Pelvic and Perineal Neurology Lecture (Dr. Olinger)

Question 1

Pelvic components of the Lumbar Plexus (L1-L4; see Abdomen)

Answer 1

1. ILIOINGUINAL N. (L1)
   a. (♂) ANTERIOR SCROTAL N. (innervates the anterior Scrotum)

b. (♀) ANTERIOR LABIAL N. (innervates the anterior Labia Majora)

2. GENITOFEMORAL N. (L1-2)
   a. GENITAL BRANCH (to Scrotum in Males and Labia Majora in
   Females)
3. OBTURATOR N. (L2-4; enters the Pelvis along the lateral Pelvic Wall, travels into the Obturator Canal with the Obturator A. and V., branches into an anterior and posterior division and innervates Medial Thigh musculature)
4. LUMBOSACRAL TRUNK (L4-5; feeds into the Sacral Plexus)

Question 2

Sacral Plexus (L4-S4)

Answer 2

1. SUPERIOR GLUTEAL N. (L4-S1; innervate Gluteus Medius M. and Gluteus Minimus M.)
2. INFERIOR GLUTEAL N. (L5-S2; innervate Gluteus Maximus M.)
3. MUSCULAR Branches
   a. NERVE to QUADRATUS FEMORIS M. (L4-S1)

b. NERVE to OBTURATOR INTERNUS M. (L5-S2)
c. NERVE to PIFIROMIS M. (S1-2)

4. POSTERIOR FEMORAL CUTANEOUS N. (S1-3; to the Buttock and upper most
   region of posterior Thigh)
   a. PERINEAL BRANCH ((♂) to the Scrotum, (♀) to Labia Majora)
5. PERFORATING CUTANEOUS BRANCHES (S2,3; to the Medial Buttock)
6. PUDENDAL N. (S2-4; to structures of Perineum, produces the Perineal N., Inferior Rectal N. and Dorsal N. of the Penis in Males)
   a. INFERIOR RECTAL N. (innervates Anal Canal inferior to the Pectinate Line and External Anal Sphincter M.)

b. (♂) DORSAL N. of PENIS (travels along the dorsum of the Penis)

c. (♀) DORSAL N. of CLITORIS (travels along the dorsum of the
Clitoris)

d. DEEP PERIEAL N. (innervates Superficial and Deep Transverse Perineal Ms., Ischiocavernosus M., Bulbospongiosus M., Vaginal Vestibule and Inferior most part of the Vagina)

e. SUPERFICIAL PERINEAL N. (produces Posterior Scrotal N. in the male and Posterior Labial N. in the female)
1. (♂) POSTERIOR SCROTAL N. (terminal branch of Perineal N. to posterior aspect of Scrotum)
2. (♀) POSTERIOR LABIAL N. (terminal branch of Perineal N. to posterior aspect of Labia Majora)

7. Sciatic N. (L4-S3; travels through Greater Sciatic Foramen to posterior aspect of Thigh)
   a. TIBIAL N. (L4-S3; Lower Extremity)

b. COMMON FIBULAR N. (L4-S2; Lower Extremity)
8. PELVIC SPLANCHNIC N. (S2-4; see Autonomic Nervous System)

Question 3

Coccygeal Plexus (S4, S5 and Coccygeal N.)

Answer 3

1. ANOCOCCYGEAL N. (innervates a small area of skin in the Coccygeal region)
2. MUSCULAR BRANCHES
   a. NERVE to the LEVATOR ANI (S4)
   b. NERVE to the COCCYGEUS (S4,5)

Question 4

Autonomic Nervous System components in the Pelvis and Perineum

SYMPATHETIC DIVISION

Answer 4

A). LUMBAR (Abdominal) SYMPATHETIC TRUNK (Paravertebral Sympathetic Trunk; continuous superiorly with the Thoracic Sympathetic Trunk and inferiorly with the Sacral (Pelvic) Sympathetic Trunk)

