Abdomen Flashcards
Abdominal boundaries
Superior: Diaphragm
Inferior: Pelvis
Posterior: Vertebral column and posterior and inferior ribs
Lateral: Muscles of the flank
Anterior: Abdominal muscles
Three distinct spaces in the abdomen
- Peritoneal Space -
Organs covered by abdominal (peritoneal) lining - Retroperitoneal Space
Organs posterior to the peritoneal lining ***most damage occurs - Pelvic Space
Organs contained within pelvis
Structure of abdominal cavity
Superiorly it is formed by diaphragm which separates the abdominal cavity from the thoracic cavity
Inferiorly the abdominal cavity is continuous with the pelvic cavity through the pelvic inlet
Structure of abdominal wall
Anteriorly:
The abdominal wall is formed above by lower part of the thoracic cage
Below by the rectus abdominis, external oblique, internal oblique, and transversus abdominis muscles and fasciae
Structure of anterior abdominal wall
It is made up of skin, superficial fascia, deep fascia, muscles, extraperitoneal fascia and parietal peritoneum
The abdominal walls are lined by a fascial envelope and the parietal peritoneum
Muscles of the abdominal wall
- Rectus abdominus
2.External Obliques - Internal Obliques
- Transverse Abdominus
Rectus Abdominis - Origin and insertion
Inferiorly - attached by two tendons;the larger one is attached to the pubic crest, from the pubic tubercle to the pectineal line, while the small, medial tendon is attached to the pubic symphysis
Origin- Pubic symphysis, pubic crest
Insertion- Xiphoid process of sternumandcostal cartilages of the 5th, 6th and 7th ribs
Rectus Abdominis - Blood Supply
Inferior and superior epigastric arteries
Rectus Abdominis Innervation
Innervated by the thoracoabdominal nerves, which enter the rectus sheath by piercing its anterior surface.
They pass between the transversus abdominis and internal oblique muscle layer and pierce the sheath of the rectus abdominis muscle.
The nerves are simply the anterior divisions of the 7th to 11th lower intercostal nerves, that continue to supply the abdominal wall after the intercostal spaces they supplied end medially.
External Oblique - Origin, insertion, action
Origin:(proximal attachments) External surfaces of ribs 5-12.
Insertion:(distal attachments) Anterior iliac crest and abdominal aponeurosis to Linea alba.
Action:
Flexes the Vertebral Column (draws Thorax downward)
Rotates the Vertebral Column
Laterally Flexes the Vertebral
Column`
Internal Oblique - origin /insertion
Origin: (proximal attachments)
Anterior iliac crest, lateral half of inguinal ligament, and thoracolumbar fascia.
Insertion: (distal attachments)
Costal cartilages of ribs 8-12; abdominal aponeurosis to Linea alba.
Transverse Abdominis origin
The transversus abdominis originates from multiple locations in the body, which include:
Costal margin: inner surface of costal cartilage and ribs 7-12.
Thoracolumbar fascia: large, diamond-shaped sheet of connective tissue located at the lower back
Front two-thirds of iliac crest: top border of the pelvic bone. Outer third of the inguinal ligament: a band of connective tissue the extends diagonally down the front of the pelvis
Transverse abdominis Insertion
Linea alba: fibrous band of connect tissue that runs down the front of the abdominal wall
Pubic symphysis: connective tissue that joins the left and right sides of the lower, front pubic bone
Xiphoid process: hardened cartilage that extends off the bottom of the sternum (i.e. breast plate)
Transverse Abdominis Innervation
The transversus abdominis is innervated by several nerves, which include:
Lower five intercostal nerves:
The intercostal nerves are a collection of nerves that originate from the spinal cord in the first eleven thoracic vertebrae (T1-T11). The transversus abdominis is innervated by the lower five of these intercostal nerves (T7-T11).
Subcostal nerve: A nerve that originates from the spinal cord in the bottom thoracic vertebrae (T12).
Iliohypogastric nerve: A branch of the lumbar plexus, which is a network of nerves in the lower back. Nerve fibers of the iliohypogastric nerve originate from the L1 section of the spinal cord.
Ilioinguinal nerve: Another branch of the lumbar plexus that also originates from the L1 section of the spinal cord.
Blood supply of the abdominal skin areas
Skin near the midline is supplied by branches of the superior epigastric artery (br. of int. thoracic artery) and the inferior epigastric artery ( br. of external iliac artery)
Skin of the flanks is supplied by branches from the intercostal, lumbar, and deep circumflex arteries
Abdominal Venous Drainage
Venous blood is collected into a network of veins that radiate from the umbilicus
The network is drained above into the axillary vein via the lateral thoracic vein
Below into the femoral vein via the superficial epigastric and the great saphenous veins
Few small veins, the paraumbilical veins form a clinically important portal-system venous anastomosis.
Caput Medusae
The superficial veins around the umbilicus and the paraumbilical veins connecting them to the portal vein may become grossly distended in case of portal vein obstruction
The distended subcutaneous veins radiate out from the umbilicus, producing in severe cases the clinical picture called Caput Medusae.
** Can be liver issue, alcoholism,
liver tumor, cancer metastasizing and backing up into the venus system
Nerves of the anterior abdominal wall
supply the skin, muscles and the parietal peritoneum
They are derived from the anterior rami of lower six thoracic and the first lumbar nerves
Inflammation of parietal peritoneum causes pain in the overlying skin and also a reflex increase in tone of the abdominal musculature in the same area
Lymph drainage of the skin of the anterior abdominal wall
above the umbilicus is upward to the anterior axillary (pectoral group of nodes)
Below the level of umbilicus drains downward and laterally to the superficial inguinal nodes
Swelling in the groin is may be due to enlarged superficial inguinal node
Rectus Sheath- general
Is a long fibrous sheath
Encloses the rectus abdominis and pyramidalis muscle (if present)
Contains the anterior rami of lower six thoracic nerves and the superior and inferior epigastric vessels and lymph vessels
Formed mainly by aponeurosis of three lateral abdominal muscles
Three levels of the Rectus Sheath
- Above the costal margin the anterior wall is formed by the aponeurosis of the external oblique and posterior wall is formed by the thoracic wall
That is the 5th , 6th and 7th costal cartilages and the intercostal spaces
- Between the costal margin and the level of the anterosuperior iliac spine, the aponeurosis of the internal oblique splits to enclose the rectus muscle
The external oblique aponeurosis is directed in front of the muscle
Transversus aponeurosis is directed behind the muscle
- The posterior wall of the rectus sheath is not attached to the rectus abdominis muscle
The anterior wall is firmly attached to it by the muscle’s tendinous intersections
Digestive Tract Anatomy
- Esophagus:
Carries food/liquid to stomach - Small intestine:
Duodenum, jejunum, ileum - Large intestine:
Cecum, ascending colon, transverse colon, descending colon, sigmoid colon
3.Rectum and Anus
Retroperitoneal Structures
- Kidneys
- Adrenals
- Pancreas
- abdominal aorta
- IVC
- Nerve roots and lymph nodes
Visceral Pain
Stretching of hollow viscus or capsule of solid viscus
Visceral fibers enter the spinal cord at several levels leading to poorly localized, poorly characterized pain. (dull, cramping, aching).