Case 20- Innervation and nose Flashcards
The three branches of the trigeminal nerve
- V1- Opthalmic- exits the skull through the superior orbital fissure
- V2- Maxillary- exits the skull through the foramen rotundum
- V3- Mandibular- exits the skull through the foramen ovale
V1- Opthalmic division of the Trigeminal nerve
- Goes to the orbit
- Main branches= Nasociliary, Lacrimal, Frontal
- Supply= Proprioception, touch, temperature and pain sensation from the forehead, cornea, upper eyelid and dorsal nose
V2- Maxillary division of the Trigeminal nerve
- Goes to the Pterygopalatine fossa
- Main branches- Zygomatic, infraorbital, superior alveolar and the ganglionic branches
- Supply= Proprioception, touch, temperature and pain sensation from the lateral nose, upper teeth, hard palate, upper cheek
V3- Mandibular division of the trigeminal nerve
Goes to the infratemporal fossa. Has an anterior (mainly motor) and posterior (mainly sensory) trunk
Anterior division of the V3 mandibular division of the Trigeminal nerve
- Buccal nerve which gives sensory innervation to the anterior cheek
- Nerve to the masseter, medial and lateral pterygoids, temporalis provides motor innervation to the muscles of mastication
- Tensor tympani supplies the middle ear and the tensor veli palatini supplies the soft palate
Posterior division of the V3 mandibular division of the Trigeminal nerve
- Inferior alveolar nerve gives sensation to the lower jaw, lower teeth, chin. Exits the mental foramen as the mental nerve, goes along the mandible
- Auriculotemporal nerve gives sensation to the temple. Encircles the middle meningeal artery
- Lingual nerve gives sensation to the anterior 2/3rds of the tongue
- Nerve to Mylohyoid gives motor innervation to the mylohyoid and the anterior belly of the digastric.
Sensory distribution of the Trigeminal nerve
- Trigeminal (CNV) overview= anterior 2/3rds of the head, dura matter and cranial blood vessels
- Ophthalmic division (V1)= forehead, cornea, upper eyelid and dorsal nose
- Maxillary division (V2)= Lateral nose, upper teeth, hard palate, upper cheek
- Mandibular division (V3)- Lower jaw, lower teeth, chin, posterior cheek, temple, anterior 2/3rds of the tongue
Route of sensory innervation
- Small sensory fibres pick up Proprioception, Temperature, Pain, Touch. This is then detected by the main branches V1, V2, V3
- This is sent to the Trigeminal ganglion then the Trigeminal root and the Ventrolateral pons
Trigeminal sensory nucleus
- Mesencephalic- midbrain (proprioception, muscles of mastication and the tempero mandibular joint)
- Principle sensory- Pons (touch/pressure)
- Spinal nucleus- pain, temp
- The spinal nucleus continues inferiorly into the spinal cord, receives afferents from the CNV as well as afferents from CNVII, IX, X and cranial nerves
Sensory innervation of the face
- Trigeminal nerve to the Trigeminal sensory nucleus
- Then to the Trigeminothalamic tract (ventral). Second order sensory fibres from the trigeminal sensory nucleus decussate. Terminates in the ventral posteromedial (VPM) nucleus of the thalamus.
- Then goes to the VPM nucleus thalamus and then the Somatosensory cortex
- Some fibres follow the dorsal trigeminothalamic tract to the ipsilateral VPM of the thalamus.
- Additional fibres go to the cerebellum and establishes several reflex connections
Course of the facial nerve
The facial nerve passes through the internal acoustic meatus into the petrous temporal. It passes through the facial canal and then exits the skull via the stylomastoid foramen. It gives off 3 branches and enters via the Parotid gland
Branches of the facial nerve
• Posterior auricular nerve- muscles around the ear and occipital portion of the occipitofrontalis
• Posterior belly of digastric
• Stylohyoid
Terminal branches of the facial nerve= Temporal, Zygomatic, Buccal, Marginal mandibular, Cervical
Nmonic= To Zanzibar By Motor Car
Muscles of facial expression
- Origin- facial bones
- Insertion- skin and superficial fascia, no deep fascia in the face
- Innervation- facial nerve
- Embryology- 2nd pharyngeal arch
Muscles used to raise the eyebrows
Occipitofrontalis- frontalis portion and occipital portion connected by an aponeurosis. The Frontalis portion raises eyebrows
Muscles used to close the eyes tightly
Orbicularis Oculi, sphincter of the eyelids. Has two portions the Orbital part (tight closure), Palpebral part (gentle closure/blinking)
Muscles used to bare the teeth
- Zygomaticus major
- Zygomaticus minor
- Lavator anguli oris
- Levator labii superioris
- Levator labii superioris alaqeque nasi
Muscles used to blow out cheeks with closed lips
- Blow out cheeks- Buccinator is a muscle of the cheek which lies at deeper level than other facial muscles
- Closed lips: Orbicularis Oris is a sphincter of the mouth which narrows the mouth and closes the lips (most contracted when whistling)
Buccinator muscle
- Deeper to other facial muscles. Attachments:
- Anterior- Orbicularis oris
- Posteriorly- Pterygomandibular raphe
- Superior: Maxillary alveolar margins
- Inferior: mandibular alveolar margins
- Parotid duct pierces buccinator
Muscles used in a Grimace
Plastyma: large, flat superficial muscle