Unit VII - Sympathetics Flashcards
Where are the cell bodies located for preganglionic sympathetic neurons?
Lateral horn of cord levels T1-L2 or L3
Preganglionic sympathetic neurons exit the cord via what structure?
Anterior rootlets
Preganglionic sympathetic neurons follow what structure during their course?
Anterior primary ramus
How do preganglionic sympathetic neurons enter the sympathetic trunk?
Via white ramus communicans
Where do most preganglionic sympathetic neurons synapse?
On postganglionic cells in ganglia of the sympathetic trunk
Where do preganglionic sympathetic neurons synapse if they pass through the sympathetic trunk?
Prevertebral plexuses associated with abdominopelvic viscera
Preganglionic sympathetic neurons that pass through the sympathetic trunk are carried in what nerves?
Splanchnic nerves
What primary neurotransmitter is released by preganglionic sympathetic fibers?
Acetylcholine
What primary neurotransmitter is released by postganglionic sympathetic fibers?
Norepinephrine
Celiac, superior mesenteric, and inferior hypogastric plexuses are examples of what kind of plexuses?
Prevertebral
What is the name for the two paravertebral columns of interconnected ganglia involved in sympathetic pathways?
Sympathetic trunk
What general types of fibers are contained in the sympathetic trunk?
BOTH ascending and descending
What is the beginning and end of the sympathetic trunk?
Beginning = superior cervical ganglion End = Ganglion impar
What is the term for the location where the right and left trunks of the sympathetic trunk connect?
Ganglion impar
About how many ganglia are seen in each sympathetic trunk?
21 or 22 Cervical - 3 Thoracic - 11 Lumbar - 4 Sacral - 4
What would be the reason for seeing 21 sympathetic trunk ganglia instead of 22?
Formation of a stellate ganglion via fusion of the lowest cervical and highest thoracic ganglia
Where does the sympathetic trunk lie in the cervical region?
Posterior to carotid sheath
Where does the sympathetic trunk lie in the upper thoracic region?
Anterior to the necks of the ribs
Where does the sympathetic trunk lie in the lower thoracic and lumbar areas?
Resting on lateral aspect of the vertebral bodies (more medially as they descend)
Where does the sympathetic trunk lie in the sacrococcygeal region?
Anterior aspect of sacrum, eventually joining at the level of the coccyx
The cervical sympathetic trunk lies between what structures?
Carotid sheath and longus colli and capitis muscles
In which part of the sympathetic trunk do we NOT see white rami communicans?
Cervical sympathetic trunk and ganglia
What are the names of the cervical ganglia?
Superior, middle, and inferior (usually 3)
What forms the stellate ganglion?
Inferior cervical ganglion with first thoracic ganglion
What is the largest of the cervical sympathetic ganglia?
Superior cervical ganglion
What forms the superior cervical ganglion?
Union of upper four cervical ganglion
Where is the superior cervical ganglion located?
At C2-C3 level, between carotid sheath and longus capitis muscle
Postganglionic fibers from the superior cervical ganglion are distributed in what branches?
Anterior, medial, or lateral
Which postganglionic branches of the superior cervical ganglion are the gray rami communicans that communicate with the anterior primary rami of C1-C4 and some cranial nerves (IX, X, XII)?
Lateral branches
Which postganglionic branches of the superior cervical ganglion travel to the larynx, pharynx, and heart?
Medial branches
What is the name for the postganglionic branches that travel to the heart from the superior cervical ganglion?
Superior cardiac nerves
The superior cardiac nerves carry only what type of information?
Efferent
Which postganglionic branches of the superior cervical ganglion follow the common and external carotid arteries?
Anterior branches
What do the anterior branches of the postganglionic fibers of the superior cervical ganglion innervate?
Vessels that supply blood to structures inside and outside the skull
Which is the smallest of the cervical sympathetic ganglia?
Middle cervical ganglion
Where is the middle cervical ganglion located?
C6 level
The middle cervical ganglion communicates with anterior primary rami of C5 and C6 nerves via what structures?
Gray rami communicans
What branches of the middle cervical ganglion travel to the thyroid and parathyroid glands?
Thyroid branches
The thyroid branches of the middle cervical ganglion carry what type of fibers?
Vasomotor
Cardiac branches of which cervical ganglion travel to heart as middle cardiac nerves?
Middle cervical ganglion
The cardiac branches contribute to what plexus?
Deep part of the cardiac plexus
What is the frequency of the formation of a stellate ganglion?
80%
What is the location of the inferior cervical ganglion?
C7 transverse process level and neck of first rib
The inferior cervical ganglion communicates with the anterior primary rami of C7 and C8 (sometimes T1, if stellate ganglion is present) via what structures?
Gray rami communicans
Cardiac branches from the inferior cervical ganglion travel to the heart as what nerves?
Inferior cardiac nerves
Branches from the inferior ganglion are sent to which vessel?
