Abdomen

Question 1

Definie the abdominal cavity ( where does it bound, what it contains, where does it reach)

Answer 1

Abdominal cavity is surrounded by the musculomembranous walls

Bounded;

1. superiorly diaphram
2. inferiorly pelvic inlet

Extents;

1. superiorly as high as the fourth intercostal space
2. is continious
3. inferiorly with the pelvic cavity

Contains;

1. peritoneal cavity
2. abdominal visceral

Question 2

Four-guadrant pattern

Answer 2

Horizontal;

horizontal transumbilical plane passing through the

1. umbilicus
2. intervertebral disk ( vertebrae LII and LIV)

Vertical;

vertical median plane divides it into 4 quadrants;

1. right upper
2. right lower
3. left upper
4. left lower

Question 3

Nine region pattern

Answer 3

Based on two horizontal and two verical planes.

superior horizontal plane is the sabcostal plane;

1. inferior to the costal margins
2. places it at the lower border of the costal cartilage of rib X
3. posteriously passes through the body of vertebra LIII

Inferior horizontal plane is the intertubecular plane;

1. connects the tubercles of the iliac crests which are palpable structures 5cm posteriorly to the anterior superior iliac spines and passes through the body of veterba LV

Both the vertical planes pass from;

1. the midpoint of the clavivles
2. inferiorly to a point midway between the anterior superior iliac spine and pubic symphysis.

Question 4

Abdominal wall ( connects to +layers)

Answer 4

superior; costal margins and xiphoid processes

inferior; upper parts of pelvic bones

anterior; vertebral column

layers;

1. skin
2. superficial fascia
   
   • deep fascias
   • extraperitoneal fascia
   • parietal peritoneum
3. muscles

Question 5

Superficial fascia

Answer 5

A layer of fatty connective tissue

usually a single layer

however in the lower region of the abdominal wall (bellow the umbilicus) there are two layers;

1. superficial fatty layer
2. deeper membranous layer

Superficial layer;

• contains fat and varies in thickness
• is continuous over the the inguinal ligament
• in men; continues over the penis and after losing its fat and fusing with the deeper layer of superficial fascia it continious into the scrotum forming DARTOS fascia (specialized fascia layer containing smooth muscle fibers)
• In women; this superficial layer retains some fat and is a component of LABIA majora

Deeper layer;

• is thin, membranous and contains little to no fat
• It firmily attatches into two places;
  
  • midline;
    
    • linea alba
    • symphysis pubis
  • anterior part of the perineum
    
    • ischiopubic rami
    • posterior margin of the perineal membrane

In men;

• the deeper membranous layer blends with the suoerficial layer as they both pass over the penis forming the superficial fascia of the penis before they continue in the scrotum where they form the DARTOS fascia
• extensions of the deeper membranous layer of superficial fascia attatched to the pubic symphysis pass inferiorly onto the dorsum and sides of the penis to form the fundiform ligament of penis

In women;

• the membrenous layer of the superficial fascia continuous into the labia majora and the anterior part of the perineum

Question 6

Anterolateral muscles

Answer 6

1. Lateral wall; Three flat muscles
   
   • fibers begin posterolaterally, pass anteriorly and are replaced by aponeurosis as muscle continues towards the middle
2. Anterior wall; Two vertical muscles
   
   • near the midline
   • enclosed with a tendinous sheath formed by the aponeuroses of flat muscles
3. Posteriorwall
   
   • Post vertebral muscles –erector spinae group
   • Psoas, quadratus lumborum and iliacus muscles

Each one has specific actions but together;

1. form a firm flexible wall that keeps the abdominal visceral within the abdominal cavity
2. protects the viscera from injury
3. helps maintain position of the viscera
4. contraction helps both quiet and forced expiration by pushing the viscera upwards ( helps push the diaphragm further into the thoracic cavity) +coughing +vomiting
5. help in any action that increases intraabdomina pressure (parturition, micturition and defecation)

