deep fascia resists the abdomen enlargement,

thus it is absent in women to allow the enlargment of the uterus

forward and upward during pregnancy

Before talking about the muscular layer, let’s talk about linea alba

because it serves as an insertion point to all these abdominal muscles…

األبيض الخط or linea alba: a fibrous connective tissue, it extends along

the midline, from the xiphoid process to symphysis pubis, it is formed

by the fusion of aponeuroses of three abdominal wall (Ex. In, Tran.

Abd. muscles) it has little supply of blood, it is important surgically,

because midline incisions are usually performed there, and this has

some advantages and disadvantages,

- Advantages:

o Good access to both sides of the abdomen, In case of

tumors in the abdomen for example, or any other

purpose that requires wide opening of the abdomen, a

midline incision in the linea alba could be a good option.

o less bleeding, because it is fibrous.

- Disadvantages:

o Postsurgical healing process is poor and takes long time,

because of poor blood supply .

In addition to midline incision, there are other types of abdominal

incisions: Rectus sheath/ pararectal (Battle’s incision)/ Transverse and

many others

4. Muscular layer, we have four muscles,

All the abdominal muscles insert themselves in the linea alba, by their

aponeuroses, (from the most superficial to the deepest, 1) external

abdominal oblique 2) Internal abdominal oblique 3) transversus

A) External oblique muscle (external abdominis muscle)

It is a thin, broad muscle that comes from the back and extends in

an oblique fashion -> the fibers run obliquely downward forward

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and medially (analogous to someone’s hands in the pockets of their

pants)

a. Origin: outer surface of lower 8 ribs

b. Insertion:

- Xiphoid process, Linea alba

- Pubic crest and Pubic tubercle, and it reaches Iliac crest

(anterior half)

c. Nerve Supply:

-T7 -T12 (Lower 6 thoracic/intercostal nerves)

-L1 ( iliohypogastric nerve , ilioinguinal nerve).

d. Muscle’s Contributions

The muscular part of External oblique becomes aponeurotic

(aponeurosis) before reaching linea Alba, the aponeurosis of this muscle

contributes to:

i. Inguinal ligament: folding of the lower border of aponeurosis of the

external oblique muscle on itself, extends between anterior superior

iliac spine and pubic tubercle.

ii. Lacunar ligament: reflection of inguinal ligament, it forms the medial

boundary to the femoral canal.

Slides: extension of aponeurosis of external muscle backward and

upward to the pectineal line, on the superior ramus of the pubis, its

sharp, free crecentric edge forms the medial margin of the femoral ring

iii. Pectineal ligament: (aka, Cooper ligament) reflection of inguinal

ligament and it is the continuation of lacunar ligament at pectineal line

and continues with a thickening of the periosteum

iv. Superficial inguinal ring,

- it is a defect in external oblique aponeurosis,

- it lies above and medial to the pubic tubercule

- this ring is triangular in shape and it has medial crus/ lateral crus..

- it transmits structures of the female and male inguinal canal such as

the round ligament of uterus (females) and spermatic cord (males) w

its associated nerves, blood vessels, vas deferens ..

- it contributes in the spermatic cord coverings (external spermatic

fascia)

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v. the anterior layer of rectus sheath

vi. it also contributes to the boundaries of the inguinal canal, which is

found between deep and superficial inguinal rings

ExtraNote: (you can skip)

lat·er·al crus of the su·per·fi·cial in·gui·nal ring (portion of the external oblique aponeurosis that passes lateral to

the superficial inguinal ring blending into the inguinal ligament and forming the lateral boundary of the ring.

me·di·al crus of the su·per·fi·cial in·gui·nal ring : portion of the external oblique aponeurosis that passes medial

to the superficial inguinal ring forming the medial boundary of the ring.

B) Internal oblique muscle (deep to external oblique muscle, its fibers

run upward forward and medially)

a. Origin

Lumbar Fascia, Anterior 2/3 of iliac crest, lateral 2 /3 of inguinal

ligament.

b. Insertion:

Lower three ribs and costal cartilage, Xiphoid process,

Symphysis pubis (Linea alba)

c. Nerve Supply: (like external oblique)

Lower 6 thoracic nerves, and iliohypogastric nerve &ilioinguinal

nerve (L1).

d. Muscle’s Contributions,

i. Cremasteric muscle and fascia,

Internal oblique has free lower border arches over the spermatic cord

or ligament of uterus

The spermatic cord and testes (in males) are covered by cremasteric

fascia.

