Lecture 2 Flashcards
What does the endoderm compose of?
majority of gut, including most of epithelium and glands of digestive tract
What does the mesoderm compose of?
Muscular layer
What does the ectoderm compose of?
epithelium at extremities of tract (cranial and caudal)
What are the two folds of the primitive gut?
Cranial-caudal and lateral
at 4 weeks the cranial and caudal ends are still closed by what type of membranes?
Bucco-pharyngeal and cloacal
What does the foregut compose of?
Oesophagus Stomach Proximal half Duodenum Liver Pancreas
What does the midgut compose of?
Distal half duodenum, Jejunum, Ileum, Cecum, Asc. + ¾ Transv. Colon
What does the hindgut compose of?
¼ Transv. + Desc. + Sigmoid Colon & rectum
What is the primitive gut held by?
It’s held in position by mesenteries (a structure of mesodermal origin)
Describe the mesentery
formed by a double layer of peritoneum. dorsal or ventral according to its relative position with respect to gut tube. Suspends gut organs
Pathway for blood, innervation, lymphatics etc to reach the gut
Describe the dorsal mesentery
attaches gut organs to posterior abdominal wall (‘back’)
gives rise to: gastrosplenic ligament, lienorenal ligament, greater omentum and mesentery of S and L intestine.
Describe the ventral mesentery
At foregut region only it gives rises to: ligaments around the liver, falciform ligament and the lesser omentum
What is the lesser omentum?
attaches lesser curvature stomach to back of liver
has a free edge
Describe the abdomen
Trunk below diaphragm
Abdominal cavity called abdominopelvic (Abdomen proper
+ greater pelvis
What is the composition of the abdomen wall (external)?
Flat abdominal muscles and the lumber vertebral column.
Describe the muscles of the anterior abdominal wall
External oblique:
From: outer surface of lower eight ribs
To: linea alba, iliac crest,pubic tubercle
Internal Oblique:
From:lat 1/3 inguinal ligament, ant 2/3 of iliac crest
To:linea alba, costal margin, crest of pubic bone
Transversus Abdominis:
From: lat 1/3 inguinal ligament, int surf lower 6 ribs, iliac crest
To: linea alba, crest of pubic bone
Rectus Abdominis:
From: pubic symphysis + crest
To: xyphoid process, 5th-7th costal cartilages
state the Blood supply/drainage of the anterior abdominal wall
Arteries: Sup and Inf epigastric, intercostal, circumflex iliac
Veins: thoracoepigastric
State the innervation of the anterior abdominal wall
Thoracoabdominal nerves (also thoracic and subcostal nerves for rectus abdominis)
What is the function of the anterior abdominal wall?
Ext Obl: work with Int Obl for torsional movement of trunk
Int Obl: flex and rotate trunk; compress viscera
Transv Abd: compress and support viscera
Rectus Abd: flexes trunk; compress viscera
Describe the lesser and greater sacs
formed as a result of organ rotation
lesser sac behind stomach
rest of peritoneal cavity -greater sac
communicate via the epiploic foramen (of Winslow)
Describe the inguinal canal
The inguinal canal serves as a passageway for the
- spermatic cord to reach the scrotum in the male - the round ligament of the uterus to reach the labia majora in the female
Limited by the superficial and deep inguinal rings (DR)
For both genders the genital nerve (a branch from the genitofemoral) and other blood and lymphatic vessels also travel through this canal
The inguinal canal is considerably larger in males, compared with females
describe the spermatic cord
The spermatic cord consists of
vas deferens, gonadal vessels, nerves, lymphatics and the cremaster muscle.
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
