Cranial nerves, sympathetic trunk Flashcards
Motor fibres are efferent and travel out of the CNS, whereas, sensory fibres are afferent and travel into the CNS. True or False?
True
All cranial nerves carry fibres with multiple functions. True or False.
False. Optic nerve carries only sensory function
Motor fibres can be either somatic efferent to voluntary muscles or autonomic to smooth muscle and glands. True or False.
True
What does the autonomic nervous system consist of?
Sympathetic and parasympathetic divisions
Where does the sensory information that sensory nerves carry from peripheral structures ultimately go?
Into the CNS
What are the two classifications of sensations?
- Special
2. General
What are some examples of special sensations? (5)
- Smell
- Taste
- Vision
- Hearing
- Balance
What are some examples of general sensations? (4)
- Temperature
- Pain
- Touch
- Proprioception (position)
Where do somatic motor axons/fibres arise?
From neurons in either the brain or spinal cord
Where do somatic motor axons pass into?
They pass into peripheral nerves and via these nerves directly to the skeletal muscle that they innervate.
Is there a second cell body for somatic motor axons?
No.
What divisions does the ANS have? (2)
- Sympathetic
2. Parasympathetic
What are autonomic nerves involved in? (2)
- Secretion from glands (secretomotor)
2. Smooth muscle contraction in blood vessels (vasomotor) , internal organs, erector pili muscles
All organs havea dual sympathetic and parasympathetic supply with oppositie effects. (e.g. one stimulating and the other inhibiting) True or False?
False. Many but not all organs.
How many neurons does the autonomic pathway involve? What are they?
Two.
- The neuron of origin in the brain or spinal cord
- In peripheral ganglion
What is the definition of a ganglion?
A collection of nerve cell bodies outside the CNS.
What are preganglionic fibres?
Myelinated axons of autonomic nerves that have not undergone a second synapse.
Post-ganglionic fibres are usually myelinated. True or False.
False. They are usually unmyelinated.
Where do the parasympathetic nerves leave the brainstem? (5)
- Occulomotor
- Facial
- Glossopharyngeal
- Vagus
- Via 2nd - 4th sacral spinal nerves
Where do pre-ganglionic fibres from the parasympathetic nerves synapse in?
- Ciliary ganglion in orbit = occulomotor
- Pterygopalatine ganglion in pterygopalatine fossa = facial nerve
- Submandibular ganglion adjacent to submandibular salivary gland = facial nerve
- Otic ganglia just below foramen ovale = glossopharangeal nerve
- Thoracic and abdominal ganglia = vagus
What is different about other classes of fibres (i.e. not pre-ganglionic fibres) that pass through the parasympathetic ganglia?
They do not synapse in these ganglia
What is the sympathetic trunk? Where is it situated?
Chain of axons and ganglia
Along the sides of the vertebral bodies.
Where does the sympathetic trunk extend?
Cranial base to coccyx.
Where is the sympathetic trunk in the neck?
Posterior to carotid sheath and anterior to vertebral transverse processes.
Where do sympathetic nerves arise?
From neurons in the thoracic and upper lumbar spinal cord.
How do pre-ganglionic fibres of the sympathetic trunk leave the spinal cord?
Via mixed spinal nerves through the intervertebral foramen.
What does it mean when a nerve is classified as mixed?
They carry motor fibres leaving the spinal cord and sensory fibres passing into the spinal cord.
Where are mixed spinal nerves connected to the sympathetic trunk? What are they connected by?
In the thorax and upper lumbar regions via fine communicating branches (white rami)
What do white rami transmit?
The preganglionic sympathetic fibres to the sympathetic trunk
Where do preganglionic fibres synapse on? (2)
Somewhere in the sympathetic trunk:
- Adjacent to their point of exit from the spinal cord
- Some other more distant ganglion
Where are post ganglionic fibres derived from?
Axons derived from neurons in the sympathetic ganglia
Where do the post ganglionic fibres travel?
- Up the sympathetic trunk to supply the head and neck
2. Leave via the mixed spinal nerves to supply trunks and limbs.
The sympathetic trunk extends into the neck even though there is no sympathetic outflow. True or False.
True.
What are the 3 interconnected ganglia on the cervical part of the sympathetic trunk?
- Cervicothoracic
- Stellate
- Middle cervical and superior cervcical
Where does the sympathetic trunk proper terminate?
In the superior cervical ganglion.
What nerve supplies to some neck structures?
The two lower ganglia (cervicothoracic and middle)
Where do the two lower ganglia (cervicothoracic and middle) send branches to form plexuses? What is an example?
On cervical blood vessels (thyroid artery)
What is the sympathetic supply to the head and other neck structures?
Upper ganglion (superior cervical ganglion)
Where does the upper ganglion (superior cervical ganglion) send branches to form plexuses?
Form plexuses on carotid arteries and their branches.
Where are the sympathetic fibres on the arterial plexuses transmitted to?
- Cranial nerves in the head
2. Sends branches to join the glossopharyngeal and vagus directly or pass to plexuses in the thorax
What are the two types of sensory neurons? (2)
Either unipolar or less commonly bipolar
Where are the cell bodies of these sensory neurons? (2) What is an example?
- In the dorsal root ganglia adjacent to the spinal cord
- Along cranial nerves.
