Abdomen and GI tract

Question 1

Wall: lateral and anterior

Answer 1

4 muscles:
- external oblique
- internal oblique
- transversus abdominis
- rectus abdominis

Question 2

Superficial layer

Answer 2

Skin (1), Subcutaneous tissue
Camper’s fascia, fatty (2), Scarpa’s fascia,
membranous (3)

Question 3

Deep layer

Answer 3

Muscles (4,5,6,10) enclosed in
investing fascia
- Transversalis fascia – situated
deep to abdominal muscles (7)
- Extraperitoneal fat – variable
amount (8)
- Parietal peritoneum (9)

Question 4

Vessels of Anterolateral Abdominal Wall

Answer 4

• Superior epigastric vessels (branches of
  internal thoracic vessels)
• Inferior epigastric vessels (branches of
  external iliac vessels)

Question 5

Muscles of Anterolateral Abdominal Wall obliques

Answer 5

External oblique (#4) - fibers run supero-medially, flexes and rotates the trunk, works with internal oblique
Internal oblique (#5) - fibers run perpendicular to those of external oblique.
flexes and rotates the trunk, works with external oblique

Question 6

Muscles of Anterolateral Abdominal Wall: abdominis

Answer 6

Transversus abdominis (#6) - fibers run horizontally, no skeletal movement, horizontal orientation does not permit flexion or lateral bending, primarily raises intra-abdominal pressure
Rectus abdominis (#10) - paired muscles separated by linea alba, attachments on pubic symphysis inferiorly and XP and CC 5-7 superiorly, contained within rectus sheath, fused aponeuroses of 3 flat abdominal muscles

Question 7

AM movements

Answer 7

Rectus abdominis- flexes the trunk
External and internal obliques- flex & rotate the trunk
Transversus abdominis- no skeletal movement, horizontal orientation does
not permit flexion or lateral bending, primarily raises intra-abdominal pressure

Question 8

DS overview

Answer 8

alimentary canal (GI tract) - mouth, pharynx, and esophagus, stomach, small intestine, and large intestine (colon)
accessory digestive organs - teeth and tongue, salivary glands, liver, gallbladder, pancreas

Question 9

Chewing apparatus

Answer 9

Mandible: Lower Jaw
Maxilla: Upper Jaw, Hard Palate
Mastication: mandible, chewing, mandibular branch of the trigeminal nerve (CN V3)

Question 10

Chewing

Answer 10

Temporalis muscle – Elevates mandible; retracts mandible
Masseter muscle – Elevates mandible, limited protrusion of mandible
Lateral Pterygoid muscle – Protracts mandible; produces lateral chewing motions
Medial Pterygoid muscle – Elevates mandible (working with masseter);
provides more subtle grinding motion

Question 11

Tongue

Answer 11

lies partly in the oral
cavity and partly in the oropharynx, taste and speech, highly mobile and assists in chewing and swallowing

Question 12

Extrinsic muscles of tongue

Answer 12

• genioglossus – tongue protraction
• hyoglossus – tongue depression
• styloglossus – tongue retraction and elevation
  Hypoglossal Nerve (motor), CN XII

Question 13

Deglutition

Answer 13

process that transfers the food bolus from
the oral cavity (mouth) through the oro-pharynx, into the pharynx and
eventually through the esophagus into the stomach

Question 14

Swallowing

Answer 14

1. bolus of food is squeezed back into OC, pushes tongue against palate
2. NP sealed off by epiglottis, larynx elevates, enlarged pharynx gets food
3. pharyngeal constrictors contract, squeeze food into esophagus
4. bolus of food moves down it by peristaltic contractions

Question 15

Palate muscles

Answer 15

Tensor veli palatini: Tenses SP opens pharyngotympanic tube during swallowing
Levator veli palatini: elevates SP during
swallowing
Palatoglossus: elevates P part of tongue
Palatopharyngeal: tenses SP pulls walls of
pharynx superiorly, anteriorly and medially during swallowing

Question 16

Esophagus

Answer 16

muscular tube propels food into stomach, pharynx continuation, descends inferior through thorax, voluntary (striated) muscle in the upper 1/3 and involuntary (smooth) muscle in the lower 1/3. A mixture of muscle fibers in middle 1/3, Vagus (CN X)

Question 17

Esophagus and abdominal cavity

Answer 17

pierces through diaphragm, terminates at the esophago-gastric junction where contents dump into cardial portion of stomach

Question 18

Stomach

Answer 18

Mobile intraperitoneal muscular organ, S part of peritoneal cavity, mechanical breakdown of food churned into chyme by peristalsis, chemical breakdown of proteins via acids and enzymes, gastric fluids slowly convert food mass into a liquid mixture which passes to the duodenum

Question 19

Stomach features

Answer 19

1. cardiac region – at the junction with the esophagus
2. fundus – the stomach’s dome
3. pylorus – termination of the stomach
4. greater curvature – convex, lesser curvature – concave
5. rugae – longitudinal folds that allow distention

Question 20

Small intestine

Answer 20

convoluted tube that runs from the pyloric sphincter of the stomach to the large intestine, 2.7 - 5 m. Longest part of alimentary canal: site of most enzymatic digestion and all nutrient absorption, duodenum, jejunum, and ileum

Question 21

Duodenum

Answer 21

5% of total length of small intestine:
- shortest, widest, and most fixed portion
- mostly secondarily retroperitoneal
- a complex organ receiving digestive enzymes from the pancreas (via the main
pancreatic duct) and bile from the liver and gallbladder (via the bile duct)

Question 22

Jejunum and Ileum

Answer 22

Jejunum - begins at duodenojejunal
junction, 40% of total length
Ileum - ends at ileocecal junction, 55% of total length

