The pelvic region includes the pelvic bones, sacrum, coccyx, pubic symphysis, as well as ligaments, joints and membranes. Some experts also refer to it as the buttocks area.
The article discusses the anatomy of the pelvis: the skeletal system, muscles, genital and excretory organs.
Pelvic skeletal system
The pelvic skeleton consists of the pelvic bones, the sacrum and the coccygeal bone. Each of them is firmly fixed. The ilium, as well as the coccygeal, articulates with the sacrum.
The pelvis is divided into large and small sections.
The first consists of the sides with the wings of the ilium. On the inner surface is the iliac fossa, and on the outside - the gluteal pits.
The small pelvis consists of a cylindrical cavity with upper and lower openings (that is, inlet and outlet).
The coccygeal bone is slightly movable, which helps women during childbirth. The pelvic bone anatomy has the following differences between men and women:
- men's pelvis is long and narrow, women's are shorter and wider;
- the male pelvic cavity is conical, the female is cylindrical;
- wings of the ilium in menare more vertical, in women - more horizontal;
- branches of the pubic bones in men make an angle of 70-75 degrees, in women - 90-100 degrees;
- for men, the shape of the entrance resembles a heart (as on cards), for women it is rounded, although it happens that women also have an entrance like a “card heart”.
Bundles
Well-developed ligaments fix the four bones of the pelvis, the anatomy of which is discussed above. Three joints help them to connect to each other: pubic fusion (two unpaired), sacroiliac (pair) and sacrococcygeal fusion.
One is located on the pubic bones from the top edge, the other - from the bottom. The third ligament strengthens the joints of the sacrum and ilium.
Muscular system of the pelvis
In this section, the anatomy of the pelvis is represented by parietal and visceral muscles. In the first part, in the large pelvis, there is a muscle consisting of three interconnected m.iliacus, m.psoas major and m.psoas minor. In the small pelvis, the same parietal muscles are represented by the piriformis muscle, obturator internus, and coccyx.
The visceral muscles take part in the formation of the pelvic diaphragm. It includes paired muscles that lift the anus and unpaired m.sphincter ani extremus.
Here are the pubococcygeal muscle, iliococcygeus, and a powerfully developed circular muscle of the distal part of the rectum.
Blood supply and lymphatic system
Blood enters the pelvis(anatomy here involves the participation of the walls of the pelvis and internal organs) from the hypogastric artery. It divides first into anterior and posterior, and then into other branches.
The blood enters the soft tissues of the pelvis through a single vessel a.iliolumbalis, which branches into two terminal branches.
The walls of the small pelvis provide four arteries:
- lateral sacral;
- obturator;
- upper gluteus;
- lower gluteus.
The vessels of the abdominal walls and retroperitoneal space are involved in the roundabout blood circulation. In the roundabout venous circle, the main veins pass between the large and small pelvis. There are abundant venous anastomoses located near the wall of the rectum and in its thickness, as well as under the peritoneum of the pelvis. When blockade of large pelvic veins, the veins of the spine, lower back, anterior abdominal wall and retroperitoneal tissue serve as a roundabout way.
The anatomy of the pelvis, like other systems, involves the variability of the morphology of the vessels in the lymph.
The main lymphatic collectors from the pelvic organs are the iliac lymphatic plexuses, which divert the lymph.
Lymphatic vessels under the peritoneum mainly pass at the level of the middle floor of the pelvis.
Innervation
The nerves of this area are divided into:
- somatic;
- vegetative (parasympathetic and sympathetic).
The somatic system of nerves is represented by the sacral plexus associated with the lumbar. Sympathetic - sacral part of the border trunks and unpaired coccygeal node. The parasympathetic nerves are nn.pelvici s.splanchnici sacrales.
Buttocks
The anatomy of the gluteal region is often not included in the pelvis. However, topographically, it should be assigned here, and not to the lower extremities. Therefore, we will briefly touch on it.
The gluteal region is bounded from above by the iliac crest, and from below by the gluteal crease, under which is the gluteal groove. On the lateral side, one can imagine a vertical line of a row of bones, and on the medial side, both areas are separated by the intergluteal fissure.
Let's look at the anatomy here in layers:
- the skin of this area is thick and dense;
- well-developed subcutaneous tissue with superficial, middle and lower nerves;
- followed by the superficial lamina of the gluteal fascia;
- gluteus maximus;
- gluteal fascia plate;
- fat tissue between the large muscle and the middle layer of muscle;
- middle muscle layer;
- deep muscle layer;
- bones.
Excretory organs
Anatomy of the small pelvis includes an unpaired muscular organ - the bladder. It consists of top, body, bottom and neck. One department here passes into another. The bottom is fixed with the urogenital diaphragm. When the bladder begins to fill, its shape becomes ovoid. When the bubble is empty, the shape is close to saucer-shaped.
The blood supply comes from the system of the hypogastric artery, and the venous outflow is directed into the thickthe cystic plexus, which is adjacent to the lateral surfaces and the prostate gland.
Innervation is carried out by somatic and autonomic fibers.
The rectum begins to develop from embryonic rudiments. The upper section is derived from the endoderm, and the lower one appears by screwing in from the surface of the ectodermal layer.
The rectum is at the level of the posterior pelvis. It is divided into three sections: upper, middle and lower.
Musculature outside is represented by powerful longitudinal fibers, and inside - circular. The mucous membrane consists of numerous folds. The innervation here is similar to that in the bladder.
Reproductive system
Without the reproductive system, it is impossible to view the pelvis (structure). The anatomy of this area in both sexes consists of the gonad, Wolffian body, canal, Müllerian duct, urogenital sinus and genital tubercles, folds and ridges.
The sex gland is laid in the lower back and turns into a testicle or ovary, respectively. Wolf's body, canal and duct of the Mullers are also laid here. However, further in the female, the Müllerian canals are differentiated, and in the male, the Wolf body and ducts.
The rest of the rudiments are reflected in the external organs.
The testicle and ovary grow behind the peritoneum.
The male reproductive system is represented by:
- integument of the testis, consisting of skin, tunica pelvis, Cooper's fascia, cremaster, common and intrinsic vaginal tunic, albuginea;
- seedgland;
- lymphatic system;
- an appendage consisting of three sections (head, body and tail);
- spermone;
- seminal vesicles (hollow tubes with coiled protrusions);
- prostate gland (glandular-muscular organ between the diaphragm and the bottom of the bladder);
- penis, consisting of three sections (root, body and head);
- urethra.
The anatomy of the female pelvis includes the reproductive system from:
- uterus (derivative of Mullerian canals);
- ovaries located in a special ovarian fossa;
- fallopian tubes, consisting of four sections (funnel, dilated part, isthmus and part perforating the wall);
- vagina;
- external genital organs, consisting of the labia majora and vulva.
Cerineum
This area is located from the pubic hillock to the top of the coccygeal bone of the pelvis.
The anatomy of the perineum in both men and women is divided into 2 areas: pudendal (front) and anal (back). In front of the area corresponds to the genitourinary triangle, and behind - rectal.
Conclusion
This is the structure of the pelvis as a whole. The anatomy of this area, of course, is the most complex system. This article only gives a brief overview of what it consists of and how it works.
