To avoid a perineal tear the obstetrician cuts the perineum posteriorly before delivery. This process is called

Correct Answer: B

Rationale: The correct answer is B: Episiotomy. An episiotomy is a surgical incision made in the perineum during childbirth to enlarge the vaginal opening and prevent severe perineal tears. This procedure is performed to facilitate the delivery of the baby and reduce the risk of complications for both the mother and the baby. Perineorrhaphy (A) is a surgical repair of a perineal tear or episiotomy after childbirth, not the procedure of making the incision. Cesarean section (C) is a surgical procedure to deliver a baby through an incision in the mother's abdomen and uterus, not related to perineal tears. Tubal ligation (D) is a permanent form of female sterilization by blocking or sealing the fallopian tubes to prevent pregnancy, not relevant to perineal tears during childbirth.

Correct Answer: C

Rationale: The patella is a sesamoid bone located within the tendon of the quadriceps femoris muscle. Sesamoid bones are small, round bones embedded within tendons, providing protection and improving the mechanical advantage of the muscle. It is not irregular (A), short (B), or flat (D) as it does not fit the structural characteristics of those bone types. Therefore, the correct answer is C.

Correct Answer: B

Rationale: The correct answer is B: Rotation. Circular movement around an axis is described as rotation. This movement involves turning or spinning around a fixed point. Dorsiflexion (A) is the movement of bringing the top of the foot towards the shin. Extension (C) refers to straightening or increasing the angle of a joint. Pronation (D) is the inward rotation of the forearm or foot. Rotation (B) specifically signifies movement around an axis, making it the most appropriate choice for circular movement.

Correct Answer: C

Rationale: The correct answer is C: scrotum. The scrotum is a pouch of skin that houses the testes, which are responsible for producing sperm and testosterone. It is considered an external male reproductive organ because it plays a crucial role in maintaining the optimal temperature for sperm production. The penis is also an external male reproductive organ, but it is not part of the scrotum. The urethra is a passage for both urine and semen, and while it is part of the male reproductive system, it is not considered an external reproductive organ. The prostate and seminal vesicle are internal male reproductive organs involved in producing and secreting seminal fluid, making them incorrect choices in this context.

Correct Answer: D

Rationale: The correct answer is D: Liquid. Sound vibrations travel through the inner ear mainly through the liquid-filled cochlea. When sound waves reach the ear, they cause the fluid inside the cochlea to move, stimulating hair cells that convert the vibrations into electrical signals sent to the brain. Choice A (Bone) is incorrect as bone conduction bypasses the middle ear, while sound must pass through it to reach the cochlea. Choice B (Nerve fibers) is incorrect because nerves transmit the electrical signals generated by the hair cells, not sound vibrations themselves. Choice C (Air) is incorrect as the inner ear is filled with liquid, not air, and sound waves need a medium like air to travel through the ear canal but not inside the inner ear.