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
Facial nerve
- Facial motor nucleus has two components, superior and inferior
- Bilateral due to superior portion of facial nucleus which innervates the forehead
- Contralateral single innervation to the inferior portion which innervates the rest of the face
LMN lesion of CNVII
Removes messages from both the superior and lower motor nucleus so the entire one side of face will be paralysed.
UMN lesion of CNVII
Loss of fibres to the superior motor nucleus. You will still get fibres from the ipsilateral side so there is still movement in the forehead. Only loss of movement in the lower face on one side. Is forehead sparing
Anatomical sieve of facial pain
- Eye- orbital cellulitis, glaucoma
- Upper respiratory- sinusitis, infections
- Ear- Otitis media/externa
- Teeth- Dental abscess
- Bone- TMJ pain, mastoiditis
- Parotid gland- mumps, calculi
- Soft tissue- cell
Surgical sieve of facial pain
- Neoplastic
- Headaches- cluster/migraines /overuse of medication
- Vascular- Temporal arteritis
- Neurological- trigeminal neuralgia, herpes zoster, post-herpetic neuralgia
- Atypical or idiopathic- may be related to stress or depression
Trigeminal neuralgia- facial pain
- Pain in the region of 1 or more divisions of the trigeminal nerve, rare but most frequent facial neuralgia
- Peaks in 50-60, increases with age
- Site- unilateral, V2/V3 distribution
- Character- episodic, severe, sharp, shock like pain. Lasts secs-mins
- Precipitating symptoms- light tough, washing face, cold wind, eating
- Associated symptoms- none
- Impact of pain- decreased quality of life including weight loss, isolation and depression
- Majority of cases are due to nerve compression which is usually vascular i.e. due to a sagging cerebellar artery
Post herpetic neuralgia- facial pain
- In 10% of patients with herpes zoster (shingles)
- Site- distribution of shingles rash
- Character- burning, aching, sometimes sharp
- Precipitating symptoms- vesicular rash and pain
- Associated symptoms- hypersensitivity over shingles scar
- Impact of pain- can be debilitating, depression, insomnia and social isolation
The nasal cavity
- Piriform in shape
- It is wider below and is covered superior by the nasal bones
- The cavity is divided into a left and right side by the medial wall
- There are respiratory and olfactory regions
Boundaries of the nasal cavity- Anterior, Posterior, Roof, Floor
- Anterior- Cartilaginous region of the nose
- Posterior- Nasopharynx
- Roof- Nasal bone, Frontal bone, Cribiform plate of the ethmoid bone, Sphenoid bone
- Floor- Palatine process of the maxilla, Horizontal plate of the palatine bone
Boundaries of the nasal cavity- Medial, Lateral wall
- Medial wall- Perpendicular plate of the ethmoid bone, Nasal crest of the maxilla, Nasal crests of the palatine bone, Vomer, Septal cartilage
- Lateral wall= Nasal bone, Frontal bone, Ethmoid bone (Superior/Middle conchae), Inferior conchae, Sphenoid bone, Nasal cartilage, Maxilla and the Palatine bone
Nose- Conchae, Recesses
The Conchae are bony projections. The superior and middle conchae are connected. The recesses:
• Spheno-ethmoidal recess- above the superior conchae
• Superior meatus- between the superior and middle conchae
• Middle meatus- between the inferior and middle conchae
• Inferior meatus- below the inferior conchae
Paranasal sinus’s
Sinuses are air filled spaces within the bones. The Paranasal sinuses- Maxillary, Sphenoidal, Frontal, Ethmoidal. They are bilateral structures. They are lined with mucous membranes.