Subclavian artery
Branches from the inferior cervical ganglion form plexuses around which vessels?
Subclavian, axillary, and vertebral arteries
USUALLY, how many thoracic ganglia do we see?
11 (sometimes 12)
In what area of the spine do we seen both white and gray rami communicans at all levels?
Thoracics
Where is the thoracic sympathetic trunk located in the superior thorax?
Anterior to rib heads
Where is the thoracic sympathetic trunk located in the lower part of the thorax?
Lateral aspects of vertebral bodies
What kinds of fibers are carried in the branches from the upper five thoracic ganglia?
Postganglionic and visceral afferent
Structures in the thoracic cavity are supplied by which of the thoracic ganglia?
Upper five
Three splanchnic nerves are associated with which of the thoracic ganglia?
Lower seven
What type of fibers are carried in the splanchnic nerves to plexuses in the abdominal and pelvic cavities?
Preganglionic and visceral afferent
What forms the greater splanchnic nerves?
5th-9th thoracic ganglia
Where does the greater splanchnic nerve terminate?
Celiac ganglion
What forms the lesser splanchnic nerve?
9th and 10th/10th and 11th ganglia
Where does the lesser splanchnic nerve terminate?
Aorticorenal ganglion
What forms the least splanchnic nerve?
12th ganglion
Where does the least splanchnic nerve terminate?
Renal plexus
What is the location of the lumbar sympathetic trunk?
In the retroperitoneal space on the lateral aspects of the lumbar vertebral bodies
Which lumbar ganglia have a white ramus communicans that carries preganglionic axons into the sympathetic trunk?
First 2, sometimes the 3rd
Which splanchnic nerves carry preganglionic axons to the plexus surrounding the abdominal aorta?
Two to four lumbar splanchnic nerves
What is the location of the sacral sympathetic trunks?
Anterior aspect of sacrum, medial to the anterior sacral foramina
How many sacral ganglia are there?
Four (five counting ganglion impar)
Where is the ganglion impar formed?
Anterior surface of coccyx
Generally, which fibers ascend in the sympathetic trunk?
From the T1 to T5 levels
Generally, which fibers descend in the sympathetic trunk?
From the T5 to L2 levels
Axons that carry information to the head and neck are carried in which nerves?
T1 and T2
Where do axons that carry information to the head and neck synapse?
Superior cervical ganglion
Axons that influence the heart arise from which levels?
T1-T4
Where do axons that influence the heart synapse?
One of three cervical ganglion (some pass directly to the heart)
Axons carrying information that influences the lungs leave the cord in which nerves?
T2-T4
Where do axons carrying information that influences the lungs synapse?
2nd, 3rd, and 4th thoracic ganglia
Preganglionic fibers carrying information for the upper extremities are carried in which nerves?
T3-T7
Where do preganglionic fibers heading for the upper extremities synapse?
Middle cervical and inferior cervical/stellate ganglia
Fibers that influence the abdominal viscera arise from which levels?
T5-T12
Where do fibers that influence the abdominal viscera synapse?
Lower thoracic ganglia or pass through trunk to be carried by greater, lesser, and least splanchnic nerves
Fibers that influence the pelvic viscera arise from what levels?
T10-L2
Where do fibers that influence the pelvic viscera synapse?
Ganglia in the lower thoracic, lumbar, and pelvic areas
Preganglionic fibers carrying information for the lower extremities are carried in which nerves?
T10-L2
Where do preganglionic fibers carrying information for the lower extremities synapse?
Second lumbar through fourth sacral ganglia
In what three ways are fibers carried from the sympathetic trunk?
Nerves, blood vessels, direct branches
Virtually all nerves carried from the sympathetic trunk carry what type of fibers?
Postganglionic sympathetic
What are the three types of postganglionic sympathetic fibers seen leaving the sympathetic trunk?
Vasoconstrictor/vasomotor, sudomotor, pilomotor (motor to the arrector pili)
What effect do direct branches from the sympathetic trunk have on blood vessels?
Constriction
What effect do direct branches from the sympathetic trunk have on the bronchial tree?
Dilation
What effect do direct branches from the sympathetic trunk have on glandular secretion?
Stimulation
What effect do direct branches from the sympathetic trunk have on the pupils?
Dilation
What effect do direct branches from the sympathetic trunk have on digestive activity?
Inhibition
The superior cervical ganglion sends branches to which cranial nerves?
Glossopharyngeal (inferior ganglion), vagus (recurrent laryngeal and auricular), hypoglossal nerves
What are the branches from the cervical sympathetic trunk that accompany blood vessels?
Internal carotid nerve, branches accompanying the inferior thyroid artery, branches from the inferior cervical/stellate ganglion to the subclavian, axillary, and brachial arteries
The internal carotid nerve is a branch from which ganglion?
Superior cervical ganglion