B). ABDOMINOPELVIC SPLANCHNIC N. Originating in the Abdomen
1. LUMBAR SPLANCHNIC N. (Presynaptic Sympathetic Fibers
from the Lumbar Sympathetic Trunk, L1-5, travel primarily to the Inferior Mesenteric Ganglion to synapse onto Postsynaptic Cells, with some Postsynaptic fibers feeding into the Superior Hypogastric Plexus)

C). PRE VERTEBRAL GANGLIA (location of Postsynaptic Cell Bodies for the Presynaptic Fibers that form the Abdominopelvic Splanchnic Nerves)
1. INFERIOR MESENTRIC GANGLION (Prevertebral Sympathetic Ganglion; lies superior to the origin of the Inferior Mesenteric A., houses Postsynaptic Cell Bodies corresponding to the Presynaptic fibers from the Lumbar Splanchnic N., with branches from the Intermesenteric Plexus forms the Inferior Mesenteric and Superior Hypogastric Plexuses)

D). SACRAL SYMPATHETIC TRUNK (Paravertebral Sympathetic Trunk; continuous superiorly with the Lumbar Sympathetic Trunk, 4 paired ganglia, ending inferiorly in the midline as the Ganglion Impar)
1. GANGLION IMPAR (Coccygeal Ganglion; inferior union of the right and left Paravertebral Trunks)

2. RAMI COMMUNICANTES (Postsynaptic Sympathetic Fibers
   leaving the Sacral Sympathetic Trunk entering the Ventral Rami of Sacral and Coccygeal Spinal Nerve to provide Sympathetic Innervation to the Lower Extremity)

E). ABDOMINOPELVIC SPLANCHNIC N. Originating in the Pelvis
1. SACRAL SPLANCHNIC N. (Postsynaptic Sympathetic Fibers
arising from the Sacral Sympathetic Trunk, feed into the Inferior Hypogastric Plexus)

Question 5

Autonomic Nervous System components in the Pelvis and Perineum

PARASYMPATHETIC DIVISION

Answer 5

A). PELVIC SPLANCHNIC N. (Presynaptic Parasympathetic Fibers from the 2nd through 4th levels of the Sacral part of the Spinal Cord, the Parasympathetic Fibers meet with the Sympathetic fibers of the Hypogastric N. to form the Inferior Hypogastric Plexus)

Question 6

Helpful Note: Visceral Sensory Fibers

Answer 6

• Visceral Sensory fibers accompany the Parasympathetic Fibers of the Pelvic Splanchnic Ns. conveying retrograde pain impulses through Pelvic Splanchnic Ns. into Ventral Rami of Sacral Spinal Nerves then onto the Dorsal Root and Dorsal Root Ganglion where the Cell Bodies exist, finally synapsing in the Dorsal Horn if the Spinal Cord.

Question 7

Pelvic Autonomic Plexuses

Answer 7

A). INTER MESENTERIC PLEXUS (mixed Sympathetic and
Parasympathetic, Sympathetic and Parasympathetic input from the Superior Mesenteric Plexus, part of the Aortic Plexus, forms the Periarterial Plexus which follow the gonadal arteries, also feeds Sympathetic into the Inferior Mesenteric Plexus and Superior Hypogastric Plexus)
1. PERIARTERIAL PLEXUS (descends with the Ovarian A.)
a. OVARIAN PLEXUS (innervates the Uterine Tubes and Ovaries)

B). SUPERIOR HYPOGASTRIC PLEXUS (continuous with the
Intermesenteric Plexus and Inferior Mesenteric Plexus, exclusively Sympathetic, Sympathetic input from Lumbar Splanchnic Ns., lies anterior to the bifurcation of the Abdominal Aorta, produces the Ureteric Plexus and Testicular Plexus, which travel along the Common Iliac As., sends paired Hypogastric Ns. to the Inferior Hypogastric Plexus)
1. HYPOGASTRIC N. (feed into the Inferior Hypogastric Plexus)

