The Scalp, Face, Parotid, Infra-temporal Fossa, and Muscles of Mastication Flashcards
Branches of trigeminal nerve (CN V)
V-1(opthalmic branch)
V-2 (maxillary branch)
V-3 (mandibular branch)
Where does CN V arise?
The pons
CN V-1
The ophthalmic branch - courses through the superior orbital fissure
CN V-2
The maxillary branch traverses the inferior orbital foramen
Also innervates maxillary region and the nasal cavity
CN V-3 (sensory)
The mandibular branch of the trigeminal nerve
Also innervates mandibular teeth and gum (for general sensation - coffee is hot/cold not taste) and tongue.
Runs through the mental foramen to give sensory innervation to the front of the chin
CN V-3 (motor)
Muscles of mastication - also gives motor inneravation to the medial and lateral pterygoid muscles that allow side-to-side movement of the mandible
Note the motof cell bodies lie further interior - branchial motor neurons
CN VII branches
- Facial nerve proper
- Chorda tympani nerve
- Greater petrosal nerve
Nerve and branch that gives a clinical finding of facial palsy
CN VII - the facial nerve proper
What nerve and branch is responsible for sensation of taste?
CN VII - Chorda tympani nerve (also responsible for salivation)
What nerve and branch is responsible for lacrimation?
CN VII - the greater petrosal nerve
(a little involved with taste)
Where does CN VII arise?
The pons
Where does the facial nerve proper traverse shortly after leaving the pons?
The internal acoustic meatus, exiting the base of the skull at the stylomastoid foramen
What gland does the facial nerve proper pass through but not innervate?
Muscles of facial expression innervated by the facial nerve proper
Frontalis muscle (wrinkles forehead)
Orbicularis oculi muscle (circular muscle that closes eyes)
Nasalis muscle (flares nose)
Zygomaticus muscle (smiling)
Orbicularis oris (circular muscle that purses lips close)
What innervates the anterior 2/3 of the tongue?
CN VII the chorda tympani nerve
What does the chorda tympani nerve innervate?
The tongue and lateral submandibular and sublingual glands
CN VII mnemonic
CN VII
- Closes your eye (Facial nerve proper)
- Tastes pie (chorda tympani)
- Makes you cry (greater petrosal nerve)
What nerve and branch innervates the pterygopalantine ganglia?
CN VII - the third branch (vidian nerve branch of the greater petrosal nerve)
Also fibers from the maxillary branch of the trigeminal nerve (CN V-2) pass through without synapsing
The greater petrosal nerve stimulates the lacrimal glands via the pterygopalantine ganglion (parasympathetic control)
What nerve(s) and branch(es) arise from the geniculate ganglion?
Branches from CN VII (the facial nerve) It contains the cell bodies of the fibers responsible for conducting taste sensation from the anterior two-thirds of the tongue.
Branches of the facial nerve proper (CN VII)
After penetrating the parotid gland
What allows you to move your ears?
The posterior auricular nerve (posterior branch off of the facial nerve proper *CN VII)
Also innervates the occipitalis which forms a functional unit with the frontalis muscle (wrinkles forehead) - innervated by
Temporal branch of the facial nerve proper
Runs to the orbital and forehead
Zygomatic branch of the facial nerve proper
Go to the zygomatic/orbital muscles and infraorbital regions
Buccal branches of the facial nerve proper
to cheek and upper lip (motor innervation)
Marginal mandibular branches of the facial nerve proper
Cervical branches of the facial nerve proper
To neck for innervation of the platysma
Trigeminal nerve
CN V
Infratemporal fossa
o Roof: Infra-temporal surface of the sphenoid bone (including foramen ovale and spinosum).
o Medial wall: Lateral pterygoid plate.
o Anterior wall: Maxilla and pyramidal process of the palatine bone
o Lateral wall: Deep surface of the ramus of the mandible.
Trigeminal nerve
CN V - principal sensory nerve of the head and dura, and motor nerve of all muscles of mastication
3 large divisions that exit the skull via different foramina
Major divisions of the maxillary artery
The first part of the maxillary artery is composed of five branches that are deep to the neck of the mandible
Buccal artery (2nd part) - supplies blood to the muscles of mastication and the cheek
Third part - runs through the pterygomaxillary fissue to the pterygopalantine foss to supply the nasal mucosa
First part of the maxillary artery
Five divisions:
Deep auricular artery - toward external ear
Anterior tympanic artery - through the petrotympanic fissure to the ear
Inferior alveolar artery - through the mandibular foramen to the mandible, gums, teeth, and chin
Middle meningeal artery - through the foramen spinosum to the epidural space (it grooves the internal surface of the cranium).
Accessory meningeal artery - through the foramen ovale to the dura mater
A fracture to the squamos part of the temporal bone risks rupturing what artery?
The middle meningeal artery (first part of the maxillary artery)
Resuls in suacer shaped epidural hematoma on CT
What does the pterygoid plexus communicate with and where does it drain?
This highly variable deep venous plexus lies lateral to the pterygoid muscles. It communicates with the facial veins anteriorly and the inf. ophthalmic veins superiorly. It drains intra-cranially via the cavernous sinus and infection can spread as a result.
o The pterygoid veins unite to form the maxillary vein which then joins the superficial temporal vein to form the retromandibular vein.
o The posterior division of the retromandibular v. unites with the posterior auricular v. to form the external jugular v. (EJ).
o The anterior division joins the facial v. to form the common facial v. which flows to the internal jugular vein.
