Prosection Videos for Week 5 Anatomy

What is the innervation of the diaphragm?

C3-5

Which nerve runs anterior to the root of the lung and innervates the diaphragm?

Phrenic nerve

Which nerve runs posterior to the root of the lung and gives off branches to the esophageal plexus?

Vagus nerve (CN X)

What branch of the vagus nerve loops under the ligamentum arteriosum and ascends to the larynx?

Left recurrent laryngeal nerve (a branch of the left vagus nerve)

Which nerve loops under the right subclavian artery and ascends to the larynx?

Right recurrent laryngeal nerve (a branch of the right vagus nerve)

What innervates the cremaster muscle in males?

Genital branch of the genitofemoral nerve

What nerve innervates the skin of the groin and upper thigh and passes through the superficial inguinal ring?

Ilioinguinal nerve (L1)

What nerve innervates the skin above the pubic symphysis and runs more superiorly than its L1 counterpart?

Iliohypogastric nerve (L1)

What is the sympathetic nerve that originates from T5–T9, does not synapse in the sympathetic chain, and pierces the diaphragm?

Greater thoracic splanchnic nerve

What connects the intercostal nerves (ventral rami) to the sympathetic chain?

Rami communicantes (white and gray)

What is the primary action of the rectus abdominis muscle?

Flexes the trunk (e.g. during sit-ups or abdominal crunches)

What is the function of the cremaster muscle in males?

Elevates the testis (part of the cremasteric reflex)

Why is the left recurrent laryngeal nerve clinically important?

loops under the ligamentum arteriosum

can be compressed by an aortic aneurysm, enlarged lymph nodes, or tumors, leading to hoarseness or vocal cord paralysis.

Why are foreign objects more likely to lodge in the right main bronchus during aspiration?

Because the right main bronchus is shorter, wider, and more vertical than the left.

What can result from thoracic duct injury during thoracic surgery?

Chylothorax, a condition where lymphatic fluid accumulates in the pleural space.

What nerve is at risk during hernia repair or incisions near the superficial inguinal ring?

The ilioinguinal nerve

How does a direct inguinal hernia travel through the abdominal wall?

It passes medial to the inferior epigastric vessels, through Hesselbach’s triangle, and exits through the superficial inguinal ring.

How does an indirect inguinal hernia travel through the abdominal wall?

It passes lateral to the inferior epigastric vessels, through the deep inguinal ring, inguinal canal, and exits the superficial ring — often following the spermatic cord in males.

What is the anatomical path of an indirect inguinal hernia?

It passes lateral to the inferior epigastric vessels, through the deep inguinal ring, then the inguinal canal, and exits via the superficial inguinal ring — often following the spermatic cord in males.

What is the anatomical path of a direct inguinal hernia?

It passes medial to the inferior epigastric vessels, through Hesselbach’s triangle, and exits the superficial inguinal ring.

What nerve is at risk during hernia repair or lower abdominal surgery near the inguinal region?

The ilioinguinal nerve, which passes through the superficial inguinal ring and provides sensory innervation to the groin and upper scrotum/labia.

Where do the superior and inferior epigastric arteries anastomose?

On the deep posterior surface of the rectus abdominis muscle.

What are the three major branches of the aortic arch, in order?

Brachiocephalic trunk, left common carotid artery, and left subclavian artery

(Mnemonic: Arch → Brachiocephalic, Carotid, Subclavian)

What arteries supply the posterior intercostal spaces?

Posterior intercostal arteries, which arise from the descending thoracic aorta.

What is the source of the inferior epigastric artery, and what does it supply?

It arises from the external iliac artery and supplies the lower anterior abdominal wall, traveling up the posterior surface of rectus abdominis.

What is the source of the superior epigastric artery, and what does it supply?

It is a continuation of the internal thoracic artery, travels down the posterior rectus sheath, and anastomoses with the inferior epigastric artery.

What forms the anterior wall of the inguinal canal?

The external oblique aponeurosis

What forms the posterior wall of the inguinal canal?

The transversalis fascia (and conjoint tendon medially, though not mentioned in transcript)

What forms the floor of the inguinal canal?

