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