HNS26, HNS27 Nerves Of Head And Neck I, II Flashcards
Classification of nervous system
CNS:
Brain + Spinal cord
PNS:
Cranial nerves + Spinal nerves + Ganglia + Plexuses
Gross anatomical approach
Structures:
- Ganglia
- Nerves
Nerves to:
- Skin
- Muscles
- Viscera
- Special sensory organs
Special sensory organs
- Vision
- Smell
- Taste
- Hearing
- Balance
Nerve and Neuron
Nerve:
- Visible gross anatomically —> Bundle of neurons
- Can have mixture of neurons —> ∴ can be mixed sensory / motor
Neuron:
- Cell with extension + cell body (Histological)
- Either Sensory / Motor —> cannot be both at the same time
Functional division of CNS / 5 types of peripheral tissue
Motor nerves:
- Skeletal muscle (Somatic motor)
- Smooth muscle (Autonomic)
- Gland (Autonomic)
Modified sensory neuron —> Modified nerves:
- General sensory organs
- Special sensory organs
- Reflexes
Example: innervation of gland
When need to secrete:
CNS (Nucleus) —> Ganglion —> Cranial nerves —> Parasympathetic fibres —> Gland
Innervation of head and neck
Nerves:
- Cranial nerve (12)
- Spinal nerve (5)
Ganglia:
- Autonomic ganglia
—> Sympathetic trunk (Cervical part) (3)
—> Parasympathetic ganglia (4)
***Ganglia of Head and Neck
Rmb: Ganglia (唔係Nucleus!!!)
Motor (Autonomic) ganglia:
- Sympathetic ganglia (within sympathetic chain)
1. Superior cervical ganglion
2. Middle cervical ganglion
3. Inferior cervical ganglion - Parasympathetic ganglia
1. Ciliary ganglion
2. Pterygopalatine ganglion
3. Submandibular ganglion
4. Otic ganglion
Sensory ganglia:
- General sensory
1. Dorsal root ganglia (T2-T5)
2. Trigeminal ganglion (CN5) —> Trigeminal nucleus
3. Superior glossopharyngeal ganglion (CN9) —> Trigeminal nucleus
4. Superior vagal ganglion (Jugular ganglion) (CN10) —> Trigeminal nucleus
(5. Geniculate ganglion (CN7)) - Special sensory
1. Vestibular ganglia + Spiral ganglion (CN8) —> Vestibular + Cochlear nucleus
2. Geniculate ganglion (CN7) —> Gustatory nucleus
3. Inferior glossopharyngeal ganglion (half general sensory, half special sensory (posterior 1/3 tongue taste)) (CN9) —> Trigeminal / Gustatory nucleus
(4. Bipolar cells in olfactory epithelium (CN1))
(5. Retinal ganglion cells (CN2))
(6. Inferior vagal ganglion (Nodose ganglion) (CN10) epiglottis taste buds) - Visceral sensory
1. Inferior glossopharyngeal ganglion (CN9) —> Solitary nucleus
2. Inferior vagal ganglion (Nodose ganglion) (CN10) —> Solitary nucleus
Organisation of spinal nerves
Spinal cord
—> Spinal nerve roots (Dorsal + Ventral root)
—> Spinal nerve
—> Branch (Dorsal + Ventral rami + Rami communicantes (gray / white rami —> leads to sympathetic ganglion))
Somatic motor
Anterior horn cells
—> Ventral root
—> Ventral / Dorsal ramus
—> Skeletal muscles
Sympathetic motor
Lateral horn (Cell bodies of Preganglionic neuron)
—> Ventral root
—> White ramus
—> Sympathetic ganglion (Sympathetic chain, Secondary neuron)
—> Gray ramus
—> Spinal nerves at the same level —> Ventral / Dorsal ramus (skin of body)
OR
—> Sympathetic nerve at other levels —> Ventral / Dorsal ramus (head and neck)
Cervical spinal nerves
- 8 segments
- 1st pair between foramen magnum and C1 vertebra
***Spinal nerves dermatomes
Spinal nerve ONLY supply
- posterior scalp
- neck
—> C2-C5
Anterior neck: Anterior rami of spinal nerves (C2-4 of Cervical plexus + C5)
Posterior scalp + neck: Posterior rami of spinal nerves (C2-5)
(Face supplied by Cranial nerve)
***Cutaneous distribution of spinal nerves
Posterior rami of spinal nerve
- Greater occipital nerve (C2) (posterior scalp)
- Third occipital nerve (C3) (posterior neck)
