Mr jibril.ANA 214 Lecture note on Gross anatomy.pptx

Anatomy for 200l students

1. ANA 214 GROSS ANATOMY

2. ABDOMEN

3. ABDOMEN The abdomen is the part of the trunk between the thorax and the pelvis. It is a flexible, dynamic container, housing most of the organs of the alimentary system and part of the urogenital system. The dynamic, multi-layered, musculo-aponeurotic abdominal walls not only contract to increase intra-abdominal pressure, but also distend considerably, accommodating expansions caused by ingestion, pregnancy, fat deposition, or pathology Containment of the abdominal organs and their contents is provided by musculo-aponeurotic walls anterolaterally, the diaphragm superiorly, and the muscles of the pelvis inferiorly.

4. ABDOMEN Interposed between the more rigid thorax and pelvis, this arrangement enables the abdomen to enclose and protect its contents while providing the flexibility required by respiration, posture, and locomotion. Nine regions of the abdominal cavity are used to describe the location of abdominal organs. These regions are delineated by four planes: two sagittal (vertical) and two transverse (horizontal) planes. The two sagittal planes are usually the midclavicular planes that pass from the midpoint of the clavicles.

5. ABDOMEN Most commonly, the transverse planes are the subcostal plane, passing through the inferior border of the 10th costal cartilage on each side, and the transtubercular plane, passing through the iliac tubercles (approximately 5 cm posterior to the ASIS on each side) and the body of the L5 vertebra. Both of these planes have the advantage of intersecting palpable structures. The anterolateral abdominal wall and several organs lying against the posterior wall are covered on their internal aspects with a serous membrane or peritoneum (serosa) that reflects (turns sharply and continues) onto the abdominal viscera (soft parts, internal organs), such as the stomach, intestine, liver, and spleen

6. ABDOMEN Thus, a bursal sac or lined potential space (peritoneal cavity) is formed between the walls and the viscera that normally contains only enough extracellular (parietal) fluid to lubricate the membrane covering most of the surfaces of the structures forming or occupying the abdominal cavity. Visceral movement associated with digestion occurs freely, and the double-layered reflections of peritoneum passing between the walls and the viscera provide passage for the blood vessels, lymphatics, and nerves. Variable amounts of fat may also occur between the walls and viscera and the peritoneum lining them.

7. MUSCLES OF THE ABDOMINAL WALL There are five (bilaterally paired) muscles in the anterolateral abdominal wall: three flat muscles and two vertical muscles. The three flat muscles are the external oblique, internal oblique, and transversus abdominis. Two vertical muscles rectus abdominis and pyramidalis.

8. Muscle Origin Insertion Innervation Main Action External oblique External surfaces of 5th–12th ribs Linea alba, pubic tubercle, and anterior half of iliac crest Thoraco-abdominal nerves (T7–T11 spinal nerves) and subcostal nerve Compresses and supports abdominal viscera, flexes and rotates trunk Internal oblique Thoracolumbar fascia, anterior two thirds of iliac crest, and connective tissue deep to lateral third of inguinal ligament Inferior borders of 10th–12th ribs, linea alba, and pecten pubis via conjoint tendon Thoraco-abdominal nerves (anterior rami of T6–T12 spinal nerves) and fi rst lumbar nerves ‘’ Transversus abdominis Internal surfaces of 7th–12th costal cartilages, thoracolumbar fascia, iliac crest, and connective tissue deep to lateral third of inguinal ligament Linea alba with aponeurosis of internal oblique, pubic crest, and pecten pubis via conjoint tendon ‘’ Compresses and supports abdominal viscera Rectus abdominis Pubic symphysis and pubic crest Xiphoid process and 5th–7th costal cartilages Thoraco-abdominal nerves (anterior rami of T6–T12 spinal nerves) Flexes trunk (lumbar vertebrae) and compresses abdominal viscera; stabilizes and controls tilt of pelvis (antilordosis)

9. RECTUS SHEATH The rectus sheath is the strong, incomplete fibrous compartment of the rectus abdominis and pyramidalis muscles. Also found in the rectus sheath are the superior and inferior epigastric arteries and veins, lymphatic vessels, and distal portions of the thoraco-abdominal nerves (abdominal portions of the anterior rami of spinal nerves T7–T12) The rectus sheath is formed by the decussation and interweaving of the aponeuroses of the flat abdominal muscles. Beginning approximately one third of the distance from the umbilicus to the pubic crest, the aponeuroses of the three flat muscles pass anterior to the rectus abdominis to form the anterior layer of the rectus sheath, leaving only the relatively thin transversalis fascia to cover the rectus abdominis posteriorly.

