ANTERIOR ABDOMINAL WALL Part 2

PHYSIOLOGICAL UMBILICAL HERNIA(SA)


     During the 5th – 10th week of intrauterine life the midgut loop herniates into the extra-     embryonic part of coelomic cavity. Thus the midgut loop appears as a content of     physiological umbilical hernia. This loop  returns back to the abdominal cavity during the     10th- 12th week of intrauterine life.
Persistence of this  in new born is called exomphalos.


RASPBERRY TUMOUR(SA)


The vitellointestinal duct communicates the primitive midgut with the extra- embryonic     part of yolk sac.
In 98% cases the duct disappears.
When the distal part of the duct persists, it may discharge mucus at the surface     ,evaginating the surface at the umbilicus producing raspberry red tumour( cherry red     tumour).


TRANSPYLORIC PLANE AND STRUCTURES LIE ON IT(SA)
It is an imaginary horizontal plane.
Anteriorly – it passes through the tips of 9th costal cartilages and posteriorly through     the lower part of the body of L1 vertebra. This plane lies midway between the     suprasternal notch and pubic symphysis.
Structures lying at the level of this plane
Pylorus of stomach
Fundus of gall bladder
Hila of both kidneys


ILIOINGUINAL NERVE(SA)
It is the anterior primary ramus of L1 spinal nerve
It pierces the internal oblique muscle below and lateral to iliohypogastric nerve and     enters the inguinal canal.
The nerve runs along the inferolateral side of spermatic cord and comes out through the     superficial inguinal ring.
It has no lateral cutaneous branch.




INGUINAL LIGAMENT(SA)
 The inguinal ligament is formed by the lower border of external oblique aponeurosis which     is thickened and folded backwards on itself.
It extends from the anterior superior iliac spine to the pubic tubercle.
The lateral half of the ligament is rounded and oblique and the medial half is grooved     upwards and horizontal.


Lower border – attachment of fascia lata
Upper surface- lateral2/3rd  - internal oblique
• Lateral 1/3rd- transversus abdominis
                Middle part – cremaster muscle




CREMASTRIC REFLEX(SA)
Upon stroking the skin of the upper medial aspect of thigh, there is reflex contraction of     cremaster muscle leading to elevation of testis.
This reflex is more brisk in children.
Afferent limb- femoral branch of genitofemoral nerve
Efferent limb- Genital  branch of genitofemoral nerve
Reflex center- LI and L2 spinal segments


PYRAMIDALIS MUSCLE(SA)
It is a small triangular muscle lying anterior to the lower part of rectus abdominis     muscle.
This muscle lies within the rectus sheath.
Apex is directed above and medially and base lies in front of the pubis.
It is rudimentary in human beings.
Nerve supply – subcostal nerve
Action –It tenses the lineaalba


NERVE SUPPLY TO PYRAMIDALIS AND DARTOS MUSCLE(SA)
Pyramidalis
     It is supplied by subcostal (T12) nerve.
Dartos muscle
It is supplied by sympathetic fibres through genital branch of genitofemoral nerve.


RECTUS SHEATH- MUSCLES FORMING, CONTENTS(SA)
Contents
Muscles
Rectus abdominis
Pyramidalis
Arteries
Superior epigastric artery – terminal branch of internal thoracic artery
Inferior  epigastric artery- a branch of external iliac artery
Veins
Superior epigastric vena comitantes join the internal thoracic vein
          inferior epigastric vena comitantes join the external iliac vein
Nerves
Terminal branches of lower six thoracic nerves


MENTION THE LAYERS PRESENT IN THE ANTERIOR WALL OF RECTUS SHEATH AT DIFFERENT LEVELS(SA)
Above the costal margin:
Anterior wall- external oblique aponeurosis
Between the costal margin and arcuate line
Anterior wall- external oblique aponeurosis
                                      -Anterior lamina of internal oblique aponeurosis
Below the arcuate line
Anterior wall – aponeurosis of all the 3 flat muscles of abdomen








ARCUATE LINE(SA)
The posterior wall of the rectus sheath, at the level midway between the pubic symphysis     and umbilicus, ends in an arcuate line or lineasemicircularis( fold of douglas).
The line is concave downwards.
Below the level of arcuate line the anterior wall of rectus sheath is formed by the     aponeurosis of all three muscles of abdomen.


DESCRIBE INGUINAL CANAL UNDER FOLLOWING HEADINGS  (a)LOCATION & EXTENT 
 (b)BOUNDARIES (c) CONTENTS (d) APPLIED ANATOMY. ADD A NOTE ON INGUINAL HERNIAS. MENTION FACTORS PREVENTING INGUINAL HERNIAS(LE)      
         Inguinal canal is a musculoaponeurotic canal
Location & Extent
             It is located in the lower part of anterior abdominal wall, just above the medial half of inguinal     ligament.
          It extends from deep inguinal ring to superficial ingunal ring.
                                                  



Boundaries
                         



                                   

Deep inguinal ring:
It is an oval gap in fascia transversalis situated about 1.25 cm above the midinguinal point &     lateral to stem of inferior epigastric artery.
Superficial inguinal ring:
It is a triangular gap in external oblique aponeurosis
Anterior wall: from outwards to inwards
             Skin
             Superficial fascia
             External oblique aponeurosis
             Internal oblique muscle (only in lateral 1/3)
Posterior wall: from inwards to outwards
             Parietal peritoneum
             Extraperitoneal fat
             Fascia transversalis
             Internal oblique muscle (only in medial 2/3)
             Conjoint tendon (only in medial ¼)
         Roof:
             Arching fibres of
             Internal oblique muscle
             Transversus abdominis
          Floor:
             Inguinal ligament’s grooved upper surface
             Lacunar ligament (at medial end)


   Contents
     Spermatic cord in males or Round ligament of uterus in females
     Ilioinguinal nerve
  Applied anatomy
          Inguinal hernia:
              Protrusion of any of the abdominal contents through the inguinal wall or inguinal canal is called     inguinal   


         
 Hernia
          Types of inguinal hernia:
Direct inguinal hernia
           Indirect inguinal hernia

		Direct inguinal hernia	Indirect inguinal hernia
1.	Congenital / Acquired	Acquired	Congenital Acquired
2.	Etiology	Weakness of Abdominal wall muscles	Persistence of patent processus vaginalis
3.	Age	Old	Children ,Young age
4.	Unilateral / bilateral	Bilateral	Unilateral / bilateral
5.	Relation to inferior epigastric artery	Medial	Lateral
6.	Enters inguinal canal  through	Inguinal triangle	Deep inguinal ring





 Factors preventing inguinal hernias:
Obliquity of inguinal canal- since the inguinal canal is oblique, the anterior & posterior walls are
       approximated like flap valve when the intra abdominal pressure is raised.
Superficial inguinal ring is guarded from behind by conjoint tendon
Deep inguinal ring is guarded from front by internal oblique muscle
Shutter mechanism of internal oblique muscle
Contraction of cremaster pulls the testis upwards & superficial inguinal ring is plugged by     spermatic cord (ball valve mechanism)
Contraction of external oblique results in approximation of 2 crura of superficial inguinal ring (slit mechanism)