• Olfactory nerve: sense of smell; damage = inability to smell (anosmia), distortion in the sense of smell (parosmia), or distortion/lack of taste
  • Optic nerve: visual information; damage = may not be able to see objects on their left or right sides (homonymous hemianopsia), or may have difficulty seeing objects on their outer visual fields (bitemporal hemianopsia) if the optic chiasm is involved
  • Oculomotor nerve: coordinate eye movement; damage = double vision (diplopia) will likely occur because the movements of the eyes are no longer synchronized; inability to coordinate the movements of both eyes (strabismus), also eyelid drooping (ptosis) and pupil dilation (mydriasis). Lesions may also lead to inability to open the eye due to paralysis of the levator palpebrae muscle. Individuals suffering from a lesion to the oculomotor nerve may compensate by tilting their heads to alleviate symptoms due to paralysis of one or more of the eye muscles it controls
  • Trochlear nerve: coordinate eye movement; damage = double vision (diplopia) will likely occur because the movements of the eyes are no longer synchronized (eyes adducted and elevated); The result will be an eye which can not move downwards properly (especially downwards when in an inward position). This is due to impairment in the superior oblique muscle, which is innervated by the trochlear nerve.
  • Trigeminal nerve: Combined, these nerves provide sensation to the skin of the face and also controls the muscles of mastication/chewing. damage = Conditions affecting the trigeminal nerve include trigeminal neuralgia (mostly V2 maxillary nerve and V3 mandibular nerve), cluster headache, and trigeminal zoster. contains the Ophthalmic, Maxillary, and Mandibular nerves
  • Abducens nerve: coordinate eye movement; damage = double vision (diplopia) will likely occur because the movements of the eyes are no longer synchronized; This is due to impairment in the lateral rectus muscle, which is innervated by the abducens nerve.
  • Facial nerve: movement of the face; damage = lesions as facial palsy. This is where a person is unable to move the muscles on one or both sides of their face. A very common and generally temporarily facial palsy is known as Bell's palsy. Bell's Palsy is the result of an idiopathic (unknown), unilateral lower motor neuron lesion of the facial nerve and is characterized by an inability to move the ipsilateral muscles of facial expression, including elevation of the eyebrow and furrowing of the forehead. Patients with Bell's palsy often have a drooping mouth on the affected side and often have trouble chewing because the buccinator muscle is affected
  • Vestibulocochlear (auditory) nerve: splits into the vestibular and cochlear nerve. The vestibular part is responsible for innervating the vestibules and semicircular canal of the inner ear; this structure transmits information about balance, and is an important component of the vestibuloocular reflex, which keeps the head stable and allows the eyes to track moving objects. The cochlear nerve transmits information from the cochlea, allowing sound to be heard; damage = vestibular sensation of spinning and dizziness, vestibulocochlear can also present as repetitive and involuntary eye movements (nystagmus), particularly when looking in a horizontal plane, and cochlear nerve will cause partial or complete deafness in the affected ear
  • Glossopharyngeal nerve: innervates the stylopharnygeus muscle and provides sensory innervation to the oropharynx and back of the tongue, also provides parasympathetic innervation to the parotid gland; damage = unilateral damage of gag reflex
  • Vagus nerve: provides the bulk of the parasympathetic input to the gastrointestinal system and to the heart; damage= loss of parasympathetic innervation to a very large number of structures. Major effects of damage to the vagus nerve may include a rise in blood pressure and heart rate. Isolated dysfunction of only the vagus nerve is rare, but can be diagnosed by a hoarse voice, due to dysfunction of one of its branches, the recurrent laryngeal nerve; difficulties swallowing and can reduce gag reflex
  • Spinal accessory nerve: cranial part and the spinal part; damage = lead to ipsilateral weakness in the trapezius muscle (This can be tested by asking the subject to raise their shoulders or shrug, upon which the shoulder blade ( scapula) will protrude into a winged position), weakness or an inability to elevate the scapula may be present because the levator scapulae muscle is now solely able to provide this function, Depending on the location of the lesion there may also be weakness present in the sternocleidomastoid muscle, which acts to turn the head so that the face points to the opposite side
  • Hypoglossal nerve: innervated from both the motor cortex of both hemispheres of the brain; damage = at lower motor neuron level may lead to fasciculations or atrophy of the muscles of the tongue, upper motor neuron damage will not lead to atrophy or fasciculations, but only weakness of the innervated muscles, nerve is damaged, it will lead to weakness of tongue movement on one side. When damaged and extended, the tongue will move towards the weaker or damaged side
nov 9 2015 ∞
nov 9 2015 +