Nervous System - General Principles of Nerve Supply Flashcards
What happens to a nerve once it supplies a structure in an embryo?
It never alters it’s course. Wherever the structure in the fetus goes it brings the nerve with it.
What inner ages skeletal muscles?
Motor neuron pools.
What are motor neuron pools?
Groups of motor nerve cell bodies in certain cranial nerve nuclei of the brain stem and anterior horns of the spinal cord.
How are their motor neuron pools arranged?
The pool that supplies one muscle overlays the pool that supplies that other.
Where will you not see the arrangement of motor neuron pools and muscles?
C4 and C6 nerves since they only supply one muscle - superior oblique and lateral recuts of the eye).
Are limb muscle nerves purely motor?
No - they contain afferent sensory fibres for proprioception.
Where do the nerves go from the posterior rami?
Pass backwards and supply the extensor muscles of the vertebral column and skull and the skin that overlies them (to an extent).
Where do the nerves go from the anterior rami?
Supply all muscles of trunk, limbs and skin at sides and front of the neck and body.
What does the posterior rami of the spinal nerves supply?
- Erector spinal muscles.
- Transversospinalis groups (lie deep to thoracolumbar fascia).
- Lavatory costae muscles of the thorax.
What does each posterior rami divide into?
- Medial branch.
- Lateral branch.
What do the branches of the posterior rami supply?
Both medial and lateral supply muscle. But only one branch will reach and supply the skin.
Does C1 have a cutaneous branch?
No.
DO the posterior rami of the 12 Thoracic nerves and 5 sacral nerves supply skin?
Yes.
Describe the exception with the posterior rami and the spinal nerves?
Posterior rami of lower two cervical and lumbar nerves do not reach the skin.
Which branches of the posterior rami supply the skin?
- Medial - upper half of the body.
- Lateral - lower half of the body.
Do nerves of posterior ramus supply skin or muscles in limbs?
No.
What does the anterior rami supply?
- Pre-vertebral flexor muscles segmentally by separate branches from each nerve.
What anterior rami supply the muscles of the body wall?
12 thoracic nerves and L1.
What is the pathway for the intercostal nerves?
Each nerve supplies the muscles of the intercostal space and the lower six nerves pass beyond the costal margin to supply the muscles of the antihero abdominal wall.
What is the lowest spinal nerve to supply the anterior abdominal wall?
L1 - ilihypogastric and ilioingual nerves.
What anterior rami supply skin in the neck?
C2-C4. Innervated by the cervical plexus.
What anterior rami supply skin in the upper limb?
C5-8 and T1. Innervated via the brachial plexus.
What anterior rami supply the skin in the funk?
T2-L1 - in strips of zones in regular sequence.
How do the lower 6 thoracic nerves supply the skin of the abdominal wall?
Pass beyond the costal margin obliquely downwards.
What does each anterior ramus do?
Supplies a strip of skin that overlies it (dermatology).
What does each spinal nerve contain?
Mixture of sensory and motor fibres.
Where is the neurovascular plane?
The neurovascular bundle spirals around the walls of the thorax and abdomen in a plane between the middle and deepest of the three muscle layers.
Where are the nerves in the neurovascular plane?
Below the arteries around the body wall, but cross the arteries posterior lay alongside the vertebral column and again anteriorly near the ventral midline.
Where does the nerve always lie?
Closer to the skin.
Where does the sympathetic trunk lay?
Not in the neurovascular plane, but runs vertically within the arterial circle.
What makes up the arterial circle?
- Aorta.
- Intercostal arteries.
- Lumbar arteries.
- Interbank thoracic.
- Superior and inferior epigastric arteries.
Where do the spinal nerves run?
- Come out from the intervertebral for Amin’s.
- Pass laterally behind vertebral artery in the neck.
- Pass behind the posterior inter-costal arteries in the thorax.
- Pas behind the lumbar arteries in the abdomen.
- Pass behind the lateral sacral artery in the pelvis.
Where do the anterior terminal branches of the spinal nerves pass?
In front of the internal thoracic and superior/inferior epigastric arteries.
What lies posterior to the sympathetic trunk?
Segmental vessels - vertebral, posterior, intercostal, lumbar and lateral sacral arteries.
What do sympathetic fibres do?
They are the main vasoconstrictor in function. Main function is temperature regulation.