10. POSTERIOR ABDOMINAL WALL The posterior abdominal wall is mainly composed of the: Five lumbar vertebrae and associated IV discs (centrally). Posterior abdominal wall muscles, including the psoas, quadratus lumborum, iliacus, transversus abdominis, and oblique muscles (laterally). Diaphragm, which contributes to the superior part of the posterior wall. Fascia, including the thoracolumbar fascia. Lumbar plexus, composed of the anterior rami of lumbar spinal nerves. Fat, nerves, vessels (e.g., aorta and IVC), and lymph nodes

11. MUSCLES OF THE POSTERIOR ABDOMINAL WALL The main paired muscles in the posterior abdominal wall are the: Psoas major: passing inferolaterally. Iliacus: lying along the lateral sides of the inferior part of the psoas major. Quadratus lumborum: lying adjacent to the transverse processes of the lumbar vertebrae and lateral to superior parts of the psoas major. Applied anatomy; Abdominal hernia

12. DIAPHRAGM The diaphragm is a double-domed, musculotendinous partition separating the thoracic and abdominal cavities. Its mainly convex superior surface faces the thoracic cavity, and its concave inferior surface faces the abdominal cavity. The diaphragm is the chief muscle of inspiration (actually, of respiration altogether, because expiration is largely passive). It descends during inspiration; however, only its central part moves because its periphery, as the fixed origin of the muscle, attaches to the inferior margin of the thoracic cage and the superior lumbar vertebrae.

13. DIAPHRAGM The pericardium, containing the heart, lies on the central part of the diaphragm, depressing it slightly. The diaphragm curves superiorly into right and left domes; normally the right dome is higher than the left dome owing to the presence of the liver. The muscular part of the diaphragm is situated peripherally with fibers that converge radially on the trifoliate central aponeurotic part, the central tendon. The central tendon has no bony attachments and is incompletely divided into three leaves, resembling a wide cloverleaf. Although it lies near the center of the diaphragm, the central tendon is closer to the anterior part of the thorax.

14. DIAPHRAGM Sternal part: consisting of two muscular slips that attach to the posterior aspect of the xiphoid process; this part is not always present. Costal part: consisting of wide muscular slips that attach to the internal surfaces of the inferior six costal cartilages and their adjoining ribs on each side; the costal parts form the right and left domes. Lumbar part: arising from two aponeurotic arches, the medial and lateral arcuate ligaments, and the three superior lumbar vertebrae; the lumbar part forms right and left muscular crura that ascend to the central tendon.

15. APERTURES OF THE DIAPHRAGM Caval opening ; Inferior vena cava Esophagial hiatus ; Esophagus, right and left vagal trunks, esophageal branches of the left gastric vessels, and a few lymphatic vessels. The fibers of the right crus of the diaphragm decussate (cross one another) inferior to the hiatus, forming a muscular sphincter for the esophagus that constricts it when the diaphragm contracts. Aortic hiatus ; Descending aorta, thoracic duct, azygous and hemiazygous veins. Smaller openings; for sphlancnic nerves and lymphatic vessels

16. ACTIONS OF THE DIAPHRAGM When the diaphragm contracts, its domes are pulled inferiorly so that the convexity of the diaphragm is somewhat fl attened. Although this movement is often described as the “descent of the diaphragm,” only the domes of the diaphragm descend. The diaphragm’s periphery remains attached to the ribs and cartilages of the inferior six ribs. As the diaphragm descends, it pushes the abdominal viscera inferiorly. This increases the volume of the thoracic cavity and decreases the intrathoracic pressure, resulting in air being taken into the lungs. In addition, the volume of the abdominal cavity decreases slightly and intra-abdominal pressure increases somewhat. Applied anatomy; Paralysis of the diaphragm