Question 23

SI walls

Answer 23

circular folds (plicae circulares)
- transverse ridges of the
mucosa and submucosa
- villi – finger-like projections

Question 24

Large intestine

Answer 24

Last major organ of alimentary
canal, absorbs water and electrolytes, cecum (vermiform appendix), colon: ascending, transverse, descending, sigmoid, rectum, and anal canal

Question 25

LI features

Answer 25

- Teniae coli: 3 thickened bands of longitudinal smooth muscle fibers - Haustra: sacculations or pouches of the colon between the teniae - Omental appendices: small, fatty appendices or projections of visceral peritoneum - Caliber: much larger internal diameter compared to small intestine

Question 26

Anus

Answer 26

- Rectum: fixed terminal part of LI continuous with the sigmoid colon at S3 vertebral level. - Anal canal: last subdivision of large intestine: - internal anal sphincter (involuntary) - external anal sphincter (voluntary) - anal columns: rectal vessels - pectinate line

Question 27

Pectinate line

Answer 27

Marks the junction between gut tube and body wall. * Structures above line are innervated by visceral motor and sensory fibers; veins drain into the portal VS * Structures below the line are innervated by somatic motor and sensory fibers; veins drain into the caval VS

Question 28

Liver

Answer 28

largest internal organ and gland in body, intraperitoneal, every substance absorbed by the alimentary canal (except lipids), 1st to liver, metabolic functions, storage of glycogen, bile secretion

Question 29

External liver

Answer 29

right, left, caudate, quadrate Porta hepatis: passage of the hepatic portal vein, hepatic artery, hepatic ducts, hepatic nerve plexus, and lymphatics Falciform ligament - binds the liver to the anterior abdominal wall

Question 30

External liver part 2

Answer 30

- Round ligament (ligamentum teres): extends from umbilicus to the liver, obliterated remnant of UV that carried O2 blood from the placenta to fetus. - Ligamentum venosum: a cord remnant of the ductus venosus that shunted blood from the UV to the IVC, attached to the P aspect of liver fissure

Question 31

Gallbladder

Answer 31

muscular sac occupies gallbladder fossa, stores and concentrates bile -> absorbs water and salts, expels bile into duodenum, Right and left hepatic ducts drain right and left portal lobes of liver, unite to form common hepatic duct joined by cystic duct on right side to form bile duct

Question 32

Pancreas

Answer 32

accessory digestive organ, lies retroperitoneally in C- shaped curvature of duodenum, main pancreatic duct joins bile duct from the gallbladder, both empty in duodenum

Question 33

Mesentery

Answer 33

2x layer of peritoneum, extends from body wall to digestive organs, holds the organs in place, provides a route for circulatory vessels and nerves, length determines motility of an organ

Question 34

Mesenteries

Answer 34

Lesser omentum – runs from the liver stomach. Greater omentum – links inferior surface of stomach to adjacent organs, enlarged and covers small and parts of LI, highly mobile, may form adhesions around inflamed organs

Question 35

Omentum and ligament

Answer 35

Omentum – a 2x layer extension of peritoneum attaching stomach and first part of the duodenum to adjacent organs Ligaments - two layers of peritoneum that connect 2 organs to each other or an organ to the abdominal wall, may transmit neurovascular structures

Question 36

Ligament types

Answer 36

- hepatoduodenal ligament -hypogastric ligament - falciform ligament (liver to anterior abdominal wall) - splenorenal ligament (spleen to left kidney)

Question 37

Gut tube divisions in yolk sac

Answer 37

1. foregut- rise to the esophagus, stomach, pancreas, duodenum, liver, and bile ducts 2. midgut: SI distal to the bile duct, cecum, appendix, ascending and most of transverse colon 3. hindgut: remainder of the colon

Question 38

Blood supply in oral cavity

Answer 38

branches of the external carotid artery supply O2 blood to viscera, muscles and glands of OC, via branches such as the lingual, facial, superior thyroid and maxillary

Question 39

Arterial Supply of the Alimentary Tract

Answer 39

supply to the abdominal part of the alimentary tract, spleen, liver, gallbladder, and pancreas is derived from the abdominal aorta: celiac trunk, superior mesenteric artery (SMA), Inferior Mesenteric artery (IMA)

Question 40

Venous drainage of AT

Answer 40

main channel of PVS is the hepatic PV, formed by the union of the superior mesenteric and splenic veins, PVS collects blood from abdominal part

Question 41

Enteric nervous system

Answer 41

gut's brain, continuation of ANS, in alimentary canal, within walls,

Question 42

Enteric neurons

Answer 42

Within the wall of the alimentary canal, these form reflex arcs of sensory, interneuron and motor neurons that control the muscular and secretory functions of the digestive tract organs

Question 43

Enteric neuron locations

Answer 43

- Myenteric plexus is located in the SM (muscularis externa), this plexus controls peristalsis. - Submucosal plexus is located in the submucosal layer, this plexus controls secretion of GI glands and the muscularis mucosae

Question 44

Muscularis externa

Answer 44

SM of tubular organs, composed of 2 layers with muscle fibers running in opposite directions. This muscle powers peristalsis

Question 45

Muscularis mucosae

Answer 45

thin layer of SM in mucosal layer, assist with secretion by compressing glands (Goblet cells) and can assist movement across the surface of the mucosal epithelium

Question 46

ENS Innervation

Answer 46

Vagus and Splanchnic nerves transmit afferent (sensory) signals to the CNS. - Visceral motor fibers from the ANS (Postganglionic S, Pre/ Postganglionic PS) synapse on the enteric neurons S inhibits digestive function PS stimulates digestive function