Rectum, Anal Canal and Ischioanal Fossa Flashcards
How long is the Rectum?
5 inches (12cm)
Where is the Rectum?
From Vertebral level S3 to the level of the apex of the prostate in males and the lower vagina in females
What is the space between the Rectum and the Bladder in the male called?
Recto-vesical pouch
What is the space between the Rectum and the Uterus in the Female called?
Recto-Uterine Pouch of Douglas
What does the Rectum look like in a Coronal Section?
- Curved along the Sacrum
- S Shaped
- Has Valves of Houston going Left, Right, Left
What happens if the Ampulla of the Rectum is stretched?
The Internal Anal Sphincter Relaxes
Which of the Rectal Valves of Houston is the biggest?
The Right one–> because it has muscle
What is the importance of the Valves of Houston?
Important in Colonoscopy
Where is the Ampulla of the Rectum?
It is the lower final end of the Rectum
What are the features of the Rectum?
- No Taeniae Coli
2. No Appendices Epiploicae
Which parts of the Rectum are covered by Peritoneum?
- Upper 1/3–> Front and Sides
- Middle 1/3–> Front only
- Lower 1/3–> None
What structures are posterior to the Rectum?
- Sacrum
- Coccyx
- Spinal Nerves S3, S4, S5
- Rectal Vessels and Lymphatics
- Waldeyer’s Fascia
What structures are lateral to the Rectum?
- Distensible Fascia
2. Levator Ani
What structures are anterior to the Rectum in Males?
- Upper 2/3 of Peritoneum
- Coils of Ileum
- Sigmoid Colon
- Rectovesical Pouch
- Denonvillier’s Fascia
- Base of Bladder
- Prostate
- Seminal Vesicles
What structures are anterior to the Rectum in Females?
- Upper 2/3 of Peritoneum
- Coils of Ileum
- Sigmoid Colon
- Rectouterine Pouch of Douglas
- Denonvillier’s Fascia
- Cervix
- Vagina
What is the blood supply to the Rectum?
- Superior Rectal Artery
- Middle Rectal Artery
- Median Sacral Artery
Where is the Superior Rectal Artery from?
From the Inferior Mesenteric Artery
Where is the Middle Rectal Artery from?
Internal Iliac Artery
Where is the Median Sacral Artery from?
Aorta at level L4
What is the Venous Drainage of the Rectum?
- Inferior Mesenteric Vein to the Portal Vein
- Middle Rectal Vein to the Internal Iliac Vein to Systemic Venous Drainage
- Inferior Rectal Vein to Internal Iliac Vein to Systemic Venous Drainage
What is the Lymphatic Drainage of the Rectum?
- Presacral nodes
- Internal Iliac nodes
- Preaortic nodes
Where are the Internal Iliac Lymph Nodes?
In the lateral wall of the pelvis
What muscle is at the junction of the rectum and anus?
Puborectalis
What group of muscles is Puborectalis from?
Levator Ani
What is the nerve supply to Puborectalis?
Pudendal Nerve (Voluntary Control)
What are the attachments of puborectalis?
- Pubic Symphysis
2. Splits around the posterior rectum
What is the function of Puborectalis?
- Relaxes to allow defaecation
2. Increase the ankle between the rectum and anal canal
Where is the Anal Canal?
Between the Rectum and the Anus
How long is the Anal Canal?
4cm
What are the Anal Columns?
Mucosal organised into longitudinal folds, in between which anal glands open into the anal sinuses
What forms the inferior aspect of the Anal Columns?
Anal Valves
What do the Anal Valves form?
The Dentate/Pectinate Line
What kind of epithelium is the upper 2/3rds of the Anal Canal?
Columnar Epithelium
What kind of Epithelium is is the lower 1/3 of the Anal Canal?
Stratified Squamous Epithelium
What is the significance of Hilton’s White Line?
Divides the Lower 1/3 of the Anal Canal into Non-Keratinised and Keratinised Squamous Epithelium (Non-Keratinised on top)
What is the blood supply of the Anal Canal?
- Superior Rectal Artery from the Inferior Mesenteric Artery
- Inferior Rectal Artery from the inferior Pudendal Artery, which is from the Interior Iliac Artery
What is the Venous Drainage of the Anal Canal?
