Applied Anatomy | Medical Science Optional Notes for UPSC PDF Download

Inguinal Canal 

Boundaries

Openings

Inguinal Region - Applied anatomy

Ischiorectal Fossa - Boundaries

• An anatomical region with a wedge-shaped configuration situated on both sides of the anal canal beneath the pelvic diaphragm.
• Measuring 5 cm in length, 2.5 cm in width, and 5 cm in depth.
• The base, directed downward, is formed by the skin, while the apex, located upwards, marks the point where the obturator fascia intersects with the inferior fascia of the pelvic diaphragm—the origin of the levator ani.
• The medial wall inclines upwards and laterally, with its lower part comprising the external anal sphincter and the upper part consisting of the levator ani.
• The lateral wall is vertical and shaped by the obturator internus along with the obturator fascia and ischial tuberosity.
• Anteriorly, it is bordered by the perineal membrane, while posteriorly, it is defined by the sacrotuberous ligament and the lower border of the gluteus maximus.
• The ischiorectal fossa facilitates the distension of the rectal canal during the passage of feces.

Ischiorectal Fossa - Anatomy

Clinical Anatomy - Ischiorectal Fossa

• Abscesses around the anal region (bilateral, attributed to a horseshoe-shaped recess).
• Anal fistula of the ischiorectal type.
• Rectal prolapse.
• Ischiorectal hernia characterized by the hiatus of Schwalbe.

Anorectal Abscesses

• Typically manifests as a painful, pulsating swelling in the anal region, often accompanied by swinging pyrexia in the patient.
• Categorized based on anatomical location into perianal, ischiorectal, submucosal, and pelvirectal types.
• Associated underlying conditions encompass fistula-in-ano (most prevalent), Crohn's disease, diabetes, and immunosuppression.
• Initial treatment involves the drainage of pus, coupled with the administration of appropriate antibiotics.

Perineal Spaces (Superficial and Deep)

Superficial Perineal Space

Deep Perineal Space

Bartholin's Gland Cysts

• Positioned within the superficial perineal pouch of the urogenital triangle, the Bartholin's glands function to produce a small quantity of mucus-like fluid.
• Typically, Bartholin's glands are not discernible during routine physical examination. Nevertheless, obstruction of the duct can lead to their enlargement, resulting in the formation of fluid-filled cysts.
• These cysts have the potential to become infected and inflamed, a condition referred to as bartholinitis.
• Infections are most frequently caused by bacteria such as Staphylococcus spp. and Escherichia coli.

Pelvic Diaphragm

The pelvic diaphragm consists of muscle fibers from the levator ani and the coccygeus muscle.

Levator ANI

• The right and left levator ani lie almost horizontally in the pelvic floor, separated by a narrow gap transmitting the urethra, vagina, and anal canal.
• The levator ani is commonly divided into three parts: pubococcygeus, puborectalis, and iliococcygeus.
• The pubococcygeus, the primary component of the levator, extends backward from the body of the pubis toward the coccyx and may be affected during childbirth. Some fibers are inserted into the prostate, urethra, and vagina.
• The right and left puborectalis unite behind the anorectal junction to form a muscular sling, with some considering them as part of the external anal sphincter.
• The iliococcygeus, the most posterior part of the levator ani, is often poorly developed.

Coccygeus
The coccygeus, located behind the levator ani and frequently more tendinous than muscular, stretches from the ischial spine to the lateral margin of the sacrum and coccyx.

Pelvic Diaphragm - Functions

• It plays a crucial role in offering support to pelvic organs such as the bladder, intestines, and, in females, the uterus.
• It contributes to the maintenance of continence, serving as a component of the urinary and anal sphincters.
• It aids in the process of childbirth by resisting the descent of the presenting part, inducing forward rotation of the fetus to navigate through the pelvic girdle.
• It assists in sustaining optimal intra-abdominal pressure.

Thoracoabdominal Diaphragm

• The diaphragm is a curved musculofibrous dome-shaped sheet that serves as a partition between the thoracic and abdominal cavities.
•  Its predominantly convex upper surface is oriented toward the thorax, while its concave inferior surface faces the abdomen.
• It is a primary muscle involved in respiration.

Parts of the Diaphragm

Vasculature of the Diaphragm

Structures passing through the Diaphragm

Congenital Diaphragmatic Hernia

Hiatal Hernia

Applied Anatomy - Repeats 

• Describe in brief the anatomy and applied significance of inguinal canal. Add a note on descent of testis (1995). 
• Describe the formation of inguinal canal. Add a note on inguinal hernias (2000).
• Describe the boundaries of inguinal canal. Add a note on the anatomy of different types of inguinal hernias. (2014) 
• Write a short note on pelvic diaphragm. (1995) 
• Describe pelvic diaphragm. Add a note on supports of uterus (2001).  
• Describe pelvic diaphragm; write in brief about its applied anatomy (2007). 
• Describe be the gross anatomy of thoracic-abdominal diaphragm. Mention the structures that pass through it (2009). 
• Write short notes on Ischio-Rectal abscess (2001) 
• Discuss boundaries and contents of superficial and deep perineal spaces (pouches). Add a note on their applied Anatomy (2004).