Lecture 7: Gluteal Region + Lumbosacral Plexus Flashcards
What is the nerve network supplying the lower extremities with sensory and motor nerves?
Lumbosacral plexus
Where does the lumbosacral plexus originate?
Ventral primary rami of spinal nerves including L1-S3
What 9 branches of the lumbosacral plexus emerge in the gluteal region?
Superior gluteal n. Inferior gluteal n. Nerve to piriformis Sciatic n. Posterior femoral cutaneous n.
Motor nerves to quadratus femoris, inferior and super gemelli, and obturator internus
Where does the sciatic n. originate?
Spinal cord levels L4-S3
What does the sciatic n. pass through to get into the gluteal region?
Greater sciatic foramen
What are the 2 divisions of the sciatic n.?
Tibial division
Peroneal division
Which division of the sciatic n. supplies the hamstring muscles in the posterior thigh?
Tibial division
The tibial division of the sciatic n. passes through what to get into the posterior compartment of the leg?
Popliteal fossa
What nerve supplies all muscles in the posterior compartment of the leg?
Tibial n. (Branch of sciatic n.)
The tibial division of the sciatic n. eventually enters the tarsal tunnel and divides to supply the sole of the foot as what 2 nerves?
Lateral plantar n.
Medial plantar n.
The peroneal division of the sciatic n. begins as what major nerve positioned next to the head of the fibula?
Common peroneal n. (Fibular)
Why is the position of the common peroneal n. a potential issue?
Its position next to the head of the fibula makes it susceptible to traumatic injury
What are the 2 branches of the common peroneal n. and what do they supply?
Superficial peroneal n. - lateral compartment of the leg
Deep peroneal n. - anterior compartment of the leg
Where does the posterior femoral cutaneous n. originate?
Spinal cord levels L2-L4
The posterior femoral cutaneous n. passes under what structure to enter the anterior thigh?
Inguinal ligament
What is the final branch of the posterior femoral cutaneous n.?
Saphenous n.
Where does the obturator n. originate?
Spinal cord levels L2-L4
What does the obturator n. pass through to get into the medial thigh?
Obturator foramen in the obturator membrane
The obturator n. supplies all muscles in the medial compartment of the thigh except which one? What nerve supplies that muscle?
Pectineus - femoral n.
The lumbar aspect of the lumbosacral plexus is located in the lumbar region within what muscle?
Psoas major m. (Anterior to transverse processes of lumbar vertebrae)
The lumbar aspect of the lumbosacral plexus is formed by the _______ rami of L__-__
Anterior; L1-4
[also receives contributions from T12]
What are the 6 major peripheral nerves of the lumbar aspect of the lumbosacral plexus?
Iliohypogastric n. Ilioinguinal n. Genitofemoral n. Lateral cutaneous n. of the thigh Obturator n. Femoral n.
The iliohypogastric n. is the first major branch of the lumbar plexus. It runs to the iliac crest, across the _____ ______ muscle, and perforates the _____ ______ muscle where it divides into its terminal branches
Quadratus lumborum
Transversus abdominis
What are the roots of the iliohypogastric n.?
L1 (with contributions from T12)
The iliohypogastric n. supplies motor function to what 2 muscles?
Internal obliques
Transversus abdominis
Iliohypogastric n. supplies sensory innervation to what area?
Posterolateral gluteal skin in pubic region
What nerve of the lumbar plexus also stems from L1 and follows the same course as the iliohypogastric n.?
Ilioinguinal n.
After innervating the muscles of the anterior abdominal wall, the ilioinguinal n. passes through what structure to innervate the skin of the genitalia and middle thigh?
Superficial inguinal ring
The ilioinguinal n. supplies motor function to what 2 muscles? (Hint: same as iliohypogastric n.)
Internal oblique
Transversus abdominis
The ilioinguinal n. supplies sensory innervation to what areas?
Skin on upper middle thigh
Males: skin over root of penis and anterior scrotum
Females: skin over mons pubis and labia majora
After leaving the psoas major m., the genitofemoral n. quickly divides into what 2 branches?
Genital branch
Femoral branch
What are the roots of the genitofemoral n.?
