Pelvic Girdle

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What is Pelvic girdle?

Pelvis is the lower section of the trunk. The region between the thighs and abdomen is called the pelvic region. It is also called pelvic girdle or bony pelvis. This basin-shaped structure of bones associates the legs and the trunk. The pelvic girdle is a part of the appendicular skeleton, which connects the lower limbs to the axial skeleton. The upper limb is connected by the pectoral girdle to the axial skeleton.

The appendicular skeleton is made up of 126 bones and includes the pectoral girdle and limbs apart from the pelvic girdle.

The pelvic girdle forms the bony framework of the pelvis together with the sacrum of the vertebral column and coccyx. It provides support and stability to the body and transfers the weight of the upper body from the axial skeleton to the hips and lower limbs. It also protects the abdominal and pelvic visceral organs.

What is Pelvic bone?

Pelvis the large bone structure present in the lower part of the body. The sacrum and the coccyx posteriorly forms the pelvis skeleton. A pair of hip bones forms the pelvis skeleton anteriorly and laterally. Each of the hip bones comprise 3 sections – Pubis, Ischium and Ilium. At the time of puberty, these sections fuse forming one bone.

Read more: Pelvic Bone and Its Types

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Parts of the Pelvis

The anatomy of the Pelvic girdle shows the bony pelvis. It contains the skeletal framework of the pelvic region enclosing the pelvic structures. Generally, it is classified into two different regions – the pelvic spine and the pelvic girdle. The pelvic spine is the posterior section of the pelvis after the lumbar spine. It comprises the coccyx and the sacrum. The hip bone or the pelvic girdle comprise three bones – ilium, ischium and the pubic bone.

Pelvic girdle is made up of a pair of single bones called coxal bone (hip bone), which are strongly joined to the sacrum of the vertebral column. Unlike the pectoral girdle, which provides more range of movement, hip bones allow relatively limited movement and form the strong foundation for the upper body and support the body weight. Coxal bones together with the coccyx and the sacrum constitute the pelvis.

The hip bone (coxal bone) is an irregularly shaped part of the bony pelvis. Each half of the pelvic girdle is composed of a single hip bone or coxal bone.

• Coxal bone is made up of a fusion of three bones, namely ilium, ischium and pubis.
• Ilium- Ilium is the largest part of the coxal bone. It is the upper part and has a fan-like structure. It is attached to the sacrum of the vertebral column strongly by the sacroiliac joint.
• Ischium- It makes the posterior part of the pelvic girdle below the ilium. It provides support while sitting.
• Pubis- It makes the lower anterior part of the pelvic girdle.
• Pubic symphysis- It is a joint between the pubis part of the two hip bones in the middle portion. It contains fibrous cartilage.
• Acetabulum- It is a cavity formed by the fusion of ilium, ischium and pubis. The femur or thigh bone articulates with the acetabulum.
• The coccyx is attached to the lower part of the sacrum by sacrococcygeal symphysis.
• Obturator foramen- It is the large opening between the ischium and the pubis bone. It is round or oval in shape. It is filled with the lining of connective tissue and is the attachment site for muscles.

Functions of the Hip joint

The hip is the largest weight-bearing joint in the body; it is a ball-and-socket joint. The joint connects the lower extremities with that of the axial skeleton. The main function of the hip joint is to support the weight of the body dynamically as it promotes load and force transmission to the lower parts from the axial skeleton. Thus it allows mobility. Hip joint enables movement in three main axes; these are all perpendicular to each other.

Further, the hip joint brings about weight-bearing. As a result of the depth of the acetabulum and its shape, the complete head of the femur can be confined by it.

The pelvic girdle divides the pelvic region into two portions, the upper is known as the false pelvis or greater pelvis and the lower part is known as the lesser pelvis or true pelvis.

• Greater pelvis- It is also known as the false pelvis. It is the upper part and encloses the small and large intestine.
• Lesser pelvis- It is the lower part of the pelvis. It contains pelvic organs such as the urinary bladder, internal sex organs, etc. and known as the true pelvis.
• The Pelvic inlet separates the two regions, the outer surface of the pelvic inlet is known as the pelvic brim.
• The lower limit of the lesser pelvis is marked by the pelvic outlet. In females, it is wider.

The female pelvis differs from the male and is adapted for the foetal development and childbirth. The female pelvis is wider and broader than the male pelvis. The bones are lighter compared to males. The pubic arch is greater than 90°, whereas in males it is narrower and less than 90°.

Also see: Locomotion and Movement

The true pelvis has rectum, some bowel, the reproductive structures and the urinary bladder. The false pelvis is superiorly and anteriorly in association with the abdominal cavity. It has sections of colon, most parts of small bowel and the iliac vessels.

Pelvis is the lower section of the torso found between the legs and the abdomen. The region supports the intestines and comprises the bladder and the reproductive structures. The female pelvis, in addition, comprises the cervix, vagina, uterus, ovaries and fallopian tubes. It must accommodate and provide enough space for the development of the foetus and provide a passageway during parturition. Thus, the female pelvis is typically wider and broader compared to the male pelvis.

The pelvic area connects the trunk, upper body to the lower extremities of the body. There are a few structural, functional and anatomical differences between the male and the female pelvis.

The framework of lower limb enables to  perform functions pertaining to balance, weight-bearing and mobility. In comparison to the upper limb, the muscles and bones of the lower limb are much stronger and larger.

The bones of the lower limb are femur, pelvic girdle, tibia, patella, fibula and the bones present in the foot.

Pelvic girdle – Comprises the sacrum and the hip bone. The hip bone in turn comprises the ilium, pubis and the ischium.

Patella – The knee cap or patella is a bone (sesamoid) which is located anterior to the junction of tibia and femur. It is placed in the quadriceps tendon causing the tendons to be placed even more anteriorly, this increases the leverage of the quadriceps. Between the femur and patella, the cartilage present provides cushioning facilities.

Femur – The thigh bone or the femur is the strongest and the longest bone on the human body. It has a rounded head which is found in the medial and proximal facet of the femur, sitting in the acetabulum forming the hip joint.

Tibia and Fibula – They are the bones of the leg. Tibia, the weight-bearing bone is found medial to the fibula and is larger; it is part of the knee joint.

Conclusion

To sum up, the pelvic girdle is made up of a pair of hip bones, which are joined to the axial skeleton through the sacrum. It connects the lower limbs to the trunk. The pelvic girdle, sacrum and the coccyx constitute the pelvis. The pelvis of male and female differs.

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