C). INFERIOR HYPOGASTRIC PLEXUS (Mixed Sympathetic and
Parasympathetic; Sympathetic input from Hypogastric Ns. and Sacral Splanchnic Ns., Parasympathetic input from the Pelvic Splanchnic Ns.; in addition to Parasympathetically innervating the Descending and Sigmoid Colon the Inferior Hypogastric plexus forms multiple subplexuses generically referred to as Pelvic Plexuses, these include the Vesical Plexus, Uterovaginal Plexus in females and Prostatic Plexus in males, in addition to the Prostatic Plexus many direct branches innervate Pelvic Viscera in the male, as well as the Anal Canal above the Pectinate Line in both males and females)

Question 8

Inferior Hypogastric Plexus

Answer 8

• Mixed Sympathetic and Parasympathetic; Sympathetic input from HYPOGASTRIC Ns. and SACRAL SPLANCHNIC Ns., Parasympathetic input from the Pelvic Splanchnic Ns.; in addition to Parasympathetically innervating the Descending and Sigmoid Colon the Inferior Hypogastric plexus forms multiple subplexuses generically referred to as Pelvic Plexuses, these include the Vesical Plexus, Uterovaginal Plexus in females and Prostatic Plexus in males, in addition to the Prostatic Plexus many direct branches innervate Pelvic Viscera in the male, as well as the Anal Canal above the Pectinate Line in both males and females
  1. FUNCTION TO THE RECTUM AND ANAL CANAL (Sympathetic: contraction of the Internal Anal Sphincter M., Parasympathetic: inhibits contraction of the Internal Anal Sphincter M. and stimulates peristalsis)

2. VESICLE PLEXUS (Mixed Sympathetic and Parasympathetic, continuous with the Inferior Hypogastric Plexus, innervates the Detrusor M. and Internal Urethral Sphincter M.)
   a) . FUNCTION OF THE URINARY BLADDER (Sympathetic: causes contraction of the Internal Urethral Sphincter M.; Parasympathetic: causes contraction of the Detrusor M. and relaxation of the Internal Urethral Sphincter M.)
3. (F) UTEROVAGINAL PLEXUS (Mixed Sympathetic and Parasympathetic, continuous with the Inferior Hypogastric Plexus, innervates the Uterus, Uterine Tubes, Vagina and Ovaries)
   a) . UTERINE PLEXUS (innervates the Uterus and Uterine Tubes)

b). CAVERNOUS Ns. (Parasympathetic innervation to
the Bulbs of the Vestibule, Clitoris and Vestibular Glands)
1. FUNCTION: (produces erection of the Clitoris, engorgement of the Bulbs of the Vestibule and increases vaginal secretion)

4) . PROSTATIC PLEXUS (Mixed Sympathetic and Parasympathetic, innervates the Prostate Gland and much of the male Urethra)
a) . CAVERNOUS Ns. (convey Parasympathetic innervation to the Helicine arteries that supply the erectile tissue)
1. FUNCTION: (Parasympathetic: producing penile erection)

b) . NERVES OF THE DUCTUS DEFERENS (Mixed Sympathetic and Parasympathetic, innervates the Ductus Deferens)
1. FUNCTION: (Sympathetic: contraction of the Internal Urethral Sphincter M., peristalsis-like contraction of the Ductus Deferens)

c). NERVES OF THE EJACULATORY DUCT (Mixed Sympathetic and Parasympathetic, innervates the Ejaculatory Ducts)
1. FUNCTION: (Sympathetic:
peristalsis-like contraction of the Ejaculatory Ducts)

d) . NERVES OF THE SEMINAL VESICLES (Mixed Sympathetic and Parasympathetic, innervates the Seminal Vesicles)
1. FUNCTION: (Sympathetic: contraction and secretion of the Seminal Vesicles to add to Semen)