Written Examination September 15, 2011: Part III Short Answer - Answer Guide

Ovary - jai134

Indicate the lymphatic drainage, innervation, and vasculature of the ovary. (6 pts)

Lymphatic Drainage

  • Follows blood supply
  • Ovary is drained by 3 routes:
  • Primary route is following the embryological decent of the ovary, following the ovarian arteries. Lymphatics follows vessles through the suspensory ligament to lumbar nodes.
  • Lymphatics follow uterine arteries in the cardinal or ovarian ligament. Drains to pelvic nodes→ lower preaortic nodes/lumbar nodes → cisterna chyli
  • Lymphatics can follow the route of the round ligament, draining to the superficial inguinal lymph nodes. Superficial inguinal lymph nodes → external iliac nodes → common iliac nodes → lumbar nodes → preaortic nodes → cisterna chyli → thoracic duct

Innervation

  • Parasympathetic: innervation to the ovaries by the pelvic splanchnics (off of ventral rami S2-S4) or via the vagus nerve (CN X). Synapse in intrinsic ganglia of the ovary.
  • Sympathetic: Fibers originate at T10 and T 11. Ventral root→ spinal nerve → ventral rami → white rami comminicans → sympathetic trunk → lesser splanchnic nerves → aortic/superior mesenteric/aorticorenal ganglia (synapse). Postganglionic fibers enter the aortic plexus and extend along the ovarian artery (through the suspensory ligament) to the ovaries.
  • Visceral Afferents: follow sympathetics to T10, additional fibers follow parasympathetics back to S2-S4.

Vasculature

  • Primary blood supply is form the ovarian aa and vv. Run within the suspensory ligament of the ovary.
  • ovarian aa arise form the aorta as paired inferiorly running aa (arise ~L2). Run anterior to renal vessels, psoas major and pelvic brim into the pelvis.
  • Also receive secondary blood supply form the uterine aa and vv which anastomose with ovarian blood supply
  • Ovarian VV: on right drain directly into the IVC and on the left drain to the renal vein then into the IVC.

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Tunica Vaginalis - mdl19

Discuss the anatomy of the tunica vaginalis, its relationship to the testis, and its embryological origin. (6 pts)

Anatomy

  • Tunica vaginalis (TV) is reflected from the testes (visceral) superficial to the tunica albuginea onto the internal surface of the internal spermatic fascia (transversalis fascia) as parietal tunica vaginalis and is derived from periotoneum. The visceral layer covers the entirety of the testis except for the most posterior aspect. Posteriormedially the tunica vaginalis is reflected anteriorly and becomes the parietal layer of tunica vaginalis. Posteriorlaterally the visceral layer of TV passes to the medial aspect of the epididymis and lines the epididymal sinus, and then passes laterally to its posterior border where it is reflected forwards to become continuous with the parietal layer. The visceral and parietal layers are continuous at both poles, but at the upper pole the visceral layer surmounts the head of the epididymis before reflexion. A small amount of fluid lies between the two layers. The parietal layer reaches inferior to the testis and ascends anterior and medial to the spermatic cord.

Embryology

  • If development occurs properly, the distal portion of the processus vaginalis will become the tunica vaginalis in the adult. During the transabdominal phase, during the descent of the testes, a layer of peritoneum evaginates and grows inferiorly. Because of this, the space between the future visceral and parietal layers of the tunica vaginalis (at this point processus vaginalis) is continuous with the peritoneal cavity until the cranial portion of the processus vaginalis closes. The processus vaginalis develops on three sides of the gubernaculum (not posterior). The evagination of the processus vaginalis is closely related to the evagination of the anterior abdominal wall which will become the coverings of the spermatic cord. As the processus vaginalis elongates, it plays a role in the formation of the scrotal cavity into which the testes descend, however the processus vaginalis IS NOT the location/space that testes descend into. As the testes descend superficial to the peritoneum on the posterior abdominal wall and into the the scrotal sac, the testes become enveloped anteriorly by the processus vaginalis. The visceral layer of the processus vaginalis is closely related to the testes. The reflection of visceral and parietal processus vaginalis is due to the inferior descent of the testes. Finally, the cranial portion of the processus vaginalis becomes obliterated resulting the formation of only a distal sac as a potential space: tunica vaginalis lying ventral to the testes and composed of both a visceral and parietal layer.
  • If the cranial portion of the processes vaginalis remains patent, abdominal viscera may herniated into the vaginal process leading to indirect inguinal hernias. Complete indirect inguinal hernias will be found anterior within the scrotal sac between the visceral and parietal layers of tunica vaginalis.

