T2 L1 Defining the pelvic region Flashcards
What are the 4 bones that form the pelvis?
2 x innominate bones
Sacrum
Coccyx
What forms the innominate bones?
Ilium
Ischium
Pubis
What forms the sacrum?
Formed by fusion of the 5 sacral vertebrae
Describe the sacroiliac ligament
Between the sacrum and ilum
Describe the sacrococcygeal ligament
Between the sacrum and the coccyx
Describe the sacrospinous ligament
Between ischial spine and sacrum / coccyx
Describe the sacrotuberous ligament
Between lateral aspect of the sacrum and coccyx onto the medial margin of ischial tuberosity
What is the perineum?
Diamond-shaped surface extending from mons pubis to medial surface of the thighs. Posterior to gluteal folds
What divides the perineum into 2 triangles?
By a transverse line which joins the 2 ischial tuberosities
What are the 2 triangles that make up the perineum?
Urogenital triangle
Anal triangle
What is the perineal body?
Where several sphincter and perineal pouch muscles converge
What is enclosed in the deep perineal pouch?
Urethra
Vagina
Glands such as bulbourethral
Perineal muscles
What is enclosed in the superficial perineal pouch?
Urethra
Vagina or root of penis
Glands
Perineal pouch
What is the function of perineal muscles in the deep perineal pouch?
Act as a sphincter
What is the function of perineal muscles in the superficial perineal pouch?
Provide support to external genitalia such as bulbospongiosus or ischiocavernous muscles
What forms the pelvic brim?
Promontory and Ala of sacrum
Right and left linea terminalis
What is the posterior border of the pelvic cavity?
Sacrum / coccyx
What is the anterior border of the pelvic cavity?
Pubic symphysis
What is the inferior border of the pelvic cavity?
Pelvic cavity
What is the superior border of the pelvic cavity?
Pelvic brim
What is the lateral border of the pelvic cavity?
Obturator internus muscle
What is contained in the pelvic cavity?
Reproductive organs / tracts
Bladder
Rectum
What muscles line the walls of the pelvis?
Piriformis
Obturator internus
What muscles line the floor of the pelvis?
Coccygeus
Levator ani
What makes up the levator ani?
Iliococcygeus
Pubococcygeus
Puborectalis
Describe the path of the piriformis muscle
From anterior surface of sacrum through greater sciatic foramen (over ischial spine) to insert onto greater trochanter of femur
Describe the path of the obturator internus
From internal surface of obturator membrane through the lesser sciatic foramen (below ischial spine) to insert onto the greater trochanter of the femur
Where does the coccygeal run from and to?
From ischial spine
To inferior end of sacrum and coccyx
Where does the iliococcygeus run from and to?
From tendinous arch to anococcygeal body
What is the tendinous arch?
Line extending from ischial spine to posterior aspect of pubic bone
Where does the pubococcygeus run from and to?
From posterior aspect of pubic bone
Insert to coccyx (lateral fibres) or merges with contralateral fibres
Where does the puborectalis run from and to?
Originates from posterior aspect of pubic bone
Slings behind the rectum
What are the functions of the pelvic floor?
Support abdominopelvic viscera
Resistance to increases in intra-pelvic / abdominal pressure
Urinary and faecal continence
What are the arteries supplying the pelvic region?
Anterior division of internal iliac into uterine, vesicle or internal pudendal
What are the veins draining the pelvic region?
Internal iliac into common iliac veins
Gonadal into IVC or left renal vein
What are the 2 nerve plexuses that supply the pelvic region
Somatic plexus (L4 to coccyx) Visceral plexus
Describe the somatic plexus
Lumbrosacral (L4 to S4) Coccygeal Motor or sensory function -sciatic nerve -superior / inferior gluteal -pudendal nerve
What is the lumbosacral trunk?
Sacral plexus is joined by anterior primary rami of lumbar L4/5
What are the branches of the lumbosacral trunk?
Superior gluteal nerve
Inferior gluteal nerve
Sciatic nerve
Pudendal nerve
