Gluteal Region and Thigh (Week 4--Miller) Flashcards
Structures of gluteal region
Gluteal muscles (maximus, medius, minimus)
Superior and inferior gluteal vessels and nerves
Sciatic nerve
Posterior femoral cutaneous nerve
Muscles that laterally rotate the thigh (piriformis, superior/inferior gemilli, obturator internus, quadratus femoris)
Pudendal nerve
Internal pudendal vessels
Cluneal nerves
Cutaneous innervation of gluteal region
Superior cluneal: from dorsal rami of L1-3
Middle cluneal: from dorsal rami of S1-3
Inferior cluneal: from posterior femoral cutaneous nerve (which is a branch of sacral plexus, so ventral rami nerves)
Gluteal muscles
Gluteus maximus (superficial): inferior gluteal nerve; extention and lateral rotation of thigh
Gluteus medius (intermediate): superior gluteal nerve; abduction and medial rotation of thigh
Gluteus minimus (deep): superior gluteal nerve; (abduction and) medial rotation of thigh
Trendelenburg Test
Evaluates strength of gluteus medius as an abductor
Patient asked to stand on one leg
Point of reference is posterior superior iliac spines (PSIS)
Negative (normal): pelvis slightly elevates as gluteus medius contracts (abducts) on supported side
Positive: pelvis remains in position or descends (indicates weak or nonfunctioning gluteus medius on supported side)
Trochanteric bursa
Separates gluteus maximus from lateral side of greater trochanter of femur
Membranous sac containing synovial fluid to reduce friction
Sciatic nerve
Halfway between greater trochanter and ischial tuberosity, comes out below piriformis muscle
Largest branch of sacral plexus
Formed by ventral rami fibers from L4-S3
Two divisions: tibial division innervates hamstrings and posterior leg muscles and common peroneal (fibular) division innervates short head of biceps femoris and anterior and lateral compartment of leg muscles
Controls basically everything below gluteal region except for anterior compartment of thigh
Sacral plexus
Somatic nerve plexus formed by ventral rami fibers from L4-S4
Branches: sciatic nerve, superior/inferior gluteal nerves, posterior femoral cutaneous nerve, pudendal nerve, nerves to lateral rotator muscles of hip and levator ani
Part of lumbosacral plexus
Lumbosacral plexus
Sacral plexus plus lumbar plexus
Responsible for innervation of lower limb
Course of the sciatic nerve
Leaves pelvis to enter gluteal region
Courses inferiorly in posterior compartment of thigh
Divides in popliteal region into tibial nerve and common peroneal nerve
Safe area for intragluteal injections is upper outer (lateral) quadrant of gluteal region so don’t hit sciatic nerve
What exact movements does the sciatic nerve control?
Tibial nerve: controls posterior compartment of leg (plantar flexion) and all of the foot
Common peroneal nerve: controls anterior (dorsiflexion) and lateral (eversion) compartments of leg
Piriformis muscle
Laterally rotates and abducts the extended thigh
Right above piriformis muscle is superior gluteal vessels and nerves
Right below piriformis muscle is sciatic nerve and inferior gluteal vessels and nerve, and other muscles that laterally rotate thigh
Superior and inferior gluteal arteries
Branches of internal iliac artery
Originate in pelvis then reach gluteal region by going through greater sciatic foramen
Superior and inferior gluteal nerves
Branches of the sacral plexus
Originate in pelvis and reach gluteal region by going through greater sciatic foramen
Muscles that rotate the thigh laterally
Superior and inferior gemelli muscles
Obturator internus
Quadratus femoris
(Piriformis)
All are innervated by branches from sacral plexus
Greater sciatic foramen
Formed by greater sciatic notch, sacrospinous ligament and sacrotuberous ligament
Doorway from pelvis to gluteal region
Superior/inferior gluteal nerves and vessels, piriformis muscle comes out of it
Lesser sciatic foramen
Formed by sacrospinous and sacrotuberous ligaments
Doorway from gluteal region to perineum
Pudeneal nerve/vessels go from gluteal region to perineum
3 compartments of the thigh
Anterior (extensor): sartorius, iliopsoas, quadriceps; femoral nerve; femoral artery
Posterior (flexor): hamstrings; sciatic nerve; perforating branches of profunda femoris artery
Medial (adductor): adductors, gracilis, pectineus; obturator nerve; obrurator artery and profunda femoris artery
What separates the 3 compartments of the thigh?
Fascial (intermuscular) septa that attach from linea aspera of femur to fascia lata of thigh
Fascia lata
Fascial sleeve of deep fascia that completely surrounds all of muscles of lower limb like a sock
In the thigh, is called fascia lata and is continuous with inguinal ligament (above)
In the leg, it is called crural fascia
Posterior compartment of the thigh
Hamstring muscles (biceps femoris, semitendinosus, semimembranosus) to flex knee and extend hip
Sciatic nerve (tibial division except short head of biceps femoris)
Perforating branches of profunda femoris (deep femoral artery)
3 muscles of the hamstrings (posterior thigh)
To be a true hamstring muscle must be innervated by tibial division of sciatic nerve and must attach to ischial tuberosity
Semitendinosus: medial; superficial to semimembranosus;
Semimembranosus: medial; deep to semitendinosus
Biceps femoris: lateral; 2 heads; long head is true hamstring but short head is NOT true hamstring because innervated by common peroneal division of sciatic nerve and attaches to linear aspera!