[vc_row row_type=”row” use_row_as_full_screen_section=”no” type=”full_width” oblique_section=”no” text_align=”left” css_animation=””][vc_column][ultimate_heading main_heading=”Candidate brief” main_heading_color=”#000000″ sub_heading_color=”#000000″ main_heading_style=”font-weight:bold;” main_heading_font_size=”desktop:36px;”]

“Please examine this patient’s cranial nerves.”

[/ultimate_heading][vc_empty_space image_repeat=”no-repeat”][vc_video link=”https://vimeo.com/149972956″][vc_empty_space image_repeat=”no-repeat”][vc_row_inner row_type=”row” type=”full_width” use_row_as_full_screen_section_slide=”no” text_align=”left” css_animation=””][vc_column_inner width=”1/4″][stat_counter icon_size=”32″ counter_title=”Station Time” counter_value=”20″ counter_suffix=” minutes” speed=”3″][/vc_column_inner][vc_column_inner width=”1/4″][stat_counter icon_size=”32″ counter_title=”Time for this encounter” counter_value=”10″ counter_suffix=” minutes” speed=”3″][/vc_column_inner][vc_column_inner width=”1/4″][stat_counter icon_size=”32″ counter_title=”Maximum time to examine your patient” counter_value=”6″ counter_suffix=” minutes” speed=”3″][/vc_column_inner][vc_column_inner width=”1/4″][stat_counter icon_size=”32″ counter_title=”Minimum time for discussion and questions” counter_value=”4″ counter_suffix=” minutes” speed=”3″][/vc_column_inner][/vc_row_inner][vc_empty_space image_repeat=”no-repeat”][/vc_column][/vc_row][vc_row row_type=”row” use_row_as_full_screen_section=”no” type=”full_width” oblique_section=”no” text_align=”left” css_animation=””][vc_column][vc_accordion style=”accordion”][vc_accordion_tab title=”Common examiner questions”][vc_column_text]Common examiner questions include the following:

  1. What do you think this patient has?
  2. How would you like to investigate this patient next?
  3. What do you think the underlying cause of this patient’s signs is?

[/vc_column_text][/vc_accordion_tab][vc_accordion_tab title=”Diagnosis and clinical signs”][vc_column_text]This patient has a right IIIrd cranial nerve palsy.  The eye exhibits ptosis and is deviated down and out.[/vc_column_text][/vc_accordion_tab][vc_accordion_tab title=”Discussion”][vc_column_text]The extraocular muscles that control the position of the globe within the orbit are the third, fourth and sixth cranial nerves – also known as the oculomotor, trochlear and abducens nerves respectively.

The oculomotor nerve controls by some margin the greatest number of extraocular muscles, and thus a palsy of this nerve is the most clinically apparent:  The eye will be deviated downwards and outwards, and will exhibit a marked ptosis.  It is likely that you (or the patient) will have to hold the eye open in order to appreciate the gaze deviation.

In addition to gaze deviation and ptosis, the pupil may also display dilatation which may cause the symptom of glare in bright light and difficulty in accommodation.  This arises because parasympathetic innervation to the pupil joins the third nerve.  As a consequence compressive lesions affecting the third nerve will cause pupillary dilatation whereas medical causes (such as a mononeuritis associated with diabetes) will not.

The path of the oculomotor nerve starts either side of the midbrain tegmentum before passing ventrally through the red nucleus towards the cerebral peduncle.  The nerve then passes through the subarachnoid space.  This is of pertinence because a Berry aneurysm at the junction of the internal carotid artery and the posterior communicating artery is an important cause of a third nerve palsy.

Subsequently the nerve runs through the lateral wall of the cavernous sinus – another space in which pathology may cause a lateralising sign in the eye.  Finally the oculomotor nerve enters the orbit through the superior orbital fissure and branches to innervate the following muscles:

  • Levator palpebrae;
  • Superior rectus;
  • Inferior rectus;
  • Medial rectus;
  • Inferior oblique;
  • Ciliary muscle;
  • Iris sphincter.

[/vc_column_text][/vc_accordion_tab][vc_accordion_tab title=”Specimen case presentation”][vc_column_text]”This patient has a right IIIrd cranial nerve palsy.  To complete my examination I would like to examine the rest of the cranial nerves.  It is hard to speculate on an underlying cause on examination features alone – I would need to take a thorough history.”[/vc_column_text][/vc_accordion_tab][/vc_accordion][/vc_column][/vc_row]