Question 7

Flat muscles

Answer 7

1. External oblique
2. Internal oblique
3. Transverse abdominis

External oblique

1. most superfecial from the anterolateral (situated in front and side) muscles
2. is immediatly deep to the superfacial fascia
3. its laterally placed muscle fibers pass in an inferomedial direction
4. its aponeurotic component covers the anterior part of the abdominal wall to the midline
   
   • approching the midline the aponeuroses are entwined forming the linea alba, ( extends from the xiphoid process to the pubic symphysis)

Associated ligaments;

• it is the lower border of the external oblique aponeurosis
• forms the INGUINAL LIGAMENT on each side
• this thickened reinforced free edge passes
  
  • LATERALLY from the ANTERIOR and SUPERIOR iliac spine
  • MEDIALLY from the PUBIC TUBERCLE
  • folds under itself and forms a trough which plays an important role in the formation of the INGUINAL cannal

other ligaments that are formed by extentions of the fiber at the medial end of the inguinal ligament

• Lacunar ligamnet; crescent-shape extention of fibers at the medial end of the inguinal ligament that pass backwards to attach to the PRECTEN PUBIS on the superior ramus of the pubic bone
• aditional fibers extend from the lacunar ligament along the pecten pubis of the pelvic brim to form PECTENEAL (COOPER’S) LIGAMENT

Attached to:

• External surface of lower 8 ribs
• Free posterior border
• Fans out to attach to xiphoid process, linea alba, pubic crest & tubercle, anterior half of iliac crest.
• Muscle fibres are directed down ward and forward

Internal Oblique

1. Deep to external oblique muscles
2. smaller and thinner
3. most of the muscle fibers pass in a SUPERMEDIAL direction
4. its LATERAL muscular components end anteriorly as aponeurosis that blends into the linea alba at the midline

Transversus abdominis

1. deep to the internal oblique muscle
2. named after the direction of most of their fibers
3. ends at anterior aponeurosis which blends into LINEA ALBA in the midline

Attachmetns

1.Lateral:

• Thoracolumbar fascia
• Iliac crest - anterior 2/3rd
• Inguinal ligament - lateral half

2.Medial:

• Lower 3 ribs and costal cartilages
• Xiphoid process,
• Rectus sheath,
• Conjoint tendon

Muscle fibres are directed downward and backward

1. compress abdomenen
2. felx and rotare the trunk
3. supports viscera

Question 8

Vertical muscles

Answer 8

1. Rectus abdominis
2. Rectus sheath

Rectus abdominis

1. long, flat muscle
2. extents the lenght of anterior abdominal wall
3. paired muscle (seperated in the midline by the linea alba
4. widens and thins as it ascends from the pubic symphysis to the costal margin
5. it is intersected by transverse fibrous bands or TENDINOUS INTERSECTIONS (six pack)
6. costal cartilages 5 – 7

Superior attachment

• 5-7 costal cartilages
• Xiphoid process

Inferior attachment

• Symphysis pubis
• Pubic crest

Rectus sheath

1. is an aponeurotic tendinous sheath
2. rectus abdominus and pyramidalis muscles are enclosed there
3. formed by a unique layering of the aponeuroses of the external, internal oblique and transversus abdominis muscles
4. completly encloses the upper three quarters of the rectus abdominis
5. covers the anterior surface of the lower one-quarter of the muscle
6. no sheat covers the rectus abdominis muscle, the muscle is in direct contact with the transversalis fascia

The anterior wall of the rectus sheath consists of

• the aponeurosis of the external oblique
• half of the aponeurosis of the internal oblique
  
  • which splits at the lateral margin of the rectus abdominus
• is complete from the xiphoid process and costal cartilages to pubic symphysis and crest.

Posterior wall of the sheath

• incomplete, stops short below the umbilicus at the arcuate line.
• consists of the other half of the aponeurosis of the internal oblique and the transversus abdominis

At the lateral margin of the rectus abdominis the aponeuroses of the three flat muscles fuse to form the linea semilunaris before enclosing the rectus muscle and fusing again in the midline at the linea alba.

