Abdominal Wall

Question 1

Abdominal Wall functions

Answer 1

-support and protect viscera
-locomotion and other movements (spinal flexion and lateral flexion, extension, and rotation)
-helps increases pressure in abdominal cavity (forces expiration, straining)

Question 2

Lumbar Vertebrae number per animal

Answer 2

-Dogs: 7 (sometimes 6)
-Cats: 7 (sometimes 6 or 8)
-Cattle: 6 (sometimes 7)
-Horses: 6 (sometimes 5 or 7)
-Pigs: 6 (sometimes 7)
-Goats: 6 or 7
-Sheep: 6 or 7

Question 3

Main components of lumbar vertebrae

Answer 3

-Spinous process
-Transverse process
-Body
-Vertebral arch
-Vertebral foramen
-Cranial articular process
-Caudal articular process

Question 4

Interspinous ligament

Answer 4

-present in some animals, especially horse and cow; not in carnivores
-Results in less flexion of spine
-connects lumbar vertebrae, and eventually becomes nuchal ligament

Question 5

Visible space of abdomen

Answer 5

-space depends on the structure of the last rib, not the number of lumbar vertebrae

Question 6

Erector spinae muscles

Answer 6

-epaxial
-dorsal part of lumbar vertebrae
-includes transversospinalis system, longissimus system, and iliocostalis system
-extension of spine

Question 7

Sublumbar muscles

Answer 7

-hypaxial
-ventral part of lumbar vertebrae
-includes psoas minor, psoas major, quadratus lumborum, iliopsoas

Question 8

Abdominal Wall muscles

Answer 8

-External abdominal oblique
-Internal abdominal oblique
-Transverse abdominis
-Rectus abdominis (“abs”)
-Cutaneous trunci (everywhere in dog, more ventral in larger animals)

Question 9

Arteries of abdomen

Answer 9

-cranial abdominal artery
-deep circumflex iliac artery (right beside lateral cutaneous femoral nerve)
-Cranial epigastric artery
-Caudal epigastric artery

Question 10

Spinal Nerve ventral branches on transversus abdominis

Answer 10

-T13, L1, L2 spinal nerves

Question 11

Rectus sheath

Answer 11

-sheath of rectus abdominis formed by the aponeuroses of transverse abdominis, external abdominal oblique, and internal abdominal oblique (transverse abdominis aponeurosis more caudally, and internal lamina mostly transverse abdominis aponeurosis except cranial to umbilicus which is internal abdominal oblique)

Question 12

Linea alba

Answer 12

-fibrous, white mid-ventral raphe between the xiphoid cartilage and ossa pubis that separates right and left rectus abdominis
-made of fascia and aponeuroses of the abdominal wall muscles

Question 13

What passes through the Inguinal Canal

Answer 13

-external pudendal artery and vein
-genitofemoral nerve
-lymph vessels draining the superficial inguinal lymph nodes
-cremaster muscle
-diverticulum of peritoneum (vaginal process in females, vaginal tunic in males)

Question 14

Inguinal canal parameters

Answer 14

-cranial border=caudal border of internal abdominal oblique
-medial border=lateral border of rectus abdominis
-lateral border=aponeurosis of external abdominal oblique
-caudal border=inguinal ligament (which is the thickened aponeurosis of external abdominal oblique)

Question 15

Paralumbar fossa

Answer 15

-created by last rib, transverse process, and part of the internal abdominal oblique that passes over the last rib to the linea alba creating distinct line

Question 16

Umbilical scar

Answer 16

-a weakness in the linea alba
-can result in hernias

Question 17

Linea alba importance in surgery

Answer 17

-poorly vascularized and innervated, making it the best incision site
-parietal pleura sticks to it and stays together even when cutting whereas it often peels away in other areas

Question 18

Falciform ligament

Answer 18

-bit of peritoneum, that during development took umbilical vein to liver and caudal vena cava.
-reason to cut slightly off midline to ensure you avoid it
-a lot of fat stored around this ligament

Question 19

Abdominal Wall Layers

Answer 19

1.Skin
2. External fascia of the trunk= Superficial fascia (cutaneous trunci) and Deep fascia
*deep fascia of ungulates is tunica flava
3.External abdominal oblique
4.internal abdominal oblique
5.Rectus abdominis
6.Transversis abdominis
7. internal fascia of trunk
8. Parietal peritoneum

Question 20

Abdominal Wall Blood supply order

Answer 20

-abdominal aorta
-Celiac artery –> hepatic artery, left gastric artery, splenic artery
-cranial mesenteric artery
-phrenic artery
-renal artery
-testicular artery
- caudal mesenteric artery
-deep circumflex iliac artery

Question 21

Abdominal Wall Nerve Supply

Answer 21

-spinal nerves give off ventral (muscles and skin ventral to transverse processes) and dorsal branch (supplies epaxial muscles and dorsal skin). Dorsal branch also has a ventral branch that extends ventrally

Question 22

Blocking abdominal cavity

Answer 22

-must block T13, L1, L2 (proximal NB) OR tips of L1, L2, L4 (distal NB) OR inverted L shape
-nerves come out caudally
-must ensure block of both ventral and dorsal branches

Question 23

Proximal paravertebral nerve block

Answer 23

-Find L5 (most prominent transverse process in ruminant) and count back
-find cranial edge of L2, go close to spinal cord and walk out slightly. Needle through the interspinous ligament
-repeat for L1, T13

Question 24

Distal paravertebral nerve block

Answer 24

-needle at tips of transverse process (not the cranial edge of vertebra anymore)
- to block same nerves, must block tips of L1, L2, and L4 because of where the nerves come out

Question 25

Deep inguinal canal

Answer 25

-caudal border of internal abdominal oblique
-lateral border of rectus abdominis
-inguinal ligament

Question 26

Superficial inguinal ring

Answer 26

-slit in aponeurosis of external abdominal oblique

Question 27

Vaginal ring

Answer 27

-site of parietal peritoneum invagination
-not present in female cats or ungulates

Question 28

Hernia and inguinal canal

Answer 28

-external oblique forms quite a small superficial inguinal ring
-internal oblique can form a slightly larger deep inguinal ring (very large in pig)
»vaginal ring can be stretched out easily by intestines and result in hernia
*large problem in pigs because their ring is already larger