Sacral plexus Flashcards
What spinal roots make up the sacral plexus
S1-4 and contributions from L4-5
Location of sacral plexus
Surface of posterior pelvic wall, anterior to piriformis
How are the lumbar and sacral plexi joined
By lumbosacral trunk from combination of roots L4-5
What do the spinal roots divide into
Cords
What do the cords combine to form and how many
5 branches (major peripheral nerves)
What are the branches of the sacral plexus
Superior gluteal nerve,
Inferior gluteal nerve,
Sciatic nerve (covered in separate deck),
Posterior femoral cutaneous nerve/posterior cutaneous nerve of thigh
Pudendal nerve
(Some Irish sailors pester polly)
Destination of branches of sacral plexus
- Leave pelvis via great sciatic foramen
2. Remain in pelvis
Roots of superior gluteal nerve
L4-5 and S1
Course of superior gluteal nerve
Leaves pelvis via great sciatic foramen, entering gluteal region superior to piriformis
Motor Innervation of superior gluteal nerve
Gluteus minimus,
Gluteus medius,
Tensor fascia lata
Sensory Innervation of superior gluteal nerve
None (entirely motor)
Roots of inferior gluteal nerve
L5 and S1-2
Course of inferior gluteal nerve
Leaves pelvis via great sciatic foramen, entering gluteal region inferior to piriformis
Motor Innervation of inferior gluteal nerve
Gluteus maximus
Sensory Innervation of inferior gluteal nerve
None (entirely motor)
Roots of posterior cutaneous nerve of thigh
S1-3
Course of posterior cutaneous nerve of thigh
Leaves pelvis via great sciatic foramen, entering gluteal region inferior to piriformis.
It then descends deep to gluteus maximus and runs down back of thigh to knee
Motor Innervation of posterior cutaneous nerve of thigh
None
Sensory Innervation of posterior cutaneous nerve of thigh
Skin over posterior thigh and leg
Skin over perineum
Roots of pudendal nerve
S2-4
Course of pudendal nerve
Leaves pelvis via great sciatic foramen then re-enters via lesser sciatic foramen.
It moves anterosuperiorly along lateral wall of ischiorectal fossa and terminates by dividing into several branches
Motor Innervation of pudendal nerve
Skeletal muscles in perineum,
External urethral sphincter,
External anal sphincter,
Levator ani
Sensory Innervation of pudendal nerve
Penis,
Clitoris,
Most skin over perineum
Minor branches of sacral plexus
Nerve to piriformis S2,
Nerve to obturator internus L5 and S1-2,
Nerve to quadrator femoris L4-5 and S1
(Root values may not be correct)
Anterior or posterior rami
anterior
