Lecture 1 Flashcards
How many cranial nerves do we have?
12
What are cranial nerves?
They are peripheral nerves that emerge from the brainstem before travelling through the tissues and foramina to the skull in order to reach their target organs.
Name cranial nerve X and state what is special about it
the vagus nerve
It is the only cranial nerve that leaves the head and neck regional’s
What does the vagus nerve supply?
structures of the head, neck, thorax and abdomen.
Name the 5th cranial nerve
The trigeminal nerve
What does the trigeminal nerve do?
The trigeminal nerve provides the general sensory nerve supply to ALMOST all of the structures of the mouth
Also provides the general sensory supply to a much wider area of the head, including the orbits, the nasal cavity, the paranasal air sinuses and most of the skin on the face and forehead.
What structures in the mouth does the trigeminal nerve not supply?
Some structures in the posterior aspect of the oral cavity, including the posterior part of the tongue (These are supplied by the glossopharyngeal nerve)
Where does the trigeminal nerve arise from?
The brain stem
Specifically the lateral aspects of the pos
What does the trigeminal nerve emerge as from the brainstem?
It emerges as two separate nerve roots
Name the 2 nerve roots the emerge from the brainstem to give the trigeminal nerve
the sensory and the motor roots of the trigeminal nerve.
Which root is bigger the sensory or motor root?
The sensory root is much bigger than the motor root.
What do the 2 nerve roots of the trigeminal nerve do once they have emerged from the brain stem?
The two roots run together, passing anteriorly through the posterior cranial fossa.
Name the 3 fossa we can see if we look inside someones head from above
- Anterior fossa
- Middle fossa
- Posterior fossa
What does the posterior fossa contain?
The foramen magnum
What happens at the foramen magnum?
The brainstem becomes continuous with the spinal cord
What route do the 2 roots of the trigeminal nerve take to reach the middle cranial fossa ?
The two roots of the trigeminal nerve continue anteriorly, passing over a ridge of bone (the petrous part of the temporal bone) to enter the middle cranial fossa.
Name the hardest piece of bone in the body
The petrous part of the temporal bone
What happens to the roots of the trigeminal nerve once they enter the middle cranial fossa?
It develops a large swelling called the trigeminal ganglion
In which cranial fossa is the trigeminal ganglion located?
The middle cranial fossa
What does the trigeminal ganglion contain?
It contain the cell bodies of all the sensory nerve fibres in the trigeminal nerve
Describe the cell bodies found inside the trigeminal ganglion
They are much wider than nerve fibres and they take up a lot more space
What is a ganglion?
It is where there are large numbers of nerve cell bodies clustered together in the peripheral nervous system, we find a swelling on the nerve called a ganglion
What do nerve contain thousands of?
Nerve cells
What do nerve cells have?
Processes that arise from the cell body called fibres
Name the divisions of the trigeminal nerve
V1 - the ophthalmic nerve
V2 – the maxillary nerve
V3 – the mandibular nerve
Which nerve cells are found in the trigeminal ganglion?
ONLY sensory nerve cells
What type of nerve is the ophthalmic nerve?
An entirely sensory nerve
What does the ophthalmic nerve supply?
It supplies the:
- Orbit
- Eye
- Much of the skin of the anterior aspects of the upper part of the head
- The upper eyelid
- Parts of the nasal cavity,
- Some of the paranasal air sinuses
- The skin running down the centre of the nose
What type of nerve is the maxillary nerve?
An entirely sensory nerve
What does the maxillary nerve do?
Provides the general sensory supply to the:
- Upper teeth
- Gingivae
- The hard
- Soft palates
- The central part of the skin of the face including the lower eyelid, the sides of the nose and the upper lip.
Where does the maxillary nerve travel after emerging from the trigeminal ganglion?
It travels anteriorly to leave the cranial cavity through the foramen rotundum (round foramen)
Where is the foramen rotundum (round foramen) found?
It is a foramen in the sphenoid bone
After passing the foramen rotundum where does the maxillary nerve go?
It emerges into a space called the pterygopalatine fossa.
Where is the pterygopalatine fossa located?
It is a space that lies adjacent to the palatine bone and the pterygoid plates of the sphenoid bone, just posterior to the maxilla.
What happens at the pterygopalatine fossa?
Some branching of the maxillary nerve occurs
How does the maxillary nerve pass the pterygopalatine fossa?
It passes anteriorly anteriorly through a space called the inferior orbital fissure,
What is the inferior orbital fissure?
a slit which lies between the greater wing of the sphenoid bone (superiorly) and the maxilla (inferiorly
What happens to the maxillary nerve as it passes the inferior orbital fissure?
It changes its name to the infra orbital nerve