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What comprises the anterior motor unit of the lumbar spine

vertebral body, disc, ant and post long. ligaments. this portion bears 70 % of load.

Posterior portion of lumbar spine

facet joints, joint capsule, lig. flavum, pedicles and lamina. bears 30 % of load

Describe the intervertebral discs

They comprise 25 % of spine height, act as shock absorbers, allow mmt and hold vert together

describe the weak zone of the intervertebral discs.

the posterior annular fibers are thinner and weaker than the anterior, the posterior longitudinal ligament is the weakest of all the ligaments.

describe the 2 mmts in lumbo-pelvic rhythm

lumbar flattening and then inversion of lordosis. pelvic rotation around the transverse axis of hips and increase of sacral angle.

strongest spinal ligaments (2)

anterior longitudinal and intertransverse

weakest spinal ligament

posterior longitudinal (disc herniates lateral to it)

lumbar flexors

iliopsoas and rectus abdominis

lumbar extensors

erector spinae, multifidus and intrinsics (from superficial to deep)

lateral flexors and rotators

internal and external obliques, quadratus lumborum, transverse abdominus

lumbar plexus

l1-l4. lateral femoral cutaneous nerve and femoral nerve (these are the peripheral nerves that branch off from the plexus)

lumbosacral plexus

l4-s3. sciatic nerve is the peripheral nerve that branches off from this plexus.

path of sciatic nerve

passes inf to sciatic notch, between the ischial tuberosity and greater trochanter, passes in posterior thigh under musculature, enters popliteal fossa and splits into tibial and peroneal nerves

what is cauda equina syndrome?

numbness and tingling in saddle distribution, loss of bowel/bladder control, emergency situation.

what is the cauda equina

the spinal cord ends at L1, and the nerve tails that hang below L1 are known as this.

what is ankylosis?

when the cartilage of the spine/sacrum wear down and the bones fuse together.

diff btw disc extrusion and sequestration

extrusion is when AF is perforated and part of NP moves out into epidural space. sequestration is when fragments of np and/or af are outside of disc and free floating


s/s: repetitive activities, pain that radiates from back/buttock into thigh. a symptom (pain&paresthesiain buttocks to back of thigh/calf i.e. peripheral nerve root distribution, or it can be a dermatomal distribution if coming from the nerve root). not a diagnosis.sciatic nerve comes out below the piriformis, in some people sciatic nerve comes out through the piriformis.

piriformis syndrome

chronic compression of peroneal and/or tibial nerve d/t excessive hypertrophy or tightness of piriformis. s/s: hip or gluteal pain that may radiate into the leg in a peripheral pattern not dermatomal


chronic low back pain which worsens over years of activity, increased lordosis

Mechanical Low back pain

activity related, due to improper movement, pain rarely radiates below knee

neurogenic low back pain

pain and or paresthesias below knee

static low back pain

either due to extension or lordotic load/williams condition (relieved by flexion), or due to prolonged seated or flat back load (relieved by extension)


6 lumbar, congenital cond, L-6 is non-fused to S-1 and so increased ROM and decreased stability


congenital, 4 lumbar, L5 fused to sacrum, decreases lumbar ROM and increases degeneration of L4 disc

spina bifida

congeital, birth defect in which lamina incompletely fuse (no spinous process) which can lead to decreased function and organ control

vertebral fractures

usually from falling from height

lumbar facet syndrome s/s

rarely in central spine, pain in lateral back and can radiate to below knee

gluteus medius weakness

d/t compression of the innervation of this muscle, s/s: c/o chronic back or hip pain, atrophy of lateral gluteal area

meralgia paresthetica

path: entrapment of lateral femoral cutaneous nerve at inguinal ligament and ASIS. lateral hip pain and paresthesia at lat thigh

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