Anterior Abdominal Wall & Inguinal Region

Question 1

What are the superficial layers of abdominal fascia? What does the membranous layer attach to?

Answer 1

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

Question 2

What are the deep layers of abdominal fascia?

Answer 2

1. Fascial covering of the superficial + deep surfaces of the individual anterior abdominal wall muscles. Several of these coverings contribute to spermatic cord
2. Transversalis fascia

Question 3

What is the transversalis fascia?

Answer 3

The deep fascia covering the innermost surface of the deep anterior wall muscle layer, derived posteriorly from thoracolumbar fascia

Question 4

What is the extraperitoneal fascia?

Answer 4

Analogous to endothoracic fascia, it is between the parietal peritoneum + transversalis fascia. It is also called extraperitoneal connective tissue

Question 5

What is the origin, insertion, innervation, and action of the external abdominal oblique?

Answer 5

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

Question 6

How are the fibers of the external abdominal oblique oriented?

Answer 6

Towards midline, like external intercostals

Question 7

What is the inguinal ligament?

Answer 7

Ligament between the anterior superior iliac spine and pubic tubercle on both sides which forms from the external abdominal oblique aponeurosis

Question 8

What is the origin, insertion, innervation, and action of the internal abdominal oblique?

Answer 8

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

Question 9

What is the origin, insertion, innervation, and action of the transversus abdominis?

Answer 9

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

Question 10

What is the conjoined tendon?

Answer 10

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

Question 11

What is the origin, insertion, innervation, and action of the rectus abdominis?

Answer 11

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

Question 12

What is the rectus sheath?

Answer 12

Dense connective tissue enclosing the rectus abdominis muscle. The anterior and posterior layers are formed by aponeuroses of abdominal obliques + transverse abdominus muscles.

Question 13

What are the linea semilunaris and linea alba?

Answer 13

White and semilunar lines in the rectus sheath.
Linea semilunaris - lateral edge of rectus abdominis
Linea alba - midline between rectus abdominis

Question 14

How does the rectus sheath differ above and below the umbilicus? What is the major landmark called?

Answer 14

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

Question 15

What contributes to the anterior and posterior rectus sheaths? Where can this definitely be found?

Answer 15

Above the umbilicus:

External abdominal oblique aponeurosis: anterior only
Internal abdominal oblique aponeurosis: splits to anterior + posterior
Transversus abdominis aponeurosis: posterior only

Question 16

What are the thoracoabdominal nerves?

Answer 16

Intercostal nerves (ventral rami of T7-T11) which continue into anterior abdominal wall

Question 17

What is the subcostal nerve?

Answer 17

From anterior ramus of T12 which enters anterior abdominal wall

Question 18

What are the iliohypogastric and ilioinguinal nerves?

Answer 18

From anterior ramus of L1 enters anterior abdominal wall

Question 19

In what plane are the nerves of the anterior abdominal wall?

Answer 19

Within neurovascular plane between internal abdominal obliques and transversus abdominus. They course medially and inferiorly.

Question 20

What are the major dermatomes of the anterior abdominal intercostals?

Answer 20

Xiphoid process - T7
Umbilicus - T10
Pubis - L1 (iliohypogastric)

Question 21

What is the course of the ilioinguinal nerve and what does it supply?

Answer 21

A branch of L1, it enters the inguinal canal and supplies the anterior scrotum / labium majus + upper medial thigh

Question 22

What is the course of the superior epigastric artery?

Answer 22

Branches from ITA, descends in posterior rectus sheath, anastomoses with inferior epigastric artery

Question 23

What is the course of the inferior epigastric artery?

Answer 23

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

Question 24

What is the deep circumflex iliac artery?

Answer 24

A branch of the external iliac, it lies on top of the transversus abdominis

Question 25

What is the superficial circumflex iliac vein? What other superficial arteries supply the anterior abdominal wall?

Answer 25

A branch of the external iliac, it lies atop the muscles, along with the superficial epigastric artery + intercostals.

Question 26

What is the thoracoepigastric vein and where does it drain?

Answer 26

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

Question 27

What is caput medusae?

Answer 27

The appearance of the thoracoepigastric vein during portal hypertension, when the portal vein is backed up due to liver isues

Question 28

Where does lymph of the anterior abdominal wall drain?

Answer 28

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

Question 29

What is the inguinal canal?

Answer 29

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

Question 30

Where is the inguinal canal located?

Answer 30

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.

Question 31

What makes up the floor of the inguinal canal?

Answer 31

laterally: Inguinal ligament medially: Lacunar ligament (posterior extension of inguinal ligament attaching to pectin pubis)

Question 32

What is the pectineal ligament?

Answer 32

An extension of the lacunar ligament along the pectineal line of pelvis

Question 33

What makes up the anterior wall of the inguinal canal?

Answer 33

Laterally: Aponeurosis of external abdominal oblique + IAO fibers originating from inguinal ligament Medially: Aponeurosis of external abdominal oblique which forms the superficial inguinal ring

Question 34

What makes up the posterior wall of the inguinal canal?

Answer 34

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

Question 35

What forms the superficial and deep inguinal rings?

Answer 35

Superficial: External abdominal oblique aponeurosis Deep: Transversalis fascia of lateral posterior wall of inguinal canal

Question 36

What happens to the testes during embryonic development?

Answer 36

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

Question 37

What is the processus vaginalis?

Answer 37

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

Question 38

What is the internal spermatic fascia?

Answer 38

evagination of the transversalis fascia ensheathing the ductus deferens, testis, and blood vessels. It is the innermost fascial layer from embryonic development of testes

Question 39

What is the deep inguinal ring? What is medial to it?

Answer 39

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

Question 40

What is the cremasteric muscle?

Answer 40

Muscle formed from the internal abdominal oblique. Innervation: Genital branch of genitofemoral nerve Action: Raises testicle for temperature regulation

Question 41

What is the cremasteric reflex?

Answer 41

Stroking upper, medial thigh retracts the testicle of the ipsilateral side and confirms integrity of L1-L2 spinal cord segments

Question 42

What is the middle spermatic / cremasteric fascia?

Answer 42

Derived from fascia of internal abdominal oblique muscle, it is the middle layer of fascia over the spermatic cord

Question 43

What is the external spermatic fascia?

Answer 43

It is the outermost covering of the spermatic cord, derived from the aponeurosis of the external abdominal oblique muscle

Question 44

What is the inguinal (Hasselbach's) triangle?

Answer 44

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

Question 45

What is an inguinal hernia?

Answer 45

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

Question 46

What is a direct inguinal hernia?

Answer 46

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.

Question 47

What is an indirect inguinal hernia?

Answer 47

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