Anatomy- Gut wall Flashcards
How are the abdominal and pelvic cavities separated?
They are continous except for the presence of the pelvic brim/inlet
List the 9 regions of the abdomen, from superior to inferior
- Right hypochondrium
- Epigastric
- Left hypochondrium
- Right lumbar(/flank)
- Umbilical
- Left lumbar(/flank)
- Right iliac(/groin)
- Hypogastric(/suprapubic)
- Left iliac(/groin)
How can the abdomen be divided?
- 9 regions
- 4 quadrants
Describe the contents of the abdominal wall from superficial to deep
- Skin
- Subcutaneous fat
- Campers fascia
- Scarpas fascia
- External oblique
- Internal oblique
- Transversys abdominis
- Extraperitoneal fat
- Endoabdominal fat
- Parietal peritoneum
Describe how the campers fascia and scarpas fascia differ in structure
- Campers fascia is fatty layer of subcutaneous tissue
- Scarpas fascia is deep, membranous layer of subcutaneous tissue
List the muscles in the anterior wall of the abdomen
Paired rectus abdominis muscles within the rectus sheath
List the muscles in the lateral wall of the abdomen
- External oblique
- Internal oblique
- Transversus abdominis
List the muscles in the posterior wall of the abdomen
- Post vertebral muscles (erector spinae)
- Psoas, quadratus lumborum and iliacus muscles
What is another name for the muscles making up the lateral wall of the abdomen?
Flank sheet muscles
List the function of the flank sheet muscles
- Compress the abdomen, increasing the intra-abdominal pressure to aid expiration, evacuation of urine, faeces, partuition, heavy lifting
- Supports viscera (mainly intestines)
- Flex and rotate the trunk
List the attachments of the external oblique
- External surface of lower 8 ribs
- Free posterior border
- Fans out to attach to the xiphoid process, linea alba, pubic creast & tubercle, anterior half of the iliac crest
Describe the direction of the muscle fibres in the external oblique
Downward and outward
Describe where the aponeurosis of the external oblique attaches to, and the structure it forms
- Fuses medially with the rectus sheath
- Lower edge rolls inwards to form the inguinal ligament
List the lateral attachments of the internal oblique
- Thoracolumbar fascia
- Iliac crest (anterior 2/3rd)
- Inguinal ligament (lateral half)
List the medial attachments of the internal oblique
- Lower 3 ribs and costal cartilages
- xiphoid process
- Rectus sheath
- Conjoint tendon
Describe the direction of the internal oblique
Downward and backward
List the lateral attachments of the transversus abdominis
- Lower 6 costal cartilages
- Thoracolumbar fascia
- Iliac crest (anterior 2/3rd)
- Inguinal ligament (lateral 2/3rd)
List the medial attachments of the transversus abdominis
- xiphoid process
- Linea alba
- Symphysis pubis
- Conjoint tendon
- Neurovascular plane lies between the internal oblique and transversus absominis
Describe the direction of muscle fibres in the transversus abdominis
Horizontally
List the attachments of the rectus abdominis
- Lateral attachment to the linea semilunaris
- Superior attachment to 5-7 costal cartilages and xiphoid process
- Inferior attachment to the symphysis pubis and pubic crest
- Meets at the linea alba (midline)
What is the rectus sheath, and how does its structure change?
- The rectus sheath is formed by the aponeuroses of 3 muscles
- Above the umbilicus, the internal oblique aponeurosis splits to enclose the rectus abdominis, while the external oblique is infront and the transversus behind the rectus muscle
- Below the umbilicus all 3 aponeurotic layers are anterior to the rectus muscle
What is the function and attachment of the psosis major?
- Attachment to bodies and discs of all 5 lumar vertebrae and the lesser trochanter of femur
- Acts as the flexor of the hip and trunk
What is the function and attachment of the quadratus lumborum?
- Attachment to the lower border of 12th rib and transverse process of 5th lumbar vertebra and adjacent iliac crest
- Stabilises the 12th rib and acts as a lateral flexor of the trunk
Describe the blood supply of the rectus muscle
- Superior epigastric artery (terminal branch of internal thoracic)
- Inferior epigastric artery (branch of external iliac)
- Enter the rectus sheath and anastomose to form a bypass to the abdominal aorta
Describe the blood supply of the flank muscles
- Segmentally supplied
- Intercostal arteries 7-11
- Subcostal artery
- Lumbar arteries
- Deep circumflex iliac arteries
What is the neurovascular plane of the abdominal wall?
Between the internal oblique and transversus abdominis muscle
List the motor nerves supplying the abdominal wall
- Segmentally supplied by T7-T12 and L1
- External oblique is supplied by T7-T11
- Internal oblique and transversus by T7-T12&L1
- Rectus by T7-T12
What are the dermatomes in the abdomen?
T7 - epigastrum
T10 - umbilicus
L1 - inguinal ligament
Compare the innervation of the parietal and visceral peritoneum.
