Anterior Abdominal Wall & Surface Anatomy Flashcards
What is the role of the abdominal wall?
- Firm flexible wall which keeps abdominal viscera in abdominal cavity.
- Protection from injury.
- Assists in forceful expiration by pushing the abdominal viscera upwards.
- Assists with actions (coughing, vomiting) that increases intra-abdominal pressure
What are the 4 quadrants?
- RUQ, LUQ, RLQ, LLQ
What are the planes that form the nine regions?
- 2 vertical
1. The midclavicular lines. - 2 horizontal planes:
1. Transpyloric plane: Horizontal line halfway
between the xiphoid process and the umbilicus
2. Inter-tubercular plane: Horizontal line that joins the iliac crests
What are the nine regions formed?
- Right and left hypochondria
- Epigastric region
- Umbilical region
- Right and left flank
- Pubic region
- Right and left groin/ iliac fossa.
What are the positions of the horizontal planes with respect to the Lumbar vertebrae?
- Transpyloric Plane – L1
- Umbilicus –L3/4 intervertebral disc
- Transtubercular – L4-5
Discuss surgical incisions.
What are the layers of the abdominal wall?
- Skin
- Superficial fascia (or subcutaneous tissue)
- Muscles and associated fascia
- Transversalis fascia
- Parietal peritoneum
What makes up the superficial fascia?
- Made of fatty connective tissue.
- Two layers:
1. Camper’s fascia (fatty superficial layer)
2. Scarpa’s fascia (membranous deep layer)
*Superficial vessels and nerves run between these two layers of fascia.
What are the 5 muscles of the abdominal wall?
- Flat muscles: Situated laterally
1. External oblique
2. Internal oblique
3. Transverse abdominis - Vertical muscles – Situated near the
mid-line
1. Rectus abdominis
2. Pyrimdalis
What are the features of the External oblique?
-Most superficial. Runs inferomedially and form aponeurosis at midline.
Discuss the origins, insertions, innervation, blood supply and action of the External oblique.
- Origin: Ribs 5-12
- Insertion: Iliac crest and linea alba
- Innervation: Thoraco-abdominal T7-11 and
subcostal nerve T12 - Blood Supply: Lower intercostal arteries and
branches of either the deep circumflex iliac artery or the ilio-lumbar artery - Action: Compresses abdomen contents, contralateral rotation of torso
What is made from the aponeurosis of the abdomen?
- Linea alba.
- It extends from the xiphoid process to the pubic symphysis.
What is the inguinal ligament?
- A rolled in free lower border of the external oblique aponeurosis.
- Origins: ASIS
- Insertions: Pubic tubercle.
What is the inguinal canal?
- Canal between peritoneal cavity and abdominal wall.
- The medial half of inguinal ligament forms floor of inguinal canal.
What are the ligaments of the external oblique?
- Lacunar ligament: Crescent shaped extension of medial fibres
- Pectineal Ligament: Extended fibres along pelvic brim.
What are the features of the Internal oblique?
- Deep to external oblique. Smaller.
- Runs superomedially and forms aponeurotic fibres which contribute to the linea alba.
Discuss the origins, insertions, innervation, blood supply and action of the Internal oblique.
- Origin: Lateral 2/3 inguinal ligament, iliac crest and thoraco-lumbar fascia.
- Insertion: Linea alba, pectineal line, pubic crest, inf. border of ribs 9-12.
- Innervation Thoraco-abdominal T7-11 and
subcostal nerve T12, iliohypogastric (L1) and
ilioinguinal (L1). - Blood Supply: Subcostal arteries
- Action: Compresses abdomen contents, ipsilateral trunk rotation.
What are the features of the Transversus Abdominis?
- Deepest flat muscle. Runs transversely.
- Contributes aponeurotic fibres to the linea alba. Deep to this muscle is transversalis fascia.
Discuss the origins, insertions, innervation, blood supply and action of the Transversus Abdominis.