- C4 (posterior neck)
- C5 (posterior neck)
Anterior rami of spinal nerve
- Lesser occipital nerve (C2, C3 —> cervical plexus) (lateral scalp)
- Greater auricular nerve (C2, C3 —> cervical plexus) (anterior neck, angle of mandible, ear)
- Transverse cervical nerve (C2, C3) (anterior neck)
- Supraclavicular nerve (C3, C4) (Lateral + Intermediate + Medial) (clavicular region)
- Superior / Inferior root of Ansa cervicalis
Cervical plexus: formed from C1-C4
Ansa cervicalis: part of Cervical plexus that ***also carries Cranial nerves e.g. CN12
Cranial nerves
CN3-12 emerges from Brainstem
12 pairs of CN related to 12 structures in head and neck
—> NOT all similar anatomically (NOT have similar structures e.g. root, rami)
***Functional classifications of Cranial nerves
Sensory (Special sensory):
- Olfactory (CN1)
- Optic (CN2)
- Vestibulocochlear (CN8)
Motor (only Somatic motor except CN3):
- Oculomotor (CN3) —> Visceral + Somatic
- Trochlear (CN4)
- Abducent (CN6)
- Accessory (CN11)
- Hypoglossal (CN12)
Mixed (General sensory + Visceral sensory + Special sensory + Somatic motor + Visceral motor):
- Trigeminal (CN5)
- Facial (CN7)
- Glossopharyngeal (CN9)
- Vagus (CN10)
Cranial “Purely” somatic motor nerves
- Movement of eyeball (somatic)
- CN3
- CN4
- CN6 - Intraocular muscles (autonomic)
- CN3 (with ***Ciliary ganglion: Parasympathetic —> Pupillary light reflex) - Neck, back muscles (SCM, Trapezius)
- CN11 - Tongue muscles (except palatoglossus)
- CN12
Cranial “Purely” special sensory nerves
- Smell
- CN1 - Vision
- CN2 - Hearing
- CN8 (Spiral ganglion) - Balance
- CN8 (Vestibular ganglion)
***Cranial mixed nerve
CN5:
- General sensation of face (somatic sensory)
- CN5 (Trigeminal ganglion) - ***Muscles of mastication, Tensor tympani, Tensor veli palatini, Mylohyoid, Anterior belly of digastric (somatic motor)
- CN5 (CNV3)
CN7:
-
**Muscles of facial expression, **Stapedius, **Stylohyoid, **Posterior belly of digastric etc. (somatic motor)
- CN7 - Taste (anterior 2/3 tongue) (special sensory)
- CN7 (***Geniculate ganglion) - Submandibular, Sublingual gland (visceral motor)
- CN7 (***Submandibular ganglion: Parasympathetic) (From Superior salivatory nucleus) - Lacrimal gland + Nasal gland + Palatine gland (visceral motor)
- CN7 (***Pterygopalatine ganglion: Parasympathetic) (From Superior salivatory nucleus)
CN9:
- ***Stylopharyngeal muscle (somatic motor)
- CN9 - Pharynx, Palate, Carotid sinus, Carotid body, Posterior 1/3 tongue (somatic + visceral sensory)
- CN9 (Superior + Inferior glossopharyngeal ganglion) - Posterior 1/3 tongue (special sensory)
- CN9 (***Inferior glossopharyngeal ganglion) - Parotid gland (visceral motor)
- CN9 (***Otic ganglion: Parasympathetic)
CN10:
- Pharynx, Larynx (somatic motor)
- CN10 - External ear and meatus (somatic sensory)
- CN10 (Superior vagal ganglion) - Pharynx, larynx (visceral sensory)
- CN10 (Inferior vagal ganglion) - Taste bud in epiglottis (special sensory)
- CN10 (***Inferior vagal ganglion)
***Innervation of tongue
Somatic motor:
ALL glossus except Palatoglossus: CN12
Palatoglossus: CN10
Visceral motor (saliva): Submandibular, Sublingual gland (Submandibular ganglion): CN7 Parotid gland (Otic ganglion): CN9
Somatic sensory:
Anterior 2/3 tongue (Trigeminal ganglion): CNV3
Posterior 1/3 tongue (Superior glossopharyngeal ganglion): CN9
Special sensory:
Anterior 2/3 tongue (Geniculate ganglion): CN7
Posterior 1/3 tongue (Inferior glossopharyngeal ganglion): CN9
***Summary of skeletal muscle innervation of head and neck
Pharynx:
- Pharyngeal plexus: CN9, 10, Sympathetic
