Defining the pelvic region Flashcards
The four bones that make up the pelvis
Two innominate bones: ilium, ischium and pubis
Sacrum formed by the fusion of the 5 sacral vertebrae
Coccyx formed by the fusion of the 4 coccygeal vertebrae
The innomiate bones
Ilium
Ischium
Pubis
Ligaments of the pelvis
Sacroiliac ligament
Sacrotuberous ligament
Sacrospinous ligament
Sacrococcygeal ligament
Sacroiliac
Between the sacrum and the ilium
Has an anterior and posterior component
Sacrococcygeal
Between the sacrum and coccyx
Sacrospinous
Between the spine and the sacrum/ coccyx
Sacrotuberous
Posterior to the sacrospinous
Between the lateral aspect of the sacrum and coccyx onto medial margin of ischial tuberosity
The perineum
Refers to the space located at the pelvic outlet and inferior to the pelvic diaphragm
Describes the narrow region between the thighs
Diamond shaped surface extending from the mons pubis to the medial surface of the thighs and posteriorly to the gluteal folds
The perineum diamond
A transverse lining joins the two ischial tuberosities splits the perineum into two triangles
- urogenital and anal triangles
The mid point of this line defines the perineal body
The perineal body sees the convergence of several sphincter and perineal pouch muscles
Deep perineal pouch encloses
Urethra
Vagina in females
Glands such as bulbourethral glands in males
Perineal muscles that act as sphincters, such as compressor urethrae or urethrovaginal sphincter in females
Superficial perineal pouch encloses
Urethra
Vagina in females, root of penis in males
Glands, such as bartholin in females and cowper in males
Perineal muscles that provide support to the external genitalia, such as the bulbospongiosus or ischiocavernosus muscles
Pelvic joints
Sacroiliac
Sacrococcygeal
Pubic symphysis
The pelvic brim
Formed by the
- promontory and ala (wing) of sacrum
- right and left linea terminalis (arcuate line and pectineal line)
Pelvic cavity borders
Posterior: sacrum/ coccyx
Anterior: pubic symphysis
Inferior: pelvic floor
Superior: pelvic brim
Lateral: obturator internus m
Contents of the pelvic cavity
Reproductive organs/ tracts
Bladder
Rectum
Pelvic musculature lining the wall
Piriformis
Obturator internus
Pelvic musculature lining the floor
Coccygeus
Levator ani (iliococcygeus, pubococcygeus and puborectalis)
Piriformis
From the anterior surface of the sacrum
Through the grater sciatic foramen
Inserts onto the greater trochanter of the femur
Obturator internus
From the internal surface of the obturator membrane
Through the lesser sciatic foramen
Also inserts onto the greater trochanter of the femur
Coccygeal
From the ischial spine to the inferior end of the sacrum and coccyx
Iliocyccygeus
From the tendinous arch (a line extending from the ischial spine to the posterior aspect of the pubic bone)
To the annococcygeal body
Pubocyccygeus
From the posterior aspect of the pubic bone
Inserts to the coccyx (lateral fibres) or merges with the contralateral fibres of the same named muscle (medial fibres)
Puborectalis
A continuous muscle that originates from the posterior aspect of the pubic bone and slings behind the rectum
Arterial supply to the pelvis
Anterior division of internal iliac, providing several branches e.g. uterine, vesical or internal pudendal
Gonadal, from abdominal aorta, supplying gonads
Venous drainage of the pelvis
Internal iliac to common iliac veins
Gonadal to IVC or L renal vein
Nervous control
Somatic plexuses
Visceral plexuses
Somatic plexuses
L4-Co
Divided into
- lumbosacral (L4-S4)
- coccygeal (S4-Co_
Function as motor or sensory
Visceral plexuses
Paravertebral/ prevertebral
Sympathetic/ parasympethtic/ viscreal fibres
Erection/ ejaculation
Lumbosacral trunk
Superior gluteal
Inferior gluteal
Sciatic
Pudendal
Parasympathetic flor
Pelvic splanchnic nerves (S2-S4
Sympathetic flow
Sacral sympathetic trunk
Superior and inferior hypogastric plexuses
Posterior pelvis (gluteal)
Sciatic nerve
Pudendal nerve
Gluteal vessels
- superior
- inferior
