Anatomy: Know Your Abdomen

Glossary

Abdomen - part of the body below the thorax (chest cavity); separated by the diaphragm. Anterior - towards the front of the body. For example, the umbilicus is anterior to the spine. Appendix - blind ended pouch. Autonomic nervous system – part of the nervous system responsible for functions we are not consciously aware of, such as heart rate and digestion. Aponeurosis – thin, flat fibrous sheath that replaces tendon for thin flat muscles.

Bile - yellow/brown fluid produced and secreted by the liver and stored in the gallbladder. Aids digestion of lipids (fats).

Conjoint tendon – the posterior wall of the inguinal canal directly behind the superficial inguinal ring formed by the union of the internal oblique and transversus abdominis muscles. CT – computerised topography. A method of using x-rays to examine the internal structures by rotating the x-ray source around the body.

Dorsal – this term relates to the ‘back’ of an organism. For humans this is similar to ‘posterior’ and is used more when describing embryological development. Distal – far from the centre of the body or point of attachment. For example, the wrist is distal to the elbow. Duodenum - the first part of the small intestine. It is continuous with the stomach and jejunum (second part of the small intestine), so food will pass from stomach to duodenum to jejunum. Duodenal papillae - small round elevations in the mucosa of the second part of the duodenum. There are two duodenal papillae, major and minor. The major papilla is also known as the ‘Papilla of Vater’. The major duodenal papilla is where the ampulla of Vater (joining of pancreatic duct and common bile duct) opens into the duodenum, allowing bile and enzymes to be delivered to facilitate digestion. The minor duodenal papilla allows the accessory pancreatic duct to drain enzymes into the duodenum. It is also in the second part of the duodenum, 2cm proximal to the major papilla.

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Enteric nervous system – similar to the autonomic nervous system, a mesh of neurones embedded in the lining of the gastrointestinal tract. Responsible for digestive function.

Foregut – the first part of the digestive system, from the mouth to the duodenal papillae in the 2nd part of the duodenum.

Gall bladder – a pouch like structure that stores bile. Ganglia – a collection of nerve cell bodies in the peripheral nervous system. Greater omentum – a double layer of peritoneum that extends from the stomach to the transverse colon, spleen and diaphragm. Comprised of the gastrocolic, gastrosplenic and gastrophrenic ligaments. The gastrocolic ligament is usually synonymous with the greater omentum and has an important role in acting as a heat insulator and can help limit the spread of infection. It is often referred to as the policeman of the abdomen.

Hernia – protrusion of an organ/tissue from its normal position through the wall that contains it (i.e., inguinal hernia – fat or bowel covered in peritoneum passes through a weakened portion of the abdominal wall in the inguinal region). Hindgut – distal 1/3rd of transverse colon to pectinate line in the anal canal. Histology - the study of tissue structure using stains and microscopy.

Inferior – this term relates to something being lower in the vertical plane. For example, the heart is inferior to the neck.

Inguinal – groin region.

Inguinal canal – a pair of oblique passageway on either side of the abdomen formed from the complex arrangement of anterior abdominal wall muscles. It permitted the testes to pass from the abdominal cavity to the scrotum during development.

Inguinal ligament – the inferior free edge of the external oblique muscle. It forms the floor of the inguinal canal.

Interdigitate - the interlocking arrangement of the aponeuroses from the anterior abdominal wall muscles in the midline.

Intraperitoneal organ – an organ that is surrounded by peritoneum and is typically suspended from the posterior abdominal wall by a peritoneal ligament of mesentery (double layer of mesentery). 2

Kidneys – a paired organ that is positioned along the posterior abdominal wall either side of the aorta. The kidneys are responsible for maintaining the acid-water balance of the body.

Lateral – away from the midline. For example, the little toe is lateral to the big toe.

Large intestine – the portion of the gastrointestinal tract that is continuous with the ileum of the small intestines. It consists of the caecum, ascending colon, transverse colon, descending colon and sigmoid colon.

Lesser omentum – a double layer of peritoneum that passes from the lesser curvature of the stomach and duodenum to the liver. Comprised of the hepatogastric and hepatoduodenal ligaments.

Liver – the largest gland of the body located within the right hypochodirum and epigastrium of the abdomen. It carries out a number of important functions related to metabolism and digestion.

Medial – towards the midline. For example, the eyes are medial to the ears.

Mesentery – a double layer of peritoneum that suspends an organ from the posterior abdominal wall.

Midgut - 2nd part of the duodenum (distal to the duodenal papillae) to 2/3rds of the transverse colon.

Oesophagus – a muscular tube that extends from the throat (pharynx) to the stomach.

Papillae - a small rounded elevation.

Pancreas – a leaf shaped gland that is positioned posterior to the stomach. It has exocrine and endocrine functions.

Peritoneal ligament – a double layer of peritoneum that passes between the organs or from an organ to the abdominal wall.

Peritoneum – a serous membrane that lines the abdominal walls (parietal peritoneum) and organs (visceral peritoneum).

Plexus - a network of autonomic nerve fibres.

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Porta hepatis – an opening on the visceral surface of the liver that contains the hepatic portal vein, hepatic artery and hepatic ducts.

Portal triad – the collective name for the hepatic portal vein, hepatic artery and bile duct within the free-edge of the hepatoduodenal ligament.

Posterior - towards the back of the body. For example, the spine is posterior to the heart.

Proximal – close to the centre of the body or point of attachment. For example, the knee is proximal to the ankle.

Rectus sheath - the arrangement of aponeuroses around the rectus abdominis muscle.

Renal pelvis – the dilated proximal portion (beginning) of the ureter that passes through the renal hilum.

Retroperitoneal organ – an organ that has a covering or peritoneum over its anterior surface only and is not suspended.

Small intestines – the portion of the gastrointestinal tract that is continuous with the stomach. It consists of the duodenum, jejunum and ileum.

Splanchnic nerve – a nerve associated with the autonomic nervous system (i.e., parasympathetic or sympathetic).

Spleen – an ovoid shaped organ located in the left hypochondrium. Involved in the immune response, filtering dead red blood cells and acts as a reservoir of blood.

Stomach - a J-shaped muscular bag that is the direct continuation of the oesophagus and leads to the duodenum. It is composed of the cardia, fundus, body and pylorus. It is responsible for mechanically churning the food and via the gastric juice begins the chemical breakdown of the ingested food into a semi-liquid chyme.

Superior – this term relates to a structure being higher in the vertical plane. For example, the head is superior to the neck.

Suprarenal gland – a paired gland that is associated with the superior pole of each kidney. Each gland has an outer cortex and an inner medulla. The cortex releases corticosteroids. The medulla release adrenaline and noradrenaline.

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Thorax – the chest cavity, separated from the abdominal cavity by the diaphragm.

Umbilicus – the ‘belly button’, where the umbilical cord was attached to the foetus.

Ventral – this term relates to the ‘belly’ of an organism. For humans this is similar to ‘anterior’ and is used more when describing embryological development.

Vagus – the tenth cranial nerve that provides parasympathetic innervation to the foregut and midgut.

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