Proximal LE Myology

1. Define OKC vs CKC 2. explain the difference between lengthening and shortening a muscle 3. begin to understand the difference between concentric, eccentric, isometric 4. explain hip and pelvis motions 5. identify proximal LE muscles, their attachments, innervations and actions

Kenetic chain

segments of the body that are connected together (also called kinematic chain)

Lower extremity kinetic chain includes

pelvis, thigh, lower leg, foot

Open chain (OKC)

1. moving limb is non-weight bearing

2. proximal segment is fixed

3. distal segment is not fixed and free moving

Closed chain (CKC)

1. moving limb is weight bearing

2. distal segment is fixed relative to proximal segment

Planes of pelvic movement (sagittal plane, anterior pelvic tilt)

lumbar extension and hip flexion at the femoral-acetabular joint

Planes of pelvic movement (sagittal plane, posterior pelvic tilt)

lumbar flexion coupled with hip extension

Planes of pelvic movement (sagittal plane, neutral position)

ASIS and PSIS within 10-15 degrees of each other

Planes of pelvic movement (frontal plane, hip hike)

ipsilateral lumbar side bending, contralateral hip hike to standing leg

Planes of pelvic movement (transverse plane, pelvis rotation) “headlights”

contralateral rotation of pelvis and torso, keeping head neutral

proximal attachment (origin)

usually more fixed/stationary point, closer to center of body

Distal attachment (insertion)

Usually the more mobile point, further from center of body

Concentric contractions

Muscle fibers shorten as they contract

Eccentric contraction

Muscle fibers lengthen while they still contract, muscle working against force to slow down or control movement

Isometric contraction

Muscle fibers do not change length during contraction. Muscle is holding a position without moving

Innervation

The nerve that goes to the muscle tto activate it

Action

What movement a muscle creates when it concentrically contracts

Synergists

Muscles that work together to create the same action

Antagonists

Muscles that create opposite motion

reverse action

when distal attachment is fixed and proximal attachment moves (closed chain)

how to lengthen a muscle?

do the opposite of the muscle’s concentric action

two-joint muscles

cross two joints and have actions at both joints, cannot feel stretch with single-joint motion in two-joint muscles

Psoas Major Location

Deep abdomen, behind the organs

Psoas Major attachments

Proximal: transverse process of T12-L5 → anterior of the pelvis and posterior of the inguinal ligament → lesser trochanter

Actions of Psoas Major

Hip flexion (primary) Hip external rotation

reverse actions of psoas major

lumbar flexion (if head moves forward) lumbar extension (if head stays neutral)

Iliacus location

On interal iliac fossa inside the pelvis

Iliacus attachments

Iliac fossa → merges with psoas tendon and they both insert on the lesser trochanter

Iliacus actions

Hip flexion and external rotation

psoas minor attachments

T12-L1 vertebrae (only upper portion) → superior pubic ramus

psoas minor actions

posterior pelvic tilt and weak lumbar spine flexor

Gluteus Maximus location

superficial, covers deep rotators

Gluteus maximus attachments

posteriolateral sacrum, PSIS, sacrotuberous ligamnet → gluteal tuberosity of femur and iliotibial band

Gluteus maximus actions

hip extension (primary), hip abduction (superior fibers), hip adduction and external rotation (inferior fibers)

Gluteus Medius location

lateral hip, on external iliac fossa (gluteal surface)

Gluteaus medius attachments

external iliac fossa between anterior and posterior gluteal lines → superolateral aspect of greater trochanter

actions of gluteus medius

hip abduction (entire muscle), hip flexion and internal rotation (anterior fibers), hip extension and external rotation (posterior fibers)

gluteus medius open chain

acts as hip abductors

gluteus medius closed chain

with single left support, activation causes contralateral hip hike

Gluteus minimus location

anterior superior gluteal region

Gluteus minimus attachments

external iliac fossa between anterior and inferior gluteal lines → anteriosuperior aspect of greater trochanter

Gluteus minimus actions

hip abduction (primary), hip internal rotation (only anterior fibers, no posteriorfibers for external rotation)

Piriformis Location

sits underneath glutes, attaches to anterior lateral sacrum and passes through greater sciatic notch to reach hip

piriformis attachments

anteriolateral sacrum → trochanteric fossa of femur

piriformis action

hip external rotation (anatomic position, primary), hip abduction when slightly flexed (secondary)

Obturator internus location

on inside of obturator foramen (pelvic memebrane)

obturator internus attachments

internal surface of obturator foramen and membrane → throug lesser sciatic notch to trochanteric fossa

obturator internus action

hip external rotation

obturator externus location

on outside of obturator foramen → trochanteric fossa

obturator externus action

hip external rotation

Gemellus superior attachments

ischial spine → trochanteric fossa (via obturator internus tendon)

Gemellus superior action

hip external rotation

Gemellus Inferior attachments

ischial tuberosity → trochanteric fossa (via obturator internus tendon)

Gemellus inferior action

hip external rotation

Quadriceps Femoris attachments

ischial tuberosity → intertrochanteric crest

Quadriceps femoris actions

Hip external rotation and hip adduction