Abdomen I: Abdominal Wall and Inguinal Canal Flashcards
Abdominal Landmarks
Surface Anatomy
Right Illiac Region - Appendix
Left Lumbar Region - Descending Colon, spleen, left kidney
Left Hypochondriac Region - Stomach, Spleen, some of the liver, Pancreas
Semi Lunaris - Lateral border of Rectus Abdominus
Position of Transpyloric Plane
L1 - Pylorus*
Position Of Subcostal Plane
L2
Position Of Transtubecular Plane
L4/L5 - tubercles of iliac crest
Surface Anatomy 2 (which planes are the arrows pointing to?)
Lateral muscles made up of three muscles:
1- External Oblique
2 - Internal Oblique
3- Tranverse Abdominis
Superficial Facia becomes two distinct layers
Camper’s Fascia
Scarpa’s Fascia
Camper’s Fascia
- Fatty
Continuous with:
- Superficial fascia of thigh
- Superficial fascia of penis
- Dartos Fascia ♂
- Perineum and labia majora ♀
Scarpa’s Fascias
- Membranous
Continuous with:
- Superficial fascia of thigh
- Superficial fascia of penis
- Dartos Fascia ♂
- Perineum and labia majora ♀
Extravasation of Urine
Rupture of urethra leading to collection of urine and blood in superficial perineal space, scrotum and potentially lower anterior abdominal wall.
Muscles of Anterior Wall
External Oblique Muscle
- Outmost layer.
- Inferomedial fibre direction (hands in pockets)
- Becomes Aponeurosis medially: Anterior border of rectus sheath.
- Inferior border of external oblique is the Inguinal Ligament
- (It stretches from the anterior superior iliac spine (ASIS) to the pubic tubercle (PT))
Origin:
Insertion:
Nerve supply:
Function:
External Oblique Muscle
- Origin: External surfaces of 5 – 12th ribs
- Insertion: Linea alba, pubic tubercle, ant. half of iliac crest
- Nerve supply: Thoracoabdominal nerves (T7- T11) and subcostal nerve (T12)
- Function: Compresses and supports abdominal viscera; flex and rotate trunk
Internal Oblique Muscle
- Absolutely perpindicular to external oblique
- Intermediate layer
- Superomedial fibre direction.
- Medial aponeurosis*
Origin:
Insertion:
Nerve supply:
Function:
Internal Oblique Muscle
- Origin: Thoracolumbar fascia, anterior 2/3rds of iliac crest and connective tissue deep to inguinal ligament
- Insertion: Inferior border of 10th-12th ribs, linea alba and pubis via conjoint tendon
- Nerve supply: Thoracoabdominal (T7 - T11), subcostal (T12), iliohypogastric (L1) and ilioinguinal (L1)
- Function: compresses and supports abdominal viscera; flex and rotates trunk
Transversus Abdominis Muscle
- Innermost muscle layer.
- Transverse fibre direction.
- Medial aponeurosis: Posterior layer of rectus sheath.
- Neurovascular plane between internal oblique and rectus abdominis.
She mentions how the arterial and nerve structures go through this area between external & internal obliques
Origin:
Insertion:
Nerve supply:
Function:
Transversus Abdominis Muscle
- Origin: Internal surface of 7th – 12th costal cartilages (CC), thoracolumbar fascia, iliac crest and connective tissue deep to lat. 1/3rd inguinal ligament
- Insertion: Linea alba, pubic crest and pectin pubis via conjoint tendon
- Nerve supply: Thoracoabdominal (T7-T11), Subcostal (T12), iliohypogastric (L1) and ilioinguinal (L1)
- Actions: compresses and supports abdominal viscera * antagonistic to diaphragm
Layers of the (lateral) Abdominal Wall - Summary
Rectus Abdominis Muscle
- Paired strap muscle separated by linea alba (white line).
- Three of more tendinous intersections.
- Lateral border forms linea semilunaris.
- Origin:
- Insertion:
- Nerve supply:
- Action:
Rectus Abdominis Muscle
- Origin: Pubic symphysis and pubic crest.
- Insertion: Xiphoid process and 5th - 7th costal cartilages.
- Nerve supply: Thoracic abdominal nerves (T7-T11) and subcostal nerve (T12).
- Action: Flexion of trunk, compresses abdominal viscera and controls tilt of pelvis.