This Cremasteric Fascia is Related to the Inguinal Canal

ii. this muscle assists in the formation of the roof of the inguinal canal

iii. Conjoint tendon,

o combined fibers of internal oblique and transversus abdominis

muscles.

o The conjoint tendon is -inserted on- the pubis.

o Attached medially to linea alba supporting the inguinal canal

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o Has lateral free border

It is important to take stitches in herniorrhaphy (in inguinal hernia فتق)

because it is very strong tendon

iv. It contributes to layers of the rectus sheath.

C) Transversus abdominis muscle, as the name implies, its fibers run

transversely (horizontally).

i. Origin: (from back)

lumbar fascia, lower 6 costal cartilage, anterior 2 thirds of the iliac crest,

the lateral one third of the inguinal ligament.

ii. Insertion:

linea alba (the xiphoid process to symphasis pubis.)

iii. Nerve supply :

Lower 6 thoracic nerves, L1 (illiohypogastric and illioinguinal nerves)

iv. Muscle’s contributions,

(with the internal oblique muscle’s fibers, it forms the conjoint tendon.

which attaches to pubic crest and pectineal line) and (contributes to the

layers of rectus sheath)

- NoTE:

The collection of the abdominal muscle fibers (downward, upward,

transverse) make a very strong network, thus the abdominal muscles are

very strong muscles. (protection of the abdominal viscera).

let’s talk about the muscular contents of rectus sheath in detail ..

D) Rectus abdominis muscle

Rectus abdominis is a long strap muscle, it extends along the whole

length of the anterior abdominal wall and it differs from the previously

mentioned muscles in many aspects:

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It is found inside the rectus sheath (between the linea alba

and the semilunaris.)

It has tendinous intersections (they are adherent to rectus

sheath, anteriorly)

No L1 nerve supply

the rectus abdominis is colloquially called abs ("six-pack" :P). (it is divided

into squares according to the record) This is due to tendinous

intersections, which are 3 transverse fibrous bands (can be palpated as a

transverse depressions)

these tendinous intersections divide the rectus abdominis muscle into

distinct segments,

1- at level of xiphoid process 2- at level of umbilicus 3- one half

way between these two In embryos, these tendinous intersections come

from myotome, then continue as a separated myotome because of the

tendons.

v. Origin: (lower part) symphysis pubis and pubic crest

vi. Insertion: upwards in the 5th,6th,7th costal cartilage and

the xiphoid process. (linea alba)

vii. Nerve supply: lower 6 thoracic nerves. (but NOT L1)

E) Pyramidalis muscle:

- It lies in front of the lower part of the rectus abdominis muscle

- May be absent

- Inside the rectus sheath in the lower part ( if present).

- Used surgically as reconstructive muscle (in addition to assisting

abdominal muscles in their actions)

o Origin: from the anterior surface of the pubis.

o Insertion: linea alba .

o Action: pulls linea alba.

o Nerve supply: 12th subcoastal nerve ( the last intercostal N.)

5. Transversalis fascia:

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thin layer of fibrous connective tissue covering the muscles, continues to

diaphragm, iliac muscle and pelvis, Found in the posterior wall of the

rectus sheath , below the anterior superior aliac spine

we’ve talked about this fascia (in the MSS System) we said it forms the

anterior wall of femoral sheath

- remember: posterior wall of femoral sheath is formed by the

fascia iliaca

Transversalis fascia contributions:

- femoral sheath

- the posterior layer of rectus sheath

- deep inguinal ring and thus a fascia that covers the spermatic

cord (internal spermatic fascia)

6. Extraperitoneal fascia

- usually it is in the form of adipose tissue(fat).

- Located above the parietal peritoneum, and below the

transversalis fascia.