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Descending Colon - bsl162

Discuss the innervation, vasculature, and lymphatic drainage of the descending colon. (6 pts).

Innervation

  • Sympathetic:
    • Sympathetic Trunk L1-L3 gives rise to Lumbar Splanchnic Nerves
    • Preganglionics to Inferior Mesenteric Ganglion
    • Postganglionics to Descending Colon following vasculature
    • Inhibition of activity of Gastrointestinal Tract
  • Parasympathetic:
    • Pelvic Splanchnic Nerves originate in ventral rami S2-S4 and enter Inferior Hypogastric Plexus
    • Inferior Hypogastric Plexus dividese into Hypogastric Nerves, which send fibers to Intrinsic Ganglia
    • Stimulation of activity and peristalsis

Vasculature

  • Arterial Supply
    • Inferior Mesenteric Artery originates from Abdominal Aorta at L3
    • Left Colic Artery arises from Inferior Mesenteric Artery
    • Left Colic Artery anastomoses with the Marginal Artery of Drummond
  • Venous Drainage
    • Left Colic Vein into Inferior Mesenteric Vein into Splenic Vein into Portal Vein to Liver
    • Inferior Mesenteric Vein can drain into the confluence of Splenic and Superior Mesenteric Veins or directly into Superior Mesenteric Vein which will then drain into Portal Vein

Lymphatic Drainage

  • Paracolic nodes along Left Colic Artery
  • Inferior Mesenteric nodes
  • Lumbar nodes
  • Right and Left Lumbar Trunks
  • Cisterna chyli
  • Thoracic Duct
  • Junction Left Internal Jugular and Subclavian Veins

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Esophageal Hiatus - amk397

Discuss the anatomy of the esophageal hiatus and list the structures passing through this hiatus. (6 pts). (amk397)

Anatomy

  • Opening in diaphragm
  • Located at T10
  • Superior, anterior, and to the left of the aortic opening
  • Bounded by muscle fibers that originate in the right crus and cross the midline.
  • Adjacent structures:
    • Inferior phrenic arteries
    • Splanchnic nerves pierce right crus
    • Ligament of Treitz

Contents

  • Esophagus
  • Gastric nerves (anterior and posterior vagal trunk)
  • Esophageal arteries of left gastric vessels
  • Esophageal veins (Portal-caval shunt)
  • Lymphatics

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Urethral Crest - sas630

Discuss the anatomy of the urethral crest. (6 pts)

Location and structure

  • A midline ridge along the posterior wall of the prostatic urethra:
  • The prostatic urethra is 3-4 cm in length and tunnels through the prostate near the anterior surface of the gland
  • The urethral crest is continuous with the pre-prostatic urethra and the membranous urethra which becomes the penile (spongy) urethra

Topography and Relationships

  • Prostatic sinus is located on each side of the crest as a shallow depression
  • The floor of the prostatic sinus is perforated by orifices (pores) of 15-20 prostatic ducts
  • The seminal colliculus is an elevation or widening at the middle of the urethral crest
  • The urethral crest is used as a landmark during TURP
  • The prostatic utricle is a slit like orifice medially located on the seminal colliculus
  • The utricle is Cul-de-sac in shape, 6 mm long and runs upwards and backwards in the substance of the prostate posterior to the median lobe
  • The prostatic utricle develops from the paramesonephric ducts or UG sinus and is thought to be homologous to the female vagina or the uterus (depending on the source)
  • Ejaculatory ducts are located on both sides of the prostatic utricle somewhat inferiorly

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-- LorenEvey - 30 Aug 2011
Topic revision: r1 - 11 Oct 2011, UnknownUser
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