Female Pelvis and Girdle Anatomy

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Questions and Answers

What is the anatomical conjugate dimension of the pelvis?

12 cm (correct)

9 cm

11 cm

13 cm

Which pelvic diameter can be estimated through vaginal examination?

Transverse diameter

Anteroposterior diameter

Diagonal/internal conjugate (correct)

Sacrocotyloid diameter

What is the smallest diameter for the fetus to navigate during childbirth?

Obstetric conjugate (correct)

Anteroposterior diameter

Transverse diameter

Sacrocotyloid diameter

What is the width of the sacrocotyloid diameter approximately?

9-9.5 cm Signup and view all the answers

Which diameters constitute the four principal pelvic diameters?

Anteroposterior, transverse, and two oblique diameters Signup and view all the answers

What angle does the pelvic brim make with the horizontal?

55˚ Signup and view all the answers

What shape is the pelvic outlet?

Ovoid/Diamond Signup and view all the answers

Which anatomical landmark is NOT associated with the pelvic cavity?

Clavicle Signup and view all the answers

What is the angle of inclination of the pelvic cavity due to the curvature of the spine?

15˚ Signup and view all the answers

What is the length of the anterior wall of the pelvis?

4.5 cm Signup and view all the answers

What is the function of the curve of Carus during childbirth?

To facilitate fetal descent Signup and view all the answers

What forms the two walls of the pelvic cavity?

Anterior wall and posterior wall Signup and view all the answers

What landmark is located at the pelvic outlet?

Symphysis pubis Signup and view all the answers

What is the primary function of the pelvic floor muscles?

To support the bladder, vagina, uterus, and rectum Signup and view all the answers

What bones comprise the adult female pelvis?

Two pelvic bones, one sacrum, one coccyx Signup and view all the answers

Which joints are involved in the articulation of the pelvic girdle?

Two sacroiliac joints and one sacrococcygeal joint Signup and view all the answers

Which part of the pelvis is considered the smallest?

Pubis Signup and view all the answers

What structure is formed by the meeting of the pelvic bones anteriorly?

Symphysis pubis Signup and view all the answers

What part of the pelvic bone forms the superior flattened area?

Ilium Signup and view all the answers

What defines the separation between the true pelvis and the false pelvis?

Iliopectineal line Signup and view all the answers

Which bone is NOT part of the pelvic girdle?

Femur Signup and view all the answers

Which structure can be felt through the buttocks while sitting?

Ischial tuberosities Signup and view all the answers

How many bones are in the adult female pelvis?

4 Signup and view all the answers

During vaginal birth, the fetus rotates using which part of the pelvis?

True pelvis diameters Signup and view all the answers

Which of the following describes the acetabulum?

A deep socket for the head of the femur Signup and view all the answers

Which components are included in the true pelvis?

Pelvic brim, cavity, and outlet Signup and view all the answers

Ischial spines are important for which purpose?

Defining the descent of the fetus Signup and view all the answers

What shape does the pelvic brim resemble?

Oval Signup and view all the answers

Which important anatomical features are located below the iliopectineal line?

True pelvis Signup and view all the answers

What is the primary function of the pelvic floor in relation to the body's posture?

Providing support to pelvic contents Signup and view all the answers

Which of the following muscles are part of the deep muscle layer of the pelvic floor?

Iliococcygeus Signup and view all the answers

How do the pubococcygeus muscles contribute to pelvic health?

They support the urethra, vagina, and rectum Signup and view all the answers

What role do the iliococcygeus muscles play after childbirth?

They pull the coccyx anteriorly Signup and view all the answers

Which action is NOT associated with the pelvic floor?

Articulation of sounds Signup and view all the answers

The ischiococcygeus muscles originate from which anatomical structures?

Ischial spines Signup and view all the answers

What is a significant role of the pelvic floor during labour and birth?

Assisting in fetal descent Signup and view all the answers

Which muscle group primarily helps resist intraabdominal pressure?

Deep pelvic muscles Signup and view all the answers

What characterizes a 1st degree tear during childbirth?

Injury to the skin only Signup and view all the answers

Which of the following correctly describes a 3rd degree tear?

Injury involving the anal sphincter and surrounding muscles Signup and view all the answers

What effect does progesterone have on the pelvis during pregnancy?

Relaxes pelvic ligaments and joints Signup and view all the answers

What is a 4th degree tear characterized by?

Injury to the anal sphincter complex and anal epithelium Signup and view all the answers

What happens to pelvic ligaments and joints postnatally?

They tighten quickly after birth Signup and view all the answers

How may relaxation of pelvic floor muscles during pregnancy impact women postnatally?

It can lead to stress incontinence Signup and view all the answers

What is the distinction between a 3a and 3b degree tear?

Thickness of the external anal sphincter torn Signup and view all the answers

Which statement about mediolateral episiotomy is true?

