Radiographic Anatomy
Digestive System
Educational Objectives
By the end of this lecture you should be able to:
• Identify the anatomical parts of the digestive system on
diagrams and radiographs.
• Identify the relations between the different parts of the GIT
• Explain how to hang GIT radiographs on the view box
•
State and locate the surface land marks associated with the
abdomen.
References
1. Text book of radiographic positioning and related anatomy; by
Kenneth L.Bontrager,6th edition.
2. Introduction to Human Anatomy and Physiology: by Eldra
Pearl Solomon:W.B.Saunders Company
3. Handbook of Anatomy and physiology for Students of Medical
Radiation Technology: Mallett.M:Jaspar
Websites
http://www6.district125.k12.il.us/science/anatomy/
http://www.innerbody.com/htm/body.html
http://www.e-radiography.net/
http://www.getbodysmart.com/index.htm
4
Digestive System
(gastrointestinal; GI tract)
–
Stomach
A. Fundus
(fluid level seen in erect position)
A. Body
B. Pyloric Antrum
–
Small intestines (small bowel)
A. Duodenum ("c" shape; bulb)
B. jejunum
C. ileum
Digestive System
(gastrointestinal; GI tract)
Large intestine (colon)
A.
B.
C.
D.
E.
F.
G.
H.
Caecum (valve; appendix)
Ascending colon
Hepatic flexure
Transverse colon
Splenic flexure
Descending colon
Sigmoid colon (flexure)
Rectum and anal canal

Accessory GI tract organs
A.
B.
C.
Salivary glands
Liver &Gall bladder
Pancreas
Quadrants & Regions of the abdomen
• Abdomen divisions
4 Quadrants (clinically)
9 Regions (anatomically)
Quadrants & Regions of the abdomen
MSP: mid-sagittal plane
TUP: transumblical plane (L4/5)
RLL: right lateral plane
LLL : left lateral plane
TPP: transpyloric plane (L 1)
TTP: transtubercular plane (L 5)
Regions of the abdomen
Digestive System
(I): Alimentary canal:
– 9 m length
– Extend from mouth to anus
►Oral cavity
►Pharynx
►Esophagus
►Stomach
►Intestine (small & large)
(II): Accessory organs:
– Salivary glands
– Pancreas
– Liver and biliary system
Pharynx
◙ Levels : from skull base to level of C-6 (13 cm).
◙ 3 parts:
(I): Nasopharynx:
•
•
•
•
•
Skull base to the level of soft palate
Anterior: nasal cavity (posterior nares)
Inferior: nasopharyngeal isthmus
Lateral wall: opening of auditory tube
Roof: adenoid
(II): Oropharynx:
• Level of soft palate to tip of epiglottis
• Anterior: oropharyngeal isthmus
(III): Laryngopharynx:
• Tip of epiglottis to level of C-6
• Pyriform fossa
Esophagus
◙ Levels : from C-6 to T-11 (25 cm).
Normal points of narrowness: (1) Level of cricoid cartilage; (2) Level of left main bronchus;(3)
Passing through the diaphragm. Venous drainage of the lower oesophagus form a point of
communication between portal and systemic veins; any obstruction of the portal venous system
may lead to oseophageal varices.
◙ Relations: (3 areas)
(I): In the neck:
• Anterior: trachea, thyroid
• Posterior: cervical vertebrae
• Lateral: common carotid artery
(II): In the thorax:
• Anterior: trachea, Lt. main bronchus, Lt. atrium
• Posterior: thoracic vertebrae, thoracic duct, descending aorta
• Lateral:
– Right side: azygous vein, right lung
– Left side:
• Superior med.: Lt. subclavian artery, aortic arch, Lt. lung
• Inferior med.: descending aorta, Lt. lung
(III): In the abdomen: 1-3 cm ; the phrenic ampulla lies just above the
cardia and may simulate hiatus hernia. The abdominal part is called
(submerged segment) and help to prevent reflux from the stomach.