17. INGUINAL REGION The inguinal region (groin) extends between the ASIS and pubic tubercle. It is an important area anatomically and clinically: anatomically because it is a region where structures exit and enter the abdominal cavity, and clinically because the pathways of exit and entrance are potential sites of herniation. Although the testis is located in the perineum postnatally, the male gonad originally forms in the abdomen. Its relocation out of the abdomen into the perineum through the inguinal canal accounts for many of the structural features of the region

18. INGUINAL REGION The inguinal ligament is a dense band constituting the inferiormost part of the external oblique aponeurosis. Although most fibers of the ligament’s medial end insert into the pubic tubercle, some follow other courses to form the: Lacunar ligament (of Gimbernat) Pectineal ligament (of Cooper). Reflected inguinal ligament

19. INGUINAL CANAL The inguinal canal is formed in relation to the relocation of the testis during fetal development. The inguinal canal in adults is an oblique passage, approximately 4 cm long, directed inferomedially through the inferior part of the anterolateral abdominal wall. It lies parallel and superior to the medial half of the inguinal ligament. The main occupant of the inguinal canal is the spermatic cord in males and the round ligament of the uterus in females. These are functionally and developmentally distinct structures that occur in the same location. The inguinal canal also contains blood and lymphatic vessels and the ilio-inguinal nerve in both sexes.

20. INGUINAL RINGS The deep (internal) inguinal ring is the entrance to the inguinal canal; Ductus dfeference, round ligament (in females), Testicular vessels enter the inguinal canal Superficial inguinal ring is the exit of the inguinal canal; Through here the testicular vessels, round ligament and spermatic cord. Applied anatomy; Inguinal hernia

21. SPERMATIC CORD The spermatic cord contains structures running to and from the testis and suspends the testis in the scrotum. The spermatic cord begins at the deep inguinal ring lateral to the inferior epigastric vessels, passes through the inguinal canal, exits at the superficial inguinal ring, and ends in the scrotum at the posterior border of the testis. Fascial coverings derived from the anterolateral abdominal wall during prenatal development surround the spermatic cord. The coverings of the spermatic cord include the following: Internal spermatic fascia: derived from the transversalis fascia. Cremasteric fascia: derived from the investing fascia of both the superficial and deep surfaces of the internal oblique muscle. Also contains the cremasteric muscle External spermatic fascia: derived from the external oblique aponeurosis and its investing fascia.

22. SPERMATIC CORD The cremaster muscle reflexively draws the testis superiorly in the scrotum, particularly in response to cold. In a warm environment, such as a hot bath, the cremaster relaxes and the testis descends deeply in the scrotum. Both responses occur in an attempt to regulate the temperature of the testis for spermatogenesis (formation of sperms), which requires a constant temperature approximately one degree cooler than core temperature, or during sexual activity as a protective response. The cremaster typically acts coincidentally with the dartos muscle, smooth muscle of the fat-free subcutaneous tissue of the scrotum (dartos fascia), which inserts into the skin, assisting testicular elevation as it produces contraction of the skin of the scrotum in response to the same stimuli.

23. CONTENTS OF SPERMATIC CORD Ductus deferens (vas deferens): a muscular tube approximately 45 cm long that conveys sperms from the epididymis to the ejaculatory duct. Testicular artery: arising from the aorta and supplying the testis and epididymis. Artery of ductus deferens: arising from the inferior vesical artery. Cremasteric artery: arising from the inferior epigastric artery. Pampiniform venous plexus: a network formed by up to 12 veins that converge superiorly as right or left testicular veins. Sympathetic nerve fi bers on arteries and sympathetic and parasympathetic nerve fibers on the ductus deferens. Genital branch of the genitofemoral nerve: supplying the cremaster muscle. Lymphatic vessels: draining the testis and closely associated structures and passing to the lumbar lymph nodes.