Question 9

Extraperitoneal fascia

Answer 9

• is deep to transversalis fascia
• layer of connective tissue
• seperates the transversalis fascia from the peritoneum
• also lines the pelvic cavity (has a varaity amount of fat)
• abudant on the posterior abdominal wall (especially around kidneys)
• vasculature is located in this thin layer
• viscera in the extraperitoneal fascia is called retroperitoneal
• fascia in the anterior side–> pre-peritoneal
• fascia in the posterior–> retroperitoneal

Question 10

Nerve supply

Answer 10

Skin-Muscles and parietal peritoneum of the anterolateral abdominal wall are supplied by;

1. T7 to T12
2. L1 spinal nerves

Which supply which

1. External oblique – by T7- T11
2. Internal oblique & Transversus – by T7 – T12 & L1
3. Rectus – T7-T12 (no L1)

Parietal peritoneum:

Same segmental nerves of the body wall provide somatic sensory supply to the underlying parietal peritoneum.

Visceral peritoneum has NO somatic sensory innervation

How do the intercostal nerves T7 to T11 work;

1. leave the interecostal spaces
2. pass deep to costal cartilages
3. continue onto the anterolateral abdominal wall ( between the internal oblique and transversus abdominous muscles)
4. reach and enter the rectus sheath
5. pass posterior to the lateral aspect of the rectus abdominus muscle
6. approching the midline an anterior cutaneous branch passes through the rectus abdominis muscle and the anterior wall of the rectus sheath to supply the skin (check p290)

How the spinal nerve T12 (subcostal nerve)

1. follows a similar route as the intercostal nerves

How the L1 nerve branches

1. ilio-hypogastric and ilio-inguinal nerve
2. originate from lumbar plexus
3. initially follow similar course but diviate from this pattern near their final destination
4. the ilio-inguinal nerve (branch of L-1) is also responsible for supplying the the anterior surface of the scrotum and sends a small cutaneous branch to the thigh

Skin;

1. nerves T7-T9 supply skin from the xiphoid processes to just above the umbilicus
2. T10 supplies around the umbilicus
3. T11, T12, L1 supply from the umbilicus up to the pubic region

(for the poaterior abdominal wall) antero- lateral abdominal wall

1. Subcostal nerve (T12)
2. ilio hypogastric & ilioinguinal nerves (L1)

Motor supply to:

1. Quadratus lumborum- T12 & L1- L4
2. Psoas major- L2-L4
3. Iliacus – femoral n. L2–L4

Lumbar plexus (L1 - L4)

1. Motor and sensory, mainly for the lower limb.
2. Sensory branches to the parietal peritoneum of the posterior abdominal wall

Question 11

Blood supply to abdominal wall

Answer 11

Arterial supply

Blood vessels that supply Superficially

1. Superior part of the wall
   
   1. musculophrenic artery; a terminal branch of the internal thoracic artery
2. Inferior part of the wall
   
   1. _​_Medially placed; superficial epigastric artery
   2. laterally placed; superficial circumflex iliac artety
   3. Both are branches of femoral artery

Blood vessels that supply at a deeper level

1. Superior part of the wall
   
   1. superior epigastric artery
   2. is a branch of the internal thoracic artery
2. Lateral part of the wall
   
   1. branches of the 10nth abd the 11nth intercostal arteries
   2. subcostal artery
3. Inferior art of the the wall
   
   1. Superior epigastric artery
   2. Deep circumflex iliac artery
   3. both branches of external iliac artery

The superior and inferior epigastric arteries both enter the rectus sheath and anastomose forming a potential by-pass to abdominal aorta.( posterior to the rectus abdominis)

• Blood supply of the flank muscles Flank muscles are segmentally supplied
  
  • Intercostal arteries 7-11 Subcostal artery
  • Lumbar arteries
  • Deep circumflex iliac arteries
• Venous drainage: Deep veins bearing the same names accompany the arteries

Question 12

Lymphatic drainage

Answer 12

Superficial lymphatics:

1. Above the umbilicus
   
   • pass in a superior direction to the axilarry nodes
2. Below the umbilicus
   
   • pass in an inferior direction to the superficial inguinal nodes
3. Superficial lymphatics accompany subcutaneous veins

Deeper tissues:

1. Deep lymphatics accompany deep veins in the extraperitoneal tissues.
2. Above transumbilical plane
   
   • to mediastinal nodes
3. Below transumbilical plane
   
   • to external iliac and para-aortic nodes

( Grays ;

Deep lymphatics follow deep arteries;

1. parasternal nodes along the internal thoracic artery
2. lumbar nodes along the abdominal aorta
3. external iliac nodes along the external iliac artery

)

Question 13

The Inguinal Region (Groin)

Answer 13

Deifinition;

Junction between the anterior abdominal wall and the thigh

• In this area the abdominal wall is weakened from changes that occur during development
  
  • this is why a peritoneal sac or diverticulm can protude it, creating a inguinal hernia ( with ot without abdominal contents)
• This area is between the ASIS and the pubic tubercle

Formation of the inguinal cannal;

• part of the processus vaginalis (=embryonic developmental outpouching of the parietal peritoneum)

steps;

1. transversalis fascia forms the deepest covering
2. masculature of the internal oblique forms the second covering ( covering from transversus abdominis is not acquired because the processes of vaginalis passes under the arching fibers of this muscle)
3. aponeurosis of the external oblique form the most superficial layer

It is tranformed into a tubular structure with multiple coverings

• Final event is the descent of the testis in the scrotum or the ovaries in the pelvic cavity
  
  • depends on the development of the gubernaculmn ( extends from the inferior border of the developing gonand to the labioscrotal swealings)

Descending of testes;

• Descend into scrotum
• testes and the acompaning vessels, ducts and nerves pass through the inguinal cannal
• completes the processes of the spermatic cord formation in men

Descending of ovaries

• descend into the pelvic cavity and become associated with the developing uterus
• the only remaining structure passing through the canal is the round ligament of the uterus (remenant of the gubernaculmn)

In both sexes the development sequence is concluded with the processus vaginalis obliterates

If it does not occur or is incomplete, a potential weakness occurs in the anterior abdominal wall and an inguinal hernia might develop

big gap filled with ligament

femoral hernia more common in females

inguila hernias are more common in men

genral men have higher frequnce of hernias

inherited weakness

Question 14

Inguinal cannal

Answer 14

Inguinal cannal

1. slit-like passage
2. extends in a downward and medial direction
3. above and parallel to the lower half of the inguinal ligament
4. Extends from deep inguinal ring (a hole in transversalis facia) to superficial inguinal ring (a hole in external oblique aponeurosis) 4cm
5. Contents:
   
   1. In males spermatic cord & ilioinguinal nerve genital branch of genitofemoral nerve and illinguinal nerve
   2. In females round ligament & ilioinguinal nerve

Deep inguinal ring

1. midpoint between the anterior superior iliac spine adn the pibic symphisis
2. above the medial half inguinal ligament
3. immediately lateral to the inferior epigastric vessels
4. Deep ring is about 1.5 cm above the midpoint of inguinal ligament

Superficial inguinal ring

1. superior to the pubic tuburlence
2. triangular opening in its aponeurosis of the external oblique
3. apex points superolaterally
4. base formed by the pubic crest and
5. two remaining sides of triangles
   
   • medial crus–> attached to pubic symphysis
   • lateral crus–> attached to pubic tubercle
6. at the apex the two crura are held together by crossing (intercrural) fibers –> prevents widening of the superficial ring
7. Superficial ring immediately above and medial to pubic tubercle

Walls of the canal

Anterior wall

• Formed by the external oblique aponeurosis (whole length)
• reinforced laterally by the lower fibers of the internal oblique muscle reinforces the lateral (originate from the lateral two thirds of the inguinal ligament)
• this adds an additional covering over the deep inguinal ring ( new layer–> cremasteric fascia containing cremasteric muscle)

