Head and neck anatomy Flashcards
Identify the indicated layers of the scalp
Expand briefly on the layers of the scalp
Scalp is multilayered structure which can be remembered by mnemonic SCALP:
-Skin
-Connective tissue (deep)- this contains blood supply and nerves. Deep connective tissue hold vessels open which can cause profuse bleeding when incision is made
-Aponeurotic layer: occipitofrontalis muscle
-Loose connective tissue: separates aponeurotic layer from pericranium. Because of consistency-> infections tend to localise and spread through tissue
-Pericranium-periosteum on outer surface of calvaria skull (top part of skull)
What is the origin and insertion of the occipitofrontalis muscle?
What is the nerve supply for the:
-frontalis belly
-occipital belly
What is the mechanism of action?
occipitofrontalis muscle consists of 2 frontal bellies and 2 occipital bellies. 2 frontal bellies start from skin of eyebrows and insert into aponeurotic tendon known as epicranial tendon. 2 occipital bellies start from tendon and insert into superior nuchal line of occipital bone.
Nerve supply:
-frontalis belly–> temporal branches of facial nerve
-occipital belly–> posterior auricular branches of facial nerve
MOA:
-elevate and wrinkle forehead; raise eyebrows; move scalp
What is the sensory innervation of the scalp anterior to the ears and vertex?
sensory innervation of the scalp anterior to the ears:
4 branches of the trigeminal nerve
-supratrochlear nerve:exits orbit-> passes through frontalis-> supplies forehead in midline
-supraorbital nerve exits through supraorbital foramen-> extends to vertex of scalp
-zygomaticotemporal nerve-> exits through zygomatic foramen-> supplies small area of temporal
-auriculotemporal nerve-> exits deep to parotid gland-> supplies area anterior to ear and temporal area
What is the sensory innervation of the scalp posterior to the ears and vertex
sensory innervation of the scalp posterior to the ears and vertex
from spinal nerves C2-C3; 4 main branches: greater auricular, lesser occipital, greater occipital, 3rd occipital
-Greater auricular from anterior ramus of C2 to C3, pass anterior to SCM to supply area of scalp inferoposterior to ear
-lesser occipital from anterior ramus o C2-> posterior border of SCM-> supply scalp posterior to ear
-greater occipital from posterior ramus of C2-> emerge inferior to obliquus capitis inferior muscles between C1/C2-> extends superiorly to supply vertex
-3rd occipital from posterior ramus of C3-> pierce semispinalis and trapezius to supply posterior neck
Describe the blood supply to the scalp to vertex and lateral face
What 2 main vessels do the blood vessels originate from?
Blood supply arise from 2 main sources:
1. opthalmic artery-supratrochlear and supraorbital arteries arise from opthalmic artery in orbit-> supply scalp as far as vertex
2. external carotid artery-3 main branches
-superficial temporal artery that supplies lateral part of face. A/P branches
-posterior auricular artery that supplies area back of ear
-occipital artery that pierces through back muscles to supply the occipital area of scalp
Describe the lymphatic drainage of the scalp
-chin area
-anterior to vertex of scalp
-posterior to vertex of scalp
Describe the lymphatic drainage of the scalp
-chin area: submental, submandibular LN
-anterior to vertex of scalp: pre-auricular and parotid LN
-posterior to vertex of scalp: mastoid LN behind ear
drain to upper deep cervical LN
Tear trough filler injection techniques-what to avoid
Facial muscles
How can you subdivide the facial muscles into groups?
Where do they originate and insert into?
Describe the innervation of muscles
Facial muscles
Control muscles of facial expression and are sphincters/dilators of the orifices of face (orbit, nose, oris)
They originate from superficial fascia or bone and insert into the skin
They are innervated by branches of the facial nerve VII
Orbital group of facial muscles
Describe the origin, insertion, innervation and MOA of orbicularis oculi (palpebrae part and orbital part) and the corrugator supercili?
Orbital group of facial muscles
Orbicularis oculi is made out of palpebrae part (eyelid) and orbital part:
-palpebrae part originates from the medial palpebral ligament and inserts into lateral palpebral raphe. It is innervated by facial nerve. It closes eyelids gently
-orbital part originates from medial palpebral ligament and nasal part of frontal bone. It forms an ellipse around the eye. It is innervated by facial nerve. It closes eyelids forcefully
Corrugator supercili/depressor supercilli originates from medial angle of eyebrow and inserts into medial 1/2 of skin of eyebrow. Also innervated by facial nerve. It depresses and draws medial 1/2 of eyebrows
Nasal group of facial muscles
Describe the origin, insertion, innervation and MOA of nasalis (transverse and alar nasalis), depressor septi nasi and procerus
Nasal group of facial muscles
Nasalis controls the flaring and closing of nostrils. It is made up of the tranverse nasalis and alar nasalis:
-transverse nasalis arises from maxilla lateral to nose and inserts into aponeurosis in the midline of the nose bridge. It is innervated by facial nerve. It depresses the nasal aperture
-Alar nasalis (just below alar) arises from maxilla above lateral incisor and inserts into alar cartilage. It
isinnervated by facial nerve. It pulls on alar cartilage to flare nostrils
Depressor septi nasi arises from maxilla above medial incisor and inserts into mobile part of nasal septum. It depresses the nasal septum and flares nostrils.
