Bones of Pelvis

What is the pelvis?

The pelvis, the lowest portion of the trunk situated between the abdomen and the thighs, is an uneven bony ring of complicated bones. Several joints and ligaments reinforce and support it. It creates attachment points for certain significant muscles and a cavity that can house numerous significant internal organs. It houses the cervix, uterus, fallopian tubes, and ovaries in females and the prostate and seminal vesicles in males. The human pelvis is made up of bony pelvis, pelvic cavity, pelvic floor, and the perineum.

• Bony pelvis − The pelvic girdle /hip bone (ilium, ischium and pubis) and pelvic spine (sacrum and coccyx) are two distinct anatomical parts that make up this area.

• Pelvic cavity − It is the area between the pelvic bones, connected to the abdominal cavity above and the pelvic floor in its inferior border. The greater and lower pelvis make up its two components. The greater pelvis (false pelvis)- is a component of the abdomen. The lower pelvis (true pelvis)- is a component of the pelvic cavity. The rectum, pelvic colon,reproductive organs of the body, and urine bladder all reside in the pelvic cavity. Other internal organs and tissues, such as muscles, arteries, veins, nerves, and the pelvic connective tissue, are also housed in the pelvic cavity.

• Pelvic floor − The pelvic diaphragm is another name for it; it is located immediately below the pelvic cavity. It divides the perineum- located beneath the pelvic floor, from the pelvic cavity- located superiorly. It supports the weight of the visceral organs and serves as a barrier between the pelvis and abdominal cavity.

• Perineum − It stands in for the most inferior portion of the pelvic outflow and is situated between the thighs. The superior pelvic floor separates the perineum from the pelvic cavity. It is crucial for urination, faeces, sexual activity, and delivery.

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Parts of pelvis

The pelvic girdle and pelvic spine are the two anatomical parts that typically make up the pelvis. Ilium, ischium, and pubic bone are the three fused bones that make up the pelvic girdle also called hip bone. These three bones are separated from one another by cartilage known as the triradiate cartilage before puberty in humans and later start to fuse between the ages of 15 and 17. The sacrum and coccyx make up the pelvic spine, which is the back of the pelvis located below the lumbar spine. The pelvic anatomy supports the abdominal contents and aids in distributing weight from the spine to the lower limbs.

• Ilium − One of the three hip bone segments, is the largest and widest and is positioned superiorly with broad and flared bones.

• Ischium − The frontmost part of the pelvic girdle, also called the pubis. Structure consists of a body, superior ramus, and inferior ramus.

• Pubic bone − The posteroinferior portion of the hip bone. A body, an inferior ramus, and a superior ramus are also parts of it.

• Sacrum − A major bone that makes up the rear of the pelvis and is arranged toward the end of the spinal canal. It is unusually thick and helps sustain and transmit the body's weight. The five sacral vertebrae fuse to form the sacrum. It is concave and triangular inverted in form.

• Coccyx − The tailbone, or coccyx, is the last fragment of the spinal segment. It is composed of four vertebrae that combine to frame a triangle shape. It helps in movement and offers weight support.

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Anatomical variations (male and female)

The female pelvis is often larger and wider than a male pelvis as it is constructed in such a way that there is sufficient room for the baby to grow and proceed through the female pelvic birth canal.

Male Pelvis	Female Pelvis
Smaller, leaner, and with larger, thicker bones.	Broader and larger, with lighter, thinner, and denser bones.
The greater pelvis is deep and slender.	Shallow and wide greater pelvis.
Large, clearly visible muscular attachments.	Less pronounced, less noticeable attachments.
Male pelvic structures complement large bodies and solid muscle mass.	Designed to make childbearing and simpler delivery goals possible.
Pelvic inlet with a heart shape.	Oval transverse inlet
Leaner pelvic outlet	Wider pelvic outlet
The sacrum is long, slender, and equally curved.	The sacrum is shorter, wider, and less curved.
The coccyx is stiff and inwardly swollen.	The coccyx is straighter and more elastic.

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Types of pelvis

Pelvises can be categorised into four primary groups based on their diameter: gynaecoid, android, anthropoid, and platypelloid.

• Gynaecoid − It is the most prevalent typical kind of female pelvis. It has a round, shallow, and open overall shape.

• Android − Android pelvis resembles the male pelvis. It has a form more akin to a heart or a wedge and is narrower.

• Anthropoid − Small and deep pelvis that resembles an upright oval or egg in shape.

• Platypelloid − It is a shallow but wide and least frequent type pelvis also called a flat pelvis. It looks like an oval or an egg turned sideways.

Functions of pelvis

• The pelvis serves as the body's and the spine's stable foundation, supports the abdomen, protects the pelvic organs, and attaches to the lower trunk muscles.

• It provides structural support and stability for activities like standing, walking, running etc.

• Supports the body's weight (transmitted along lumbar vertebrae).

• Forms a solid route for the birth canal in females.

Conclusion

The pelvis is an organ-protecting structure with a basin shape that supports the spinal column. It includes the sacrum, coccyx, and three hip bones. The pelvis supports the body's weight as well as numerous other actions including running and walking. There are four varieties of the pelvis such as gynaecoid, android, anthropoid, and platypelloid. The pelvis of both males and females shows a wide range of anatomical variances in terms of shape and size.

FAQs

Q1. What maintains the pelvis' position?

Ans. The sacrococcygeal, lumbosacral, pubic symphysis and sacroiliac joints are the pelvic joints. The sacrotuberous, sacrospinous, and iliolumbar ligaments, among others, keep the pelvic joints intact.

Q2. What happens if your pelvis breaks?

Ans. Organs within the pelvic ring, such as the intestines, kidneys, bladder, or genitalia, may sustain damage after a pelvic fracture.

Q3. On what bone do people sit?

Ans. The seat bones, often referred to as the ischial tuberosity, are a bony projection at the bottom of the pelvic bones. When you sit, it assists in distributing your weight.

Q4. Explain pelvic fracture?

Ans. Fracture caused by fall from height or high-speed accidents occuring in one area of the structure is frequently accompanied by ligament injury or a fracture in another area of the structure. Based on the degree of damage, fractures are frequently classified as "stable" or "unstable."

Q5. What is brachypellic?

Ans. Brachyypellic also called android is the condition when the pelvis of a female shows resemblance to a male pelvis.