Floor(inferior wall)

• formed by one half of the inguinal ligament
• Rolled inferior edge (gutter like) of the external oblique aponeurosis - this is the inguinal ligament (stretches between ASIS and pubic tubercle)

Roof (superior wall)

• Is formed by the arching fibres of the internal oblique muscle and transverse abdominis muscle (whole length)
• they pass from the inguinal ligament to their common medial attachment as the conjoint tendon
• Posterior wall
• The posterior wall of the inguinal cannal is formed by Transversalis fascia (all the lenght)
• It is reinforced along its medial one third by the conjoint tendon
• this tendon is the combined insertion of the transversus abdominis and internal oblique muscles into the pubic crest and pectineal line
• tendon is posterior to the superficial inguinal (additional support)

Ilio-inguinal nerve

1. is a branch of the lumbar plexus
2. enters the abdominal wall posteriorly by piercing teh internal surface of transversus abdominis muscle
3. continues through the layers of the anterior abdominal wall by percing internal oblique muscle
4. continues down the cannal to exit through the superficial inguinal ring

Question 15

Two Areas of Inherent Weakness in the Groin

Answer 15

Inguinal canal –

• The testis and spermatic cord descend from the abdomen into the scrotum via the developing inguinal canal.

in the female the uterine round ligament descends through the developing inguinal canal. (testicular descent starts after 7th wk of IUL and enter the inguinal canal around 28 wks of IUL and enters the scrotum by 32-36 wks of IUL.)

Femoral canal

• Another canal below the inguinal ligament through which femoral artery and vein pass

These two canals remain vulnerable throughout life for potential herniation of the abdominal viscera to occur.

Question 16

Hernia

Answer 16

Definition

A hernia is a condition in which part or whole of an organ or tissue abnormally protrude through the wall of the structure containing the organ or tissue.

Anatomy

1. Weakness/defect/hole on the wall through which the hernia protrudes
2. Hernial Sac – e.g. peritoneum with neck, body and fundus
3. Contents of the hernial sac - e.g. bowel, bladder​

Sign and symptoms

1. A lump or protrusion in the groin
2. Appears intermittently or present all the time
3. Painless/painful and uncomfortable
4. Hernia may be reducible or irreducible
5. May be strangulated with tissue death- and associated with vomiting, constipation, intestinal obstruction – this is an emergency situation

Common types;

1. Inguinal Hernia
   
   • Indirect inguinal hernia
   • Direct inguinal hernia
2. Femoral Hernia

Question 17

Indirect

Answer 17

• Most common type
• Tend to be in younger adults and children
• The hernia takes an indirect path through the abdominal wall
• The defect is a dilated deep ring
• The hernia enters the deep ring then passes through the inguinal canal, external inguinal ring and into the scrotum (or labia majus in women)
• the extent of excursion depends on the amount of processus vaginalis that remains patent
• An Indirect hernial defect is always the internal ring which is always LATERAL to the inferior epigastric vessels

Question 18

Direct

Answer 18

• Older age group
• Acquired defect in posterior wall of the inguinal canal
• Associated with chronic straining
• Associated with weak musculature
• The hernia’s path is straight through the posterior wall of the inguinal canal ( a weakend spot)
• A direct hernial defect tends to go through Hesselbach’s Triangle (inguinal traingle) which is always MEDIAL to the inferior epigastric vessels

Question 19

Femoral hernias

Answer 19

1. Hernia through the femoral canal
2. Not as common as inguinal hernias
3. Commoner in elderly and females
4. Have a high incidence of obstruction and strangulation (bowel)
5. passes through the femoral cannal and into the medial aspect of the anterior high
6. lies at the medial edge of the femoral sheath ( contains femoral artery, vein and lymphatics )
7. more common in women

On examination:

1. Femoral hernias tend to be irreducible, and hot and painful if they are strangulated
2. They can be distinguished from inguinal hernias because they appear below and lateral to the pubic tubercle
3. Inguinal hernias are above and medial to the pubic tubercle