1.5 - Nerves of the Thorax Flashcards
What do somatic spinal nerves provide somatic sensory innervation to?
Body wall but NOT to viscera
Whats a dermatome?
An area of skin that is supplied by a single spinal nerve on one side or from a single spinal cord level
What is a myotome?
Part of a skeletal muscle that is supplied by a single spinal nerve on one side or from a single spinal cord level
How many intercostal nerves are there?
11 intercostal + 1 subcostal
What are the branches of the intercostal nerves?
There is a lateral cutaneous branch (anterior and posterior branches) and an anterior cutaneous branch (medial and lateral branches)
What structures do the phrenic nerves provide sensory and motor innervation to?
Motor = diaphragm
Sensory:
Central diaphragm
Mediastinal pleura
Pericardium
Peritoneum of central diaphragm
Where do sympathetic preganglionic neurones to the body wall synapse?
In the ganglia of the sympathetic trunk
Where do sympathetic preganglionic neurons to the viscera synapse?
In unpaired ganglia
The sympathetic trunk receive which spinal nerves?
T1-L2
What is the significance of sympathetic fibres in spinal nerves T5-T12?
These are the thoracic splanchnic nerves that carry sympathetic fibres to the abdomen.
What are the five sets of nerves that contain parasympathetic fibres?
Occulomotor (III)
Facial (VII)
Glossopharyngeal (IX)
Vagus (X)
Sacral spinal nerves (S2-S4)
Which spinal nerves do sympathetic fibres to the heart and lungs come from?
T2-T4 passing through cervical and upper thoracic ganglia
Where do many of these fibres synapse?
In ganglia of the pulmonary and cardiac plexuses rather than in the trunk ganglia
What effect do sympathetic and parasympathetic nerves have on bronchioles?
Sympathetic - Bronchodilation
Parasympathetic - Bronchoconstriction
What are the effect of sympathetic and parasympathetic efferents to the heart?
Sympathetic - increase heart rate and force of contraction (inotropic and chronotropic effect)
Parasympathetic - decrease heart rate and vasoconstrict coronary arteries