24. TESTES The testes (testicles) are the male gonads—paired ovoid reproductive glands that produce sperms (spermatozoa) and male hormones, primarily testosterone. The testes are suspended in the scrotum by the spermatic cords, with the left testis usually suspended (hanging) more inferiorly than the right testis. The surface of each testis is covered by the visceral layer of the tunica vaginalis, except where the testis attaches to the epididymis and spermatic cord. The tunica vaginalis is a closed peritoneal sac partially surrounding the testis, which represents the closed-off distal part of the embryonic processus vaginalis.

25. TESTES The visceral layer of the tunica vaginalis is closely applied to the testis, epididymis, and inferior part of the ductus deferens. The slit-like recess of the tunica vaginalis, the sinus of the epididymis, is between the body of the epididymis and the posterolateral surface of the testis. The internal spermatic fascia, is more extensive than the visceral layer and extends superiorly for a short distance onto the distal part of the spermatic cord. The small amount of fluid in the cavity of the tunica vaginalis separates the visceral and parietal layers, allowing the testis to move freely in the scrotum.

26. TESTES The testes have a tough fibrous outer surface, the tunica albuginea, that thickens into a ridge on its internal, posterior aspect as the mediastinum of the testis. From this internal ridge, fibrous septa extend inward between lobules of minute but long and highly coiled seminiferous tubules in which the sperms are produced. Applied anatomy; cryptochidism

27. EPIDIDYMIS The epididymis is an elongated structure on the posterior surface of the testis. Efferent ductules of the testis transport newly developed sperms to the epididymis from the rete testis. The epididymis is formed by minute convolutions of the duct of the epididymis, so tightly compacted that they appear solid. The duct becomes progressively smaller as it passes from the head of the epididymis on the superior part of the testis to its tail. At the tail of the epididymis, the ductus deferens begins as the continuation of the epididymal duct. In the lengthy course of this duct, the sperms are stored and continue to mature.

28. EPIDIDYMIS The epididymis consists of the: Head of the epididymis: the superior expanded part that is composed of lobules formed by the coiled ends of 12–14 efferent ductules. Body of the epididymis: major part consisting of the tightly convoluted duct of the epididymis. Tail of the epididymis: tapering continuation with the ductus deferens, the duct that transports the sperms from the epididymis to the ejaculatory duct for expulsion via the urethra during ejaculation

29. PENIS The penis is the male copulatory organ and, by conveying the urethra, provides the common outlet for urine and semen. The penis consists of a root, body,and glans. It is composed of three cylindrical cavernous bodies of erectile tissue: the paired corpora cavernosa dorsally and the single corpus spongiosum ventrally. In the anatomical position, the penis is erect; when the penis is flaccid, its dorsum is directed anteriorly. Each cavernous body has an outer fibrous covering or capsule, the tunica albuginea. Superficial to the outer covering is the deep fascia of the penis (Buck fascia), the continuation of the deep perineal fascia that forms a strong membranous covering for the corpora cavernosa and corpus spongiosum, binding them together

30. PENIS The corpus spongiosum contains the spongy urethra. The corpora cavernosa are fused with each other in the median plane, except posteriorly where they separate to form the crura of the penis. Internally, the cavernous tissue of the corpora is separated (usually incompletely) by the septum penis crura, bulb, and ischiocavernosus and bulbospongiosus muscles. The root is located in the superficial perineal pouch, between the perineal membrane superiorly and the deep perineal fascia inferiorly The body of the penis is the free pendulous part that is suspended from the pubic symphysis. Except for a few fibers of the bulbospongiosus near the root of the penis and the ischio cavernosus that embrace the crura, the body of the penis has no muscles.

31. PENIS The penis consists of thin skin, connective tissue, blood and lymphatic vessels, fascia, the corpora cavernosa, and corpus spongiosum containing the spongy urethra. Distally, the corpus spongiosum expands to form the conical glans penis, or head of the penis. The margin of the glans projects beyond the ends of the corpora cavernosa to form the corona of the glans. The corona overhangs an obliquely grooved constriction, the neck of the glans, which separates the glans from the body of the penis. The slit-like opening of the spongy urethra, the external urethral orifi ce (meatus), is near the tip of the glans penis. Applied anantomy; Erectile dysfunction