Other factors: Acute gastro-oesophageal angle,pressure of right crus
of the diaphragm and intrinsic muscles sphincter.
Stomach
◙ Shape: J-shaped, but may varies (volume, position, resp., build)
◙ 2 Orifices:
1.
2.
Cardiac
Pyloric
◙ 2 Curvatures:
1.
2.
Lesser
Greater
◙ 3 Parts:
1.
Fundus (air bubble)
2.
3.
Body
Antrum
◙ Mucosa: gastric rugae
- Longitudinal: on lesser curvature
- Random (mosaic): elsewhere
◙ Muscles:
1.
2.
3.
Outer: longitudinal
Inner: circular
Innermost: oblique
Relations of the Stomach
◙ Anterior:
–
–
–
–
Diaphragm
Left lobe of the liver
Left costal cartilage
Anterior abdominal wall
◙ Posterior (stomach bed):
–
–
–
–
–
–
Diaphragm
Left suprarenal gland
Left kidney
Pancreas
Spleen and splenic artery
Transverse colon and Splenic Flexure.
◙ Stomach lie: The fundus of the stomach is located posterioly while the pyloric
antrum is very near to the anterior abdominal wall; so with barium studies(1) In the
erect position: Air fluid level seen.(2) Supine: barium fill the fundus while pyloric
region is seen in double contrast.(3) Prone: barium fill the pylorus while the fundus is
seen in double contrast.
◙ Incisura: is that part of the stomach where there is sudden change in the plan of the
stomach from the vertical to the horizontal; it help to show whether the stomach is
eutonic, hypertonic or hypotonic according to its level in comparison with the 1st part
Small intestine
◙ Extension:
From pyloric orifice of stomach to ilio-caecal valve
◙ Length:
6 meters (range, 3-10)
◙ 3 Parts:
1.
Duodenum
2.
Jejunum
3.
Ileum
◙ Movements:
1.
Rhythmic
2.
Pendular
3.
Peristaltic
Duodenum
◙ C-shaped around the head of pancreas
◙ The shortest
◙ The widest
◙ 4 parts:
1.
Duodenal bulb: 2 inches, level of L-1, conical shape
2.
Descending: 3 inches, level of L-2
3.
Transverse: 4 inches, level of L-3
4.
Ascending: one inch, level of L-2
NB: 1. Duodenal bulb (Cap): is a common site of ulcers. It likely seen better in the right
anterior oblique.
2. Descending part: forms a curve around the head of the pancreas; the common bile
duct and the pancreatic duct open by a common opening (ampulla of Vater) =
{duodenal papilla} : through it. The opening is surrounded by sphincter of Oddi.
3. During contrast examination; barium reach the duodenal cap after 5minutes, delay
emptying more than 15 minutes may be due to obstruction.
Relations of the Duodenum
1.
Duodenal bulb:
–
Superior and anterior: liver and
gall bladder
–
Inferior: head of pancreas
–
Posterior: common bile duct,
portal vein
2.
Descending:
–
Posterior: right kidney
–
Medial: head of pancreas
–
Lateral: colon (HF)
3.
Transverse:
–
posteriorly crosses (Rt. Psoas
muscle, IVC, aorta)
4.
Ascending:
–
Posterior: lt. Psoas, lt. renal
vein, inferior mesenteric vein)
–
Anterior: transverse colon
Small intestine: 6-7 m surrounded by the
peritoneum ,so it is freely mobile
Large intestine
◙ Length:
• 1.5 m
• Extend from ileum to anus
• Characteristic shape:
Haustrated appearance
caused by the longitudinal
Muscle fibers being shorter
Than the circular muscle
Fibers; they run usually in
Three bonds called:
taenia coli.
