Defining the pelvic region Flashcards
Consider the articulated pelvis
State the four bones that together make thee 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)
** and ligaments
State a key anatomical landmark of the ileum
State two key anatomical landmarks of the ischium
State two key anatomical landmarks of the pubic bone
Iliac fossa
Ischial spine, Ischial tuberosity
Superior ramus of pubis bone, inferior ramus of pubis bone
What structure lies between L5 and the sacrum?
What structure lies behind this?
Intervertebal disc
Posterior sacral foramina
Describe the location of the sacroilliac joint
Sacroiliac joint lies in front of the sacroiliac ligament
Sacrp
What is the pubic symphysis
Interpubic disc + ligaments
Starting most superiorly state the ligaments of the pelvis and what they connect to
Sacroiliac ligament - from sacrum to ilium, has anterior and posterior components
Sacrococcygeal ligament- between the sacrum to coccyx
Sacrotuberous ligament- from lateral aspect of sacrum/coccyx onto medial aspect of ischial tuberosity
Sacrospinous ligament- from sacrum to ischial spine
What is the perineum
Space located at the pelvic outlet and inferior to the pelvic diaphragm (muscles of the pelvic floor) - THE NARROW REGION BETWEEN THE THIGHS
- diamond shaped extending from mons pubis to posteriorly to the gluteal folds
- lateral vertex = medial surface of thighs
Which anatomical structure does the transverse line of the perineum join?
Which two compartments arise from this?
What is the midpoint of this transverse line?
The ischial tuberosities
Splittinig the perineum inteo urogenital and anal triangles
The midpoint defines the perineal body
- it sees the convergence of several sphincter and perineal pouch muscles
What structures are enclosed within the deep perineal pouch?
- urethra
- vagina, in females
- glands (e.g. bulbourethral gland in males- Cowper)
- perineal muscles that act as sphincters such as compressor urethrae or urethrovaginal sphincter in females
What structures are enclosed within the superficial perineal pouch?
- urethra
- vagina, in female; root of penis in males
- glands (Bartholin in female)
- perineal muscles that provide support to the external genitalia, such as the bulbospongiosus or ischocavernosus muscles
Outline the structures that form the pelvic brim
- Promontory and wing ofsacrum
- arcuate line
- pectineal line
What are the borders of the true pelvic cavity
Think
- posteriorly
- anteriorly
- inferiorly
- superiorly
- laterally
What are the contents of the true pelvic cavity?
- Posterior: sacrum/coccyx
- Anterior: pubic symphysis
- Inferior: pelvic floor
- Superiorly: pelvic brim
- Laterally: obturator internus m
Reproductive organs, tracts
Bladder
Rectum
Consider the pelvic musculature
Outline the origin, route and insertion of the two muscles which form the lining of the wall
- PIRIFORMIS
- origin: anterior surface of sacrum
- route: traverses through the greater sciatic foramen, above the ischial spine
- insertion: the greater trochanter of the femur - OBTURATOR INTERNUS
- origin: internal surface of the obturator membrane
- route: traverse through the lesser sciatic foramen, below the ischial spine
- insertion: the greater trochanter of the femur
Starting superiorly, state the muscles that make the pelvic floor?
Where does the piriformis muscle fit into this?
Puborectalis muscle
Pubococcygeus muscle
Iliococcygeus muscle
Coccygeus muscle
Piriform muscle
State the origin and insertion of the coccygeal and iliococcygeus muscles
Coccygeal- from the ischial spine to the inferior end of the sacrum+coccyx
Iliococcygeus- from the tendinous arch to the annococcygeal body
What is the tendinous arch?
A line that extends from the ischial spine to the posterior aspect of the pubic bone
State the origin and insertion of the pubococcygeus and puborectalis muscles
Pubococcygeus: from the posterior aspect of the pubic bone, inserting onto the coccyx (lateral fibres),or merging with the contralateral fibres of the same muscle (medial fibres)
Puborectalis: continuous muscle from the posterior aspect of pubic bone and slings behind the rectum
State the arterial supply to the pelvic muscles
Anterior division of INTERNAL ILIAC, providing several branches, e.g. uterine, vesical or internal pudendal
GONADAL, from abdominal aorta - supplies gonads
State the venous drainage to the pelvic muscles
Internal iliac - to common iliac veins
Gonadal- to IVC or L renal vein
Consider the nervous control of the pelvis
Describe the somatic plexuses
(L4-Co) subdivided into
- Lumbosacal: L4-S4
- Coccygeal: S4-Co
- function as motor or sensory e.g. sciatic nerve, sup/inf gluteal, pudendal nerve
Consider the nervous control of the pelvis
Describe the visceral plexuses
- Paravertebral/prevertebral
- Sympathetic/ Parasympathetic/ visceral fibres
- Erection/ejaculation e.g. inferior hypogastric plexus
State 2 nerves that pass through the greater sciatic foramen
- Pudendal nerve
- Sciatic nerve
- Superior gluteal nerve
- Lumbosacral trunk
Consider the lumbosacral trunk
State the nerve roots for the branches of the lumbosacral trunk
Superior gluteal: L4, L5, S1
Inferior gluteal: L5, S1, S2
Sciatic: L4, L5,S1-S3 (largest branch of plexus)
Pudendal: S2-S4
The visceral plexuses consist of both a parasympathetic and sympathetic flow.
- Which nerves provide this
PARASYMPATHETIC FLOW
- Pelvic splanchnic nerves (S2-S4)
SYMPATHETIC FLOW
- Sacral sympathetic trunk
- Superior and inferior hypogastric plexuses
The posterior pelvis
- sciatic nerve
- pudendal nerve
- gluteal vessels (superior- above piriformis and inferior- below piriformis)
Put the following structures in order, from most anterior to posterior
Pudendal n, deep perineal n, dorsal nerve of the clitoris, superior perineal n, sacrotuberious ligament
Dorsal nerve of the clitoris
Deep perineal n
Superior perineal n
Pudendal n
Sacrotuberous ligament