7. Parietal peritoneum: It is a thin serous membrane, Continuous

below with the parietal peritoneum lining the pelvis.

It covers the abdominal cavity, we incise it to reach abdominal

viscera

(it is then a lining for the abdomino-pelvic cavity)

So when a doctor wants to make a surgery in the stomach , the layers

that he/she’d face are : skin , superficial fascia , (deep fascia if present) ,

the muscles, transversalis facia , extraperitoneal , parietal peritoneum ,

then the visceral peritoneum (which is adherent to viscera, e.g: stomach).

Blood supply of the Anterior Abdominal Wall (from slides)

- Arterial Supply

Sup. Epigastric artery • Inf. Epigastric artery • Intercostal

arteries • Lumbar arteries • Deep circumflex artery

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Note:

superior epigastric (a branch of internal thoracic artery)

Inferior epigastric and deep circumflex iliac artery

(branches of external iliac artery)

- Venous Supply

Below the umbilicus – Inferior (superficial) Epigastric -

<Femoral vein Superficial , meaning that the superficial

epigastric empties into femoral vein

Above the umbilicus - Lat. Thoracic. vein. –<Axillary vein

Paraumbilica veins - Ligamentum teres –< portal vein(Porto-

systemic anastomosis

- Lymphatic drainage of ant. Abdominal wall (from slides)

• Above the umbilicus: Ant.axillary L.N

•Below the umbilicus: Sup. Inguinal L.N

•Above the iliac crest: Post.axillary.L.N

• Below the iliac crest: Sup.inguinal L.N

Innervation of the Anterior Abdominal Wall

- Thoracoabdominal nerve: Lower 6th thoracic nerves & 12th

subcostal nerve

- Dermatomes (Anterior, lateral cutaneous nerve terminal branches

of Thoracoabdominal nerve – T7 to skin superior to umbilicus

below xiphoid process – T10 to skin surrounding umbilicus – L1 to

skin inferior to umbilicus above sym.pubis

- LI nerve - Iliohypogastric nerve+ ilioinguinal nerve

Note: The lumbar triangle in not required.

Fasciae of the anterior Abdominal wall:

- Rectus sheath

- Transversalis fascia:

- extraparietal fascia:

- Parietal peritoneum

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The Rectus Sheath

The rectus sheath is a long fibrous sheath • Formed mainly by the

aponeuroses of the three lateral abdominal muscles.

The rectus sheath starts from linea semilunaris and fuses (ends)

in the linea alba

Semilunaris: the lateral border of rectus abdominis muscle

This muscle has tendinous intersections attached to the

anterior wall of the rectus sheath (not the posterior, it is

separated from the wall posteriorly). It can be palpated and

it extends from 9th c.c to the pubic tubercle

Extra note: it is a bilateral feature (right&left)

The rectus sheath is formed by the aponeuroses of the transverse

abdominal and the external and internal oblique muscles. but It

contains the rectus abdominis (and pyramidalis muscle if not

absent)

It has anterior and posterior wall

Formed by the aponeurosis of the abdominal muscles (external

and internal oblique muscles and transversus abdominis muscle)

Anteriorly, tendinous intersections of the rectus abdominis

muscle, these intersections are adherent (firmly attached)

to rectus sheath but posteriorly, the posterior wall of the

rectus sheath is not attached to the rectus abdominis

muscle, meaning that you can put your hand between the

muscle and this wall of the sheath

Its Contents

a. Lower six thoracic nerves (The anterior rami of the lower

six thoracic nerves

b. Lymphatic vessels

c. Two muscles: rectus abdominis and pyramidalis.

d. two arteries:

inferior epigastric (a branch from external iliac)

superior epigastric (a branch from internal thoracic artery

which is branch from a subclavian artery which comes

from the brachiocephalic artery ).

There is an anastomosis between these two arteries

inside the rectus sheath around the umbilicus, and

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they separate the rectus abdominis muscle from the

posterior layer .

e. Rectus sheaths, We have one at left and one at right,

separated by linea alba. In other words, linea alba

separates the right and left rectus abdominis muscles.

f.