Geniculate ganglion of facial nerve
What are sensory fibres in peripheral nerves?
Peripheral processes of the unipolar neuron cell bodies
Where do the peripheral processes of unipolar neuron cell bodies attach? (2)
Neuron cell body
Where do the central processes of the same cell body take the information?
Into the spinal cord or brain.
What does this arrangement mean?
There is no PNS synapse in the communication of sensation to the CNS.
There is only white rami in the cervical and sacral regions. True or False? Why?
False.
There is only grey rami as there is no sympathetic outflow from these regions.
Where do cranial nerves arise?
From groups of nerve cell bodies called nuclei in the brain
What do cranial nerves consist of?
One or more of the following functions:
- Somatic motor (to voluntary muscles)
- Autonomic (sympathetic and parasympathetic)
- Sensory
What may cranial nerves carry?
Where are these transmitted from? How are they transmitted?
Hitch hikers from other nerves, especially autonomic fibres (parasympathetic and sypathetic).
These are transmitted from other cranial nerves or plexuses on blood vessels via tiny connecting branches.
Some cranial nerves have sensory ganglia along their course. True or False?
True
What are the cranial nerves that have sensory ganglia? (5) Where are they located?
- Trigeminal nerve (trigeminal ganglion - within dura overlying posteromedial petrous temporal bone
- Facial nerve (geniculate ganglion - in petrous temporal bone anterosuperior to inner ear)
- Vestibulocochlear nerve (spiral and vestibular ganglia. Spiral is within cochlea and vestibular is in internal acoustic meatus)
- Glossopharyngeal (2 sensory ganglia - superior and inferior - within jugular foramen)
- Vagus nerve (superior - jugular ganglion, inferior ganglion - immediately below jugular foramen)
What are the 3 divisions of the trigeminal nerve? Where do they arise
- Opthalmic
- Maxillary
- Mandibular
Trigeminal ganglion
What does the opthalmic, maxillary division arise as?
Purely sensory nerve
What does the mandibular division arise as?
Sensory and somatic motor nerve.
What do the division of trigeminal receive?
Autonomic hitch hikers
What do all 3 divisions of trigemnial have?
Cutaneous branches which are involved in sensations of face and scalp
What is the opthalmic division associated with?
Roof and upper orbit.
Where is the opthalmic division transmitted into?
Into the orbit via the superior orbital fissure
What are the 3 main branches of the opthalmic? What is their location?
- Lacrimal (lateral)
- Frontal (central)
- Nasociliary (deep and medial)
What are the cutaneous branches of the frontal branch of opthalmic? (2) Where are they located?
- Supratrochlear (more medial, smaller)
- Supraorbital (more lateral, larger and usually forms 2 branches - medial, lateral - either in the orbit or on the forehead)
What is the maxillary division of trigeminal associated with?
Pterygopalatine fossa
Floor and lower orbit
How and where is the maxillary nerve transmitted?
Via foramen rotundum into pterygopalatine fossa
What does the maxillary nerve do in the pterygopalatine fossa?
Sends sensory branches which pass through but do not synapse with the pterygopalatine ganglion
What is the pterygopalatine ganglion?
Parasympathetic ganglion of the facial nerve.
What do branches from the ganglion of the maxillary nerve contain?
Mixture of autonomic and sensory fibres and supply nose, palate etc.
Where does the maxillary nerve enter the orbit?
Via the inferior orbital fissure
What are the terminal cutaneous branches of the maxillary nerve? (2)
- Infraorbital
2. Zygomaticoorbital nerves
What is the mandibular nerve associated with?
- Mastication
2. Mandibular structures
What is the mandibular nerve transmitted through?
Foramen ovale
What are the divisions of the mandibular nerve?
- Trunk
- Anterior Division of Trunk
- Posterior Division of Trunk
Where is the trunk of the mandibular nerve located?
It is a short segment just below the foramen ovale
What are the branches of the trunk?
- Meningeal
2. Nerve to medial pterygoid (motor to medial pterygoid and tensor tympani and tensor palati)
What is the anterior division of the trunk responsible for?
Mostly motor - branches to muscles of mastication
What are the branches of the anterior division of the trunk of the mandibular nerve responsible for motor?
- Masster
- Lateral pterygoid
- Deep temporal
What are the branches of the anterior division of trunk that are sensory?
Sensory or long buccal nerve
Where does the buccinator have a motor from? Where might it get sensory innervation from?
Facial nerve and may have sensory innervation from the long buccal nerve
What is posterior division of trunk of the mandibular nerve predominantly?
Sensory except for mylohyoid nerve (usually motor)
What are the branches of the posterior division of trunk of the mandibular nerve?
- Cutaneous auriculotemporal nerve
- Inferior alveolar nerve
- Mylohyoid nerve
- Lingual nerve
What does the cutaneous auriculotemporal nerve arise as?
What purpose does it serve?
2 roots which surround the middle meningeal artery.
It carries parasympathetic fibres of glossopharangeal origin to parotid.
What is the chorda tympani branch of?
Branch of the facial nerve
What is the mental nerve a cutaneous branch of?
Inferior alveolar
Where is the mental nerve located?
Deep to orbicularis oris
What is the relation between the facial nerve and lingual nerve?
The facial nerve hitch hikes on the lingual nerve to reach the tongue.
