2.3 Flashcards
Nerves of the sacral plexus
Superior gluteal n.
Inferior gluteal n.
Posterior femoral cutaneous n.
Pundendal n.
Sciatic n.
Draw sacral plexus
Label nerves of sacral plexus.
Cutaneous innervation
Cutaneous branches of the lumbar and sacral regions give sensory innervation.
Motor innervation
The same spinal nerves that supply the skin also supply muscles, but embryologic growth creates a motor pattern that can be different from the cutaneous pattern.
Muscles of the gluteal region
Gluteus maximus
Gluteus medius
Gluteus minimus
Tensor fascia lata
Piriformis
Obturator internus
Superior and inferior gemelli
Quadratus femoris
Gluteus maximus
O: posterior ilium, sacrum, coccyx, and sacrotuberous ligament
I: IT band, gluteal tuberosity
A: primary hip extensor, lateral rotation
N: inferior gluteal n. (L5, S1, S2)
Gluteus medius
O: external surface of ilium
I: greater trochanter
A: hip abduction, medial rotation
N: superior gluteal n. (L4-S1)
Gluteus minimus
O: external surface of ilium
I: greater trochanter
A: hip abduction, medial rotation
N: superior gluteal n. (L4-S1)
Tensor fascia lata
O: ASIS
I: IT band
A: hip flexion, knee stabilization
N: superior gluteal n. (L4-S1)
Gluteal region hip abductors
Gluteal medius and minimus
They stabilize the hip in the coronal plane to maintain a level pelvis when walking or standing on one foot. These muscles abduct the hip to maintain a level pelvis when the opposite limb is elevated.
With superior gluteal nerve injury or weakness, a person is unable to maintain a level pelvis standing on one foot. Instead, the hip will tilt towards the good side and rise on the weak side.
External rotators of posterior thigh
piriformis
superior gemellus
obturator internus
inferior gemellus
quadratus
Landmarks for exiting the pelvis:
Piriformis occupies the greater sciatic foramen
Coccygeus runs superior to the lesser sciatic foramen forming a muscular borderline
Gluteal Bursae
Flattened sacs of synovial fluid
Reduce/prevent friction-related damage
Each separates gluteus maximus from another structure
Trochanteric - maximus from greater trochanter
Ischial - maximus from ischial tuberosity
Trochanteric bursitis
Etiology - stair climbing, running on elevated treadmill
Diffuse, deep pain in lateral thigh
Pain tends to radiate along IT band
Ischial bursitis
Etiology - repetitive hip extension in seated position (cycling, rowing)
Pain at ischial tuberosity
Components of posterior compartment of thigh
Fascia lata
3 muscles:
- biceps femoris
- semitendinosus
- semimembranosus
Sciatic nerve
No major arteries or veins
- blood supply from perforating branches of deep femoral artery
What are the hamstring muscles?
Biceps femoris
Semimembranosus
Semitendinosus
Which joints are crossed by hamstring muscles?
hip and knee which is why injury is so common
Proximal attachments of posterior thigh
3/4 attach proximally to ischial tuberosity and sacrotuberous ligament
Biceps short head attaches to linea aspera
Group actions of posterior thigh muscles
hip extension
knee flexion
knee rotation
Hamstring injuries
2x as common as quad strains
- 2 joint muscles are easier to injure
Usually result form jumping, kicking, running hard (esp without warming up)
Quick starts and stops
Frequently injury is distal
Posterior thigh blood supply
Superior gluteal artery: gluteus medius and minimus
inferior gluteal artery: gluteus maximus
Pudendal artery: termination of IIA to the perineum, travels under sacrotuberous ligament; perineum
Major nerves of the gluteal region
Superior gluteal n – innervates gluteus medius, gluteus minimus, and TFL
Inferior gluteal n – innervates gluteus maximus
Sciatic n – major nerve of lower limb, innervates posterior thigh, all of LL below knee
Posterior femoral cutaneous n – innervates skin of posterior thigh
Pudendal n – major nerve to perineum and external genitalia
