#21 What I Learned Today

Essentials of Clinical Practice

Exam today; no lecture.

Gross Anatomy I

Today we discussed anatomical structures found in the anterior body wall and peritoneal cavity. The muscles of the anterior body wall consist of three major layers, from external to internal: external oblique muscle, internal oblique muscle, and transversus abdominis muscle. Each have a specific direction in which their muscle fibers run. External runs downwards; same direction as your fingers if you put your hands in your pant pockets. Internal runs approximately perpendicular and upwards to external. Transversus abdominis runs horizontally, like the name implies.

Found between the epidermis and abdominal muscles is two layers:

• fatty layer (Camper's)
• fascia layer (Scarpa's)

The anterior body wall has a number of major arteries running through it, including:

• descending aorta
• superior epigastric arteries (from subclavian -> internal thoracic)
• musculophrenic arteries (from subclavian -> internal thoracic)
• superficial circumflex iliac artery
• deep circumflex artery
• inferior epigastric artery

An important structure in the body wall is the inguinal canal, which is formed by the aponeurosis of the external oblique muscle and the inguinal ligament. The inguinal ligament stretches from the anterior superior iliac spine to the pubic tubercle, and acts as the base of the canal. The inguinal canal has two openings through the body wall at the deep inguinal ring and the superficial inguinal ring. The spermatic cord passes through the canal, to bring sperm from the testes, up through the abdomen to get processed, and eventually ejaculated through the penis. The spermatic cord consists of:

• ductus (vas) deferens
• testicular artery
• pampiniform plexus of veins
• genitofemoral nerve
  

Spermatogenesis begins in the testes, where sperm is formed and stored in the epididymis. The sperm then travels up through the ductus deferns to the seminal vesicle, where more fluid is added to the volume of the sperm. The sperm continues through the ejaculatory duct and the prostate gland. It passes by the bulbourethral gland, which adds mucous to the sperm. Finally, the sperm passes through the urethra and the penis.

Gross Anatomy Lab

In dissection lab, we opened up the neck to identify the muscles, bones, vessels, nerves and glands in the area. Some of the noted structures included:

• sternocleidomastoid muscle (cut back to access the hyoid-related muscles)
  
• thyroid gland
• hyoid bone
• sternothyroid muscle
• sternohyoid muscle
• thyrohyoid muscle
• thoracic duct (hard to find)
  
• carotid sheath, containing: common carotid artery, internal jugular vein, and vagus nerve
• cartilages, including: thyroid cartilage (Adam's apple!), cricoid cartilage.
• trachea and esophagus