Exam 3 Flashcards
A 54 year old homeless man who has tested positive for tuberculosis complains of abdominal and lower back pain, especially when walking. A physical exam reveals considerable weakness in flexing his hip, and attempts at flexion are very painful. The patient also reports numbness of the skin over his anterior thigh.
A CT scan reveals an infection of the bodies of vertebrae T12-L2 and a large, fluid-density mass associated with the left-side psoas major muscle.
What is the diagnosis?
psoas abscess
the abscess is drained surgically, followed by an extended course of IV antibiotics
what lines each side of the abdominopelvic cavity?
ceiling: diaphragm
antero-lateral wall
posterior wall
floor: pelvic organs q
is there a physical barrier between the abdominal and pelvic cavities?
no
largest part of the body of the pelvis?
ilium
origin, insertion, function, innervation of iliacus
o: iliac fossa
i: femur
fxn: assists psoas major in hip flexion
inn: femoral nerve
origin, insertion, function, innervation of quadrates lumborum
o: iliac crest
I: 12th rib, transverse vertebrae on lateral side
fxn: weak extension of the spine, lateral flexion of the trunk (unilateral function), helps keep balance walking
inn: ventral rami of T12-L4
origin, insertion, function, innervation of psoas major
o: spines and bodies of T12-L5
I: femur
fxn: flexor of hip (most important hip flexor), functionally a limb muscle
inn: ventral rami of L1-L3
origin, insertion, function, innervation of psoas minor
o: vertebral bodies of T12-L5
I: pubic bone
fxn: sensing what other muscles are doing (proprioception)
inn: ventral rami of L1-L3
which muscle is absent in many people?
psoas minor
iliopsoas
iliacus + psoas
because they have the same function working together as hip flexors
function of the psoas and quadrates fascia
passage of the diaphragm
what supplies the thoracolumbar fascia?
dorsal rami of spinal nerves
lateral, median, medial arcuate ligament
thickened fascia for attachment to the diaphragm where no bone is available
what is the lumbar plexus?
a set of nerves (bilateral) made of the ventral rami of the T12 through L5 spinal nerves
what do the nerves of the lumbar plexus carry?
the types of axons that nearly all ventral rami carry
somatic motor, somatic sensory, and sympathetics to visceral body wall structures (ex. sweat glands)
most of the nerves of the lumbar plexus carry axons from
more than one spinal cord level
why are lumbar plexus necessary?
the large muscles of the limbs need to be more complex than the simple strips of muscles derived from single myotomes (think about the intercostal muscles). the limb muscles are derived from multiple myotomes, so they require innervation from the corresponding, multiple spinal nerves, it is more efficient to combine the axons supplying larger muscles into large nerves
it is more efficient to combine the — covering the limbs with nerves combining the axons that supply dermatomes associated with multiple spinal cord levels. the patterns of somatic sensory supply to the skin of the limbs differs when comparing dermatomes to nerves
skin
L1 passes — psoas major
behind
subcostal nerve
T12
under 12th rib, motor and sensory to the anterior abdominal wall
iliohypogastric nerve
L1
motor to anterior abdominal wall (superior)
ilioinguinal nerve
L1
motor, sensory, somatic
inferior
genitofemoral nerve
L1-L2
sensory only in females, males have this muscle that females dont
combination of axons from left spinal cord vertebrae/levels passes through the muscle
lateral femoral cutaneous nerve
L2-L3
sensory only in both sexes
