Nerves of the Thorax Flashcards
Somatic =
external; on the skin
Visceral =
internal; organs/vessels
What controls the autonomic NS
hypothalamus
What is dual innervation?
SNS and PSNS exert opposite effects in a particular organ/tissue but they functionally compliment each other to keep the body functioning normall
What is supplied by the SNS only?
- Certain blood vessels
- erector pili muscles
- sweat galnds
What does the autonomic NS regulate?
- Visceral activity (circulation, respiration, digestoion, excretion, reproduction)
- smooth muscle
- cardiac mucle
- glands
- body temperature
What do autonomic fibres accompany?
the visceral senses
How many neurons do autonomic nerves need to reach the end organ?
2 neurons
Where is the 1st preganglionic neuron?
gray matter of the spinal cord or brain stem
It is myelinated
Where is the 2nd (post ganglionic) neuron located?
Autonomic ganglion
unmyelinated
Describe the PSNS
Rest and digest
Give some of the effects of the PSNS
- Slows breathing and HR
- Stimulates digestion
- Opens sphincters
- constricts pupils
- secretomotor glands (salivary, lacrimal)
What is the parasympathetic innervation of the thoracic viscera?
10th cranial nerve –> Vagus
Where does the vagus leabe the cranial cavity and where does it descend between?
- Leaves through the jugular foramen
- dsecnds between the internal jugular vein and internal carotid artery
Where does the right vagus enter the thoracic cavity
Between the right subclavian and brachiocephalic vein
Where does the left vagus enter the thoracic cavity
posterior to the left brachiocephalic vein between the subclavian artery and common carotid
What comes off the right vagus and what artery does it wind around?
recurrent laryngeal never and winds around the right subclavian artery
What comes of the left vagus nerve and what does it wind around?
recurrent laryngeal nerve and winds around the aortic arch, just posterolateral to th eligamentum arteriosum
why are the recurrent laryngeal nerves different?
Due to embryological development
What do the recurrent laryngeal nerves supply?
- Intrinsic layer of laryngeal muscles (except 1)
- Middle and inferior pharyngeal constrictor muscles
- Sensory to the laryngeal cavity below the levl of the vocal cords
What is the purpose of the SNS
fight or flight
What is the effect of SNS on the body?
- Increases HR and strength of HB
- Dilates coronary arteries
- Constricts peripheral arteries
- Relaxes bronchial smooth muscles (increases respiratory efficiency)
- Closes sphincters
- Controls body temperature
What is the outflow of the SNS
thoracolumbar
Where are the preganglionic cell bodies in the SNS
intermediolateral horn of T1-L2 spinal cord segment
Where do the postganglionic cell bodies of the SNS lie?
In paravertebral sympathetic ganglia OR in prevertebral sympathetic ganglia
Where is the paravertebral sympathetic ganglia?
Anterior to the neck of the ribs (lateral aspect of vertebral bodies) and is covered by parietal pleura
What interconnects the paravetebral sympathetic ganglia?
Sympathetic chain
Where are the prevertebral sympathetic ganglai located?
Around the origins of branches of the abdominal aorta (anterior)
Where do the sympathetic trunks extend between?
Atlas and coccyx at ganglion impar
What cervical vertebrae correspond with the superior cervical ganglia?
C1-C4
What cervical vertebrae correspond with the middle cervical ganglia?
C5-C6
What cervical vertebrae correspond with the inferior cervical ganglia?
C7-C8
What composes the stellate ganglion?
Inferior cervical and T1
What are the 5 ways the sympathetic system functions?
- Synpase at its level
- Travel up the chain to synpase in cervical ganglion
- Travel down the chain and synapse in lumbar/sacral region
- Preganglionic branches pass through the sympathetic trunk without sunpasing (splanchinic nerves)
- The adrenal medulla is supplied directly
What occurs when the SNS synpases at its level?
Postganglionic axons (unmyelinated) pass in the GRC and join T1-L2 spinal nerves
GRC =
grey ramus communicantes
What occurs when the SNS tarvels up the chain to synpase in the cervical ganglion
Post ganglionic axons pass in the GRC and join cervical spinal nerves
What happens when the SNS travels down the chain and synapses in the lumbar/sacral region?
Postganglionic axons pass in the GRC and join lumbar/sacral spinal nerves
What happens when preganglionic branches pass through the sympathetic trunk without synpasing?
Travel in splanchnic nerves to the abdomen and synpase with prevertebral ganglion.
Supply the abdominal viscera
Sympathetics of the head
T1-T3
Sympathetics of the upper limb
T4-T6
Sympathetics of the thoracic and abdominal walls
T1-T12
Sympathetics of the lower limb
T12-L2
Greater splanchnic nerve
T5-T9
Lesser splanchnic nerve
T10-T11
Least splanchnic nerve
T12
What are the 3 types of splanchnic nerve?
- Thoracic
- Lumbar
- Pelvic
What are the visceral plexuses in the thorax?
- Cardiac
- Pulmonary
- Oesophgeal
Where is the carotid plexus?
Anterior to the bifurcation of the trachea and posterior to the ascending aorta
Where is the pulmonary plexus?
Anterior and (mianly) posterior to the roots of the lungs
Where is the oesphageal plexus?
Around the oesphagus
Where does the cardiac plexus recieve sympathetics from?
T1-5 ganglia and inferior and middle cervical ganglia
Where does the cardiac plexus recieve parasympathetics from?
vagus
Where does the pulmonary plexus recieve sympathetic from?
T2-T4
What is the sole motor supply of the diaphragm?
phrenic nerve
What does the phrenic nerve give sensory fibres to?
- mediastinal parietal pleura
- Parietal pericardium
- Peritoneum and pleura related to the central tendon of the diaphragm
Where do the intercostal nerves arise from?
Anterior rami of the thoracic spinal nerves
The intercostal nerves are mixed nerves - what is their function and branches?
- Motor branches to intercostal and abdominal wall muscles
- Visceromotor branches to vessels
- Lateral cutaneous branch (sensory)
- Anterior branch (sensory)
What is pancoast’s tumour?
A tumour at the apex of the lung that may affect the sympathetic trunk or stellate ganglion, compromising the synpathetic supply to the head and neck on the same side
Features of Horner’s syndrome
- Ptosis of the upper eylid
- Pupillary cosntriction (miosis)
- Anhydrosis (lack of sweating)
- Flushing of the face
Veins of the face
Superficial facial veins
Deep facial veins
Cranial Veins
- Cerebral veins
- Cerebellar veins
- Dural venous sinuses
- Diploic veins
- Emissary veins
Cervical Veins
External jugular vein
Internal jugular vein
Anterior jugular vein
Vertebral vein