32. NEUROVASCULATURE OF THE PENIS The deep arteries of the penis are the main vessels supplying the cavernous spaces in the erectile tissue of the corpora cavernosa and are, therefore, involved in the erection of the penis. They give off numerous branches that open directly into the cavernous spaces. When the penis is flaccid, these arteries are coiled, restricting blood flow; they are called helicine arteries of the penis. Others are; arteries to the bulb of the penis and dorsal arteries of the penis Venous Drainage of Penis. Blood from the cavernous spaces is drained by a venous plexus that joins the deep dorsal vein of the penis in the deep fascia. Blood from the skin and subcutaneous tissue of the penis drains into the superficial dorsal vein(s), which drain(s) into the super fi cial external pudendal vein. Some blood also passes to the internal pudendal vein. Innervation of Penis. The nerves derive from the S2–S4 spinal cord segments and spinal ganglia, passing through the pelvic splanchnic and pudendal nerves, respectively

33. PELVIS & PERINEUM

34. PELVIS In common usage, the pelvis (L. basin) is the part of the trunk that is inferoposterior to the abdomen, and is the area of transition between the trunk and the lower limbs. The pelvic cavity is the inferiormost part of the abdominopelvic cavity. Anatomically, the pelvis is the part of the body surrounded by the pelvic girdle (bony pelvis), part of the appendicular skeleton of the lower limb

35. PELVIC GIRDLE The pelvic girdle is a basin-shaped ring of bones that connects the vertebral column to the two femurs. The primary functions of the pelvic girdle are to: Bear the weight of the upper body when sitting and standing. Transfer that weight from the axial to the lower appendicular skeleton for standing and walking. Provide attachment for the powerful muscles of locomotion and posture and those of the abdominal wall, withstanding the forces generated by their actions. Contain and protect the pelvic viscera and provide support for the abdominopelvic viscera and gravid (pregnant) uterus. Provide attachment for the erectile bodies of the external genitalia.

36. BONES OF THE PELVIS In the mature individual, the pelvic girdle is formed by three bones: Right and left hip bones (coxal or pelvic bones): large, irregularly shaped bones, each of which develops from the fusion of three bones, the ilium, ischium, and pubis. Sacrum: formed by the fusion of five, originally separate, sacral vertebrae. Coccyx

37. JOINTS OF THE PELVIS Sacro-iliac joint; Anterior and posterior sacro-iliac ligaments, interrosseous sacroiliac ligaments, sacro-spinous ligaments Lumbo-sacral joint; Ilio-lumbar ligaments Pubic symphysis; inter-pubic disc, superior and inferior pubic ligament Sacro-coccygeal joint; Anterior and posterior sacro-coccygeal ligaments

38. DIFFERENCE BETWEEN MALE AND FEMALE PELVIS BONY PELVIS MALE FEMALE General structure Thick and heavy Thin and light Pelvic inlet (superior pelvic aperture) Heart shaped, narrow Oval and round; wide Pelvic outlet comparatively small Comparatively large Pubic arch and subpubic angle Narrow (<70 ) Wide (>80 ) Obtuor foramen Round Oval Acetabulum Large Small Greater sciatic notch Narrow ~70 Inverted V Almost 90 Greater pelvis (false pelvis) Deep Shallow Lesser palvis (True pelvis) Narrow and deep; tapering Wide and shallow; cylindrical

39. TYPES OF FEMALE PELVIS There are four main types of female pelvis namely; Android ; Cone or wedge shaped, Wide at the top but narrow at the buttom Anthropoid ; Oval in shape and narrower Gynecoid ; Wide and round at the top and at the buttom, best for childbirth Platypelloid ; Flat, shallow and wide, difficulty in childbirth

40. TYPES OF FEMALE PELVIS

41. RECTUM The rectum is the pelvic part of the digestive tract and is continuous proximally with the sigmoid colon and distally with the anal canal. The rectum lies posteriorly against the inferior three sacral vertebrae and the coccyx, anococcygeal ligament, median sacral vessels, and inferior ends of the sympathetic trunks and sacral plexuses. In males, the rectum is related anteriorly to the fundus of the urinary bladder, terminal parts of the ureters, ductus deferentes, seminal glands, and prostate.