Pyramidalis Muscle
- Absent in approximately 20% people.
- Landmark for median abdominal incisions.
- Origin:
- Insertion:
- Nerve supply:
- Action:
Pyramidalis Muscle
- Origin: Pubic crest
- Insertion: Linea alba
- Nerve Supply: Subcostal nerve (T12)
- Action: Tense linea alba
Rectus Sheath is the…
…Aponeuroses of External Oblique, Internal Oblique, Transversus Abdominis
Fibrous compartment enveloping:
- Rectus abdominis
- Pyramidalis
- Superior and inferior epigastric vessels
- Distal portions of thoracoabdominal nerves
- Corresponding lymphatics
Linea Alba is the…
…Interlacing fibres of anterolateral muscles (formed when left and right Aponeuroses come together and fibres cross over - thickening)
Important thing: Doesn’t have blood supply (ideal for Median surgical incision)
- Collagen: white line
- Xiphoid process to pubic crest
- Umbilicus lies in midline
Superior to arcuate line Rectus Sheath
Inferior to arcuate line Rectus Sheath
For superior to arcuate line, Internal aponeurosis splits into…
…two layers:
Anterior laminae passes anterior to rectus abdominis.
Posterior laminae passes posterior to rectus abdominis.
For inferior to arcuate line…
Rectus Sheath
- All aponeuroses pass anterior to rectus abdominis
- Posterior layer is weaker as only formed by transversalis fascia - one of the reasons why Hernias form lower down
Blood Supply of abdominals
Rectus Sheath Haematoma
Rupture in inferior epigastric artery which ascends between rectus abdominis and posterior laminae of rectus sheath
More common in patients on anticoagulants
Surgical Incisions
Inguinal ligament
Ligaments of Abdominal Wall
Free boarder of external oblique (continuation of EO muscle)
- Anterior superior iliac spine.
- Pubic tubercle.
- Medial half circled in on its self forming a ‘gutter like’ floor.
Lacunar Ligament
Ligaments of Abdominal Wall
. Crescent-shaped extension of medial fibres of inguinal ligament
. Pass back to attach to pectin pubis
Conjoint Tendon
Ligaments of Abdominal Wall
- Lower part of internal oblique and transversus abdominis (aponeuroses of internal oblique and transversus abdominis fuse together to form this structure)
- Attached to pubic crest and pectineal line.
McBurney’s point
located two thirds the distance from the navel to the right anterior superior iliac spine, or the bony projection of the right hip bone
Inguinal Canal
4 cm: An oblique passage (tunnel) that extends downwards & medially through the lower anterior abdominal wall
Inguinal Canal Function in Males & Females
- Males: Allows spermatic cord to pass to and from testis.
- Females: Permits the passage of round ligament of uterus.
Two Openings Of Inguinal Canal
- Deep inguinal ring: Entrance to canal.
- Superficial inguinal ring: Exit of canal.
Inguinal Canal Analogy (just for revision purposes)
Gonadal Development
• Gonads (testis or ovary) originally develop in the abdomen (close to the posterior abdominal wall) - develop between parietal peritoneum and the transversalis fascia
- Gonads travel down Gubernaculum
- Testis travel into scrotum, by traversing abdominal wall
- Ovaries descend into pelvis
Gubernaculum
Descent of Gonads
- Develops at 7 weeks gestation
- Made up of Mesenchymal tissue: Cord like structure
- Assist in the descent of the testis from the abdomen into developing scrotum
- Cranial attachment (to Gonad): Testis ♂ Ovary ♀
- Caudal attachment (i.e Tail): Labiosctoral fold
- Midpoint attachment: Uterus ♀
Gubernaculum attachments
Descent of Gonads
- Cranial attachment (Head of Gubernaculum to Gonad): Testis ♂ Ovary ♀
- Caudal attachment (i.e Tail): Labiosctoral fold
- Midpoint attachment: Uterus ♀
Process vaginalis
Descent of Gonads
Indentation of parietal peritoneum into abdominal walls - indentation is process vaginalis.
- Develops during 2nd to 3rd months gestation.
- Tubular extension of peritoneal cavity.
- Herniates through abdominal wall along path formed by gubernaculum.
- Extensions of layers of abdominal wall accompany PV and form walls of inguinal canal, spermatic cord and testes.