- except Stylopharyngeus (CN9)
Palate:
- Pharyngeal plexus: CN9, 10, Sympathetic
- except Tensor veli palatini (CNV3 Nerve to medial pterygoid)
Tongue:
- CN12
- except Palatoglossus (Pharyngeal plexus: CN9, 10, Sympathetic)
Facial expression + Buccinator:
- CN7
- except Levator palpebrae superioris (CN3)
Mastication:
- CNV3
- except Buccinator (CN7)
Larynx:
- CN10 Recurrent laryngeal nerve
- except Cricothyroid (CN10 external branch of Superior laryngeal nerve)
Activation of sympathetic nervous system in head and neck
- Triggered by physical / psychological stress: Flight / Fight reaction
- Pupillary dilation (+ opening of Palpebral fissure)
- Perspiration
- Vasoconstriction (blood redistribution to muscle)
- Piloerection (contraction of arrector pili muscle —> at the same time release sebum to surface of skin)
Effectors of sympathetic systems in head and neck
Smooth muscle
- ***Dilator papillae
- ***Superior tarsal muscle (upper lid)
- Blood vessel wall muscles
- Arrector pili
Gland
1. Sweat glands
Cervical part of Sympathetic chain
- Extends from base of skull to 1st rib
- Continuous with thoracic part
- 3 ganglia
- Superior cervical ganglion
- largest
- C2/3 vertebra - Middle cervical ganglion
- smallest
- C5/6 vertebra - Inferior cervical ganglion
- may be fused with first thoracic ganglion —> Cervicothoracic ganglion (aka Stellate ganglion)
***Branches of Cervical ganglia (Superior + Middle + Inferior)
Superior cervical ganglion:
1. **Internal carotid plexus (Ocular structures) (perivascular branches —> follow blood vessels to organs they supply)
—> Deep structures (e.g. Superior Tarsal Muscle, Dilator pupillae)
2. **External carotid plexus (Nasal + Salivary gland)
(Internal + External carotid plexus: perivascular branches —> follow blood vessels to organs they supply)
—> Mid + Lower face (e.g. Facial muscles, Sweat glands)
3. Gray rami (C1-C4) —> Spinal nerves
4. ***Superior cardiac nerve (Cardiac splanchnic nerve to supply visceral organs in thoracic cavity)
Arteries involved:
1. Common, External, Internal carotid arteries
Effectors:
- Dilator pupillae
- Superior tarsal muscle
- Pineal gland
- Sweat gland
(5. Salivary gland - Lacrimal gland)
Middle cervical ganglion:
1. Gray rami (C5-C6) —> Spinal nerves
Artery involved:
1. Inferior thyroid artery
Effectors:
- Larynx
- Trachea
- Pharynx
- Upper esophagus
Inferior cervical ganglion:
1. Gray rami (C7-C8) —> Spinal nerves
Artery involved:
1. Vertebral + Subclavian artery
ALL ganglion’s effector:
- Heart
- Smooth muscle (in deep arteries)
- Skin over head and neck
- Smooth muscle of cutaneous arteries
- Arrector pili
- Sweat gland
***Sympathetic innervation pathway overview (Superior cervical ganglion)
Spinal segments (T1-T3) —> Preganglionic neuron —> White rami —> ***Superior cervical ganglion (X Middle / Inferior) —> Postganglionic neuron —>
- ***Internal carotid plexus (簡單來說: Ocular structures)
—> Superior tarsal muscle (CN3)
—> Pupillary dilator (CNV1)
—> Ciliary body (CNV1)
—> Choroidal and conjunctival vessels (CNV1), Cerebral vessels
—> Lacrimal gland (Deep petrosal nerve: vasoconstriction)
(—> Nasal gland) - ***External carotid plexus
—> ALL 3 Salivary glands
(sympathetic activation do NOT produce secretion (有保留), ONLY change blood supply to glands via vasoconstriction)
(—> Nasal glands) - Gray rami
—> Skin (Vessels, Sweat gland, Arrector pili) - Cardiac splanchnic nerves
—> Visceral organs in thoracic cavity
***Before postganglionic neuron reaches its target site, it passes through different nerves e.g. Deep petrosal nerve, CN5, CN3 etc.
