Week 5- ANS of the head and neck COPY Flashcards Preview

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Flashcards in Week 5- ANS of the head and neck COPY Deck (76):

Is the autonomic nervous system part of the PNS or CNS? Where is the central control of it from?

  • Part of the central nervous system 
  • Central control from the hypothalmus (and a bit from the limbic system) 


What does the autonomic nervous system control?

  • Body functions not under concious control 
  • Generally in the body:
    • Smooth muscle in blood vessels 
    • Sweat glands
  • In the head and neck:
    • Smooth muscles relating to the:
      • Pupil
      • Lens
      • Eyelid
    • Salivary and lacrimal glands


What are the two parts of the autonomic nervous system? Where do they arise?

  • Sympathetic ('accelerator')
    • Arises from thoracolumbar (T1-L2)
  • Parasympathetic ('brakes')
    • Arises from craniosacral outflow 

N.B. 'para' means around so the parasympathetic arises either side of the sympathetic from the spinal cord 


What is the action of the sympathetic nervous system on lacrimal and salivary glands?

  • Descreses secretions 


Describe the arrangement of nerves in the autonomic nervous system 

  • Sequential 2 neurone arrangement and associated ganglion 
  • Preganglionic neurone--> ganglion --> post ganglionic neurone 


Where do sympathetic fibres going to the head and neck arise from?

  • Thoracic region (mostly T1-2)
  • So they must ascend to reach their targets 


After leaving the spinal cord what do sympathetic nerve fibres enter and ascend in?

The sympathetic ganglionic chain 


Where does the ganglionc chain extend from/to? What is it formed by? What are the 3 important ganglia that pre-ganglionic sympathetic fibres synapse at?

  • Extends from the skull to the coccyx 
  • Formed by nerve fibres and ganglia 
  • Sympathetic fibres synapse with:
    • Superior cervical 
    • Middle cervical
    • Inferior cervical  
  • Post ganglionic fibres continue to the head and neck 


what even is a ganglion?

Collections of nerve cell bodies 


Generally, what do sympathetic fibres in supply in the head and neck?

  • Arrector pili muslces (hair follicles)
  • Superior tarsal muscle 
  • Smooth muscle of vessels 
  • Sweat glands
  • Salivary and lacrimal glands 


What is each of the superior, middle and inferior cervical ganglion associated with?

  • Each associated with an artery in the head and neck 
  • Post-ganglionic sympathetic fibres hitch hike along these arteries to reach their target organs 


What is the main difference in origin of the cranial and sympathetic nerves?

  • Cranial nerves arise in the brainstem 
  • Sympathetic nerves arise in the spinal cord and run up the ganglionic chain


Describe the location of the superior cervical ganglion

  • Posterior to the carotid artery 
  • Anterior to C1-C4 vertebrae


What are the post ganglionic fibres that originate at the superior cervical ganglion?

  • Internal carotid nerve 
  • External carotid nerve 
  • Nerve to paryngeal plexus 
  • Superior cardiac branch 
  • Nerves to the cranial nerves (II, III, IV, VI and IX) 
  • gray rami communicantes


Describe the path of the internal carotid nerve (carries sympathetic fibres)

  • Hitch hikes along the interal carotid artery, forming the internal carotid plexus


What do branches from the internal carotid plexus innervate?

  • Structures in the eye 
    • Tarsal muscle 
    • Dilator pupillae
    • sympathetic innervation causes contraction of these muscles 
  • Pterygopalatine artery 
  • Internal carotid artery 


As sympathetic fibres hitch hike along the internal carotid artery and get closer to their target muscles (tarsal and dilator pupillae) what happens to them?

  • As they get closer to tarsal:
    • Leave carotid plexus and hitch hike on occulomotor nerve 
  • As they get closer to dilator pupillae:
    • Leave carotid plexus and hitch hike on trigeminal 


Describe the path of the external carotid nerve

  • Hitch hikes along the common and external carotid arteries, forming the external/common carotid  plexus


What does the common/external carotid plexus innervate? (carries sympathetic fibres)

  • Basically innervates things supplied by the external carotid artery:
    • Sweat glands
    • Structures in the face 


What forms the pharyngeal plexus?