- Parietal supplied by the same nerves as the part of the body wall it is covering
- Visceral has no somatic sensory innervation
Describe the nerves supplying the antero-lateral abdominal wall
- Subcostal nerve (T12)
- Iliohypogastric (L1)
- Iliolingual (L1)
Describe the motor supply to the posterior abdominal wall
- Quadratus lumorum T12 & L1-4
- Psoas major L2-4
- Iliacus (femoral nerve) L2-4
Describe the significance of the lumbar plexus (L1-4) in the abdomen
- Mainly for the lower limb
- Sensory branches to the parietal peritoneum of the posterior abdominal wall
Describe the lymohatic drainage on the abdominal wall
No drainage
Describe the lymphatic drainage of the superficial tissues
- Superficial lymphatics accompany veins
- Drainage occurs in quadrants
- Above the transumbilical plane, there is drainage to axillary nodes
- Below the transumbilical plane there is drainage to the superficial inguinal nodes
Describe the lymphatic drainage of deeper tissues
- Deep lymphatics accompany deep veins in the extraperitoneal tissues
- Above the transumbilical plane there is drainage to mediastinal nodes
- Below the transumbilical plane there is drainage to external iliac and para-aortic nodes
What is the inguinal region?
- The junction between the anterior abdominal wall and the thigh
- Between the anterio-superior illiac spine and the pubic tubercle
Why is the inguinal region important?
- Clinically important as it is weak so a potential site for hernias
- Anatomically important because structures enter and exit the abdominal cavity
Describe the anatomy of the inguinal canal
- ASIS to pubic tubercle
- Deep inguinal ring is superior
- Superficial inguinal ring is inferior.
- Formed due to the descent of the testes and spermatic cord in males, and the uterine round ligament in females
- Bigger in males
Describe the structure of the femoral canal
- Only has lymphatics running through it
- Lateral to the inguinal canal
- The accompanying artery and vein are inside of the femoral sheath, with the nerves outside of the sheath
Define hernia
A condition in which part or whole of an organ or tissue abnormally protrude through the wall of the structure containing the organ or tissue.
Describe the basic structure of a hernia
- Intestinal loop in the hernial sac
- Weakness in the wall
List the clinical signs and symptoms of a hernia
- A lump or protrusion in the groin
- Appears intermittently or present all the time
- Painless/painful and uncomfortable
- Hernia may be reducible or irreducible
- May be strangulated with tissue death- and associated with vomiting, constipation, intestinal obstruction – this is an emergency situation
List and describe the types of inguinal hernia
- Indirect (congenital) inguinal hernia pass through the deep and superficial ring of the iliac canal, going through the hesselbach’s triangle (medial to internal epigastric vessels)
- Direct (acquired) inguinal hernias pass through only the superficial ring, lateral to the inferior epigastric vessels
Describe the location of the inguinal canal
- 4cm long
- Lies above the medial half of the inguinal ligament
- Deep inguinal ring (hole in the transversalis facia) to superficial (hole in external oblique aponeurosis
- Deep ring 1.5cm above midpoint of inguinal ligament
- Superficial ring immediately above and medial to the pubic tubercle
List the contents of the inguinal canal
- Illiolingual nerve and genital branch of genito-femoral nerve (in males and females)
- In males spermatic cord
- In females round ligament
What is the anterior wall of the inguinal canal?
- External oblique aponeurosis (whole length)
- Internal oblique muscle reinforces the lateral 3rd of the canal
What is the floor of the inguinal canal?
Inguinal ligament (stretches between ASIS and pubic tubercle)
What is the roof of the inguinal canal?
- Arching fibres of the internal oblique muscle and transverse abdominis muscle (whole length)
- Medially conjoint tendon, formed of the internal oblique and transversus abdominis aponeurosis joining
What is the posterior wall of the inguinal canal?
- Transversalis fascia
- Medially conjoint tendon
List the causes of a direct inguinal hernia
- Older age group
- Caused by straining/weak musculature
- An acquired defect in the posterior wall of the inguinal canal
List the borders of Hasselbach’s triangle
- Rectus abdominis
- Inguinal ligament
- Inferior epigastric vessels
List the causes of indirect inguinal hernia
- Most common type
- Tend to be in younger adults and children
- The defect is a dilated deep ring
- The hernia enters the deep ring then passes through the inguinal canal, external inguinal ring and into the scrotum
List the characteristics of femoral hernias
- Hernia through the femoral canal
- Not as common as inguinal hernias
- Commoner in elderly and females
- Have a high incidence of obstruction and strangulation
- Irreducible
- Below and lateral to the pubic tubercle
List the borders of the femoral canal
Superior – Inguinal ligament
Inferior – Pectineus fascia
Medial – Lacunar ligament
Lateral – Femoral vein
Describe the location of inguinal hernias
Above and medial to the pubic tubercle
How can the borders of the inguinal canal be remembered?
M - Muscle (transversalis abdominis and internal oblique) ROOF
A - External oblique aponeurosis ANTERIOR
L - Inguinal ligament and lacunar ligament FLOOR
T - Transversalis fascia and conjoint tendon POSTERIOR
Compare the pathway of the inguinal ligament to the pathway of the inguinal canal
- Inguinal ligament passes from the ASIS to the pubic tubercle
- Inguinal canal passes from the ASIS to the pubic symphysis
