How is the abdominopelvic cavity separated from the thorax and from each other?
Abdominal and pelvic cavity are continuous, with the diaphragm separating the 2 cavities.
Upper part of abdominal cavity extends beneath thoracic cage and the pelvic inlet/brim arbitrarily separates the abdominal from the pelvic cavity
What are the visceral structures present in the abdominopelvic cavity?
Stomach, duodenum, small/large intestines
Liver, pancreas, spleen
Kidneys, ureters, urinary bladder
What are the names of the 9 regions of the abdomen?
R/L hypochondriac regions, epigastric, R/L lumbar regions, ubilical, R/L iliac region, Suprapubic region
Why do we divide it into 9 regions?
To be able to understand where the pain may be coming from in the patient's deep anatomy
What are the 4 quadrants of the abdomen?
Transumbilical plane and midsagittal line separates it
What is the surface anatomy of the antero-lateral abdominal wall?
Costal margin, xiphoid process, iliac crest, ASIS, pubic symphysis/tubercle
Umbilicus, epigastric fossa
Rectus abdominis, linea alba and linea semilunaris
Abdominal wall muscle sheets
How are the abdominal wall layers of tissue organised?
What are the three flank sheet muscles, where are they present and what do they contribute to?
Obliques and Transversus abdominis
3 muscles are separate in flanks - 3 flat muscle fibres continue anteriorly as aponeurotic sheets
Contribute to the rectus sheath
What are the functions of the three flank sheet muscles?
Compress abdomen and increase the intra-abdominal pressure to aid expiration, evacuation of urine, faeces, parturition, heavy lifting
Supports viscera - guarding mainly the intestines
Flex and rotate the trunk
What is the external oblique attached to?
External surface of lower 8 ribs; free posterior border; fans out to attach to xiphoid process, linea alba, pubic crest/tubercle, anterior half of iliac crest
What is the inguinal ligament formed from?
Aponeurosis fuses medially with rectus sheath
Lower aponeurotic edge is rolled inwards and forms the inguinal ligament from ASIS to pubic tubercle
What is the internal obique attached to?
Laterally: thoracolumbar fascia, iliac crest (anterior 2/3rd), inguinal ligament (lateral half)
Medial: Lower 3 ribs and costal cartilage, xiphoid process, rectus sheath, conjoint tendon
Where is the Transversus abdominis attached to?
Lateral: lower 6 costal cartilages, thoracolumbar fascia, iliac crest (anterior 2/3rd), inguinal ligament (lateral 1/3rd)
Medial: xiphoid process, linea alba (rectus sheath), symphysis pubis, conjoint tendon
Where does the Rectus abdominis attach to?
Superior: 5-7 costal cartilages, xiphoid process
Inferior: Symphysis pubis, pubic crest
How is the rectus sheet formed and arranged?
Formed by aponeurosis of 3 muscles
Above umbilicus: internal oblique aponeurosis splits and encloses rectus abdominis, with the aponeuroses of external oblique in front and the transversus behind the rectus muscle
Below the umbilicus: all 3 aponeurotic layers are anterior to the rectus muscle
How is the rectus sheath formed?
By the aponeuroses of external/internal obliques and transversus abdominis muscles
What are the posterior wall muscles?
Diaphragm, Transversus abdominis, quadratus lumborum, psoas major, iliacus muscle
Where does Psoas Major attach to and what is its function?
Attaches at bodies and disks of all 5 lumbar vertebrae and lesser trochanter of femur
Flexor of hip and trunk
What are the attachments and the function of the Quadratus lumborum?
Attaches to lower border of 12th rib and transverse process of 5th lumbar vertebra and adjacent iliac crest
Stabilises 12th rib and a lateral flexor of the trunk
What is aponeurosis?
Sheet of pearly white fibrous tissue which takes the place of a tendon in sheet-like muscles having a wide area of attachment.
What is the blood supply of the rectus muscle?
Superior epigastric artery (terminal branch of internal thoracic), inferior epigastric artery (branch of external iliac)
2 vessels enter the rectus sheath and anastamose forming a potential bypass to abdominal aorta
What is the motor nerve and dermatomes supply to the abdominal wall?
Motor: Segmentally supplied T7-12 and L1
External oblique (T7-11), internal oblique/Transversus (T7-12 and L1), Rectus (T7-12)
Dermatomes: epigastrum (T7), umbilicus (T10), Inguinal ligament L1
What are the nerves that supply the posterior abdominal wall?
