Caecum and vermiform appendix

1. Caecum and vermiform Appendix

2. CAECUM
• Caecum is a large blind sac (Latin blind)
• Forming the commencement of the large intestine
• Situated in the right iliac fossa, above the lateral half
of inguinal ligament
It communicates
 superiorly :- with ascending colon
 medially :- ileum
 posteromedially :-appendix

3. Anterior view of the ileocaecal region

4. Dimensions of caecum
• It is 6 cm long and
• 7.5 cm broad
• It’s width is more then its length
o Other body organs which have (width > length)
• Pons , prostate & pituitary

5. Relations
 Anterior
o Coils of intestine &
o Anterior abdominal wall
 Posterior
1. Muscle: Right psoas & ilacus
2. Nerves: genitofemoral, femoral
& lateral cutaneous nerve of
thigh
3. Vessels: testicular or ovarian
4. Appendix in the retrocaecal
recess

6. Relations of caecum

7. Vessels and Nerves
• Caecal branches of the ileocolic artery
• Veins drains into the superior mesentric vein
• The nerve supply is from T11- L1,
parasympathetic - vagus

8. ileocaecal valve
o The lower end of the ileum opens on the posteromedial
aspect of the caecocolic junction.
o The ileocaecal opening is guarded by the ileocaecal valve
Control & mechanism
1. The valve activity is controlled by sympathetic
nerves, which cause tonic contraction of the
ileocaecal sphincter
2. It is mechanically closed by the distension of the
caecum
 It prevents reflux from caecum to ileum
 It regulates the passage of ileal contents into the
caecum, & prevents them from passing too quickly

9. Structure
The valve has 2 lips & 2 frenula
1. The upper lip is horizontal and lies at the ileocolic junction.
2. The lower lip is longer and concave, and lies at the ileocaecal
junction.
• The 2 frenula are formed by the fusion of the lips at the end of
aperture
1. Left / anterior –
aperture is rounded
2. Right / posterior –
narrow and pointed

10. The ileocaecal valve seen after removal of the anterior walls of
the caecum and of the lower part of the ascending colon

11. Vermiform Appendix
• It is worm like diverticulam arising from the posteromedial
wall of the caecum
• Lies 2 cm below the ileocaecal orifice
Dimensions
• length - 2 to 20 cm (average of 9 cm)
• Diameter - 5 mm.
• The lumen is quite narrow
• It is longer in children than in adults
Position
• Lies in right iliac fossa
• Base is fixed, the tip can point in any direction
• Position compared as hour hand of clock:-

12. Vermiform Appendix
1. The appendix may pass upwards and to the right. This is
paracolic or 11 o’clock position.
2. lie behind the caecum or colon: retrocaecal or 12 o’clock
position. This is the commonest position of appendix, 65%.
3. Upwards and to the left, It points towards the spleen. Splenic
or 2 o’clock position.
• In front of ileum (preileal), behind (postileal)
4. It may pass horizontally to the left (as if pointing to the sacral
promontory) promontory or 3 o’clock position
5. It may descend into the pelvis called pelvic or 4 o’clock
position. This is the second most common position, 30%.
6. It may lie below the caecum called as midinguinal or 6 o’clock
position.

13. Positions of the appendix according to the clock

14. Positions of the appendix

15. Appendicular Orifice:-
1. Situated on the posteromedial wall of the caecum2 cm
below the ileocaecal orifice
2. It is occasionally guarded by an indistinct fold of the
mucous membrane: valve of Gerlachis
3. Orifice is marked 2cm below the junction of transtubular
& right lateral planes
4. McBurney’s point is the site of maximum tenderness
in appendicitis. The point lies at:
• The junction of lateral one-third and medial two-thirds
of line joining the right anterior superior iliac spine to
umbilicus.

17. Site of McBurney’s point

18. Blood Supply
The appendicular artery is a branch of the lower division
of the ileocolic artery.
Blood from the appendix is drained by the appendicular,
ileocolic and superior mesenteric veins, to the portal
vein.
Nerve Supply
• Sympathetic nerves: Thoracic 9 - 10 segments through
the coeliac plexus.
• Parasympathetic nerves are derived from the vagus.
 Referred pain of appendix is felt at umbilicus, similar
to that of small intestine and testis.

19. Arterial supply of caecum and appendix. Various groups of
lymph nodes are also seen

20. CLINICAL ANATOMY
Inflammation of the appendix is known as
appendicitis seen in adolescent age.