  • The nerve to pharyngeal plexus (originates in the superior cervical ganglion) and branches of the vagus and glossopharyngeal 


What is the function of the gray rami communicantes arising from the superior cervical ganglion?

  • Distributes sympathetic fibres to the anterior rami of C1-C4 


Describe the formation of the cardiac plexus in the thorax 

  • Superior cardiac branch 
    • From superior cervical ganglion 
  • Middle cardiac branch 
    • From middle cervical ganglion 
  • Inferior cardiac branch 
    • From inferior cervical ganglion 


Which symapthetic post-ganglionic fibres originate from the middle cervical ganglion?

  • Gray rami communicantes (to anterior rami of C5 and C6)
  • Thyroid branches 
    • travel along inferior thyroid artery to larynx, trachea, pharynx and upper oesophagus 
  • Middle cardiac branch 


Which sympathetic post-ganglionic fibres originate in the inferior cervical ganglion?

  • Gray rami communicantes (to anterior rami of C7, C8 and T1) 
  • To subclavian and vertebral arteries (innervates the smooth muscle in them)
  • Inferior cardiac branch 


Describe generally the passage of sympathetic fibres from when they arise in the spinal cord to their target tissues

  • Arises from spinal cord
  • Ascends through sympathetic ganglionic chain
  • Cervical ganglion 
  • Hitch hike on blood vessels of the carotid plexus
  • Branch off from the CNS
  • Reach their target tissues 


Describe a possible way in which tumours of the apex of the lung can present

  • Because sympathetic fibres arise in the thoracic area this is in close relation to the apex of the lungs 
  • If a tumour is here it can present as autonomic dysfunction in the eyes and face 


What is Horner's syndrome? What does it present as?

  • Interruption of sympathetic nerve supply to the head and neck 
  • If unilaterally disturbed this produces a triad of symptoms:
    • Partial ptosis (drooping of eyelid)
    • Miosis (constriction of pupil)
    • Anhydrosis (lack of sweat on half of face that lesion was on)


What causes the partial ptosis, miosis and anhydrosis seen in Horner's syndrome?

  • Partial ptosis 
    • Paralysis of the superior tarsal muscle which normally holds the eyelid open 
  • Miosis 
    • due to paralysis of dilator pupillae
  • Anhydrosis 
    • due to loss of innervation of sweat glands


What are possible causes of Horner's syndrome?

  • Spinal cord lesions 
  • Traumatic injury 
  • Carotid artery dissection (also causes neck pain)
  • Pancoast tumour 
    • Affects the apex of the lung and can invade ganglia 


Where do parasympathetic fibres begin in the CNS? 

  • In 4 nuclei in the brainstem:
    • Edinger Westphal 
    • Superior salivatory 
    • Inferior salivatory 
    • Dorsal motor 


Each nucleus that parasympathetic fibres arise from in the brainstem is associated with a cranial nerve which the parasympathetic fibres hitch hike on to reach their target. Which nerves are these and which nuclei are they associated with?

  • Occulomotor
    • Edinger westphal 
  • Facial 
    • Superior salivatory 
  • Glossopharyngeal 
    • Inferior salivatory 
  • Vagus 
    • Dorsal motor 


How are ganglia arranged in the parasympathetic nervous system compared to the sympathetic?

  • Ganglia are discrete in the parasympathetic whereas they are in a chain in the sympathetic 


After leaving the brain on a cranial nerve each parasympathetic fibre synapses in a peripheral ganlgion near the target viscera. What are these ganglion called and which cranial nerve are they associated with?

  • Ciliary ganglion 
    • Occulomotor
  • Otic ganglion
    • glossopharyngeal 
  • Pterygopalatine ganglion 
    • facial 
  • Submandibular ganglion 
    • facial 

N.B. the vagus nerve has no ganglia in the head and neck, it goes into the thorax to the larynx and the resp and GI tracts 


Describe the path of parasympathetic fibres which hitch hike with the occulomotor nerve from their origin in the brainstem to their target tissue

  • Brainstem (edinger westphal nuclei)
    • Parasympathetic fibres emerge with CNIII)
  • Hitch hikes on CN III
    • (pre ganglionic at this stage)
  • Ciliary ganglion 
  • After this (post-ganglionic) hitch hikes iwth branches from V1
  • Goes to the eye to innervate:
    • ciliary body/muscles
      • accomodate for near vision 
    • Sphincter pupillae 
      • contracts pupil 


What also passes through the ciliary ganglion (with parasympathetic fibres hitch hiking on occulomotor) but does not synapse there?

