Organisation Of Canial Nerves Flashcards
Sensory and motor organisation of the cranial nerves
- as a group, the cranial nerves can have both sensory and motor functions
- the cranial nerve nuclei are anatomically organised
- there are 3 columns for sensory and 3 columns for motor
Organisation of cranial nerve nuclei
- the cranial nerve nuclei are functionally specific
- a cranial nerve may have more than one function so a cranial nerve maybe involved with more than one nucleus
- this also means a nucleus maybe involved with more than 1 cranial nerve
- similar function of nuclei are arranged in columns in the brain stem.
How are the cranial nerves grouped?
1) special somatic afferent: cranial nerves associated with special senses
2) special visceral afferent: taste
3) special visceral efferent/ branching motor: innervate skeletal muscle derived from brachial arches
4) general somatic afferent: carry general sensation from receptors in skin, muscles, joints of head and neck
5) general visceral afferent: sensation from viscera of head, thorax and abdomen
6) general visceral efferent: preganglionic parasympathetic neurones for cranial, thoracic and abdominal viscera
7) general somatic efferent: innervates somatic muscles
Olfactory nerve (I)
DO NOT HAVE NUCLEUS IN THE BRAINSTEM
- a series of nerves attached to olfactory bulb
- concerned with the sense of smell
- exit foramen: cribriform plate
Optic nerve (II)
DO NOT HAVE NUCLEUS IN THE BRAINSTEM
- axons organs ting from the ganglion cells in the retina
- concerned with vision
- exit foramen: optic canal
Vestibulocochlear nerve (VIII)
HAVE NUCLEUS IN THE BRAINSTEM
- axons originate in the spinal ganglion of the cochlear and vestibular ganglion in the inner ear
- concerned with hearing (cochlear branch) and position sense (vestibular branch)
- exit foramen in auditory canal
- enters brain stem at level of cerebellopontine angle
What are the brainstem cranial nerve nuclei associated only with special sense?
- Cranial nerves associated with SSA= 1, 2 and 8
- while only cranial nerve 8 has nucleus in the brainstem
Oculomotor nerve(III)
- somatomotor to superior/ medial/ inferior rectus/ inferior oblique and levator palpebrae superior
And visceromotor (parasympathetic to ciliary muscle and iris) - exit at superior orbital fissure
Trochlear nerve (IV)
- somatomotor to superior oblique
Abducent(VI)
-somatomotor to lateral rectus
Hypoglossal nerve (XII)
- somatomotor to muscle of the tongue
- exit brainstem as multiple rootlets between pyramids and inferior olivary nucleus
- exit at hypoglossal foramen
Which cranial nerves associate only with motor functions?
- CN 3 exits brainstem ventrally
- CN 4 exits brainstem dorsally
- CN 6 exits brainstem ventrally at pontomedullary junction
- they then all exit foramen superior orbital fissure
- CN 12 exits brainstem as multiple rootless between pyramids and inferior olivary nucleus
- exits foramen at hypoglossal foramen
What is the disease called when there’s a damage to hypoglossal nerve?
- hypoglossal nerve palsy
Trigeminal nerve
- both sensory and motor
- sensory to head, face and inside mouth
-motor branch to mandibular only: innervates muscles around jaw for mastication
V1: opthalmic branch exits at superior orbital fissure
V2: maxillary branch exits foramen rotundum
V3: mandibular branch exits foramen ovale
What are the cranial nerves that have both motor and sensory functions?
- trigeminal, facial, glossopharyngeal, vagus and accessory nerves