Sensory innervation of the face (A16) Flashcards
dermatome
-area of skin supplied by the sensory fibres in a given somatic nerve
what is the nipple line supplied by
thoracic spinal nerve 4 (T4)
what is the umbilicus (belly button) supplied by
thoracic spinal nerve 1 (T1)
which two nerves supply sensory innervation to the face
- great auricular nerve (C2,C3)
- trigeminal nerve (CN V)
great auricular nerve and innervation
- C2, C3
- spinal nerve branch (connects with the spinal cord)
- supplies sensory innervation to the angle of the mandible, area underneath the mandible and the earlobe)
3 branches of trigeminal nerve (CN V)
- tri=3, germinal=same genes
- trigeminal nerve is divided into 3 branches: ophthalmic, maxillary and mandibular (and these branches have subsequent branches)
- all 3 branches are not identical (some branches of Vc contain motor fibres as well as sensory)
- supplies sensory innervation to the rest of the face (areas not innervated by the great auricular)
1st branch of trigeminal nerve (CN V)
- ophthalmic division of trigeminal/V1/Va
- branches are found in the region of the orbit, mid-nose and forehead
- ophthalmic relates to the eyes
- supplies sensory innervation
2nd branch of trigeminal nerve (CN V)
- maxillary division of the trigeminal/V2/Vb
- branches found in region of maxilla and anterior temple
- supplies sensory innervation
3rd branch of the trigeminal nerve (CN V)
- mandibular division of the trigeminal/V3/Vc
- branches found in relation to mandible and mid- temple
- supplies sensory AND motor innervation (motor fibres supply the muscles of mastication/chewing)
why does the mandibular branch of the trigeminal nerve differ to the maxillary and ophthalmic branches
- contains sensory AND motor fibres (whereas the other 2 branches only supply sensory innervation)
- motor fibres supply the muscles of mastication/chewing
different nomenclature used for the branches of the trigeminal nerve (CN V)
- 1st branch=ophthalmic division of trigeminal/V1/Va
- 2nd branch=maxillary division of the trigeminal/V2/Vb
- 3rd branch=mandibular division of the trigeminal/V3/Vc
areas of skin supplied by ophthalmic division of the trigeminal nerve
supplies all of forehead region, upper eyelid, medial and lateral corners of the eye, dorsum of the nose and medial ala (wing of nose)
areas of skin supplied by maxillary division of the trigeminal nerve
anterior part of temple, lower eyelid, majority of midface including prominence(maxillary prominence/process), maxilla, lateral aspect of ala (wing of nostril), nostrils, upper lip
areas of skin supplied by mandibular division of the trigeminal nerve
mid portion of temples, buccal area (where you would expect to find the buccinator muscle), chin
sensory innervation to the angle of the mandible
- not supplied by any branches of the trigeminal
- supplied by greater auricular nerve (C2,C3)
cervical plexus
involves spinal nerves C3,C4,C5
- how is the chicken pox virus able to reactivate to cause ophthalmic herpes zoster (“shingles”)
- symptoms
- treatment
- virus doesn’t leave the body, it stays in the trigeminal sensory ganglion in dormant states (within the dorsal root ganglia associated with spinal nerve)
- reactivates from its latent state
- chicken pox transmits over face via CNV1 (opthalmic division of trigeminal)
- causes pain/itch/blisters in the opthalmic dermatome region supplied by CNV1 (all of forehead, upper eyelid, medial/lateral corners of the eye, dorsum of the nose, medial aspect of ala/wing of nose/nostril)
- can involve the eye
- treated with antiviral
trigeminal ganglia
- CNV
- chicken pox virus can remain dormant in trigeminal ganglia (within the dorsal root ganglia associated with the spinal nerve)
- distal part of trigeminal nerve, before nerve splits into its 3 primary divisions
5 named branches of the ophthalmic division of the trigeminal nerve
1-lacrimal nerve 2-supraorbital nerve 3-supratrochlear nerve 4-infratrochlear nerve 5-external nasal nerve
lacrimal nerve
- 1st branch of ophthalmic division of trigeminal
- lacrimal gland supply
- secretomotor supply (to produce tears)
- supplies lateral aspect of skin on eyelid
supraorbital nerve
- 2nd branch of ophthalmic division of trigeminal
- supplies skin of majority of forehead, scalp (wide extensive)
- exits via supraorbital foramen/notch
supratrochlear nerve
- 3rd branch of ophthalmic division of trigeminal
- supplies skin on medial aspect of forehead, conjunctiva (lines inside of eyelids and covers sclera) and skin of upper eyelid
infratrochlear nerve
- 4th branch of ophthalmic division of trigeminal
- supplies skin on medial aspect of the eyelid
external nasal nerve
- 5th branch of ophthalmic division of trigeminal
- supplies skin of dorsum of nose and medial ala (wing of nostril)
where does the supraorbital nerve exit the skull
via supraorbital foramen from cranial cavity (neurovascular bundle comes through here)