42. RECTUM In females, the rectum is related anteriorly to the vagina and is separated from the posterior part of the fornix and the cervix by the recto-uterine pouch. Inferior to this pouch, the weak rectovaginal septum separates the superior half of the posterior wall of the vagina from the rectum. Blood supply to the rectum is by; Superior rectal arteries om the inferior mesenteric arteries Right and left middle rectal arteries from the internal iliac arteries Inferior rectal arteries from the internal pudendal arteries Veinous drainage is by the Superior, inferior and middle rectal veins

43. ANAL CANAL The anal canal is the terminal part of the large intestine and of the entire digestive tract. It extends from the superior aspect of the pelvic diaphragm to the anus. The canal (2.5–3.5 cm long) begins where the rectal ampulla narrows at the level of the U-shaped sling formed by the puborectalis muscle. The anal canal ends at the anus, the external outlet of the alimentary tract. The anal canal, surrounded by internal and external anal sphincters, descends postero-inferiorly between the anococcygeal ligament and the perineal body. The canal is collapsed, except during passage of feces. Both sphincters must relax before defecation can occur.

44. DEFECATION REFLEX The internal anal sphincter is an involuntary sphincter surrounding the superior two thirds of the anal canal. It is a thickening of the circular muscle layer. Its contraction (tonus) is stimulated and maintained by the sympathetic nervous system. Its contraction is inhibited by parasympathetic NS. This sphincter is tonically contracted most of the time to prevent leakage of fluid or flatus; however, it relaxes (is inhibited) temporarily in response to distension of the rectal ampulla by feces or gas, requiring voluntary contraction of the puborectalis and external anal sphincter if defecation or flatulence is not to occur. The ampulla relaxes after initial distension (when peristalsis subsides) and tonus returns until the next peristalsis, or until a threshold level of distension occurs, at which point inhibition of the sphincter is continuous until distension is relieved.

45. ARTERIAL SUPPLY OF THE ANAL CANAL This is done by the superior, middle and inferior rectal arteries & veins Applied anaomy; Hemorrhoids Incontinence

46. PROSTATE The prostate (approximately 3 cm long, 4 cm wide, and 2 cm in antero-posterior (AP) depth) is the largest accessory gland of the male reproductive system The firm, walnut-size prostate surrounds the prostatic urethra. The glandular part makes up approximately two thirds of the prostate; the other third is fibromuscular. It is made up of a right and left lobe seperated by an isthmus. The right and left lobes are further divided into into; inferioposterior lobule, inferiolateral lobule, anteromedial lobule and a superomedial lobule. The prostatic ducts open into the prostatic urethra emptying the prostatic fluid into it.

47. PROSTATE The prostatic arteries derived from the middle rectal and internal pudendal arteries. Veinous drainage is by the prostatic veins which ends ultimately into the internal iliac veins. Applied anatomy; BPH

48. OVARIES AND UTERINE TUBES The ovaries are almond-shaped and -sized female gonads in which the oocytes (female gametes or germ cells) develop. They are also endocrine glands that produce reproductive hormones. Each ovary is suspended by a short peritoneal fold or mesentery, the mesovarium. The mesovarium is a subdivision of a larger mesentery of the uterus, the broad ligament. Medially within the mesovarium, a short ligament of ovary tethers the ovary to the uterus. Consequently the ovaries are typically found laterally between the uterus and the lateral pelvic wall during a manual or ultrasonic pelvic examination

49. OVARIES AND UTERINE TUBES The ovarian vessels, lymphatics, and nerves cross the pelvic brim, passing to and from the superolateral aspect of the ovary within a peritoneal fold, the suspensory ligament of the ovary, which becomes continuous with the mesovarium of the broad ligament. The uterine tubes (formerly called oviducts or fallopian tubes) conduct the oocyte, discharged monthly from an ovary during child-bearing years, from the peri-ovarian peritoneal cavity to the uterine cavity. They also provide the usual site of fertilization. The tubes extend laterally from the uterine horns and open into the peritoneal cavity near the ovaries

