SACRAL PLEXUS

• Internal iliac artery arises at the bifurcation of the common iliac, artery, Opposite the lumbosacral joint (L5/S1 intervertebral disc)

Division Branch

Posterior Iliac artery

• Superior gluteal artery

• Iliolumbar artery

• Lateral sacral arteries

Anterior Iliac Artery– about 8 branches

• Obturator  artery  (occasionally  from  inferior epigastric artery)

• Inferior gluteal artery

• Umbilical   artery,   which   later   persist   as superior vesical artery (remaining artery becomes medial umbilical ligament).

• Uterine artery (females) or deferential artery (males) Vaginal artery (females, can also arise from uterine artery) or inferior vesical artery (males)

• Middle rectal artery

• Internal pudendal artery

• Artery of the perineum

• Accessory   obturator   artery:   The   obturator artery sometimes arises from the main stem or from the posterior trunk of the internal iliac, or it may spring from the superior gluteal artery; occasionally it arises from the external iliac

Ans. A. Gluteus maximus 

Superior gluteal nerve supplies:

• Gluteus medius
• Gluteus minimus &
• Tensor fasia lata
• Muscles of gluteal region are supplied by branches of the sacral plexus.

There are two sphincters of the urethra

a. Internal urethral sphincter (also k/a sphincter vesicae)

– it is involuntary in nature

– made up of smooth muscle

–  supplied by sympathetic nerves, from lower thoracic & upper lumbar segments of spinal cord

b. External urethral sphincter (also k/a sphincter vesicae)

–  it is voluntary in nature

– made up of striated muscle fibres

– supplied by the perineal branch of the pudendal nerve (derived from spinal nerves S₂,S₃ & S4) – it controls the membranous urethra and is responsible for the voluntary holding of urine.

Superior Gluteal Nerve supplies the 3 abductors of the hip joint namely the gluteus medius, gluteus minimus and tensor fascia latae.

Pudendal nerve leaves the pelvis, to enter the gluteal region, by passing through the lower part of the greater sciatic foramen. Pudendal nerve leaves the gluteal region by passing through the lesser sciatic foramen and enters the pudendal canal, and by means of its branches supplies the external anal sphincter and muscles and skin of the perineum.

Superior gluteal nerve innervates gluteus minimus, gluteus medius and tensor fascia lata. It arises from sacral nerve plexus, which is formed from anterior rami of 4th and 5th lumbar nerves and anterior rami of 1st, 2nd, 3rd and 4th sacral nerves. Gluteus maximus muscle is innervated by the Inferior gluteal nerve (L5,S1,S2 nerve root).

Muscles supplied by superior gluteal nerve (L4, L5, S1):

Pudendal nerve supplying motor part to external anal sphincter is derived from S2-4 roots. It provides motor innervation to perineal muscles, sphincter urethrae and levator ani. It is sensory to genitalia.

• Tibial nerve (L5, S1-3)– It is motor to most of the posterior thigh, posterior leg and plantar surface of the foot.
• Lateral femoral cutaneous nerve (L2,3) – It is sensory to the lateral thigh.
• Femoral nerve (L2-4)– It is motor to iliacus, psoas major, psoas minor, and muscles of the anterior thigh.
• Common peroneal nerve (L4-5, S1-2) – It is motor to the short head of biceps femoris, muscles of the lateral leg, anterior leg and dorsum of foot via superficial and deep peroneal branches.
• Superior gluteal nerve (L4,5 S1)– It is motor to the gluteus medius and minimus, and the tensor fascia lata.
• Inferior gluteal nerve (L5, S1-2)– It is motor to gluteus maximus.

• Pudendal nerve
• Pudendal artery and vein

• Perineal nerve
• Dorsal nerve of penis or clitoris.

The lesser sciatic foramen is formed by the lesser sciatic notch of the pelvic bone, the ischial, the sacrospinous ligament and the sacrotuberous ligament.

It transmits the following structures:

• The tendon of the Obturator internus
• Internal pudendal vessels
• Pudendal nerve
• Nerve to the obturator internus

A. i.e. Completely lined by stratified squamous epithelium

A i.e. Superior Gluteal Nerve

C i.e. Gluteus medius – Inferior gluteal nerve

C i.e. Superior gluteal artery 

B i.e. Gluteus Maximus

Superior gluteal nerve (L4 1_,5 S_i) supplies gluteus medius, gluteus minimus and tensor fascia lata musclesQ. Mn “Superior are those who supply to tense, middle & minimum men”

A i.e. Gluteus maximum

Branches of the sacral plexus, the pudendal nerve, and nerve to the obturator internus leave the pelvis through the lower part of the greater sciatic foramen, below the piriformis.

• They cross the ischial spine with the internal pudendal artery and immediately re-enter the pelvis through the lesser sciatic foramen; they then lie in the ischiorectal fossa.
• The pudendal nerve supplies structures in the perineum.
• The nerve to the obturator internus supplies the obturator internus muscle on its pelvic surface.

Ans. is ‘d’ i.e., Gluteus maximus

Nerve supplying muscles of gluteal region are :-

• Inferior gluteal nerve : Gluteus maximus.
• Superior gluteal nerve : Gluteus medius and minimus.
• Nerve to piriformis : Piriformis
• Nerve to obturator internus : Obturator internus, Gemellus superior.
• Nerve to quadratus femoris : Quadratus femoris, Gemellus inferior.
• Tensor fascia latae is supplied by superior gluteal nerve.

Ans.C-It leaves the pelvis through the lesser sciatic foramen

The yellow color nerve is Pudendal nerve

• The pudendal nerve leaves the pelvis, to enter the gluteal region, by passing through the lower part of the greater sciatic foramen.
• The pudendal nerve leaves the gluteal region by passing through the lesser sciatic foramen and enters the pudendal canal, and through its branches supplies the external anal sphincter and muscles and skin of the perineum.
• The pudendal nerve originates from the lumbosacral plexus (L4-S4). It consists of both sensory fibers (80%) and motor fibers (20%).