Pterygopalantine ganglion
Location - pterygopalantine fossa
Parasympathetic ganglion - suspended by two branches of maxillary nerves
Parasympathetic fibers from CN VII (greater petrosal nerve)
Sensory fivers - V2 pass through without synapsing
Important branches - greater and lesser palantine nerves and the pharyngeal nerve
Vasoactive control by blocking the ganglion with cocaine
Temporalis muscle
Origin - temporal fossa
Insertion - coronoid process of mandible and anterior margin of ramus (almost to last molar tooth)
Innvervation - Nerve to medial pterygoid from mandibular nerve (CN V-3)
Fx - Elevation (anterior fibers) and retraction of mandible while protruded (posterior fibers)
Masseter muscle
Origin - zygomatic arch and maxillary process of zygomatic bone
Insertion - lateral surface of ramus of mandible
Innveration - masseteric nerve from anterior trunk of mandibular nerve (CN V-3)
Fx - Elevation of mandible (also assists with protrusion)
Medial pterygoid muscle
Origin:
deep head =medial surface of lateral pterygoid plate and pyramidal process of palantine bone
superificial head = maxillary tubercle and pyramidal process of palantine bone
Insertion - attach inferiorly to the medial surface of the angle of the mandible
Innervation - nerve to medial pterygoid from the mandibular nerve (CN V-3)
Lateral pterygoid muscle
Origin:
Upper head - roof of infratemporal fossa
Lower head - lateral surface of lateral plate of the pterygoid process
Insertion - capsule to TMJ in the region of attachment to the articular disc and to the pterygoid fovea on the neck of the mandible
Innervation - Nerve to lateral pterygoid directly from the anterior trunk of the mandibule nerve (CN V-3) or from the buccal branch
Fx - protrusion and side-to-side movements of the mandible
Muscles that depress the jaw
digastric muscles, supra-hyoid muscles, and lateral pterygoid muscles
Injury to what fibers produces reduction in sound conduction and hearing?
Injury to CN V-3 motor fivers to the tensor veli palati and tensor tympani muscle
TMJ innervation
CN V-3 - the auriculotemporal branch (sensory)
TMJ problems - severe headaches and reverred pain over the temporalis muscle (trigeminal neuralgia)
Lower hinge joint of TMJ
Elevation and depression
What innervates the parotid gland?
Post ganglionic fibers from the glossopharyngeal nerve (CN 9) - after synapsing with the otic ganglion
The parotid duct (Stensen’s duct) emerges from the anterior surface of the parotid gland to run across (which muscle), before penetrating (which muscle), to drain into the upper part of the superior alveolar sulcus opposite (which tooth).
Masseter m., Buccinator m., Upper 2nd Molar
A 23-year-old farm worker is accidentally covered in organo-phosphate pesticide during crop spraying. Clinical examination reveals hyper-salivation from the parotid gland. This primarily indicates parasympathetic stimulation via the:
Otic ganglion
The CT scan of a 60-year-old woman clearly indicates an aggressive invasive carcinoma of the left infra-temporal fossa at the foramen ovale. On clinical examination the doctor would expect to find the following
An inability to tense the soft palate, ipsilateral reduction of hearing and the deviation of the jaw towards the left.
When the lateral pterygoid contracts unilaterally with the medial pterygoid muscle on the same side, the mandible moves to the opposite side.
CN V-3 (mandibular branch) is motor innervation of all the muscles of mastication on the ipsilateral side. Paralysis would result in an unopposed action of the right medial and lateral pterygoid m.
The buccal branch of CN V-3 also provides sensory innervation to the cheek
V
A 25-year-old racket-ball player is struck directly on the globe of the eye and presents in the ER with double vision and a fixed gaze. A ‘forced duction test’ performed is positive (i.e.: the globe cannot be moved through all planes). An upright skull X-ray reveals an air/fluid level in the maxillary sinus and the patient is sent for a follow-on CT scan. What structure(s) can be entrapped:
Inferior rectus m. and peri-ocular fat
A 16-year-old boy’s hair gets caught in the propeller during a boating accident. The injury easily avulses a significant part of his scalp. Beneath which layer of the scalp is devolving regularly encountered?
In the sub-galeal loose areolar tissue plane
A 26-year-old man presents with a classic Bell’s Palsy with a lower motor neuron injury of the involved facial nerve (N7). The clinical presentation shown is as a result of predominantly the following muscle action:
Unopposed contraction of the left lavator palpabrae superioris m
The orbiculares oculi m. is the opposition (CN VII)
A 27-year-old male is involved in a high speed MVA. He was lucid (‘awake’) but now demonstrates a progressive loss of consciousness (LOC) and symptoms consistent with a space occupying lesion. His CT scan reveals a fracture through the foremen spinosum and a enlarging saucer-shaped hematoma (red arrow). The following arterial rupture and dura level involvement is most likely:
Middle meningeal a. with epidural hematoma
Compression of CN III is common in injuries like this (results in a blown pupil)
A 24-year-old male patient presents with a stab wound of the right skull base which is localized to the stylomastoid foramen. On clinical examination the surgeon would also expect to find:
An extra-cranial CN 7 injury (aka lower motor neuron injury) with total ipsilateral facial paralysis (upper and lower divisions), and with loss of the motor innervation of the posterior belly of the digastric and stylohyoid muscles.
What nerve exits the skull at the foramen ovale?
CN V-3 (the mandibular branch of the trigeminal nerve)
Also, the accessory meningeal artery, the lesser superficial petrosal nerve and the emmissary vein