- Origin: Iliac crest, lateral 1/3 inguinal
ligament, thoracolumbar fascia and ribs 7-12. - Insertion: Linea alba, pubic crest and
pectineal line. - Innervation: Thoracoabdominal T7-11 and
subcostal nerve T12, iliohypogastric (L1) and
ilioinguinal (L1). - Blood Supply: Subcostal arteries
- Action: Compresses abdomen
contents
What are the features of the Rectus Abdominis?
- Long, paired muscle, found either side of the midline in the abdominal wall.
- Split into two by the linea alba.
- Lateral border of the two muscles create a surface marking called the linea semilunaris.
Discuss the origins, insertions, innervation, blood supply and action of the Rectus Abdominis.
- Origin: Pubic crest, tubercle & symphysis.
- Insertion: Costal cartilage of ribs 5-7, xiphoid process.
- Innervation: Thoracoabdominal T7-11,
subcostal T12. - Blood Supply: Inferior epigastric artery
- Action: Compresses abdomen contents,
tense abdominal wall.
What are the features of the Pyramidalis?
- Small triangle shaped muscle found superficial to the rectus abdominis.
- Found inferiorly with its base on the pubis bone, and the apex of the triangle attached to the linea alba.
Discuss the origins, insertions, innervation, blood supply and action of the Pyramidalis?
- Origin: Pubic symphysis and pubic crest
- Insertion: Linea alba
- Innervation: Subcostal nerve (T12)
- Blood Supply: Inferior and superior epigastric artery
- Action: Tense linea alba
What forms the Rectus Sheath?
- The aponeuroses of the 3 flat muscles.
- Anterior wall: by aponeuroses of external oblique and half of internal oblique
- Posterior wall: by aponeuroses of half internal oblique and of the transversus abdominus
What is the Arcuate line or the semicircular line of Douglas?
- When all the aponeuroses move to the anterior wall of rectus sheath.
- This happens midway between umbilicus and pubic symphysis
What are the motor and sensory nerve supply of the Abdominal wall?
Why are dermatomes important?
- Patients may experience symptoms that have been referred from other sites.
*Remember Hilton’s law.
What are the superior arterial supply of the abdominal wall?
What are the inferior arterial supply of the abdominal wall?
Identify the internal surface of the peritoneal folds as outlined in the images.
What is the femoral sheath?
- Made anteriorly of Transversalis fascia and posteriorly of Psoas fascia.
- Consists of 3 compartments:
1. Lateral compartment: contains femoral artery.
2. Intermediate compartment: contains femoral vein.
3. The medial and smallest compartment is called the femoral canal.
What is the significance of the Femoral canal?
- Potential weak spot.
- Femoral hernia:
*Palpable at saphenous opening
Discuss the descent of the testis.
- Controlled by gubernaculum.
- The swelling and migration of the gubernaculum through the inguinal canal precede the testis.
- This forces the opening of the inguinal ring, allowing the testis to move passively into the scrotum.
What is the anatomy of the testis?
- Found in the scrotum unless undescended.
- Left lower than right & oval shaped.
- Fibrous capsule: tunica albuginea.
- Serous covering: tunica vaginalis
- Epididymis: posterolateral
Discuss the blood supply of the testis.
- Arterial: Testicular artery (from lateral aspect of aorta L1-2)
- Venous: – Pampiniform plexus -gonadal veins -renal veins (Rt to IVC - Lt to left renal vein).
- Lymph: run with with arteries to para-aortic nodes.
- Innervation: visceral sensory to T10.
What are the 3 layers of the spermatic cord?
- Internal spermatic fascia (transversalis fascia)
- Cremasteric layer (internal oblique)
- External spermatic fascia (external oblique)
Discuss the blood supply and innervation of the spermatic cord.
Discuss the clinical conditions related to the testis/ spermatic cord.
- Undescended testis
- Torsion: testicle rotates, twists spermatic cord and impairs blood supply.
- Testicular carcinoma
- Swellings
- Hydrocele: Collection of fluid in tunica vaginalis
- Varicocele: Enlarged dilated veins (Pampiniform plexus, L>R ..Renal Vein)
- Spermatocele: cyst that develops in the epididymis
