FUNCTIONAL ANATOMY - Autonomic Nervous System Flashcards
What is the function of the autonomic nervous system?
Regulation of involuntary activity
What are the two functional divisions of the autonomic nervous system?
Parasympathetic nervous system
Sympathetic nervous system
Where in the central nervous system are the parasympathetic cell bodies located?
Craniosacral (brainstem and sacral region of the spinal cord)
Where in the central nervous system are the sympathetic cell bodies located?
Thoracolumbar (thoracic and lumbar regions of the spinal cord)
What is the main control centre of the autonomic nervous system?
Hypothalamus
Which three cranial nerves provide parasympathetic innervation to the viscera of the head?
Cranial nerve III (oculomotor nerve)
Cranial nerve VII (facial nerve)
Cranial nerve IX (glossopharyngeal nerve)
What is the parasympathetic function of cranial nerve III (oculomotor nerve)?
Innervation of the iris for pupil constriction (miosis)
Which parasympathetic ganglion does the pre-ganglionic fibre of cranial nerve III (oculomotor nerve) synapse with?
Ciliary ganglion
Which four visceral structures of the head receive parasympathetic innervation from cranial nerve VII (facial nerve)?
Nasal glands
Lacrimal glands
Mandibular salivary gland
Sublingual salivary gland
Which two visceral structures of the head receive parasympathetic innervation from cranial nerve IX (glossopharyngeal nerve)?
Parotid salivary gland
Zygomatic salivary gland
Which cranial nerve provide parasympathetic innervation to the cervical, thoracic and abdominal viscera?
Cranial nerve X (vagus nerve)
Where does cranial nerve X (vagus nerve) travel within the body to reach the cervical, thoracic and abdominal viscera?
Cranial nerve X (vagus nerve) leaves the brain stem and travels within the vagosympathetic trunk and branches from the vagosympathetic trunk at the level of the middle cervical ganglion and supplies the thoracic and abdominal viscera via the dorsal and ventral branches of the vagus nerve. Additionally, the vagus nerve gives rise to the recurrent laryngeal nerves which travel cranially to innervate the cervical oesophagus and the larynx
Which three spinal nerves provide parasympathetic innervation to the pelvic viscera?
S1 - S3
What are the paravertebral ganglia?
Interconnected ganglia located near the spinal cord
What is another name for the paravertebral ganglia?
Sympathetic trunk
Which five spinal nerves provide sympathetic innervation to the viscera of the head and neck?
T1- T5
Which sympathetic ganglion do the T1-T5 pre-ganglionic fibres synapse with?
Cranial cervical ganglion
Describe where in the body the pre-ganglionic fibres of the T1-T5 spinal nerves run to reach the cranial cervical ganglion
Pre-ganglionic fibres of the T1-T5 spinal nerves run cranially within the vagosympathetic trunk and synapse with the cranial cervical ganglion
Describe the pathway for the sympathetic innervation of the eye
First order neurones from the hypothalamus synapse with the T1, T2 and T3 spinal nerves (pre-ganglionic neurones) which travel cranially up the vagosympathetic trunk and synapse with the cranial cervical ganglion, and from there, the post-ganglionic neurones will continue to innervate the eye
Which three visceral structures of the eye are innervated by the sympathetic nervous system?
Iris
Third eyelid
Smooth muscle of the eyelids
What are the three effects of sympathetic innervation to the eye?
Pupil dilation (mydriasis)
Retraction of third eyelid
Widening of the palpebral fissure
Which disease is caused by the loss of sympathetic innervation of the eye?
Horner’s syndrome
What are the four clinical signs of Horner’s syndrome?
Pupil constriction (miosis)
Prolapse of the third eyelid
Narrowing of the palpebral fissure
Enophthalmos
Enophthalmos refers to your eyes sinking deeper in your eye socket
What are three possible underlying causes of Horner’s syndrome?
Intervertebral disc herniation
Brachial plexus damage
Otitis media
How can intervertebral disc herniation cause horners syndrome?
The interverterbal discs are located ventral to the intervertebral foramina so intervertebral disc herniation can cause compression of the T1 - T3 pre-ganglionic fibres as they leave the spinal cord, resulting in Horner’s syndrome
Which nerve is responsible for sympathetic innervation of the bladder?
Hypogastric nerve
What is the function of the hypogastric nerve in bladder innervation?
The hypogastric nerve relaxes the detrusor muscle and contracts the internal urethral sphincter to allow for urine storage
Which nerve is responsible for parasympathetic innervation of the bladder?
Pudendal nerve
What is the function of the pudendal nerve in bladder innervation?
The pudendal nerve contracts the detrusor muscle and relaxes the internal urethral sphincter to allow for bladder emptying
What is equine dysautonomia (grass sickness)?
Equine dysautonomia (grass sickness) is impaired gastrointestinal activity due to damage to the autonomic nervous system
What are the three clinical presentations of equine dysautonomia (grass sickness)?
Acute
Subacute
Chronic
What is the mortality rate for a horse with acute equine dysautonomia (grass sickness)?
100% mortality
Between which months is equine dysautonomia (grass sickness) most common?
April to July
What are the three risk factors associated with equine dysautonomia?
Grazing
Feed change
Pasture disturbance