The inguinal ligament (thickened inferior fibers of the external oblique aponeurosis)

What forms the roof of the inguinal canal?

The internal oblique and transversus abdominis muscles arching over the canal

Where is the deep inguinal ring located?

In the transversalis fascia, lateral to the inferior epigastric vessels

Where is the superficial inguinal ring located?

In the external oblique aponeurosis, just superior to the pubic tubercle

What are the boundaries of Hesselbach’s triangle?

• Medial: Lateral border of rectus abdominis

• Lateral: Inferior epigastric vessels

• Inferior: Inguinal ligament

What are the three branches of the aortic arch, in order from right to left?

1. Brachiocephalic trunk

2. Left common carotid artery

3. Left subclavian artery
   (Mnemonic: Aortic arch → BCS)

What vessels supply oxygenated blood to the lungs, specifically the bronchi and lung tissue?

Bronchial arteries, which arise from the descending thoracic aorta

What arteries supply the posterior intercostal spaces and thoracic wall?

Posterior intercostal arteries, which branch from the descending thoracic aorta

What is the origin of the inferior epigastric artery and what does it supply?

It arises from the external iliac artery and supplies the lower anterior abdominal wall by traveling up the posterior surface of rectus abdominis

What is the origin of the superior epigastric artery and what does it supply?

It is a continuation of the internal thoracic artery, travels down the posterior surface of rectus abdominis, and supplies the upper anterior abdominal wall

Where do the superior and inferior epigastric arteries anastomose?

On the deep surface of rectus abdominis

Why is the epigastric arterial anastomosis clinically significant?

It provides collateral circulation between the subclavian and external iliac arteries, useful in cases of aortic coarctation or aortic clamping.

What are the medial and lateral attachments of the rectus abdominis muscle as described in the prosection?

• Medially: Connected by the linea alba

• Laterally: Extends to the semilunar line, where it meets the aponeuroses of the lateral abdominal muscles

What are the attachments of the external oblique muscle mentioned in the transcript?

• Attaches via aponeurosis to:
  

  • Linea alba

  • Pubis

  • Anterior superior iliac spine (ASIS)

• Inferior aponeurotic fibers form: the inguinal ligament

Where does the internal oblique muscle arise from, according to the transcript?

• Iliac crest

• Anterior superior iliac spine (ASIS)

Where does the transversus abdominis muscle attach superiorly and inferiorly (as implied in the dissection)?

• Superior fibers not specified

• Inferior limit: Described as ending before reaching the deep inguinal ring

What structure marks the lateral edge of the rectus abdominis, and what creates it?

The semilunar line, created by the convergence of the anterior and posterior rectus sheath aponeuroses

What does the external oblique aponeurosis become in the spermatic cord?

External spermatic fascia

What does the internal oblique muscle contribute to in the spermatic cord?

The cremaster muscle and cremasteric fascia

What does the transversalis fascia become in the spermatic cord?

Internal spermatic fascia

Does the transversus abdominis muscle contribute any layers to the spermatic cord?

No — it ends superior to the deep inguinal ring, so it does not contribute a layer

What is the order of layers surrounding the spermatic cord from superficial to deep?

1. External spermatic fascia (from external oblique)

2. Cremaster muscle and fascia (from internal oblique)

3. Internal spermatic fascia (from transversalis fascia)

What embryologic structure pulls the testicle through the abdominal wall, dragging these layers with it?

The gubernaculum

The semilunar line (where

anterior and posterior rectus sheaths meet)

What nerve supplies the skin over the pubic symphysis?

Iliohypogastric nerve (L1)

Which nerve carries preganglionic sympathetic fibers from T5–T9?

Greater thoracic splanchnic nerve

Which nerve provides parasympathetic innervation to thoracic and abdominal organs?

Vagus nerve (CN X)

What arteries carry deoxygenated blood to the lungs?

Pulmonary arteries (from the pulmonary trunk)

What arteries supply oxygenated blood to lung tissue?

Bronchial arteries (from the descending thoracic aorta)

Why is this epigastric anastomosis clinically important?

It forms collateral circulation between subclavian and external iliac arteries