Sacral Plexus Flashcards
The sacral plexus is formed by what rami?
Anterior primary rami of L4, L5, S1-S3 and part of S4
Contributions of L4 and L5 are from the _____ trunk
Lumbosacral
The sacral plexus forms of the anterior surface of what muscle?
Piriformis
The sacral plexus divides into anterior and posterior divisions after exiting the ____?
IVF/sacral foremen
What nerve roots supply the nerve to the quadratic femoris and gemellus inferior?
L4, L5, S1
The nerve to the quadratus femoris and gemellus inferior leaves the pelvis through what?
Greater sciatic foramen
The nerve to the quadratus femoris and gemellus inferior supply muscles that have what two actions?
Lateral rotation and addiction of the thigh
What nerve roots form the nerve to the obturator inter us and gemellus superior?
L5, S1 and S2
What opening does the nerve to the obturator internus and gemellus superior leave the pelvis through?
Greater sciatic foramen
After the nerve to the obturator internus and gemellus superior leave the pelvis through the sciatic foramen, it gives off branches to what?
The gemellus superior
The nerve to the obturator internus and gemellus superior re-enters the pelvis through what to supply what?
Lesser sciatic foramen
Obturator internus
The nerve to the obturator internus and gemellus superior supply muscles that have what two actions?
Lateral rotation and abduction of the thigh
The pudendal nerve contains fibers from?
S2, S3, S4
The pudendal nerve exits the pelvic cavity through the ____ _____ _____ and arches around the ______ _______ and into the perineum via the _____ ____ ______
Greater sciatic foramen
Ischial spine
Lesser sciatic foramen
After the pudendal nerve re-enters through the lesser sciatic foramen, it travels in the _______ _______ inferior to the pubic symphysis to reach the dorsal side of the _____ (males) or _____ (females)
Pudendal canal
Penis
Clitoris
Do some branches come off the pudendal nerve within the pudendal canal?
Yes
What are the names of the branches that come off the pudendal nerve within the pudendal canal?
Inferior rectal nerves
Perineal nerve
Dorsal nerve of the penis/clitoris (terminal nerve of the pudendal nerve)
What is the terminal nerve of the pudendal nerve?
Dorsal nerve of the penis/clitoris
The inferior rectal nerves carry _______ information from what two areas?
Sensory
- Skin around the anus
- Inferior 2/3 of the anal canal
What nerve carries sensory information from the skin around the anus and the inferior 2/3 of the anal canal?
Inferior rectal nerves
The inferior rectal nerve has motor supply to what?
External anal sphincter
What nerve contains motor supply to the external anal sphincter
Inferior rectal nerves
The _______ nerve is a branch of the pudendal nerve and splits into deep and superficial branches
Perineal nerve
The deep branch of the perineal nerve have motor supply to what 4 muscles?
- External anal sphincter
- Bulbospongiosus
- Ischiocavernosus
- Superficial transverse perineus
What nerve has motor supply to the following muscles: external anal sphincter, bulbospongiosus, ischiocavernosus, and superficial transferee perineus?
Deep branch of the perineal N.
Superficial branches of the perineal N carry sensory fibers from what in males and females?
Males: posterior scrotum, urethral mucosa, and bulb of the penis
Females: labium majus, external urethral orifice, vestibule
What nerve carries sensory fibers from the posterior scrotum, urethral mucosa, and bulb of the penis in males and labium majus, external urethral orifice, and vestibule in females?
Superficial branches of perineal N.
What muscles does the terminal branch of the pudendal N, the dorsal nerve of the penis/clitoris, supply?
Deep transverse perineus
Urethral sphincter muscles
What nerve supplies the deep transverse perineus and the urethral sphincter muscles?
Dorsal nerve of the penis/clitoris
The dorsal nerve of the penis/clitoris carries sensory fibers from what in males and females?
Males: corpus cavernosum, glans penis, and skin covering penis
Females: corpus cavernosum, clitoris
What nerve carries sensory fibers from the corpus cavernosum, glans penis, and skin covering the penis in males and corpus cavernosum, and the clitoris in females?
Dorsal nerve of the penis/clitoris
Individual muscular branches off the sacral plexus contain fibers from ____ and supply the _____ _______ and ______ muscles
S4
Lavatory ani
Coccygeus
The pelvic splanchnic nerves contain fibers from?
S2, S3, S4
What nerves are branches of the posterior division of the sacral plexus?
- Nerve to piriformis
- Superior gluteal N
- Inferior gluteal N.
- Perforating cutaneous N
Nerve to the piriformis what fibers to the piriformis?
S1 and S2
The superior gluteal N. Is made of what fibers?
L4, L5, S1
The superior gluteal N. Leaves the pelvis through _________, superior/inferior to the piriformis and splits into superior and inferior branches
Greater sciatic foramen, SUPERIOR
What does the superior branch of the superior gluteal N. Supply?
Gluteus mediums and minimus
What does the inferior branch of the superior gluteal N supply?
Gluteus mediums, gluteus minimus and the tensor fascia lata
The inferior gluteal nerve carries fibers from?
L5, S1, and S2
The inferior gluteal nerve leaves the pelvis through the ______ superior/inferior to the piriformis and innervates what?
Greater sciatic foramen, SUPERIOR
Gluteus Maximus
What nerve supplies the gluteus Maximus?
Inferior gluteal N
The perforating cutaneous nerve is made up of what fibers?
S2 and S3
The perforating cutaneous nerves travels through what structure and then ultimately reaches what structure?
Sacrotuberous ligament
Lower medial aspect of the buttocks
The perforating cutaneous nerve may instead be formed by a branch off the ______ nerve or may even be ______
Pudendal
Absent
What nerve may also be formed from the pudendal nerve or be absent?
Perforating cutaneous nerve
What two nerves are formed by branches of both the anterior and posterior division of the sacral plexus?
- Posterior cutaneous nerve of the thigh
2. Sciatic N
what fibers form the posterior cutaneous nerve of the thigh?
S2 and S3 from the anterior division
S1 and S2 fro the posterior division
What nerve is formed by S2 and S3 from the anterior division and S1 and S2 from the posterior divisions?
Posterior cutaneous nerve of the thigh
The posterior cutaneous nerve of the thigh leaves the pelvis through the __________ and ascends/descends through the posterior thigh and inferior leg to where it ultimately communicates with the ______ nerve
Greater sciatic foramen
Descends
Sural
What does the posterior cutaneous nerve of the thigh supply?
Skin on the posterior and medial thigh
What nerve supplied the skin of the posterior and medial thigh?
Posterior cutaneous nerve of the thigh
What is the largest nerve in the human body?
Sciatic nerve
What is the diameter of the sciatic nerve?
2cm