PELVIS MUSCULATURE

Ans:D.)Gluteus Minimus.

Many of the muscles of the gluteal region are external rotators of the hip. These muscles include the gluteus maximus, piriformis, obturator internus, obturator externus, quadratus femoris, superior gemellus, and inferior gemellus. The sartorius is a flexor and external rotator of the hip. The gluteus minimus is an abductor and internal rotator of the hip.

Ans. C. Internal urethral sphincter 

There is no ‘internal urethral sphincter’ in females. It is present in males at the bladder neck and proximal urethral. Its function is to prevent retrograde ejaculation of semen into the bladder during the time of ejaculation.

In males, the detrusor muscle fibers of the bladder at the region of bladder neck and proximal urethra are organized into internal urethral sphincter which is under involuntary control.

External urethral sphincter is present in both males and females.

Vaginal sphincter is formed by the fibres of pubococcygeus known as pubovaginalis.

There are other muscles also which contribute to compressing the vaginal orifice.

The pelvic diaphragm forms a broad muscular sling and provides substantial support to the pelvic viscera.

This muscle group is comprised of the levator ani and the coccygeus muscle. 

Urogenital diaphragm is a triangular musculofascial diaphragm situated in the anterior part of perineum, filling in the gap of the pubic arch. It is formed by the sphincter urethrae, deep transverse perineal muscles enclosed between superior and inferior layer of fascia of urogenital diaphragm. Inferior layer of fascia is called perineal membrane.

Superficial muscles of perineum (lie in superficial perineal pouch) are ischiocavernosus, bulbospongiosus, and superficial transverse perinei.

Deep muscles (lie in deep perineal pouch) are sphincter urethrae, deep transverse perinei, and in females, compression urethrae and sphincter urethrovaginalis.

Ans. is ‘d’ i.e., Obturator internus

Boundries of ischeoanal (ischeorectal) fossa are :-

• Anteriorly :- Posterior border of perineal membrane .
• Posteriorly :- Gluteus maximus muscle, sacrotuberous ligament.
• Laterally :- Ischial tuberosity and obturator internus.
• Medially :- Sphincter ani externus (external anal sphincter) and pelvic diaphragm (levator ani).

Ans;D)Both A and C.

The organ marked by a “red box” in the picture above represents the anal canal.

In the anal canal Puborectalis is essential to maintain continence and Internal sphincter remains in the state of tonic contraction.

Ans;C).Obturator nerve

The structure marked by a red arrow represents the ischial spine.

ISCHIAL SPINE-

A thin pointed triangular eminence that projects from the dorsal border of the ischium and gives attachment to the gemellus superior on its external surface and to the coccygeus, levator ani, and pelvic fascia on its internal surface

The structure crossing the dorsal surface of the ischial spine is the Obturator nerve.
Psoas major, iliacus & pectineus muscles, femoral vessels and nerve, the femoral branch of the genitofemoral nerve, lateral cutaneous nerve of thigh and lymphatics pass below the inguinal ligament.
‘PIN’ structures i.e. Pudendal nerve, Internal Pudendal vessels, Nerve to obturator internus come out of greater sciatic foramen, cross the dorsal surface of ischial spine & enter into the lesser sciatic foramen.
From the posterior border of the body of the Ischium there extends backward a thin and pointed triangular eminence, the ischial spine, more or less elongated in different subjects. 
Clinical significance
It can serve as a landmark in pudendal anesthesia

The triangle shown in the picture above represents Urogenital triangle.

The perineum is divided by an arbitrary line joining the ischial tuberosities into urogenital triangle and anal triangle. The urogenital triangle is bounded by pubic rami superiorly, the ischial tuberosities laterally, and the superficial transverse perineal muscle posteriorly.

Ans. d. Located at bladder neck

External urethral sphincter
Voluntary
Made of striated muscle fibres
It is roughly pear shaped, being thickest near the middle of urethra and thicker in front than at sides or back.
Supplied by perineal branch of pudendal nerve (S2-S4)
Origin: From ischiopubic rami on each side

Internal urethral sphincter
Involuntary
Made of smooth muscle
Continuation of detrusor muscle
It is an extension of circular muscle at the bladder neck
Supplied by sympathetic nerves (T10 -L1)
Females lack internal urethral sphincter

Ans. is ‘a’ i.e., Pubococcygeus 

Pubococcygeus runs backward from the body of pubis toward the coccyx. Some of the fibres get inserted into prostate, urethra, vagina, and anorectal junction and named accordingly : Puboprostaticus , pubourethralis, pubovaginalis, puborectalis respectively.

Ans. is ‘b’ i.e., Ischiocavernosus muscle