Biology 122 Spring, 2008

Laboratory 17

Pelvic Osteology and External Genitalia

OBJECTIVES

At the end of this dissection you should:

1. Know the basic osteological features of the bony pelvis which includes the sacrum and the paired coxal bones and their three components. Know the main criteria for distinguishing the female bony pelvis from that of the male

2. Know the relationships of the inguinal ligament, inguinal canal and external genitalia.

3. Be able to trace the pathway of descent of the testis and its accompanying vessels and processus vaginalis and explain the similarities of this pathway with that of an indirect inguinal hernia.

4. Know the origin, course, and distribution of the nerves associated with the inguinal canal and scrotum (ilioinguinal which becomes anterior scrotal, and genital branch of genitofemoral which inervates the cremaster muscle). Know the afferent and efferent limbs of the cremasteric reflex and the significance of this reflex. See Moore & Dalley, p.225.

5. Know the basic parts of the penis; i.e. glans, body with its root, bulb and crura and their associated muscles and connective tissue layers. Know the arterial supply, superficial venous drainage and deep venous drainage. Know the association of the vasculature with the cavernous erectile tissue, the corpus spongiosum and cavernosum. Understand the roles played by parasympathetic, sympathetic, somatic sensory, and motor nerves in erection and blood flow.

6. Know the sensory innervation of the scrotum. Understand the fascial layers associated with the spermatic cord and testis. Know the position and function of the Dartos tunic.

7. Know the structures associated with the testis. Know the lymphatic drainage of the testis and be able to compare it with the scrotum.

8. Know the parts of the external genitalia in the female: mons pubis, labia majora, labia minora, clitoris, prepuce, frenulum, vestibule of the vaginal orifice, hymen (or its remnants), external urethral orifice and greater vestibular gland and its duct (Netter - 354).

9. Understand the position, attachments and structures associated with the urogenital diaphragm in the male and female. Know the structures that penetrate the UG diaphragm in the male and female. Understand the position of the deep and superficial perineal spaces in the male, their fascial layers, contents and continuity with other spaces.

PRELAB PREPARATION

1. Read those sections of your textbook that cover the osteology of the pelvis (pp. 357-368). Read the chapter on the perineum and the external genitalia (pp. 433-467).

2. When studying the external genitalia give special attention to the role of neurovascular structures, muscles and connective tissue sheaths in bringing about and maintaining an erection in the male.