Functions of the Paransal sinus’s
• Warm and humidify inspired air • Reduce the weight of the skull • Speech-resonance of the voice • Mucus production They all drain into the lateral wall of the nasal cavity
Frontal sinuses
- Anterior structures
- Lie between the two glabellae i.e. between the eyebrows
- They sit on top of the nasal cavity
- Drain into the hiatus semilunaris- part of the middle meatus
Ethmoidal sinus
- Relatively small
- Also called the anterior, middle and posterior ethmoidal air cells
- They sit on top of the nasal cavity
- Close proximity to the orbit (between the eyes)
Ethmoidal sinus drainage
- Anterior -> Hiatus semilunaris
- Middle -> Ethmoidal bulla
- Posterior -> Superior meatus
Maxillary sinus
- Between the upper teeth and orbit (eye)
- Lateral to the nasal cavity
- Drains into the hiatus semilunaris
- The drainage point is high on the medial wall of the sinus, normally infected due to the point of drainage as the maxillary sinus has to be full of mucus before it drains when the head is erect. When lying down it only drains medially so only the upper sinus drains
Sphenoidal sinus
- Located below the sella turcia (houses the pituitary gland)
- It sits superoposteriorly to the nasal cavity (behind)
- Drainage is to the sphenoethmoidal recess
Blood supply to the nose
- Internal Carotid -> Ophthalmic artery -> Anterior/Posterior Ethmoidal artery
- External carotid -> Maxillary artery -> Sphenopalatine / Greater palatine artery
- External carotid -> Facial artery -> Labial and nasal branches
Blood supply to the lateral wall of the nose
- Internal carotid -> Ophthalmic artery in the orbit (superior to nasal cavity) -> Anterior Ethmoidal and Posterior Ethmoidal
- External carotid artery -> Maxillary artery -> Sphenopalatine artery (in the nasal cavity) and the Greater palatine artery (outside the nasal cavity before going through the maxilla to supply the nose)
- External carotid -> Facial artery -> Lateral nasal artery (lateral)
- Main arteries which supply the lateral wall of the nose= Anterior Ethmoidal, Posterior Ethmoidal, Sphenopalatine, Greater palatine and the Lateral nasal
Blood supply to the medial wall of the nose- there are septal branches of:
- Anterior ethmoidal artery
- Posterior ethmoidal artery
- Sphenopalatine artery
- Greater palatine artery
- Facial artery -> Superior labial artery (medial)
Medial wall- Epistaxis
- On the medial wall there is an anastomosis of most of the major arteries that supply the nose
- It is known as Little’s are or Kiesselbach’s plexus
- Common site of nose bleeds (Epistaxis)
Nerve supply to the nose- Ophthalmic
Ophthalmic division VI (exits the skull via the superior orbital fissure-> Nasocillary branch -> Anterior ethmoidal
Nerve supply to the nose- Maxillary division V2
- Exits the skull via the foramen rotundum
- Infraorbital fissure -> Infraorbital canal -> Infraorbital nerve and the Ant.Sup. alveolar nerve
- Pterygopalatine ganglion (in the Pterygopalatine fossa) goes through the Sphenopalatine foramen to form the Nasopalatine nerve
- Pterygopalatine ganglion goes through the Palatine canal to form the Greater palatine nerve
Nerve supply to the medial wall
- CNVI -> Nasocilary branch -> Anterior ethmoidal
- CNV2 -> Nasal branches of the pterygopalatine ganglion via the sphenopalatine foramen -> Nasopalatine nerve
- The Olfactory nerves go through the Cribiform plate
Nerve supply to the Lateral wall of the nose
- Top near the front of the head= Nasociliary branch (CNVI) -> Anterior ethmoidal -> External nasal branch.
- Bottom near the front of the head= Infraorbital (CNV2) -> Nasal branch and branch of anterior superior alveolar nerve
- Right (near the back of the head)= Pterygopalatine ganglion (CNV2) -> Posterior superior: from nasal branches via the sphenopalatine foramen -> Posterior inferior: from greater palatine nerves
What does the ICA and ECA supply
Arteries supplying the scalp are branches of either the external carotid artery or the ophthalmic artery which is a branch of the internal carotid artery. The Internal Carotid artery supplies the brain, forehead and eyes.
Venous drainage of the scalp and face
- Supratrochlear vein and Supraorbital vein -> Anterior facial vein -> Common facial vein -> IJV
- Superior division of the Maxillary vein and the Temporal vein -> Retromandibular vein -> Anterior division -> Common facial vein -> IJV
- Superior division of the Maxillary vein and the Temporal vein -> Retromandibular vein -> Posterior division and the Posterior Auricular vein -> External jugular vein -> Subclavian vein
- The Occipital veins drain into the Suboccipital plexus of veins
Epistaxis- nose bleeds
- Bimodal age distribution, 2-10 years and 50-80 years
- 60-70% have had epistaxis once in lifetime- 10% sought medical help
Cause of Epistaxis
• Major trauma- nasal fracture involves major vessels
• Microtrauma- Little’s area of septum
Anosmia
Caused by problems with the Olfactory nerve