L1-2
Genitofemoral n. provides motor function to what muscle?
Cremasteric m.
Genitofemoral n. supplies sensory function to what areas (genital branch vs. femoral branch)
Genital branch: skin of anterior scrotum or skin over mons pubis and labia majora
Femoral branch: skin on upper anterior thigh
Which nerve of the lumbar plexus has ONLY sensory function?
Lateral cutaneous nerve of the thigh
The lateral cutaneous nerve of the thigh enters the thigh at the lateral aspect of what structure?
Inguinal ligament
What are the roots of the lateral cutaneous n. of the thigh?
L2-3
The lateral cutaneous nerve of the thigh provides sensation in which area?
Anterior and lateral thigh down to the level of the knee
What are the roots of the obturator n.?
L2-4
The obturator n. supplies motor function to what 6 muscles?
Obturator externus Pectineus Adductor longus Adductor brevis Adductor magnus Gracilis
Where does the obturator nerve supply sensation?
Medial thigh
What are the roots of the femoral n.?
L2-4
The femoral n. supplies motor function to what 5 muscles?
Iliacus Pectineus Sartorius Quadriceps femoris Rectus femoris
Where does the femoral n. supply sensation?
Skin on anterior thigh and medial leg
What are the 5 major peripheral nerves of the sacral plexus?
Superior gluteal Inferior gluteal Sciatic Posterior cutaneous Pudendal
[mnemonic: Some Irish Sailor Pesters Polly]
The sacral plexus is located on the surface of the posterior pelvic wall, anterior to what muscle?
Piriformis
The sacral plexus is formed by _______ rami of sacral spinal nerves S__-__
Anterior; S1-4
[also receives contributions from L4-5
The sacral plexus is made up of 5 major peripheral nerves that have what 2 potential destinations?
Some leave the pelvis via greater sciatic foramen and enter gluteal region
Some remain in the pelvis and supply pelvic muscles, organs, and perineum
The superior gluteal nerve leaves the pelvis via what foramen? What accompanies this nerve as it enters the gluteal region?
Greater sciatic foramen
Accompanied by superior gluteal artery and vein
What are the roots of the superior gluteal n.?
L4, L5, S1
The superior gluteal n. supplies motor funciton to what 3 muscles?
Gluteus minimis
Gluteus medius
Tensor fascia lata
Which 2 nerves of the sacral plexus have NO sensory function?
Superior gluteal n.
Inferior gluteal n.
Which nerve of the sacral plexus has ONLY sensory function?
Posterior femoral cutaneous n.
The inferior gluteal n. leaves the pelvis via what foramen? What accompanies this nerve as it enters the gluteal region?
Greater sciatic foramen
Accompanied by inferior gluteal artery and vein
What are the roots of the inferior gluteal n.?
L5, S1, S2
The inferior gluteal n. supplies motor function to what muscle?
Gluteus maximus
What are the roots of the sciatic n.?
L4, L5, S1-3
The tibial portion of the sciatic n. supplies motor function to what muscles?
All muscles of posterior thigh, including hamstring portion of adductor magnus. NOTE that it does NOT supply short head of biceps femoris (common fibular n.)
All muscles of posterior compartment of leg and sole of foot.
The common fibular portion of the sciatic n. supplies motor function to what muscles?
Short head of biceps femoris
All muscles in anterior and lateral leg
Extensor digitorum brevis
The tibial portion of the sciatic n. supplies sensation to what areas?
Skin on posterolateral and medial surfaces of the foot as well as sole of foot
The common fibular portion of the sciatic n. supplies sensation to what areas?
Skin on anterolateral surface of leg and dorsal aspect of foot
The posterior femoral cutaneous n. leaves the pelvis through what foramen?
Greater sciatic foramen
The posterior femoral cutaneous n. leaves the pelvis via the greater sciatic foramen and enters the gluteal region inferior to the _______ muscle. It descends deep to the _______ ______ muscle and runs down the posterior thigh to the knee.
Piriformis
Gluteus maximus
What are the roots of the posterior femoral cutaneous n.?
S1-3
The posterior femoral cutaneous n. supplies sensation to what areas?
