Pelvic Girdle, Anatomy, Bone, Functions and Pectoral Girdle

Pelvic Girdle: The pelvic girdle, also known as the hip girdle, is comprised of a single bone called the hip bone or coxal bone (coxal meaning "hip"). It acts as the point of attachment for each lower limb. Each hip bone is firmly connected to the axial skeleton through its attachment to the sacrum of the vertebral column. Additionally, the right and left hip bones meet at the front to attach to each other. Together, these structures form the bony pelvis, which includes the two hip bones, the sacrum, and the coccyx attached below the sacrum.

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Pre Fertilisation: Structures and Events

What is Pelvic Girdle?

PROKARYOTIC CELLS

What is Pelvic Bone?

EUKARYOTIC CELLS

Pelvic Girdle Anatomy

Bony Pelvis (Pelvic Skeleton)

• The sacrum, coccyx, and two hip bones (ilium, ischium, and pubis) fused to form this structure.
• It serves to support the weight of the upper body and transmit forces to the legs.

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Pelvic Cavity

• Greater (false) pelvis: Located superior to the pelvic brim.
• Lesser (true) pelvis: Situated inferior to the pelvic brim, containing most of the pelvic organs.

Pelvic Floor (Pelvic Diaphragm)

• It supports the pelvic organs by acting as a sling made up of muscular and connective tissue.
• It is made up of several muscle layers, including the levator ani and coccygeus muscles, which support organs and close the rectum/urogenital openings, the urogenital diaphragm, which adds support to the urogenital openings, and the external anal and urethral sphincters, which regulate urination and defecation.

Perineum

• This is the area between the anus and the scrotum/labia majora.
• It contains muscles and structures that support the pelvic organs.

Connective Tissue

Pelvic Girdle Variations Between the Sexes

• Overall Size and Shape: The female pelvis is generally wider and more rounded, while the male pelvis is narrower and more compact.
• Pelvic Inlet: The female pelvic inlet is wider and oval-shaped, whereas the male pelvic inlet is narrower and heart-shaped.
• Pelvic Sides: The female pelvic sides are wider apart, allowing for childbirth, while the male pelvic sides converge towards the pelvic outlet.
• Subpubic Angle: The angle formed by the pubic bones is wider in females (90-100 degrees) and narrower in males (70 degrees).
• Ischial Bones: The ischial bones, which form part of the pelvis, are wider apart in females, creating a larger pelvic outlet.
• Iliac Crests: The iliac crests are more prominent in males, making the false pelvis deeper and narrower.
• Sacrum: The female sacrum is shorter, wider, and more curved than the male sacrum, with a less pronounced promontory.
• Acetabula: The acetabula, which are the sockets of the hip joints, are wider apart and more anteriorly facing in females compared to males.

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The Pelvic Girdle Consists of

1. Hip Bones (Coxal Bones): Each hip bone is made up of three fused bones ilium, ischium, and pubis. These bones fuse together during adolescence to form a single bone. The ilium is the largest and uppermost bone of the hip bone, contributing to the acetabulum, the socket of the hip joint. The ischium forms the lower and back part of the hip bone and supports the body when sitting. The pubis forms the front part of the hip bone and joins the opposite pubic bone at the pubic symphysis.
2. Sacrum: The sacrum is a triangular bone located at the base of the spine, between the two hip bones. It consists of five fused vertebrae and forms the back part of the pelvic girdle. The sacrum connects the spine to the hip bones and helps transmit the weight of the body to the lower limbs.
3. Coccyx: The coccyx, also known as the tailbone, is a small triangular bone located at the base of the sacrum. It consists of three to five fused vertebrae and serves as an attachment point for ligaments and muscles of the pelvic floor.

Pelvic Girdle Bones

1. Ilium

2. Ischium

3. Pubis

Pelvic Girdle Muscles

1. Pelvic Floor Muscles

2. Hip Muscles

Pelvic Girdle Functions

1. Support: It provides support for the organs of the abdomen and pelvis, such as the intestines, bladder, uterus (in females), and rectum. Additionally, the muscles of the pelvic floor help support these organs.
2. Stability: The pelvic girdle helps maintain the stability and balance of the body during various activities like standing, walking, and running. The structure of the pelvis bones and their alignment contribute significantly to this stability.
3. Weight Transfer: It transfers weight from the upper body to the legs. When standing, the weight of the upper body is transmitted through the sacrum to the innominate bones and then to the legs.
4. Muscle Attachment: The pelvic girdle provides attachment points for many important muscles, including the hip muscles. These muscles are essential for leg movement in various directions, such as flexion, extension, abduction, adduction, rotation, and circumduction.
5. Childbirth (in females): For females, the pelvic girdle is specifically adapted for childbirth. The sacrum and coccyx are slightly movable to facilitate the passage of the baby's head during birth. During pregnancy, hormones relax the ligaments in the pelvis, allowing for slight movement of the bones.

Pelvic Girdle and Pectoral Girdle