It may help prevent severe perineal tearing Signup and view all the answers

Study Notes

Female Pelvis

Strong bony structure articulating with lumbar vertebrae superiorly and femoral heads laterally
Enables pelvic movements
Protects pelvic organs
Pelvic floor muscles support bladder, vagina, uterus, and rectum
Four bones (adult): two pelvic/hip/coxal/innominate bones, one sacrum, one coccyx
Four joints: two sacroiliac joints, symphysis pubis, sacrococcygeal joint

Pelvic Girdle

Pelvic bones unite anteriorly (symphysis pubis) and posteriorly (sacroiliac joints)
Three bones form a deep socket (acetabulum) for the hip joint
Ilium forms the superior flattened part of the pelvic bone
Ischium is smaller, forming the inferior part
Ischial tuberosities felt through buttocks
Ischial spines felt vaginally, indicating fetal descent
Pubis forms smallest/anterior part
Blood vessels and nerves pass through obturator foramen

True and False Pelvis

Divided into false pelvis (above iliopectineal line) and true pelvis
True pelvis shape and diameters important for vaginal birth
True pelvis has: pelvic brim (inlet), pelvic cavity, pelvic outlet

Pelvic Brim

Oval shape
Landmarks: sacral promontory, sacral ala, sacroiliac joint, iliopectineal line, iliopectineal eminence, superior pubic ramus, body of pubis bone, symphysis pubis

Pelvic Cavity

Extends from brim to outlet
Roughly circular
Inclined due to spinal curvature; fetus follows curve of Carus
Pelvic brim at 55° to the horizontal
Pelvic outlet at 15° due to differences in anterior and posterior wall lengths

Pelvic Outlet

Ovoid/diamond shaped
Landmarks: symphysis pubis, pubic arch, ischial spines, ischial tuberosities, sacrotuberous and sacrospinous ligaments, coccyx

Pelvic Diameters

Four principal diameters: anteroposterior, transverse, two oblique diameters
Sacrospinous diameter from sacral promontory to iliopectineal eminence (approx 9-9.5 cm)

Pelvic Conjugates

Anatomical conjugate (~12 cm)
Obstetric conjugate (smallest diameter ~11cm)
Diagonal/internal conjugate (~13 cm) estimated via vaginal examination

Pelvic Floor

Strong structure supporting pelvic contents
Involved in micturition, defecation, sexual intercourse, and labour
Consists of two layers of muscles, ligaments, and connective tissue

Deep Muscle Layer (Levator Ani)

Pubococcygeus: extends from inner pubic bone to coccyx, surrounds urethra, lower vagina, and rectum.
Iliococcygeus: from inner iliac bone to coccyx, supporting pelvic organs.
Ischiococcygeus: from ischial spines to lower sacrum and upper coccyx, supporting pelvic joints.

Superficial Muscle Layer

Ischiocavernosus: from ischial tuberosity to clitoris
Bulbocavernosus: in perineum, around vagina, embedding in clitoris
Transverse perinei: from ischial tuberosities to perineum, joining with muscles of perineal body
External anal sphincter
External urethral sphincter

Perineal Body

Area of skin, muscles, and connective tissue between vulva and anus
Vital part of pelvic floor
Muscles: bulbocavernosus, transverse perinei (superficial); pubococcygeus (deep)
Assists in vaginal birth and defecation
Commonly torn during childbirth

Perineal Trauma

Degrees of tear (1st to 4th) based on tissue involvement (skin, perineal muscles, anal sphincters)
3a less than 50%
3b more than 50%
3c EAS and IAS torn
4th degree tear = injury to anal sphincter complex

Physiological Changes to Pelvis and Pelvic Floor (Pregnancy)

Relaxing effect of progesterone affects pelvic ligaments and joints, increasing pelvic dimensions and possibly causing back pain (PGP).
Relaxing pelvic floor muscles useful for birth, but can lead to stress incontinence.

Physiological Changes to Pelvis and Pelvic Floor (Postnatal)

Pelvic ligaments and joints tighten post-birth.
Pelvic floor muscles need to regain function
Early ambulation and exercises can support recovery
Increased blood flow may result in oedema and bruising
Perineal damage may be painful

Pelvic Girdle Pain (PGP)

Pain in front and/or back of pelvis, sometimes affecting hips and thighs
Can affect symphysis pubis and/or sacroiliac joints

Incontinence

Significant proportion of pregnant women experience urinary stress incontinence due to elevated intra-abdominal pressure
Urge incontinence—sudden intense need to urinate.
Pelvic floor exercises may reduce incontinence

Pelvic Floor Exercises

Evidence-based information and advice given during antenatal period
Referral pathway to specialists.
Specific exercises for those with problems like episiotomy, significant perineal tears, or suspected bladder/bowel injury, and previous history of bladder/pelvic floor problems
Training and education should consider cultural factors.

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Description

This quiz covers the anatomy of the female pelvis and pelvic girdle, including the structure, functions, and key components such as bones and joints. Test your understanding of the true and false pelvis, along with their significance in supporting pelvic organs and enabling movement.