Procerus is small triangular muscle in glabella. It draws eyebrows medically in a frown
Oral group of facial muscles
Describe the origin, insertion, innervation and MOA of depressor anguli oris; depressor labii inferioris; risorius, mentalis muscle
Oral group of facial muscles
Depressor anguli oris- originates from the oblique line of mandible and inserts into corner of the mouth. It depresses the mouth corners
Depressor labii inferioris-originates from anterior part of oblique line of mandible and inserts into the middle of lower lip. It depresses the lower lip
Mentalis muscle-originates from anterior mandible and inserts into skin of chin. It protrudes and elevates the lower lip and skin of chin
Risorius muscle-originates from fascia of masseter and inserts into mouth corners. It pulls mouth corners laterally, “grimace”
Lip muscles
Describe the origin, insertion, innervation and MOA of the lip muscles: zygomaticus major, zygomaticus minor; levator labii superioris, levator labii superioris alaeque nasi, levator anguli oris
Orbicularis oris; buccinator
Lip muscles
There are 2 muscles from the zygomatic bone: zygomaticus major, zygomaticus minor
There are 3 levator muscles of the lips ‘‘labii’’ that elevate the lips/corners: levator labii superioris, levator labii superioris alaeque nasi, levator anguli oris
1 muscle forms muscular structure of cheek and aids in mastication: buccinator
main muscle around lips-orbicularis oris
Zygoma muscles:
Zygomaticus major originates from the upper lateral part of zygoma and inserts into the corner of the mouth. It aids in elevation of mouth corners, SMILE
Zygomaticus minor originates from lower lateral part of zygoma and inserts into upper lip. It elevates upper lip.
Levator muscles of lip:
Levator labii superioris (elevator of upper lip in latin) originates from infraorbital region of maxilla and inserts into skin of upper lip. Elevates upper lip
levator labii superioris alaeque nasi (elevator of upper lip and wing of nose) originates from maxilla and inserts into alar cartilage. Elevates upper lip and flares nostrils
Levator anguli oris originates from below infraorbital foramen and inserts into skin of mouth corners “angles”. Elevates mouth corners, SMILE
Orbicularis oris forms an ellipse around the mouth. Closes mouth and protrudes lips
Buccinator originates from mandible and inserts into angle of mouth where Orbicularis oris is. Builds muscular substructure of cheek and aids in mastication up
Ear muscles
Describe the origin, insertion, innervation and MOA of anterior auricular, superior auricular and posterior auricular muscles?
There are 3 ear muscles
anterior auricular from anterior part of temporal fascia inserts into helix of ear. Draws ear upward and forward
superior auricular from epicranial aponeurosis into upper part of auricle. Elevates ear
Posterior auricular from mastoid process of temporal bone into concha of ear. Draws ear upward and backward
Sensory innervation to face
Describe sensory innervation to face.
What are the 5 main branches of the opthalmic nerve VI?
What is supplies the skin of the medial 1/2 and lateral 1/2 of eyelid?
What nerve supplies the anterior portion of the nose?
Sensory innervation to face
-supplied by trigeminal nerve that divides into opthalmic VI, maxillary V2, mandibular V3 before exiting the middle cranial fossa
Opthalmic VI has 5 main branches:
-supratrochlear nerve and supraorbital nerves that exit orbit superiorly. Supratrochlear nerve is 15-20mm away from midline of forehead and supraorbital nerve in medial 1/3 of eyebrow at supraorbital notch. They supply the upper eyelid + forehead + scalp
-infratrochlear nerve that exit orbit medially. It supplies the skin of the medial 1/2 of upper eyelid and skin of medial corner
-lacrimal nerve that exit orbit laterally. It supplies the skin of the lateral 1/2 of upper eyelid and skin of medial corner
-external nasal nerve that supplies the anterior part of the nose
Sensory innervation to face
Describe the branches of the maxillary nerve V2
Maxillary nerve exit the skull through the foramen rotundum. It has 3 branches:
Zygomatotemporal nerve-exits above the zygomatic bone and supplies skin of temple above zygoma
Zygomatofacial nerve-exits the zygomatic bone and supplies skin over zygoma
Infraorbital nerve-exits the infraorbital foramen and supplies the lower eyelid; skin on side of nose and upper lip
Sensory innervation to face
Describe the branches of the mandibular nerve V3
Mandibular nerve exits the skull through the foramen ovale. It has 3 branches:
Auriculotemporal nerve enters posterior to TMJ joint and passes through parotid gland. It goes on to supply the temple and anterior ear-external acoustic meatus and tympanic membrane
Buccal nerve-surface of buccinator muscle which supplies the cheek
Mental nerve-mental foramen and divides into several branches that supply the skin of the chin and mucous membranes of lower lip
Motor innervation
Describe the motor innervation to facial muscles. Where does this cranial nerve exit in the skull and how many branches does it give off?