Skin on posterior surface of thigh and leg
Skin of perineum
The pudendal n. leaves the pelvis via the ______ _____ foramen, then re-enters via the _____ ______foramen, moving anterosuperiorly along the lateral wall of the ________ ________. It terminates by dividing into branches.
Greater sciatic
Lesser sciatic
Ischiorectal fossa
What are the roots of the pudendal n.?
S2-4
The pudendal n. supplies motor function to what muscles?
Skeletal muscles in perineum
External urethral sphincter
External anal sphincter
Levator ani
The pudendal n. supplies sensation in what areas?
Penis or clitoris
Most skin of perineum
Other branches of the sacral plexus tend to directly supply muscles (except the perforating cutaneous n. and the pelvic splanchnic nn.) What are 3 of these branches?
Nerve to piriformis
Nerve to obturator internus
Nerve to quadratus femoris
What nerve supplies sensation in the skin over inferior gluteal region?
Perforating cutaneous n.
Which nerves innervate the abdominal viscera?
Pelvic splanchnic nerves
Cutaneous innervation of the gluteal region comes from the lateral cutaneous branches of _____ as well as the _________ nerve and 3 sets of ______ nerves
T12; iliohypogastric (L1); cluneal
The chief cutaneous nerve supply of the gluteal region comes from 3 sets of cluneal nerves. What are they from superior to inferior?
[Superior]
Lateral branches of dorsal primary rami of L1-L3
Lateral branches of dorsal primary rami of S1-S3
Branches of posterior femoral cutaneous nerve
[Inferior]
The fascia of the gluteal region can be described in terms of superficial fascia and deep fascia. What is characteristic of the superficial fascia?
Relatively thick layer of fat; continuous with adjoining regions like the superficial fascia of the back, abdomen, perineum, and thigh
The fascia of the gluteal region can be described in terms of superficial fascia and deep fascia.
The deep fascia is attached above the crest of the _______ and ______.
Ilium
Sacrum
The deep fascia of the gluteal region covers what 2 muscles?
Gluteus maximus
Gluteus medius
The deep fascia of the gluteal region can be traced laterally or inferiorly to become continuous with what?
Fascia lata of thigh
What are the 2 major bony origins of the muscles in the gluteal region?
Os coxae
Sacrum
Origin of gluteus maximus
Posterior gluteal line, dorsal surface of sacrum and coccyx, sacrotuberous ligament
Insertion of gluteus maximus
Gluteal tuberosity of femur and IT band
Action of gluteus maximus
Thigh extension
Innervation of gluteus maximus
Inferior gluteal n.
Origin of gluteus medius
Outer surface of wing of ilium and deep fascia covering this muscle
Insertion of gluteus medius
Greater trochanter of femur
Action of gluteus medius
Abduction and medial rotation of thigh
Innervation of gluteus medius
Superior gluteal n.
Origin of gluteus minimis
Outer surface of wing of ilium
Insertion of gluteus minimis
Greater trochanter of femur
Action of gluteus minimis
Abduction and medial rotation of the thigh
Innervation of gluteus minimis
Superior gluteal n.
Origin of tensor fascia lata
Iliac crest, anterior superior iliac spine
Insertion of tensor fascia lata
IT tract
Action of tensor fascia lata
Flexion and abduction of thigh
Also assists in medial rotation of thigh and extension of leg
Innervation of tensor fascia lata
Superior gluteal n.
The piriformis muscle passes through what foramen?
Greater sciatic
Origin of piriformis
Pelvic surface of sacrum and sacrotuberous ligament
Insertion of piriformis
Medial side of greater trochanter
Action of piriformis
Lateral rotation of thigh
Innervation of piriformis
Nerve to piriformis
Origin of Obturator internus
Pelvic surface of obturator membrane and the bone surrounding the membrane
As the obturator internus exits the pelvis, it makes a sharp turn through what foramen?
Lesser sciatic foramen
Insertion of obturator internus
Greater trochanter of femur
Action of obturator internus
Lateral rotation of thigh
Innervation of obturator internus
Nerve to obturator internus
Vascular supply to obturator internus
Inferior gluteal a.
Origin of superior gemellus
Ischial tuberosity
The tendon of the inferior gemellus m. blends with the tendon of what other muscle?