- Internal Venous Plexus between the internal sphincter and epithelium
- External Venous Plexus surrounding the External Anal Sphincter
Where does the Internal Venous Plexus of Veins in the Anal Canal drain to?
- Superior Rectal Vein (Portal System)
2. External Venous Plexus
Where does the External Venous Plexus of Veins in the Anal Canal drain to?
- Superior Rectal Vein (Portal System)
- Middle Rectal Vein
- Inferior Rectal Vein
What is the nerve supply to the Anal Canal?
Upper–> Visceral Sensory (Autonomic)
Lower–> Somatic (Inferior Rectal nerve from Pudendal Nerve)
Describe the course of the Pudendal Nerve
- The Pudendal Nerve arises from Roots S2,3,4 from the Sacral Plexus
- It goes out of the pelvis through Greater Sciatic Foramen under Piriformis
- It hooks around the Sacrospinous ligament and goes back through the Lesser Sciatic Foramen
- Goes through the Pudendal Canal
How is the Pudendal Nerve located for Local Anaesthetic injections?
Located by Palpating the Ischial Spine through either the vagina or Rectum
What type of muscle makes the Internal Anal Sphincter?
Smooth Muscle
What is the nerve supply to the Internal Anal Sphincter?
Autonomic Nervous Control from the Rectal Plexus from the Inferior Hypogastric Plexus
What nerves contract the internal anal sphincter?
Sympathetic Nerves
What nerves relax the internal anal sphincter?
Parasympathetics
What causes the internal anal sphincter to relax?
Dilatation of the ampulla of the rectum
What are the 3 parts of the External Anal Sphincter?
- Subcutaneous
- Superficial
- Deep
Which part of the External Anal Sphincter is overlapping with the Internal Anal Sphincter?
The Deep part
What type of muscle is the External Anal Sphincter?
Striated Skeletal Muscle
What does the Deep part of the External Anal Sphincter attach to?
Puborectalis
What does the Superficial part of the External Anal Sphincter attach to?
Perineal body and Coccyx
What does the Subcutaneous part of the External Anal Sphincter Attach to?
Skin
What is the nerve supply to the External Anal Sphincter?
Somatic Nerve Supply from the Pudendal Nerve (S2,3,4)
What makes up the Perineal Body?
- External Anal Sphincter
- Bulbospongiosus Muscle
- Superficial Transverse Perineal Muscle
- Levator Ani
- External Urinary Sphincter
- Deep Transverse Perineal Muscle
What are the borders of the Ischioanal Fossa?
Floor: Skin beside anus
Roof: Levator Ani
Lateral Wall: Obturator Internus, Alcock’s (Pudendal) Canal, Pudendal Nerve and Vessels
What are the contents of the Ischioanal Fossa?
Fat
What is the function of the Ischioanal Fossa?
Allow expansion of the anus during defaecation
What can be palpated in a Rectal Examination in males?
- Ischial Spine/Tuberosity
- Appendix
- Prostate (Seminal Vesicles)
- Base of Bladder
- Bulb of Penis
What can be palpated in a Rectal Examination in Females?
- Ischial Spine/tuberosity
- Appendix
- Cervix
- Ovaries
- Internal Iliac Nodes
What are Haemorrhoids?
Swollen vascular structures in the anal canal which can bleed and be painful
What is the difference between internal and external haemorrhoids?
Internal–> Above Pectinate line
External–> Below Pectinate line
Where does the blood come from in internal Haemorrhoids?
Superior Rectal Vein - Inferior Mesenteric Vein - Portal System
Where does the blood come from in External Haemorrhoids?
Inferior Rectal Vein - Internal Pudendal Veins–> Inferior Vena Cava
What are Anal Fissures?
Tear f the Anus or Anal canal caused by hard stool/constipation
What is the treatment for Anal Fissures?
- Stool softeners
- Nitrate-based ointment/ Calcium channel blockers
- Botox
- Surgery
What are Rectal Carcinomas?
Tumour on the bowel wall
How will a patient present if he/she has Rectal Carcinoma?
- Bleeding
- Altered Bowel Habit
- Back Pain
- Weight Loss