  • Sympathetic nerves from the internal carotid plexus 
    •  innervate dilator pupillae
  • Sympathetic fibres from nasociliary nerve 
    • Branch of the ophthalmic division of trigeminal
    • Innervates cornea, ciliary body and iris 


Describe the passage of parasympathetic fibres that hitch hike with the facial nerve

  • Arise in the brainstem
    • parasympathetic fibres emerge with CNVII fibres 
  • Hitch hike on CNVII
  • Facial nerve splits in petrous bone to give:
    • Chorda tympani
      • to do with taste 
    • Greater petrosal 
      • pretty much just carries parasympathetic fibres 
  • Parasympathetic fibres hitch hike with both of these


What do the parasympathetic fibres that hitch hike with the chorda tympani nerve go on to innervate?

  • They reach the submandibular ganglion 
  • The post-ganglionic fibres then hitch hike with branches of CNV (trigeminal)
  • Innervates submandibular and sublingual salivary glands


What do parasympathetic fibres that hitch hike with the greater petrosal nerve go on to innervate?

  • They synapse at the pterygopalatine ganglion 
  • Post ganglionic fibres then hitch hike on branches of CNV (trigeminal) 
  • Innervates:
    • Lacrimal gland
    • Nasal and oral mucosal glands


Two or the branches that the facial nerve gives off in the petrous bone are the chorda tympani nerve and greater petrosal nerve. What is the third one? Which ganglion do they all arise from? What do they all innervate?

  • Arise from the sensory geniculate ganglion 
    • NOT a parasympathetic ganglion 
  • Greater petrosal:
    • Parasympathetic to eyes, nose and mouth glands
  • Chorda tympani:
    • Parasympathetic to salivary glands 
    • Also conveys taste
  • Stapedius nerve:
    • Parasympathetic to ossicles in the ear 


What does a lesion/pathology at/before the geniculate ganglion (between the brainstem and the ganlion) involve?

  • Involves all parasympathetic functions carried with the CN VII


What does pathology after the geniculate ganglion involve? (diagram in notes) 

  • Will NOT involve the greater petrosal (lacrimal gland is spared)
  • But may cause dry mouth and muscle weakness in the face 


One branch from the geniculate ganglion gives the greater petrosal nerve. What does the other branch give?

  • Gives a branch that goes to the parotid gland where it splits to innervate muscles of facial expression 
  • BUT off of this branch (before it split) other branches emerge:
    • Stapedius nerve 
    • Chorda tympani nerve 


Which branches of the glossopharyngeal nerve (CNIX) carry parasympathetic fibres?

  • Tympanic nerve
    • This supplies sensory to the middle ear and tympanic cavity as well as carrying autonomic fibres 
  • Tympanic nerve passes through the petrous bone and exits as the lesser petrosal nerve 
    • This also carries parasympathetic fibres
    • It goes through the foramen ovale 


Which ganlgion is associated with the parasympathetic fibres which hitch hike on the glossopharyngeal nerve? What happens to the post-ganglionic parasympathetic fibres?

  • The otic ganglion 
  • Post ganglionic fibres reach their target (the parotid gland) by hitch hiking on to CN V3


The only parasympathetic role of the glossopharyngeal nerve is to the parotid gland. What are its other roles?

  • Motor to stylopharyngeus 
  • Sensory from oropharynx and tonsils 
  • Taste and general sensation (posterior 2/3rds of tongue)
  • Sensory branches to carotid body/sinuses


Describe the path of the parasympathetic fibres which hitch hike with the vagus nerve (CN X) from their origin in the medulla of the brainstem to their target tissues

  • Brainstem (medulla)
  • Hitch hikes on CNX and its branches
  • Pre ganglionic fibres meet the ganglion at/in the target tissue:
    • Glands in the laryngopharynx, larynx, oesophagus and trachea 
    • Thorax and abdomen 


Fill in this summary table relating to sympathetic innervation to the head and neck 


Fill in this summary table relating to the parasympathetic innervation to the head and neck 


what are the different signs seen in Horner's syndrome and occulomotor nerve lesion?