3 branches of maxillary division of trigeminal
1-zygomaticotemporal nerve
2-zygomaticofacial nerve
3-infraorbital nerve
zygomaticotemporal nerve
- branch of maxillary division of trigeminal
- supplies skin on anterior region of temple,
- passes through zygomaticotemporal foramen
zygomaticofacial nerve
- branch of maxillary division of trigeminal
- supplies skin on prominence of cheek
- exits via zygomaticofacial foramen
infraorbital nerve
- branch of maxillary division of trigeminal
- supplies (extensively) to majority of mid face, lower lip/eyelid, lateral aspect of ala/nostril
- travels through the infraorbital foramen
- sits below levator labii superioris muscle
3 branches of mandibular division of trigeminal
1-auriculotemporal nerve
2-long buccal nerve
3-mental nerve
auriculotemporal nerve
- branch of mandibular division of trigeminal
- supplies mid temple region
long buccal nerve
- branch of mandibular division of trigeminal
- supplies buccinator muscle
mental nerve
- branch of mandibular division of trigeminal
- supplies skin on chin and lower lip
- travels through mental foramen
- lies below levator labii inferioris
supraorbital and infraorbital foramen
- supraorbital may be a notch (as they sit just above superior orbital rim)
- infraorbital is always a foraminae (where the infraorbital nerve exits)
other foraminae of the face
- mental
- zygomaticofacial
why does the chicken pox virus cause itchiness
-chicken pox virus infects the sensory nerve endings in the skin stimulating action potentials that travel centrally causing an itch
why is ophthalmic herpes zoster painful
- can cause post herpetic neuralgia/ trigeminal neuralgia
- neuralgia= intense, typically intermittent pain along the course of a nerve, especially in the head or face
route of ophthalmic division of trigeminal nerve
- exits cranial cavity through superior ophthalmic fissure
- passes through superior aspect of orbit
route of maxillary division of trigeminal nerve
- exits cranial cavity initially via foramen rotundum
- travels in inferior aspect/part of orbit
- and through infraorbital foramen
route of mandibular division of trigeminal nerve
-exits base of skull via foramen ovale
-and through mandibular foramen inside
-mental nerve
?
clinical testing of the sensory component of CNV (trigeminal nerve/sensory nerve supply to the face)
- ask patient to close eyes
- gently brush the skin in each dermatome with a fine tip of cotton wool
- ask the patient to tell you when they feel their skin being touched
- test both sides (bilaterally)
layers of scalp
- Skin
- Connective tissue (vascular layer-arterial blood supply to scalp contained within)
- Aponeurosis (epicranial connects frontalis to occipitalis)
- Loose connective tissue
- Pericranial periosteum (PERICRANIUM specifically)
infiltration of connective tissue layer of the scalp
- supratrochlear and supraorbital branches of internal carotid artery
- superficial temporal, occipital and posterior auricular branches of external carotid artery
external layer of scalp
skin
arteries contributing to arterial supply in connective tissue of scalp
- 3 branches of external carotid: occipital artery, posterior auricular artery and superficial temporal artery
- 2 terminal branches of internal carotid artery (which has no branches in neck): ophthalmic which then branches into supraorbital and supratrochlear
branches of internal carotid artery within the neck
- DOES NOT give branches in the neck
- only branches once inside the skull
mental artery
-branch of maxillary artery
infra-orbital artery
-branch of maxillary artery
facial artery
- branch of external carotid
- passes posterior to angle of mandible, travels up face and branches to lips and lateral to nose
maxillary artery
-contributes to supply of face
-branch of external carotid artery
further branches- infraorbital artery, mental artery
blood supply to upper face
internal carotid (rest of face supplied by external carotid)
anastomosis
-network of multiple arteries
why is it a problem if the connective tissue layer of the scalp is cut
- due to the anastomosis (network of multiple arteries), the blood can travel in both directions of network therefore will bleed profusely/ to a great degree
- dense connective tissue surrounding arteries also holds them open when cut and prevents them contracting in an attempt to close over and stop bleeding like they usually would
epicranial aponeurosis
- 3rd layer of scalp
- flat tendon connecting two muscles (frontalis and occipitalis)
- connects anteriorly to frontalis and posteriorly to occipitalis
loose connective tissue layer of scalp
allows mobility of aponeurosis sitting above it
frontal occipital complex
joining of occipitalis to frontal bone (?)
pericranium
- pericranial periosteum (say PERICRANIUM)
- very thin tissue on top of bones of skull
- responsible/allows initial bone formation/has relation to ossification