Subcostal nerve (T12), iliohypogastric and ilioinguinal nerves (L1) supply the antero-lateral abdominal wall
What are the components of the skeletal framework of the abdomen and pelvis?
Sternum, xiphoid process, costal margin and cartilages and lower ribs, iliac crest, iliac fossa and anterior superior iliac spine (ASIS), pubic symphysis, pubic tubercle, superior pubic ramus, thoracic/lumbar vertebrae, sacrum, pelvic bones
Name the 8 parts that are shown by the arrows:
How are the 9 regions of the abdomen separated?
Separated by the midclavicular lines and the subcostal plane (L2) and intertubercular plane (L5)
What are the anterior abdominal wall muscles?
Paired vertical rectus abdominis muscles within rectus sheath
What are the lateral abdominal wall muscles?
3 flat sheet-like muscles:
External oblique, Internal oblique, transversus abdominis
What are the posterior abdominal wall muscles?
Post vertebral muscles: Erector spinae group
Psoas, quadratus lumborum and iliacus muscles
What direction are the external oblique muscle fibres directed?
Downwards and forwards - putting your hands in a waistcoat pocket
What direction are the internal obliques directed towards?
Downwards and backwards - putting your hands in your back pockets
What is the direction of the Transversus Abdominis muscle fibres?
Where does the neurovascular plane lie?
Between the internal oblique and transversus abdominis muscle layers
What is the structure of the Rectus Abdominis?
Long strap muscle of the anterior abdominal wall enclosed in rectus sheath, with 2 heads
Divided into segments by tendinous intersections (3 on each side) which are attached to the anterior wall of the rectus sheath
Where does the rectus sheath connect to?
Rectus sheets meet at the midline (linea alba), and the anterior wall is complete from the xiphoid process and costal cartilage to pubic symphysis and crest
Posterior wall of sheath is incomplete, stopping short of the umbilicus at the ARCUATE LINE
Below the arcuate line the rectus abdominis is in contact with the transversalis fascia
What is the function of the rectus abdominis?
Powerful flexor of the vertebral column (lower thoracic and lumbar)
External and internal obliques of both sides are important partners
What is the bood supply to the flank muscles?
Segmentally supplied: intercostal arteries (7-11), subcostal arteries, lumbar arteries, deep circumflex iliac arteries
Venous drainage have the same names as accompanying arteries
What are the names of the main blood supplies to the abdominal wall?
What is the somatic innervation of the parietal and visceral peritoneum?
Parietal: same segmental nerves of body wall provide somatic sensory supply
Visceral: NO somatic sensory innervation
What are the nerves that supply the anterolateral abdominal wall?
Subcostal nerve (T12), iliohypogastric/ilioinguinal nerves (L1)
Which nerves provide motor supply to the quadratus lumborum, psoas major and illiacus muscles?
QL: T12 and L1-4
Psoas major: L2-4
Iliacus: Femoral nerve - L2-4
What is the lumbar plexus (L1-4)?
Motor and sensory mainly for the lower limbs
Sensory branches to the parietal peritoneum of the posterior abdominal wall
How does the lymphatic drainage of the abdominal wall work?
Superficial tissues: superficial lymphatics accompany subcutaneous veins, and drainage in quadrants
Above transumbilical plane: to pectoral group of axillary nodes
Below transumbilical plane: to superficial inguinal nodes
Deeper tissues: deep lymph accompany deep veins in extraperitoneal tissues -> above TUP to mediastinal nodes and below TUP to external iliac and para-aortic nodes
Lymphatic drainage features (IMG):
What is the inguinal region and where is it located?
The junction between the anterior abdominal wall and the thigh
Area between the ASIS and the pubic tubercle
What is the clinical and anatomical importance of the inguinal region?
Anterior abdominal wall is weakened in the inguinal region
Clinically: Potential site for most abdominal hernias to occur
Anatomically: Structures exit and enter the abdominal cavity through the inguinal region
Why is the anatomy of the inguinal region important?
Hernias occur in this area in both sexes due to the inherent weakness of the abdominal wall
BUT males have it more frequently than females
What is the anatomy of the inguinal region - name the structures that the arrows are pointing to?
What are 2 areas of inherent weakness in the groin?