Superior cervical ganglion: Sympathetic innervation of ***ocular structures
Superior cervical ganglion
—> ***Internal carotid plexus
—>
- CNV1
—> Pupillary dilator (Mydriasis) / Ciliary muscle (Accommodation) - CNV1
—> Ciliary ganglion
—> Choroidal and conjunctival vessels (Vasoconstriction) - CN3
—> Superior tarsal muscle
—> Widening of Palpebral fissure - Deep petrosal nerve
—> Pterygopalatine ganglion
—> Maxillary nerve (CNV2)
—> Zygomaticotemporal nerve (branch of CNV2)
—> Communicating branch
—> Lacrimal nerve (branch of CNV1)
—> Lacrimal gland blood vessels (Vasoconstriction)
Superior cervical ganglion: Sympathetic innervation of ***salivary gland
Superior cervical ganglion
—> ***External carotid plexus
—> (follow Lingual / Facial artery)
—> ALL 3 Salivary glands + Nasal glands
(sympathetic activation do NOT produce secretion (有保留), ONLY change blood supply to glands via vasoconstriction)
Superior cervical ganglion: Sympathetic innervation of ***skin
Superior cervical ganglion (+ Middle + Inferior)
—> Gray rami
—> Spinal nerve
—> Peripheral nerve (Ventral / Posterior rami)
—> Vessels, Sweat gland, Arrector pili
Activation of parasympathetic nervous system in head and neck
Homeostatic / Anabolic (energy-conserving system)
—> promote quiet + orderly processes of body
—> allow body to feed + assimilate
—> “Rest and digest”
***Parasympathetic innervation pathway overview
Brainstem nuclei
—> Preganglionic neuron (within CN3, 7, 9, 10)
—> 4 Ganglia (Ciliary, Pterygopalatine, Submandibular, Otic)
—> Postganglionic neuron (within ***CN5)
—>
1. Smooth muscle (Ciliary muscle / Pupillary sphincter)
2. Gland (Salivary gland / Lacrimal gland / Nasal and Palatine mucosa)
Parasympathetic innervation of ***ocular structures
- Edinger-Westphal nucleus (midbrain)
—> Preganglionic neuron (CN3)
—> ***Ciliary ganglion
—> Iris sphincter (Miosis) / Ciliary muscle (Accommodation)
2. Lacrimal nucleus (pons) —> Preganglionic neuron (CN7) —> ***Greater petrosal nerve —> ***Pterygopalatine ganglion —> ***Maxillary nerve (CNV2) —> ***Zygomaticotemporal nerve (branch of CNV2) —> Communicating branch —> ***Lacrimal nerve (branch of CNV1) —> Lacrimal gland (Lacrimation)
Parasympathetic innervation of ***salivary gland
- Superior salivatory nucleus (medulla) (記: CLS)
—> Preganglionic neuron (CN7)
—> Intermediate nerve
—> **Chorda tympani
—> **Lingual nerve (branch of CNV3)
—> ***Submandibular ganglion
—> Submandibular, Sublingual gland, Minor salivary glands of mouth, pharynx, nasopharynx
2. Inferior salivatory nucleus (記: LOA) —> Preganglionic neuron (CN9) —> Tympanic nerve plexus —> ***Lesser petrosal nerve —> ***Otic ganglion —> ***Auriculotemporal nerve (Postganglionic cell) (branch of CNV3) —> Parotid gland
Cervical plexus vs Cervical ganglion
Cervical plexus:
Anatomical definition
- C1-4
- Cutaneous branches: Lesser occipital, Greater auricular etc.
- Muscular branches: Phrenic nerve, Ansa cervicalis (Strap muscles: Omohyoid, Sternohyoid, Thyrohyoid, Sternothyroid)
Cervical ganglion: Functional definition (Sympathetic) - Superior - Middle - Inferior