Large intestine
Parts
◙ Caecum:
◙ Colon:
◙ Rectum:
◙ Anal canal:
Caecum & Colon
◙ Caecum:
– 6 cm long,
– The widest (7.5-9 cm)
– Ilio-caecal valve (ICV):
posteromedial aspect
Appendix :
– 12-24 cm length,
retrocaecal (75%)
Caecum & Colon
◙ Colon:
Ascending:
– 15 cm length, HF ?
Transverse:
– 50 cm length, SF,
transverse mesocolon
Descending:
– 25 cm length, pelvic brim
Sigmoid colon:
– 40 cm length, S-shaped
– Most movable ; may be
Too long
Rectum & Anal canal
◙ Rectum:
– Level of 3rd sacral V. (2 cm ant. to tip of coccyx)
– 12 cm length
– S-shaped (upper, middle and lower thirds), valve of Houston
– Lower third: no peritoneal cover, dilated (rectal ampulla)
– Pre-sacral space: it is the space between the rectum and the sacrum(0.61.2cm)
◙
Examined by the lateral view during barium enema studies to detect tumors ,
crohn’s disease and ulcerative colitis.
Anal canal:
– Right angle with rectum
– Sphincters: internal (involuntary), external (voluntary)
– NB: The lower part of the rectum and the anal canal form two antero-posterior
curves (S-shape) this fact must be remembered when a rectal tube or enema is
inserted to avoid serious injury. This area also have rich supply with vagus nerve;
so sever stretch or extreme temperature may lead to shock.
Rectum & Anal canal
Biliary System
◙ Gall
Bladder:
◙ Biliary
Ducts:
Gall Bladder
◙ Pear-shaped sac
◙ Capacity: 50 cc (store conc. Bile secreted by the liver.
◙ Site: inferior surface, right lobe of the liver ; there is a wide range of variation of the gall
bladder position from the 1st lumber vertebra to the level of the 5th lumber vertebra ;
due to this position ; gall bladder stones overlaps the same area of right renal stones .
Right lateral view may help to differentiate since gall bladder stones will be thrown
anteriorly. NB: 15% only from gall bladder stones are radio-opaque.
Mechanism of bile secretion: Gall bladder contracts and secrete bile under the effect of
cholecystokinin enzyme stimulated by the presence of fats in the stomach.
◙ Size: 10 cm length, 3 cm width
◙ Parts:
1.
2.
3.
Fundus: anterior abdominal wall, 9th costal cartilage
Body: upward, backward and to the left
Neck:
•
Upward and forward, then sharply downwards
•
S-shaped,
•
Cystic duct (3 cm length),
•
Mucosa: spiral valve
Biliary Ducts
◙ Hepatic ducts: right and left
◙ Common hepatic duct: 3 cm length
◙ Common bile duct:
– Common hepatic + cystic duct
– 7 cm length
– Relations:
• Supra-duodenal part: in front
of portal vein
• Retro-duodenal: first part of
duodenum
• Retro-pancreatic:
– Unites with pancreatic duct:
enter 2nd part of duodenum
Pancreas
• 5" long / 1" thick
• Head close to curve in
•
•
C-shaped duodenum
pancreatic duct joins
common bile duct from
liver
Opens 4" below
pyloric sphincter
Regions:
Head, body, tail
AP ABDOMEN
STOMACH
COLON
SM. BOWEL
Normal abdominal gas pattern with air in the stomach and
scattered non-distended loops of large and small bowel.
Barium swallow, esophagus.
Oblique view
The normal impressions made by :
(A) aortic arch,
(B) left mainstem bronchus, and
(LA) left atrium on the esophagus.
Barium Meal
FUNDUS
DUODENUM
ANTRUM
BODY
JEJUNUM
C-LOOP
NORMAL
GASTRIC
ANATOMY
SPLENIC
FLEXURE
HEPATIC
FLEXURE
Barium Enema
DESENDING COLON
TERMINAL ILEUM
CECUM
NORMAL
COLON
CT abdomen
CT abdomen