  • Horner's syndrome 
    • Miosis 
    • Partial ptosis 
    • Anhydrosis
  • Occulomotor nerve lesion
    • complete ptosis
    • Eye in down and out position  
    • Pupil may be dilated 


Why is partial ptosis seen in Horner's syndrome but full ptosis seen in occulomotor nerve lesion?

  • The occulomotor nerve supplies a large proportion of the levator palprebrae superioris muscle and without this the eyelid cannot be kept open 
  • The smooth muscle component of this musle is the Tarsal muscle and this is v small 
    • The Tarsal muscle is supplied by the sympathetic nervous system so is paralysed in Horner's 
    • However the portion supplied by occulomotor nerve is still okay and so there is only partial ptosis 


Why might there be dilation of the pupil in occulomotor nerve lesions? When might there be pupil sparing?

  • CNIII carries parasympathetic fibres to the pupil. If these are affected then there is unopposed action of the sympathetic nervous system so dilation
  • In some types of CNIII lesions e.g. diabetes, the parasympathetic fibres can be spared 


Why might the eye appear in a 'down and out' position with occulomotor nerve lesions?

  • CNIII innervates majority of the extra-ocular muscles 
  • Only the lateral rectus and supeiror oblique are spared as they are not innervated by CNIII and so these muscles pull the eye into a down and out position

N.B. Horner's syndrome only affects sympathetic innervation so would not affect extra-ocular muscles 


What would lesions at A and B cause?

  • A
    • After the geniculate ganglion so the greater petrosal has already branched from the facial nerve 
      • so secretomotor function to oral (palatine and pharyngeal), nasal and lacrimal glands are unaffected
    • All other functions of facial nerve are affected e.g. muscles of facial expression, nerve to stapedius, taste from the anterior tongue and parasympathetic to salivary glands
  • B
    • Chorda tympani and nerve to stapedius have also left by this point so lesion would only affect muscles of facial expression


If pressure increases in the cranial cavity to the extent that it causes a midline shift what will happen if the pressure is not alleiviated quickly?

  • Brain will herniate around folds of dura that hold it in place
  • Herniation of the brainstem causes it to be squeezed through the foramen magnum. This is known as coning and inevitably leads to death as the cardio-respiratory centres in the medulla become compressed 


Which arteries supply the area of skin over the side of the scalp and forehead? Which layer of scalp do they run in?

  • Superficial temporal artery (STA)
    • branch of external carotid 
  • Terminal branches (supraorbital/supratrochlear) of the ophthalamic artery
    • supply skin of forehead above eye 
  • Run in dense connective tissue layer 


If someone suffers a fall and bumps their head and there is no visible open wound but there is a discrete lump in the region of the injury; why is the swelling on their head limited forming a discrete lump?

  • Bleeding occurs in the dense connective tissue layer (above aponeurosis)
  • This areas has most blood vessels and nerve supplying the scalp and is compartmentalised by fibrous septa
  • Any bleeding here does no spread far and so forms a lump/haemotoma 


Why can a blow to the head result in a black eye (periorbital ecchymoses), despite no injury sustained to the orbital region?

  • Blow to head causes bleeding from vessels in the dense connective tissue layer AND can cause it from emissary veins that run through the aponeurosis to the loose connective tissue layer 
  • Fluid/blood under aponeurosis can move freely till the margins of the aponeurosis 
    • Posterior margin: occipitalis 
      • attaches to occipital bone
    • Lateral: temporalis fasica
      • inserts into zygomatic arch

Blood in loose connective tissue layer cannot pass beyond bony insertions so will not pass into subtemporal or occipital regions

  • Anteior margin: frontalis 
    • Inserts anteriorly by merging with skin/subcutaneous tissue in eyebrow and root of nose (not bone)

Blood can therefore pass into the orbital region, including eyelids and root of nose 


Why are infections of a deep scalp wound more of a concern than infection of a superficial wound?

