Pelvic Cavity And Sacrum

Question 1

What is the sacrum formed by?

Answer 1

5 fused sacral vertebrae

Question 2

Does the coccyx have a vertebral arch?

Answer 2

No

Question 3

What do lumbosacral joints consist of?

Answer 3

2 facet joints (zygapophysial joints) and intervertebral disc that joints bodies of L5 and S1

Question 4

Lumbosacral joints are stabilized by what?

Answer 4

Iliolumbar and lumbosacral ligaments

Question 5

Sacroiliac joints (type, force transmit, stabilized by)

Answer 5

-synovial joints
-transmit forces from LL to vertebral column
-anterior, posterior, and interosseous sacro-iliac ligaments

Question 6

Where are each of the stabilizers of the sacro-iliac joints found?

Answer 6

Anterior: front, thickening of fibrous membrane of joint capsule

Interosseous: on back, connects sacrum and ilium (largest and strongest)

Posterior: covers interosseous sacro-iliac lig

Question 7

Pubic symphysis joint (loc, stabilized by)

Answer 7

-anteriorly between pubic bones
-superior and inferior pubic ligaments

Question 8

Why are the superior and inferior pubic ligaments important?

Answer 8

For pregnant women; they allow extra “movement/stretch” when women’s bellies get bigger

Question 9

What are the two muscles of the lateral pelvic wall?

Answer 9

Obturator internus and piriformis

Question 10

Obturator internus OIIA

Answer 10

O: anterolateral wall of true pelvis

I: medial surface of greater troch of femur

I: nerve of obturator internus

A: lateral rot of extended hip, ABD of flexed hip

Question 11

Piriformis OIIA

Answer 11

O: anterior surface of sacrum between anterior sacrum foramina

I: greater troch

I: branches from L5, S1, and S2

A: lateral rotation of extended hip; ABD of flexed hip

Question 12

What forms the sacral plexus?

Answer 12

Anterior rami of S1-S4 and lumbosacral trunk (L4 and L5)

Question 13

What are the main branches of the sacral plexus?

Answer 13

Sciatic, gluteal, and pudendal

Question 14

Main motor and sensory functions of tibial nerve, from sciatic

Answer 14

M: post HS of thigh except PFSH, post leg, sole of foot

S: skin on posterolateral and medial surfaces of foot and sole

Question 15

Main motor and sensory functions of common fibular n, from sciatic

Answer 15

M: BFSH, ant and lat leg, EDB in foot

S: skin on anterolateral surface of leg and dorsal surface of foot

Question 16

Main motor and sensory functions of pudendal

Answer 16

M: perineum, external urethral and anal sphincters, levator ani

S: most skin of perineum, penis and clit

Question 17

Main motor function of superior gluteal n

Answer 17

Glute med and min, TFL

Question 18

Main motor function of inferior gluteal n

Answer 18

Glute max

Question 19

Main motor function of nerve to obturator internus and superior gemellus

Answer 19

Obturator internus and superior gemellus

Question 20

Main motor function of nerve to quadratus femoris and inferior gemellus

Answer 20

QF and inferior gemellus

Question 21

Sensory function of posterior femoral cutaneous n

Answer 21

Skin on posterior thigh

Question 22

Motor and sensory function of nerves to levator ani, coccyges, and external anal sphincter

Answer 22

M: levator ani, coccygeus, external anal sphincter

S: small patch of skin between anus and coccyx

Question 23

What forms the coccygeal plexus?

Answer 23

Minor contribution of S4, mainly formed by S5-Co