Description the rectus sheath is considered at three levels but, always the

same contents: (refer to slides 31+32+33)

A) Above costal margin (5th,6th and 7th) and xiphoid process: (look

at figure A)

- The anterior wall: skin, superficial fascia, aponeurosis of

external oblique muscle.

- Posterior Wall : costal cartilage number 5,6 and 7, then

intercostal muscle , and xiphoid process in the front

(Content: rectus abdominis muscle.)

B) Below costal margin, (between the costal margin and anterior

Superior iliac spine ASIS): (important)

Midway between umbilicus&xiphoid and Midway between

umbilicus&symphysis pubis:

As you can see from figure B in the slides, the internal oblique

muscle splits to enclose the rectus abdominis muscle, part of it

contributes to the anterior wall and the other part contributes to

the posterior wall

- Anterior Wall: the aponeurosis of external oblique and one layer

of internal oblique.

- Posterior Wall: one layer of internal oblique aponeurosis and

transversus abdominis aponeurosis.

(Contents: rectus abdominis muscle (it is enclosed by the 2 layers

of internal oblique)).

C) Below ASIS anterior superior Iliac spine

(below Midway between umbilicus and symphysis pubis): (look at

figure c) The inferior epigastric artery enters the rectus sheath

below the arcuate line , and the arcuate line is a very important

landmark, because all the muscles of the rectus sheath below at

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this level, are at the anterior wall , and the posterior wall is only

formed by fascia transversalis ,

- Anterior Wall: aponeuroses of all muscles (external oblique,

internal oblique and transversus).

- Posterior Wall: transversalis fascia and lies below it

extraperitoneal fat and peritoneum.

(Content: rectus abdominis muscle.)

Arcuate line (linea semicircularis):

Is a crescent-shaped line marking the inferior limit of the posterior layer

of the rectus sheath just below the level of the iliac crest. Below it, we can

find the transversalis fascia.

All muscles are anterior at level of this line

- The general action of the anterior abdominal muscles:

a. Increase the intra-abdominal pressure when it is

needed in the following processes: Vomiting,

Coughing, Defecation, Labor, Micturition (urination)

and Bending of the trunk forward

- These muscles protect the viscera when contracted (when you

are playing boxing, the muscles of the abdomen take the role of

the protection when contacted. If contraction didn’t take place

the viscera will be affected and bleeding may occur)

- They help in lifting heavy objects (people who lift heavy objects

usually tie a strap on the abdomen to help the muscles doing

their action, and to avoid hernia).

- These muscles keep viscera in position

Clinical Notes (SLIDES)

- Abdominal stab wounds

• Lateral to rectus sheath

• Ant. To rectus sheath

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• In the midline= Linea alba - Structures in the various layers through

which an abdominal stab wound depends on the anatomical location

- Surgical incision

- The length and direction of surgical incision through the ant.

Abdominal wall to expose the underlying viscera are largely controlled

by

1- position & direction of nerves

2- direction of muscle fibers

3- arrangement of the aponeurosis forming the rectus sheath - The

incision should be made in the direction of the line of cleavage in the

skin so that the scare is produced

Meaning that surgical incision should be parallel to skin cleavage so that

it won’t leave a scar. doctors should also be aware of the pathway of the

nerves. So they pull rectus sheath laterally to protect the nerves which

pass from medial to lateral. And the direction of the muscle fibers is also

important.

- Incision through the rectus sheath

• Widely used • The rectus abdominis muscle and its nerve supply are

kept intact • On closure the ant & post wall of the sheath are sutured

separately and the rectus muscle back into position between the suture

lines

Common types of incisions

• Paramedian incision • Pararectus incision • Midline incision •

Transrectus incision • Transverse incision • Muscle splitting •

Abdominothoracic incision

A note I could not place: L1 nerve passes above inguinal ligament and divides

into 2 branches: iliohypogastric and ilio-inguinal (Ilioinguinal – enters

from deep to superficial ring supplying scrotum and it also serves as

sensory innervation to lower abdomen)

I’ve heard record4+ used slide2 to write this sheet, Sorry if I missed anything, GOOD LUCK!!

Telos is not only about your Ultimate steps, But also your first ones -MahaAbuAja100