OCB04-2004 Flashcards
Where are the bodies of the sensory aspect of the trigeminal nerve located?
Trigeminal/Gasserion/semilunar ganglion
What does the ophthalmic division of the trigeminal nerve supply?
Sensory to:
- most of skin of forehead
- conjunctiva
- upper eyelid
- bridge of node
- frontal sinus
- anterosuperior nasal cavity mucosa
What does the maxillary division of the trigeminal nerve supply?
Sensory to:
- most of skin of cheek, upper lip and all structures deep to them (upper teeth, gums, soft and hard palate, maxillary sinus, posteroinferior nasal cavity)
What does the mandibular division of the trigeminal nerve supply?
Sensory to:
- skin of temple and most of skin over lower jaw (except over angle) and structures deep to them (lower teeth, gums, tongue)
Motor to muscles of mastication, tensor tympani, tensor palatini and anterior belly of digastric
What innervates the upper teeth?
Superior dental plexuses of V2
What innervates the lower teeth?
Inferior dental plexuses of inferior alveolar/dental nerve of V3
What is the main difference in the way the upper and lower teeth are innervated?
Upper = separate plexuses supply multiple teeth
Lower = inferior dental plexus supplies each tooth individually
Describe trigeminal neuralgia.
Sudden bursts of severe pains coming from one of more branches of C.V - V2 and V3 most commonly affected
Usually unilateral (rarely bilateral)
Most cases caused by a blood vessel pressing on the root of the nerve where it exits the skull
How can trigeminal neuralgia be treated?
Carbamazepine (anticonvulsant) calms activity of nerve and therefore pain
If ineffective then surgery (vascular decompression)
Describe the surgery often used to treat trigeminal neuralgia.
Posterior fossa craniotomy at the confluence of the sigmoid and transverse sinuses
Enter Meckel’s Cave and try to conduct vascular decompression of affected branch
What is the supraorbital nerve a branch of?
V1
What is the supratrochlear nerve a branch of?
V1
What is the infraorbital nerve a branch of?
V2
What is the mental nerve a branch of?
V3 (after inferior alveolar nerve)
What is the auriculotemporal nerve a branch of?
V3
What are the two parts of the auriculotemporal nerve?
Superior = sensory
Inferior = secretory motor parasympathetic fibres
Describe the branching of the external carotid artery that supplies the head/face.
Branches into external (facial) and internal maxillary arteries
Internal maxillary artery branches into:
- infraorbital artery
- greater palatine artery
- middle meningeal artery
- inferior alveolar artery
Where does the facial artery end?
After a tortuous journey, ends as the angular artery at the commissure of the eye
What does the infraorbital artery supply?
Skin of orbital area
What does the greater palatine artery supply?
Roof of mouth
What arteries does the middle meningeal artery anastomose with?
Ophthalmic and lacrimal arteries
Where does the (anterior) facial vein start?
Side of the root of the nose, direct continuation of angular vein
Which of the facial vein and artery has a more tortuous route?
Facial artery
What vein drains into the (anterior) facial vein?
External palatine vein
What are the possible courses for the (anterior) facial vein?
Join the anterior branch of the retromandibular vein to form the common facial vein
Drain directly into the internal jugular vein
Why is the (anterior) facial vein important clinically?
Direct connection with ophthalmic vein which leads to the cavernous sinus
Bacteria can reach the internal cranial structures from the pterygoid plexus via this route
Which muscle raises the eyebrows?
Epicranius (frontalis and occipitalis)
What makes up the epicranius?
Frontalis and occipitalis
Where is the origin and insertion of the epicranius?
Cranial aponeurosis
Eyebrows
What does the epicranius do?
Raises the eyebrows
Which muscle blinks and closes the eyes?
Orbicularis oculi
What does orbicularis oculi do?
Blinks and closes the eyes
Where is the origin and insertion of the orbicularis oculi?
Portions of frontal and maxilla bones to skin around eyes
What does the orbicularis oris do?
Closes and protrudes lips
What muscle closes and protrudes the lips?
Orbicularis oris
Where is the origin and insertion of orbicularis oris?
Skin around mouth
What does the buccinator do?
Flattens cheek against teeth
What muscle flattens the cheek against teeth?
Buccinator
Where is the origin and insertion of the buccinator?
Mandible/maxilla to skin around mouth
What does the zygomaticus do?
Raises corner of mouth
What muscle raises the corner of the mouth?
Zygomaticus
Where is the origin and insertion of the zygomaticus?
Zygomatic bone to corner of lips
What does the platysma do?
Draws mouth downwards
What muscle draws the mouth downwards?
Platysma
Where is the origin and insertion of the platysma?
Fascia of chest to lower border of mandible
What are the four types of branches found in the facial nerve?
Branchial motor/special visceral efferent
Visceral motor/general visceral efferent
Special sensory/special afferent
General sensory/general somatic afferent
Which part of the facial nerve has the main 5 branches?
Branchial motor/special visceral efferent
What does the branchial motor/special visceral efferent branch of the facial nerve innervate?
Muscles of facial expression
Posterior belly of digastric
Stylohyoid
Stapedius
What does the visceral motor/general visceral efferent branch of the facial nerve innervate?
Parasympathetic to lacrimal, sublingual and submandibular glands and mucous membranes of nasopharynx, hard and soft palates
What does the special sensory/special afferent branch of the facial nerve innervate?
Taste for anterior 2/3 of tongue, hard and soft palate
What does the general sensory/general somatic afferent branch of the facial nerve innervate?
General sensation from skin of concha of the auricle and from a small area behind the ear
Which branches of the branchial motor/special visceral efferent facial nerve control the upper muscles of facial expression? Is it bi or unilateral control?
Temporal and zygomatic
Bilateral control
Which branches of the branchial motor/special visceral efferent facial nerve control the lower muscles of facial expression? Is it contra or unilateral control?
Buccal and mandibular
Contralateral control
Describe Bell’s palsy.
Lower motor neuron lesion of facial nerve due to swelling, inflammation, infection…
Develops quickly in 1-3 days
Slowly improves or completely goes away in 1-3 months
Most recover but some are left with weakness on affected side
Most common in adults in their 40s
Symptoms:
- droopy eyelid, dry eye or excessive tears
- unilateral facial paralysis, twitching or weakness
- drooping of corner of mouth, dry mouth, impaired taste
Why is any swelling of the parotid gland painful?
Gland is tightly enclosed in fascia
What muscles does the Stensen duct lie on and pierce?
Lies on masseter
Pierces buccinator
Which structures branch within/close to the parotid gland?
Facial nerve
External carotid artery –> maxillary and superficial temporal
What are the layers of the scalp from superficial to deep?
Skin
Connective tissue (dense)
Aponeurosis of epicranius/occipitofrontalis
Loose connective tissue
Periosteum
(SCALP is an acronym for the layers)
What is the cutaneous innervation for the scalp?
Supraorbital nerve of V1 = front (forehead)
Auriculotemporal nerve of V3 = sides
Lesser occipital nerve of C2 = sides
Greater occipital nerve of C2 = back
Describe the arterial supply of the scalp.
Superficial temporal artery of ECA
Supraorbital artery
Occipital and posterior auricular artery of ECA
Free anastomoses from side to side and they run through the dense connective tissue
How do “panda’s eyes” arise?
Loose connective tissue of scalp allows fluid to pass freely from the posterior aspect to the eyelids anteriorly
Trauma at the back of the head leads to blood in the eyelids
Where does the facial nerve leave the skull?
Stylomastoid foramen
IAM = exiting the intracranial region