50. UTERINE TUBES The uterine tubes (approximately 10 cm long) lie in a narrow mesentery, the mesosalpinx and is made up of four parts; Infundibulum : the funnel-shaped distal end of the tube that opens into the peritoneal cavity through the abdominal ostium. The fi nger-like processes of the fimbriated end of the infundibulum (fi mbriae) spread over the medial surface of the ovary; one large ovarian fimbria is attached to the superior pole of the ovary Ampulla : the widest and longest part of the tube, which begins at the medial end of the infundibulum; fertilization of the oocyte usually occurs in the ampulla

51. UTERINE TUBES Isthmus : the thick-walled part of the tube, which enters the uterine horn. Uterine part : the short intramural segment of the tube that passes through the wall of the uterus and opens via the uterine ostium into the uterine cavity at the uterine horn. ARTERIAL SUPPLY Ovarian and uterine arteries from the abdominal aorta and pelvic sources Pampiniform veinous plexus which drain into the ovarian vein and then into the IVC. Applied anatomy; Tubal ligation

52. UTERUS The uterus (womb) is a thick-walled, pear-shaped, hollow muscular organ. The embryo and fetus develop in the uterus. Its muscular walls adapt to the growth of the fetus and then provide the power for its expulsion during childbirth. The non-gravid (non-pregnant) uterus usually lies in the lesser pelvis, with its body lying on the urinary bladder and its cervix between the urinary bladder and rectum. The uterus is a very dynamic structure, the size and proportions of which change during the various changes of life and although its size varies considerably, the non-gravid uterus is approximately 7.5 cm long, 5 cm wide, and 2 cm thick and weighs approximately 90 g.

53. PARTS OF THE UTERUS The body/fundus The isthmus Cervix; supravaginal part and a vaginal part Uterine cavity Uterine horns Histologically the wall of the uterus consists of; Perimetrium; peritoneum supported by CT Myometrium; middle coat of smooth muscle that is highly vascularised; also produces cramping during menses and contracts to expel foetus an6d placenta during childbirth Endometrium; inner mucous layer where blastocyte is implanted if pregnancy occurs

54. UTERINE BLOOD SUPPLY The broad ligament of the uterus is a double layer of peritoneum (mesentery) that extends from the sides of the uterus to the lateral walls and fl oor of the pelvis. This ligament assists in keeping the uterus in position. Blood supply to the uterus is via the eterine arteries while veinous drainage is by Uterine veinous plexus which empty into the internal iliac veins Applied anatomy; hysteroctomy, cervical cancer, ovarian cancer, amenorrhea, dysmenorrhea.

55. VAGINA The vagina, a distensible musculomembranous tube (7–9 cm long), extends from the middle cervix of the uterus to the vaginal orifice, the opening at the inferior end of the vagina. The vagina: Serves as a canal for menstrual fluid, Forms the inferior part of the birth canal, Receives the penis and ejaculate during sexual intercourse, and Communicates superiorly with the cervical canal and inferiorly with the vestibule of the vagina. Its blood supply comes from the vaginal and internal pudendal arteries and veinous drainage from the uterovaginal veinous plexus into the internal iliac veins

56. URINARY BLADDER The urinary bladder, a hollow viscus with strong muscular walls, is characterized by its distensibility. The bladder is a temporary reservoir for urine, and varies in size, shape, position, and relationships according to its content, and the state of neighboring viscera. When empty, the bladder is somewhat tetrahedral and externally has an apex, body, fundus, and neck. The walls of the bladder are composed chiefly of the detrusor muscle. Toward the neck of the male bladder, the muscle fibers form the involuntary internal urethral sphincter. This sphincter contracts during ejaculation to prevent retrograde ejaculation (ejaculatory reflux) of semen into the bladder

57. URINARY BLADDER The main arteries supplying the bladder are branches of the internal iliac arteries. The superior vesical arteries supply anterosuperior parts of the bladder. In males, the inferior vesical arteries supply the fundus and neck of the bladder. In females, the vaginal arteries replace the inferior vesical arteries and send small branches to posteroinferior parts of the bladder. The obturator and inferior gluteal arteries also supply small branches to the bladder. The veins draining blood from the bladder correspond to the arteries, and are tributaries of the internal iliac veins. Applied anatomy; Vesicivaginal fistula, incontinence