Body wall

What are the 3 body cavities?

Thoracic

Abdominal

Pelvic

What are the five components of the abdominal cavity boundaries?

Diaphragm

Sternum

Caudal ribs

Lumbar vertebrae and fascia

Pelvis

Lumbodorsal fascia

deep fascia of the trunk

there are superficial and deep layers

Linea Alba

Ventral midline seam where tendonous sheets meet.

What do the abdominal muscles contain?

Viscera

How many abdominal muscles make up the lateral wall?

3

What do the abdominal muscles look like?

thin, sheet-like muscles

fibres run in different directions

Where do the abdominal muscles originate and insert?

Originate: lumbar vertebrae and fascia, caudal ribs, pelvis

Insert: ventral midline via tendonous sheets

Aponeurosis

Sheet of white tissue that takes the place of tendons in flat muscles to allow for a wider area of attachment

External abdominal oblique

most superficial

fibres run dorso-cranially to ventro-caudally

inserts on linea alba

Internal abdominal oblique

middle layer

fibres run dorso-caudally to ventro-cranially

inserts on linea alba

transversus abdominis

deep layer

fibres run dorso-laterally to ventro-medially

inserts on linea alba

rectus abdominis

ventral mid-line

runs in cranio-caudal direction

rib 1 and adjacent sternum to prepubic tendon

inserts on linea alba

what are the 2 peritoneal membranes?

parietal

visceral

Parietal peritoneum

lines the abdominal cavity

visceral peritoneum

covers the abdominal organs

peritoneal membrane properties

formed from lateral plate mesoderm

single cell thick serous membranes

produce peritoneal fluid - lubricates movement

potential space between 2 membranes is peritoneal cavity

What are the 2 roles of abdominal muscles?

static - supportive

dynamic - movement (respiratory, sneezing, coughing, vomiting, micturition, defecation, parturition, spinal flexion - rectus abdominis)

Heave-line

Line formed in an equine abdominal wall following chronic expiratory effort

What are the structures passing through the femoral canal?

psoas major

femoral a & v

femoral nerve

What are the structures passing through the inguinal canal in both sexes?

genitofemoral nerve

external pudendal artery and vein

caudal superficial epigastric artery and vein

What are the structures passing through the inguinal canal in a male only?

spermatic cord

cremaster muscle

What are the structures passing through the inguinal canal in a female only?

vaginal process

What is the clinical relevance of the inguinal canal?

Site of potential weakness in the muscle layers (especially in males)

breach results in an inguinal hernia

usually herniation of fat/gut

testicles can become lodged here during normal descent and must be surgically removed

What structure separates the abdominal and thoracic cavities?

diaphragm

Why do the muscle fibres run in different directions?

Makes the abdomen stronger

What is the origin and insertion of the thoracolumbar fascia?

Origin: Spinous processes of thoracic and lumbar vertebrae

Insertion: Fascia opposite the linea alba and caudal attachment to the ilium

What is the origin and insertion of the external abdominal oblique?

Origin: Middle of 4th to 12th rib and thoracolumbar fascia

Insertion: Linea alba and prepubic tendon

What is the action of the external abdominal oblique?

Supports the abdominal wall

What is the origin and insertion of the internal abdominal oblique?

Origin: Lumbar thoracolumbar fascia caudal to the last rib and the tuber coxae

Insertion: 12th and 13th rib and linear alba

What is the action of the internal abdominal oblique muscle?

Supports the abdominal wall

What is the origin and insertion of the transverse abdominis muscle?

Origin: 8th - 9th costal cartilage (last ribs), all lumbar transverse processes and tuber coxae

Insertion: linea alba

From and to where does the Linea alba run?

From xiphoid cartilage to cranial end of pelvic symphysis via prepubic tendon

What is the origin and insertion of rectus abdominis?

Origin: Cranial sternum and first costal cartilage

Insertion: Pecten ossis pubis

What is the action of the rectus abdominis?

Support and compression of abdominal viscera

Helps with expiration, urination, defecation, parturition etc.

Falciform ligament

Vertebral attachment of the liver

runs down to the umbilicus

What artery penetrates the craniodorsal abdominal quadrant?

left phrenico-abdominal artery

What artery penetrates the caudodorsal abdominal quadrant?

left deep circumflex iliac artery

What arteries penetrate the cranioventral abdominal quadrant?

deep and superficial left cranial epigastric arteries

What arteries penetrate the caudoventral abdominal quadrant?

deep and superficial left caudal epigastric arteries

What artery is this?

left internal iliac artery

What artery is this?

left external iliac artery

What artery is this?

left internal thoracic artery

What artery is this?

Aorta

What 3 structures lie within the femoral sheath?

Femoral artery

Femoral vein

Saphenous nerve

Where is the femoral canal located?

Slit like space between the femoral vein and pectineus muscle

Function of the femoral canal

allow femoral vein to expand during increased venous return

contains mainly loose connective tissue and lymphatics - no major vessels

Inguinal ligament

Thick fibrous band formed by aponeurosis of the caudal edge of external abdominal obliques