Obturator internus
The insertion, innervation, and function of what muscles are identical to the obturator internus?
Superior gemellus
[inferior gemellus has same insertion and action, but innervation is different - nerve to quadratus femoris]
Origin of inferior gemellus
Ischial tuberosity
Innervation of inferior gemellus
Nerve to quadratus femoris
Like with the superior gemellus, the tendon of inferior gemellus blends with the tendon of what muscle?
Obturator internus
Origin of quadratus femoris
Ischial tuberosity
Insertion of quadratus femoris
Intertrochanteric crest
Innervation of quadratus femoris
Nerve to quadratis femoris
Action of quadratus femoris
Lateral rotation of the thigh
What are the 9 major muscles of the gluteal region?
Gluteus maximus/medius/minimis Tensor fascia lata Piriformis Obturator internus Superior+inferior gemelli Quadratus femoris
Muscle origin/insertion/action/innervation:
Gluteus maximus
Origin: posterior gluteal line, dorsal surface of sacrum and coccyx, sacrotuberous ligament
Insertion: gluteal tuberosity of femur and IT tract
Action: thigh extention
Innervation: inferior gluteal n.
Muscle origin/insertion/action/innervation:
Gluteus medius
Origin: outer surface of wing of ilium and deep fascia
Insertion: greater trochanter
Action: abduction and medial thigh rotation
Innervation: superior gluteal n.
Muscle origin/insertion/action/innervation:
Gluteus minimis
Origin: outer surface of wing of ilium
Insertion: greater trochanter
Action: abduction and medial thigh rotation
Innervation: superior gluteal n.
Muscle origin/insertion/action/innervation:
Tensor fascia lata
Origin: iliac crest and anterior superior iliac spine
Insertion: IT tract
Action: flexion and abduction of thigh, medial rotation of thigh, extension of leg
Innervation superior gluteal n.
Muscle origin/insertion/action/innervation:
Piriformis
Origin: pelvic surface of sacrum and sacrotuberous ligament
Insertion: medial side of greater trochanter
Action: lateral thigh rotation
Innervation: nerve to piriformis
Muscle origin/insertion/action/innervation:
Obturator internus
Origin: pelvic surface of obturator membrane and bone surrounding membrane
Insertion: greater trochanter
Action: lateral rotation of thigh
Innervation: nerve to obturator internus
Muscle origin/insertion/action/innervation:
Superior gemellus
Origin: ischial spine
Insertion: greater trochanter
Action: lateral rotation of thigh
Innervation: nerve to obturator internus
Muscle origin/insertion/action/innervation:
Inferior gemellus
Origin: ischial tuberosity
Insertion: greater trochanter
Action: lateral thigh rotation
Innervation: nerve to quadratus femoris
Muscle origin/insertion/action/innervation:
Quadratus femoris
Origin: ischial tuberosity
Insertion: intertrochanteric crest
Innervation: nerve to quadratis femoris
Action: lateral rotation of thigh
Branches of what artery supply the gluteal region?
Internal iliac a.
[branches = superior gluteal a. and inferior gluteal a.]
The superior gluteal a. exits the pelvis via what foramen to enter the buttock?
Greater sciatic foramen
The superior gluteal a. lies between what muscles?
Piriformis and gluteus medius and minimis
The superior gluteal a. lies between the piriformis and gluteu medius and minimis. It sends a superficial branch into what overlying muscle?
Gluteus maximus
The superficial branch of the superior gluteal a. supplies the gluteus maximus. Its 2 deeper branches supply what 3 muscles?
Gluteus medius
Gluteus minimis
Tensor fascia lata
The inferior gluteal a. enters the buttock below what muscle?
Piriformis
What muscles are supplied by the inferior gluteal a.?
Gluteus maximus Obturator internus Superior + inferior gemelli Quadratus femoris Superior part of hamstrings
The inferior gluteal artery sends an unnamed branch laterally and downward to anastomose with other vessels to form what major arterial network in the hip?
Cruciate anatomosis
The cruciate anastomosis in the hip consists of what vessels?
Medial and lateral femoral circumflex arteries and the first perforating branch of profunda femoris