Inguinl canal and the femoral canal
They remain vulnerable throughout life for potential herniation of the abdominal viscera to occur
What is the inguinal canal used for?
Testis and spermatic cord descend from abdomen into the scrotum via the developing inguinal canal
Uterine round ligament descends through the developing inguinal canal
What is the femoral canal used for?
Below inguinal ligament through which femoral artery and vein pass
What is a hernia?
Condition in which part/whole of organ/tissue abnormally protrude through the wall of the structure containing the organ or tissue
What is the anatomy of a hernia - name each square
What is the gross anatomy of a hernia?
Weakness/defect/hole on wall through which the hernia protrudes
Hernial sac - peritoneum w/neck, body and fundus
Contents of hernial sac - bowel/bladder
What are the clinical signs/symptoms of hernia?
Lump or protrusion in groin, appearing intermittently or present all the time
Painless/painful and uncomfortable
May be reducible or irreducible
May be strangulated with tissue death and associated with vomiting, constipation, intestinal obstruction - EMERGENCY
8 facts about hernias in groin:
1.In both sexes most of the groin lumps/swellings are hernias
2.Inguinal hernias > femoral
3.Accounts for 10% of surgical outpatient referrals
4.Inguinal hernias accounts for 7% of surgical outpatient consultations
5.Accounts for 12% of operating theatre time
6.Inguinal hernia is 8 times greater in males than in females
7.Femoral hernias are rare in males -accounts for 2.5% of the groin swellings
8.Femoral hernias are higher in women and increases with age and number of pregnancies
Wha are the 2 common inguinal hernia types?
Indirect and direct inguinal hernia
Where is the inguinal canal and what is it?
Oblique passageway in lower part of anterior abdominal wall - in both males and females, 4cm long in adults
Lies above medial half of inguinal ligament, extending from deep inguinal ring to superficial inguinal ring
What is the deep inguinal ring and where is it located?
Hole in the transversalis fascia, located 1.5 cm above the midpoint of the inguinal ligament
What is the superficial inguinal ring and where is it located?
Hole in external oblique aponeurosis, immediately above and medial to pubic tubercle
What are the contents of the inguinal canal in males and females?
Males: spermatic cord and ilioinguinal nerve
Females: round ligament and ilioinguina nerve
What are the 4 walls of the inguinal canal called?
Anterior wall, floor, roof, posterior wall
What is each of the 4 walls of the inguinal cord made of?
Anterior: external oblique aponeurosis (whole length) and internal oblique muscle feinforces the lateral 3rd
Floor: Rolled inferior edge of external oblique aponeurosis (inguinal ligament)
Roof: arching fibres of internal oblique muscle and transverse abdominis muscle (whole length) and medially the conjoint tendon
Posterior: transversalis fascia and medially conjoint tendon
Where is the inguinal ligament attached?
Between ASIS and pubic tubercle
What is the conjoint tendon and where is it attached?
Lowest fibres of internal oblique aponeurosis and similar fibres of transversus abdominis aponeurosis joining to form the conjoint tendon
Attached medially to linea alba
What is a direct hernia?
Defect goes through Hesselbach's triangle (inguinal triangle) which is always medial to the inferior epigastric vessels
What is an indirect hernia?
Defect of the internal ring which is always lateral to the inferior epigastric vessels
What is the difference between direct and indirect inguinal hernias?
Direct: herniating bowel passes medially to inferior epigastric vessels
Indirect: herniating bowel passes laterally to inferior epigastric vessels
How is an indirect inguinal hernia formed and who is it common in?
Most common type, seen in younger adults and children
Hernia takes indirect path through abdominal wall as the defect is a dilated deep ring - so hernia passes through deep ring, then inguinal canal, external inguinal ring and into the scrotum
What are femoral hernias?
Hernia through femoral canal - not as common as inguinal
Commoner in elderly and females, high incidence of obstruction and strangulation
What are the femoral canal borders?
Superior: inguinal ligament
Inferior: pectineus fascia
Medial: lacunar ligament
Lateral: femoral vein
What are some key features of femoral hernias?
Tend to be irreducible and hot/painful when strangulated
Distinguished from inguinal because they appear below and lateral to the pubic tubercle (above and medial=inguinal)
What are the muscles in the abdominal cavity called? (anterior)
What are the muscles in the posterior abdominal wall called?