Anatomy of the PNS Flashcards
What is the basic unit of the nervous system
Neurones
What are the two main types of neurones
Multipolar and unipolar
Describe multipolar neurones
- 2 or more dendrites - All motor neurones of skeletal muscle and ANS - cell body in CNS
Describe unipolar neurones
- double process - aka pseudounipolar/sensory - cell body in PNS
Describe motor (efferent) neurones
Impulse moves towards body wall, body cavity or organ
describe sensory (afferent neurones)
Impulse moves towards the brain
Collections of axons surrounded by connective tissue and blood vessels is called a ____ in the CNS
Collections of axons surrounded by connective tissue and blood vessels is called a tract in the CNS
Tracts tend to consist of _ _____ modality
Tracts tend to consist of a single modality
Name the cranial nerves, their function and their connection to the CNS
CN I - olfactory nerve, sensory special, forebrain
CN II - optic nerve, sensory (special), forebrain
CN III- oculomotor nerve. motor, midbrain
CN IV- trochlear nerve, motor, midbrain
CN V- trigeminal nerve, both, pons
CN VI- abducent nerve, motor, junction P & medulla
CN VII- facial nerve, both, junction P & medulla
CN VIII- vestibulocochlear nerve, sensory (special), junction P and medulla
CN IX- glossopharyngeal nerve, both, medulla
CN X- vagus nerve, both, medulla
CN XI- spinal accessory nerve, motor, spinal cord
CN XII- hypoglossal nerve, motor, medulla
What is the acronym for entry points of cranial nerves into the CNS
F2 Makes Many Pounds J3 Makes Men Shout Money
There are __ pairs of spinal nerves - _ cervical : __ - __ -__ thoracic : __ - ___ -_ lumbar : __-__ -_ coccygeal: ___
There are 31 pairs of spinal nerves -
8 cervical : C1 - C8
12 thoracic : T1 - T12
5 lumbar : L1 - L5
1 coccygeal: Co1
Spinal nerves are only found where?
In intervertebral foramina
Spinal nerves connect with structures of soma via ____
Spinal nerves connect with structures of soma via rami
The spinal nerves connect with the spinal cord segment of the same number via ___ and _______
The spinal nerves connect with the spinal cord segment of the same number via roots and rootlets
All sensory axons pass from the ____ ____ into the _____ root then into the _____ ______ then into the _____ ______ of the _____ _____
All sensory axons pass from the spinal nerve into the posterior root then into the posterior rootlets then into the posterior horn of the spinal cord
All ____ axons pass from the _____ horn of the spinal cord into the _____ _____ then into the _____ _____ then into the _____ _____
All motor axons pass from the anterior horn of the spinal cord into the anterior rootlets then into the anterior root then into the spinal nerve
What does each spinal nerve supply innervation to?
Unilateral area of the body
Each spinal nerve pair supplies a body segment with?
(3)
- general sensory supply to all structures
- somatic motor supply to skeletal muscles
- sympathetic nerve supply to the skin and to the smooth muscle of arterioles
What is a dermatome
Area of skin supplied with sensory innervation from a single spinal nerve
what is a myotome
the skeletal muscles supplied with motor innervation from a single spinal nerve
Dermatome landmards;
- nipple
- umbilicus
Nipple= T4 segment
Umbilicus= T10 segment
Dermatomes of posterior scalp, neck and shoulder ?
C2-C4
Dermatomes of upper limb?
C5-T1
Dermatomes of lower limb gluteal region and perineum?
L2- Co1
What are nerve plexuses
Intermingled rami from a number of adjacent spinal nerves
What are the four main plexuses and their spinal nerves
- Cervical plexus : C1-C4
- Brachial plexus: C5- T1
- Lumbar plexus: L1-L4
- Sacral plexus: L5-S4
___ to ___ have lateral horns - cell bodies
T1 to L2 have lateral horns - cell bodies
How does sympathetic outflow reach the heart?
Presynaptic axons synapse in T1 or cervical paravertebral ganglia
Postsynaptic axons pass in cardiopulmonary splanchnic nerves to the SA & AV nodes and the myocardium
How does sympathetic outflow reach the Lungs?
Presynaptic axons synapse in upper thoracic paravertebral ganglia
Postsynaptic axons pass in cardiopulmonary splanchnic nerves to the bronchiolar smooth muscle & mucous glands
How does sympathetic outflow reach the abdominopelvic organs?
Presynaptic axons synapse in one of the prevertebral ganglia
-
Where do presynaptic sympathetic axons for the foregut synapse?
celiac ganglion
Where do presynaptic sympathetic axons for the kidney synapse?
Aorticorenal ganglion
Where do presynaptic sympathetic axons for the midgut synapse?
Superior mesenteric ganglion of SM plexus
Where do presynaptic sympathetic axons for the hindgut & pelvic/perineal organs synapse?
Inferior mesenteric ganglion of IF plexus
How does sympathetic outflow reach the adrenal medulla
Presynaptic axons pass through the aorticorenal ganglion to synapse directly onto the adrenaline/noradrenaline secreting cells of the adrenal medulla
How do presynaptic parasympathetic axons leave the CNS?
Cranial nerves III, VII, IX & X
Sacral spinal nerves
What do presynaptic parasympathetic axons for the eye travel via?
ciliary ganglion
What do presynaptic parasympathetic axons for the lacrimal gland and salivary glands travel via?
Parasympathetic ganglia in the head
What do presynaptic parasympathetic axons for the organs of the neck, chest and abdomen-midgut travel via?
vagus nerve
What do presynaptic parasympathetic axons for the hindgut, pelvis and perineum travel via?
sacral spinal nerves
What are the ipsilateral symptoms of horners syndrome?
miosis
ptosis
reduced sweating
increased warmth and redness
What is horners syndrome?
Impaired sympathetic innervation to head and neck
What are the causes of compression of the cervical parts of the sympathetic trunk?
Root of neck trauma
Carotid dissection
Internal jugular vein engorgement
Deep cervical node metastases
Pancoast tumour (lung apex)
