Anterior Abdominal Wall & Inguinal Region Flashcards
What are the superficial layers of abdominal fascia? What does the membranous layer attach to?
Camper’s fascia - superficial, fatty layer (forms beer belly)
Scarpa’s fascia - deep, membranous layer, well developed in lower abdominal wall, attaches to deep thigh fascia inferior to inguinal ligament
What are the deep layers of abdominal fascia?
- Fascial covering of the superficial + deep surfaces of the individual anterior abdominal wall muscles. Several of these coverings contribute to spermatic cord
- Transversalis fascia
What is the transversalis fascia?
The deep fascia covering the innermost surface of the deep anterior wall muscle layer, derived posteriorly from thoracolumbar fascia
What is the extraperitoneal fascia?
Analogous to endothoracic fascia, it is between the parietal peritoneum + transversalis fascia. It is also called extraperitoneal connective tissue
What is the origin, insertion, innervation, and action of the external abdominal oblique?
Origin: Ribs 5-12
Insertion: Iliac crest + linea alba through aponeurosis, forms inguinal ligament through lower extent
Innervation: Anterior rami of T7-T12 (lower 6)
Action: Compresses abdominal contents during maximal expiration, coughing, and defecation. Also rotates and flexes trunk
How are the fibers of the external abdominal oblique oriented?
Towards midline, like external intercostals
What is the inguinal ligament?
Ligament between the anterior superior iliac spine and pubic tubercle on both sides which forms from the external abdominal oblique aponeurosis
What is the origin, insertion, innervation, and action of the internal abdominal oblique?
Origin: Thoracolumbar fascia, iliac crest, lateral 2/3 of inguinal ligament
Insertion: Inferior border of ribs 9-12, and linea alba, pubic crest, and pectineal line (of ilium) through the aponeurosis
Innervation: T7-T12, plus L1
Action: Same as external oblique
What is the origin, insertion, innervation, and action of the transversus abdominis?
Origin: Thoracolumbar fascia, iliac crest, costal cartilages of lower few ribs
Insertion: Aponeurosis attaches to liena alba, pubic crest, and pectineal line
Innervation: T7-T12, plus L1
Action: Compression of abdominal contents only
What is the conjoined tendon?
Also called conjoint, it is the tendon formed by fused aponeurosis of internal abdominal oblique and transversus abdominis, which formed the medial posterior wall of the inguinal canal
What is the origin, insertion, innervation, and action of the rectus abdominis?
Origin: Pubic crest, pubic tubercule, and pubic symphysis
Insertion: Costal cartilages of ribs 5-12 + xiphoid process
Innervation: T7-T12
Action: Compression of abdominal contents + flex trunk
What is the rectus sheath?
Dense connective tissue enclosing the rectus abdominis muscle. The anterior and posterior layers are formed by aponeuroses of abdominal obliques + transverse abdominus muscles.
What are the linea semilunaris and linea alba?
White and semilunar lines in the rectus sheath.
Linea semilunaris - lateral edge of rectus abdominis
Linea alba - midline between rectus abdominis
How does the rectus sheath differ above and below the umbilicus? What is the major landmark called?
At some point between the umbilicus and pubic symphysis called the arcuate line, the posterior layer of the rectus sheath is absent, and the rectus abdominis is in contact with the transversalis fascia
What contributes to the anterior and posterior rectus sheaths? Where can this definitely be found?
Above the umbilicus:
External abdominal oblique aponeurosis: anterior only
Internal abdominal oblique aponeurosis: splits to anterior + posterior
Transversus abdominis aponeurosis: posterior only
What are the thoracoabdominal nerves?
Intercostal nerves (ventral rami of T7-T11) which continue into anterior abdominal wall
What is the subcostal nerve?
From anterior ramus of T12 which enters anterior abdominal wall
What are the iliohypogastric and ilioinguinal nerves?
From anterior ramus of L1 enters anterior abdominal wall
In what plane are the nerves of the anterior abdominal wall?
Within neurovascular plane between internal abdominal obliques and transversus abdominus. They course medially and inferiorly.
What are the major dermatomes of the anterior abdominal intercostals?
Xiphoid process - T7
Umbilicus - T10
Pubis - L1 (iliohypogastric)
What is the course of the ilioinguinal nerve and what does it supply?
A branch of L1, it enters the inguinal canal and supplies the anterior scrotum / labium majus + upper medial thigh
What is the course of the superior epigastric artery?
Branches from ITA, descends in posterior rectus sheath, anastomoses with inferior epigastric artery
What is the course of the inferior epigastric artery?
Branches from external iliac artery before external iliac artery passes inferior to inguinal ligament.
It courses superiorly and medially in the extraperitoneal fascia before piercing the transversalis fascia inferior to the arcuate line, and it anastomoses with the superior epigastric within the rectus abdominis
What is the deep circumflex iliac artery?