  • Superficial infections involving skin/dense connective tissue cannot spread far
  • Infections below the aponeurosis in the loose tissue can drain via emissary veins in this area. These veins connect this area to the intra-cranial veins/venous sinuses and veins draining the skull (diploic veins) allowing a potential route of infection to spread into:
    • The skull e.g. osteomyelitis 
    • The brain 


Which of the following structures does the internal carotid artery pass through on its route extra cranially (outside of the skull) to intracranial?

  • Carotid sheath (up the neck)
  • Carotid canal 
    • small bony canal in petrous part of temporal bone


What feature of the adult skull relates to the anterior and posterior fontanelle in the infant skull?

  • Anterior
    • Bregma 
  • Posterior
    • Lambda


What should be look for when we see a fracture of the mandible?

  • A fracture in another part of the mandible as well, it often breaks in two locations 
  • Dislocation of the temporomandibular joint 


Where does the facial artery run generally?

  • Branch of external carotid, it kind of runs under the chin 


Which lymph nodes in the neck are enlarged in tonsilitis of the palatine tonsils?



What functions are carried by the facial nerve?

  • motor to muscles of facial expression
  • Autonomic innervation to the lacrimal glands 
  • Taste from the anterior 2/3rds of the tongue 
  • Autonomic innervation to salivary glands 


Which of the pharyngeal arches is the glossopharyngeal nerve derived from?

Pharyngeal arch 3


Which nerves carry special sensory?

  • Vestibulocochlear 
    • Hearing and balance 
  • Facial 
    • taste to anterior 2/3rds of tongue  
  • Glossopharyngeal 
    • taste to posterior 1/3rd of tongue 
  • Olfactory 
    • Smell 
  • Vagus 
    • minor role in taste 
  • Optic 
    • Sight


A patient has cavernous sinus thrombosis. What signs are they likely to develop?

  • Present with headache +/- fever, then:
    • Pupillary dilation
    • Diplopia
    • Orbital oedema 
    • Drooping eyelid (ptosis)


Which nerves run through the cavernous sinus?

  • CN IV
  • CN VI
  • Ophthalmic and maxillary division of the trigeminal nerve 

They are all associated with the eye in some way 


Who is more likely to get cavernous sinus thrombosis?

  • Patient with a prothrombotic tendency e.g. pregnancy, lupus 
  • Patients with infection of the midface, nasal cavity and sinuses 
  • Thrombosis in the cavernous sinus is usually a septic thrombosis 


Why do we see orbital oedema in cavernous sinus thrombosis?

  • Orbital venous drainage communicates with the cavernous sinus so blockage to drainage by thrombus causes venous congestion around the tissues of the orbit and the eye 
  • The increased pressure and venous engorgement behind the eye can cause exopthalamos. This can put tension of the optic nerve and compromise sight 


Which cranial nerves are purely motor?

  • Abducens 
  • Trochlear
  • Hypoglossal


What are the sensory (afferent) and motor (efferent) cranial nerves involved in the corneal reflex?

  • Sensory 
    • Ophthalamic division of CN V
    • Sensory innervation of the cornea and conjunctiva is via this nerve 
  • Motor
    • CNVII- Facial
    • Innervates obicularis oculi causing us to close our eye. This sweeps away any potential irritation away from the front of the eye into the lacrimal drainage system to stop further injury occuring 


Why is the cornea very densely innervated with sensory nerve fibres and very sensitive to irritation?

  • Cornea is extremely important part of the eye as it is transparent part allowing light to reach the retina at the back of the eye 



Why do we blink with both eyes due to the corneal reflex even if only one of our eyes is irritated?

  • The afferent signal from one eye communicates with facial nerve nuclei on both sides fo the brainstem so both eyes blink simultaneously 


Which nerves are involved in the afferent and efferent parts of the pupillary light reflex?

  • Afferent (sensory)
    • Optic nerve (CN II) 
    • Detects light 
  • Efferent (motor) 
    • CNIII- occulomotor 
    • Innervates sphincter pupillae causing constriction