Theme 1: Lecture 2 - Understanding the peritoneal cavity Flashcards
Which stage is the embryo in when the gut starts to develop
Gastrula
Gastrula
The embryo at the stage following the blastula
Which parts of the alimentary system develop from the endoderm
majority of gut, including most of epithelium and glands of digestive tract
Which parts of the alimentary system develop from the mesoderm
Muscular layers
Which parts of the alimentary system develop from the ectoderm
Epithelium at the extremities of tract (cranial and caudal)
Describe the primitive gut
Formed as a result of two folds:
- Cranial caudal (head to tail)
- Lateral (side to side
At 4 weeks the cranial ad caudal ends are still closed by membranes:
- Bucco-pharyngeal at the cranial end
- Cloacal at the caudal end (urinary and digestive tract not yet separate)
Held in position by mesenteries
What is in the foregut
- Oesophagus
- Stomach
- Proximal half of duodenum
- Liver
- Pancreas
What is in the midgut
- Distal half of duodenum
- Jejunum
- Ileum
- Cecum
- Ascending and 3/4 of transverse colon
What is in the hindgut
- 1/4 of transverse colon
- Descending colon
- Sigmoid colon
- Rectum
What is the cecum
The beginning of the large intestine where the ileum meets the ascending colon
Describe the mesentery
- Mesentery – formed by a double layer of peritoneum
- Mesentery – dorsal or ventral according to its relative position with respect to gut tube
- Suspends gut organs
- Pathway for blood innervation and lymphatics to reach the gut
What happens to the ventral mesentery during development
It degenerates apart from in the foregut
Why doesn’t the ventral mesentery degenerate in the foregut
It allows for more mobility in the intestines
Describe an anomaly of gut rotation
- Duodenum constriction
- Midgut volvulus, leading to ischaemia, necrosis or possibly death
What is a volvulus
A volvulus is when a loop of intestine twists around itself and the mesentery that supports it, resulting in a bowel obstruction
Common symptoms of anomaly of gut rotation
- Vomiting
- Pain
- Abdominal distention
What does the dorsal mesentery do
Attaches gut organs to posterior abdominal wall
What does the dorsal mesentery give rise too
- Gastrosplenic ligament
- Lienorenal ligament
- Greater omentum
- Mesentery of small and large intestine
What does the ventral mesentery give rise to
- Ligaments around the liver
- Falciform ligament
- Lesser omentum
What is the greater omentum
large apron-like fold of visceral peritoneum that hangs down from the greater curvature of the stomach
What is the gastrosplenic ligament
connects the greater curvature of stomach with the hilum of the spleen
What is the falciform ligament
a ligament that attaches the liver to the front body wall, and separates the liver into the left medial lobe and right lateral lobe
Describe the lesser omentum
- Attaches lesser curvature of stomach to back of liver
- Has a free edge
What is the inguinal ligament
Ligament that runs from the ASIS (anterior superior iliac spine) to the pubic tubercle on the pelvis
What makes up the external abdominal wall
- Flat abdominal muscles (anteriorly)
- Lumber vertebral column (posteriorly)
What are the muscles of the anterior abdominal wall
- External oblique
- Internal oblique
- Transversus abdominis
- Rectus abdominis
Origin and insertion of the external oblique muscles
Runs: anteriorly and inferiorly From: outer surface of lower eight ribs To: linea alba iliac crest pubic tubercle
Origin and insertion of the internal oblique muscles
Runs: anteriorly and superiorly
From: lat 1/3 inguinal ligament
ant 2/3 of iliac crest
To: linea alba
costal margin
crest of pubic boneOrigin and insertion of the transverse abdominis muscles
Runs: horizontally From: lat 1/3 inguinal ligament int surf lower 6 ribs iliac crest To: linea alba crest of pubic bone
Origin and insertion of the rectus abdominis muscles
Runs: vertically
From: pubic symphysis + crest
To: xyphoid process
5th-7th costal cartilages
Linea alba
a tendinous, fibrous raphe that runs vertically down the midline of the abdomen. It extends between the inferior limit of the sternum and the pubis, separating the rectus abdominis muscles
Iliac crest
the most prominent part of the ilium, the largest of the three bones that make up the bony pelvis or hip bone
Pubic tubercule
The pubic tubercle is a prominent forward-projecting tubercle on the upper border of the medial portion of the superior ramus of the pubis bone
Costal margin
The costal margin is the medial margin formed by the cartilages of the seventh to tenth ribs. It attaches to the manubrium and xiphoid process of the sternum
Pubic symphysis
The pubic symphysis is a secondary cartilaginous joint between the left and right superior rami of the pubis of the hip bone
Arterial supply for the muscles of the anterior abdominal wall
Sup and Inf epigastric, intercostal, circumflex iliac
Venous supply for the muscles of the anterior abdominal wall
thoracoepigastric (between lat thoracic and Superficial epigastric)
Innervation of the muscles of the anterior abdominal wall
Thoracoabdominal nerves (also thoracic and subcostal nerves for rectus abdominis)
Function of the external obliques
Work with internal obliques for torsional movement of trunk
Function of the internal obliques
- Flex and rotate trunk
- Compress viscera
Function of the transverse abdominis
Compress and support viscera
Function of the rectus abdominis
- Flexes trunk
- Compress viscera
Retroperitoneal
Behind the peritoneum
Name a retroperitoneal organ
The kidneys
Greater and lesser sacs
- The peritoneum can be divided into a greater and lesser peritoneal sac
- They are formed as a result of organ rotation
Lesser sac
- The area behind the stomach
- Also known as the omental bursa
Greater sac
All the peritoneal cavity excluding the area behind the stomach
How do the greater and lesser sac communicate
Via the epiploic foramen (aka foramen of Winslow)
What does the inguinal canal serve as a passageway for
- spermatic cord to reach the scrotum in the male
- the round ligament of the uterus to reach the labia majora in the female
- Blood vessels
- Lymphatic vessels
- The genital nerve
What are the boundaries of the inguinal canal
The superficial and deep inguinal rings
Which nerve travels through the inguinal canal
The genital nerve (a branch of the genitofemoral)
Is the inguinal canal larger in males or females
Males
What does the spermatic cord consist of
- Vas deferens
- Gonadal vessels
- Nerves
- Lymphatics
- Cremaster muscle
Vas deferens
Vessel that carries sperm from the testes and through the urethra
Cremaster muscle
Helps move sperm through the vas deferens and can move the testes closer to the body
Describe the layers of the spermatic cord and how they arise
As the spermatic cord passes through the abdominal wall it takes a sleeve or covering from each of the 3 layers:
- transversalis fascia => contributes the innermost covering of the spermatic cord – the internal spermatic fascia
- internal oblique => contributes the middle covering layer to the cord – the cremasteric fascia
- the external oblique => contributes the outer covering of the cord – the external spermatic fascia