A branch of the external iliac, it lies on top of the transversus abdominis
What is the superficial circumflex iliac vein? What other superficial arteries supply the anterior abdominal wall?
A branch of the external iliac, it lies atop the muscles, along with the superficial epigastric artery + intercostals.
What is the thoracoepigastric vein and where does it drain?
A longituinal vein running within the superficial fascia of the lateral thorax + abdomen. It drains into the SVC via the lateral thoracic vein, and IVC via the superficial epigastric vein
Also has tributaries near the umbilicus which anastomose with the paraumbilical veins and ultimately drain into portal vein
What is caput medusae?
The appearance of the thoracoepigastric vein during portal hypertension, when the portal vein is backed up due to liver isues
Where does lymph of the anterior abdominal wall drain?
Superficially: Axillary and superifical inguinal nodes
Abdominal wall muscles: Drain along PIVs and superior + inferior epigastric veins to reach the lumbar, parasternal, and external iliac nodes
What is the inguinal canal?
An oblique passage through the fascial + muscle layers in the anterior abdominal wall which connects the scrotum / labium jaus to the retoperitoneal region.
Transmits -
Males: Ductus deferens
Females: Round ligament of uterus
Where is the inguinal canal located?
Parallel and superior to the inguinal ligament, extending from the deep to the superficial inguinal ring. The femoral vessels will pass INFERIOR to the inguinal ligament.
What makes up the floor of the inguinal canal?
laterally: Inguinal ligament
medially: Lacunar ligament (posterior extension of inguinal ligament attaching to pectin pubis)
What is the pectineal ligament?
An extension of the lacunar ligament along the pectineal line of pelvis
What makes up the anterior wall of the inguinal canal?
Laterally: Aponeurosis of external abdominal oblique + IAO fibers originating from inguinal ligament
Medially: Aponeurosis of external abdominal oblique which forms the superficial inguinal ring
What makes up the posterior wall of the inguinal canal?
Laterally: Transversalis fascia, forming deep inguinal ring
Medially: Fibers of internal abdominal oblique arching over spermatic cord / round ligament, also forming cremasteric muscle. + Transversus abdominis aponeurosis forming the conjoined tendon
What forms the superficial and deep inguinal rings?
Superficial: External abdominal oblique aponeurosis
Deep: Transversalis fascia of lateral posterior wall of inguinal canal
What happens to the testes during embryonic development?
Testes + ductus defends are drawn into the scrotum from their retroperitoneal origin, which forces them to pass through the inguinal canal. This gives them several fascial coverings
What is the processus vaginalis?
Part of gut which is anterior to the inguinal canal and is included in it as the testes descend into the scrotum thru the inguinal canal. If it remains patent and does not close, it can lead to indirect inguinal hernia
What is the internal spermatic fascia?
evagination of the transversalis fascia ensheathing the ductus deferens, testis, and blood vessels. It is the innermost fascial layer from embryonic development of testes
What is the deep inguinal ring? What is medial to it?
Formed from evagination of the transversalis fascia (internal spermatic), it is located midway between the pubic symphysis and the anterior superior iliac spine, with the inferior epigastric vessels medial to it
What is the cremasteric muscle?
Muscle formed from the internal abdominal oblique.
Innervation: Genital branch of genitofemoral nerve
Action: Raises testicle for temperature regulation
What is the cremasteric reflex?
Stroking upper, medial thigh retracts the testicle of the ipsilateral side and confirms integrity of L1-L2 spinal cord segments
What is the middle spermatic / cremasteric fascia?
Derived from fascia of internal abdominal oblique muscle, it is the middle layer of fascia over the spermatic cord
What is the external spermatic fascia?
It is the outermost covering of the spermatic cord, derived from the aponeurosis of the external abdominal oblique muscle
What is the inguinal (Hasselbach’s) triangle?
A potential weak area in the anterior abdominal wall bounded by the inguinal ligament, the inferior epigastric vessels laterally and the lateral border of the rectus abdominis muscle. This is where inguinal hernias often occur
What is an inguinal hernia?
A protrusion of abdominal contents (usually a loop of small intestine) through a defect in the musculofascial walls of the inguinal canal, more common in males
What is a direct inguinal hernia?
Protrusion through the inguinal triangle (medial to inferior epigastric artery), will not usually protrude through the superficial inguinal ring into the scrotum.
Has same fascial layers as spermatic cord, but also peritoneum + extraperitoneal connective tissue. It has the conjoint tendon as the middle layer.
What is an indirect inguinal hernia?
Protrusion thru inguinal canal, but lateral to the inferior epigastric artery. Goes through deep inguinal + superficial inguinal ring and enters the scrotum. Usually in men, associated with patent processus vaginalis.
It will occur all the spermatic cord coverings + the peritoneum