- Process vaginalis obliterates and closes in a downwards direction.
- Males: Scrotal part of PV remains patent: Tunica vaginalis.
The Deep Inguinal Ring
- Opening of inguinal canal
- Indentation in the transversalis fascia produced by process vaginalis
- 1cm superior to inguinal ligament, midway between the ASIS and pubic tubercle
- Located lateral to the inferior epigastric vessels
The Deep Inguinal Ring
The Superficial Inguinal Ring
- Terminal end of inguinal canal.
- Triangular opening in aponeurosis of external oblique.
- 2 – 3 cm superior and lateral to pubic tubercle.
The Superficial Inguinal Ring
Hint: MALT
Walls of Inguinal Canal
Superior wall (roof): 2 Muscles
- Internal oblique muscle
- Transverse abdominis muscle (arches up and over)
Anterior wall: 2 Aponeurosis
Aponeurosis of external oblique
Aponeurosis of internal oblique
Inferior wall (Floor): 2 Ligaments
Inguinal ligament
Lacunar ligament
Posterior wall: 2 Ts
Transversalis fascia
Conjoint Tendon (IO + TA)
What are the contents of Inguinal Canal?
♂ Spermatic cord including genitofemoral nerve & ilioinguinal nerve
♀ Round ligament, genital branch of the genitofemoral nerve & ilioinguinal nerve
SDECITT
Layers of Testes and Spermatic Cord Overview
Layers of Testes and Spermatic Cord
Cremaster muscles significance
then answer:
Nerve responsible:
Retracts testis -
elevation of testis when outside temperature is cold,
testis retract to gain body warmth
Sensory innervation from ilioinguinal nerve which genitofemoral nerve which is responsible for elevation of testes
Sperm —> Vagina (directions)
- Sperm develop in the testicles within a system of tiny tubes called the seminiferous tubules
- Stored in Epididymis
- Travels up spermatic cord (via Vas Deferens)
- Goes through superficial inguinal ring
- Goes through inguinal canal,
- Goes out of the deep inguinal ring
- Goes round the seminal vesicles to join with ejaculatory duct
- Then into prosthetic urethra
- Out through the spongy urethra
- Then into vagina
Tunica Vaginalis
Remnant of processus vaginalis
Process Vaginalis - which is the indentation of the Parietal Peritoneum; this obliterates soon after birth & closes from superior to inferior, inferior portion remains open as the Tunica Vaginalis
Contents of Inguinal Canal ♂
Spermatic cord:
Vas deferens (sperms travel up), Lymphatics, Tunica vaginalis, Testicular artery (arises from aorta), Cremasteric artery, Artery to vas deferens, Pampiniform plexus, Genital branch of genitofemoral nerve, Sympathetic nerve
+
Ilioinguinal nerve
Contents of male inguinal canal overview
Contents of Inguinal Canal ♀
Round ligament of uterus:
Attaches to uterus, transverses inguinal canal and spreads out in labia majora
Contents of female inguinal canal overview
Inguinal Hernias
Protrusion of gut or omentum (peritoneum containing fat) through the inguinal canal
Inguinal Hernias (Direct)
- Hernia passes directly through abdominal wall
- Medial to inferior epigastric artery
Due to weakness in abdominal wall (old age or weightligting)
- Less common
- Exits via superficial inguinal ring, lateral to spermatic cord
Inguinal Hernias (Indirect - Congenital [from birth])
- Passing through length of canal.
- Lateral to inferior epigastric artery
- Patent process vaginalis - (issues with tunica vaginalis formation)
- More common
- Exits via superficial inguinal ring and can pass into scrotum/labium majora
Femoral Hernias
Females more likely to get it due to wider hips.
Happens due to femoral canal space in femoral sheath .
Varicocele
- ‘Bag of worms’ appearance
- Pampiniform plexus becomes dilated and tortuous
The pampiniform plexus is a loose network of small veins found within the male spermatic cord
Hydrocoele
• Collection of fluid in the tunica vaginalis
• Increase fluid secretion from visceral layer of tunica vaginalis
• Clinical examination: can get above the swelling and is trans-illumination positive
Testicular Torsion
• Twisting of the spermatic cord above its attachment to the testis
- Cuts of blood supply
- 5 star medical emergency
