Exam 3: Thoracic Spinal Nerves, Lumbar Spinal Nerves, Lumbar Plexus Flashcards
How many pairs of thoracic nerve roots are there?
12 pairs
What will each mixed thoracic spinal nerve divide into?
posterior and anterior primary ramus
What will the posterior primary ramus of a thoracic spinal nerve divide into? What type of information do they carry?
Medial branch–> motor and sensory function
lateral branch –> motor and sensory function
What do the medial branches of the posterior primary rami of a thoracic spinal nerves supply?
Motor:
- Semispinalis (T1-T6)
- Longissimus (T7-T12)
- Multifidi (T7-T12)
Sensory:
- skin paraspinally to T1-T12
Describe how the size of the lateral branches of the posterior ramus of the thoracic spinal nerves changes.
lateral branches increase in size from superior to inferior (b/c more inferior costal angles get further apart and therefore supply more = more fibers)
What do the lateral branches of the posterior primary rami of thoracic spinal nerves supply?
Motor at all levels to:
- longissimus
- iliocostalis
- levator costarum
Sensory:
- skin near costal angles
What course do the Anterior primary rami of thoracic spinal nerve generally follow?
the course of the rib above the nerve
Besdies the intercostal nerve, what will the anterior primary ramus of T1 additionally contribute to?
brachial plexus and a smaller branch will form the first intercostal nerve
Besides the intercostal nerve, what will the anterior primary rami of T2 (sometimes T1) additionally contribute to?
the intercostobrachial nerve
communicates with medial cutaneous nerve of the arm –branch off medial cord of brachial plexus
What will each intercostal nerve give off? What is supplied?
a lateral cutaneous branch –> which divides into an:
- anterior branch of lateral cutaneous nerve
- posterior branch of lateral cutaneous nerve
- —-> supplies overlying skin
What do intercostal nerves terminate as? What do they supply?
Anterior Cutaneous branches…an:
- Medial Branch of Anterior Cutaneous nerve
- Lateral Branch of Anterior Cutaneous nerve
- –> supply skin close to midline
What levels of the thoracic have intercostal nerves associated with them? What is the name of any that do not follow this pattern?
T1-T11 have intercostal nerves
T12 is called subcostal nerve
What muscles do the intercostal nerves supply as they course along their adjacent ribs?
- Internal intercostals
- External intercostals
- Innermost intercostals
- Serratus posterior
- Transversus thoracis
- Transverse abdominal (T7-11)
- Internal Abdominal oblique (T7-11)
- External abdominal oblique (T7-11)
- Rectus abdominus (T7-11)
Besides muscles, what else will the intercostal nerves also supply?
adjacent blood vessels, bones (ribs), joints, and ligaments
Which is the largest of the thoracic nerves?
the Subcostal Nerve (T12 nerve)
What else does the Subcostal nerve contribute to in addition to following a similar course to the intercostal nerves?
the lumbar plexus
What skin may the Subcostal nerve supply? Via what nerves?
skin close to the spine as far inferior as superior buttocks via Cluneal Nerves
How does each thoracic nerve communicate with the sympathetic trunk?
by way of BOTH white and gray rami communicans
The gray ramus communicans is more _____, while the white ramus communicans is more______. (ass. with thoracic nerves)
medial
lateral
What type of neurons is the white ramus communicans carrying? What about the grey ramus communicans? Describe where the neurons are going.
(ass. with thoracic nerves)
white ramus–> myelinated preganglionic sympathetic nurons to sympathetic trunk
gray ramus–> unmyelinated postganglionic sympathetic neurons away from the sympathetic trunk to the spinal nerve
How many pairs of lumbar spinal nerves are there? How are they named in relationship to the vertebra?
five pairs; named for vertebra above the nerve
What does each lumbar nerve root divide into?
anterior primary ramus and a posterior primary ramus
When the posterior primary ramus of the lumbar nerve travels posteriorly, what will it divide into and why type of fibers do they carry?
Medial branch–> motor
Lateral branches –> motor
(MOTOR ONLY)
What makes the posterior primary rami of lumbar nerves different than those of thoracic and cervical nerves?
only carries MOTOR info; whereas C and T’s carry sensory and motor
recall– T12 will supply skin over lumbar spine
What does the medial branch and lateral branch of the posterior primary rami of lumbar nerves supply?
medial branch–> multifidi
lateral branch–> erector spinae group
What do the anterior primary rami of lumbar spinal nerves contribute to?
lumbar plexus –> L1-L4
sacral plexus –> L4 and L5
Do the lumbar nerves have communication with the sympathetic trunk?
yes– there are usually 4 lumbar sympathetic ganglia
How many lumbar sympathetic ganglia are there?
usually 4
What lumbar spinal nerves will have association white rami communicans? Which will have gray rami communicans?
white rami communicans–> L1, L2, and (sometimes L3)
grey rami communicans –> ALL lumbar nerves
What forms the lumbar plexus?
anterior primary rami of L1-L3 and part of L4
also receives contribution from T12 via communication with L1 nerve
What lumbar nerve roots is the quadratus lumborum supplied by?
L1, L2, L3, L4
What lumbar nerve roots is psoas minor supplied by?
L1
What lumbar nerve roots is psoas major supplied by?
L2, L3, L4
What are the Muscular Branches from the anterior rami of lumbar spinal nerves supplying?
quadratus lumborum –> L1-L4
psoas minor–> L1
psoas major –> L2-L4
What are the six major nerves of the Lumbar Plexus?
- Iliohypogastric Nerve (T12, L1)
- Ilioinguinal Nerve (T12, L1)
- Genitofemoral Nerve (L1, L2)
- Lateral Cutaneous Nerve of the Thigh (L2,L3)
- Femoral Nerve (L2,L3,L4)
- Obturator Nerve (L2,L3,L4)
Describe the path of the iliohypogastric nerve.
Travels anterior and inferior b/w quadratus lumborum and the kidney
then through the transverse abdominal muscle
then travels b/w the internal abdominal oblique