Once in the parotid gland, how does the nerve split? What are the 5 main terminal branches and what do each supply?
Motor innervation
Motor innervation to facial muscles is by the facial nerve (VII). This exits the posterior cranial fossa through the internal acoustic meatus and passes through the temporal bone. It emerges from base of skull through the stylomastoid foramen. It the gives off 2 main nerves before reaching parotid gland:
-posterior auricular nerve: supplies posterior auricular muscle of the ear and occipital belly of occipitofrontalis muscle
-nerve that supplies the digastric muscle and stylohyoid muscle
It then enters the deep surface of the parotid gland. WIthin the parotid gland, it gives off 2 main branches:
-temporofacial branch
-cervicofacial branch
This then gives off 5 terminal groups:
1. temporal branches-exit parotid gland at superior border, supply muscles of temple, forehead and supraorbital region
2. zygomatic branches-exit parotid gland at anterosuperior border, supply muscles of zygoma, infraorbital region and lateral nasal area
3. buccal branches-exit parotid gland at anterior border. supply muscles of cheek and upper lip, corner of mouth
4. marginal mandibular branches-exit anteroinferior border, supply muscles of lower lip and chin
5. cervical branches-exit inferior border, supply platysma muscle
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Neuropraxia
What is neuropraxia?
What are some of the clinical consequences if these branches are affected?
Temporal branch of the facial
nerve
Zygomatic and buccal branches
of the facial nerve
Mandibular or marginal branch
Infra-orbital nerve
Mental nerve
Supraorbital and supratrochlear nerve
How long will neuropraxia take to resolve
Neuropraxia is mild peripheral nerve damage leading to temporary weakness/tingling that should resolve within 2-3 weeks.
Facial nerve neuropraxia possibly during cheek filler:
Temporal branch of the facial nerve-eyelid ptosis
Zygomatic and buccal branches-weakness and tingling over zygoma and weakness in mastification
of the facial nerve
Mandibular or marginal branch-weakness and tingling of muscles of lower lip/ unable to depress lower lip
Maxillay nerve neuropraxia
Infra-orbital nerve: weakness and tingling of lower eyelid
Mental nerve: weakness and tingling over chin/lower lip
Opthalmic nerve neuropraxia during glabellar filler:
Supraorbital and supratrochlear nerve-tingling anterior to vertex of scalp and forehead
Clinical correlation
A 42 year old male comes to clinic 2 days post treatment with inability to close his R eye and inability to raise forehead.
What is facial nerve palsy? What are the upper and lower motor neuron causes?
What are the clinical features?
How do you investigate and manage this?
Facial nerve palsy
-can be unilateral or bilateral damage to VII cranial nerve
-likely unilateral in aesthetic treatments
Upper motor neuron causes (bilateral cortical sparing-forehead):
-stroke
-SOL
-cerebellar pontine angle tumour
Lower motor neuron causes (does not spare forehead)
-bell’s palsy (most common)
-ramsay hunt syndrome
-trauma from injection
-diseases of middle/inner ear
Clinical features
important to distinguish whether it is forehead sparing and rule out stroke
-inability to close ipsilateral eye
-dry eyes
-hypersensitivity to sounds
-drooping face and loss of nasolabial folds
-altered taste
Investigations
-neurological assessment
Management
If stroke is suspected-> call 999 and arrange ambulance to A+E
If bell’s palsy is suspected-> refer to GP
corticosteroids like prednisolone
eye care-taping eye and lubricating eye drops
Arterial supply to the face
Describe the 4 main arteries that supply the face.
Describe the route of the facial artery and the branches.
In which plane are the arteries in?
How can you palpate for the facial artery on a person?
What does the facial artery terminate as?
Describe route of transverse facial artery and where does it arise from?
Arterial supply to the face
Branches mainly come from the external carotid artery apart from branches of the opthalmic artery that are from internal carotid artery
-facial artery
-transverse facial artery from superficial temporal artery
-branches of maxillary artery
-branches of opthalmic artery from ICA
Facial artery
Comes from the ECA, passes up the structures of the neck deep to platysma, emerges at the inferior border of mandible, anterior to masseter muscle where pulse can be felt
It gives off branches to the lips at the level of risorius muscle at the corner of the mouth:
-superior labial arteries that supply your upper lip
-inferior labial arteries that supply your lower lip
Labial arteries lie in layer 4 beneath the orbicularis oris muscle
It then gives off branches to nose:
-lateral nasal artery that supply the dorsum of the nose and lateral surface
Terminates as angular artery which traverses up the sides of nose, on top of muscle levator labii superioris alaeque nasii (layer 2), towards the medial canthus of the eye.
Angular artery anastamoses with branches of the opthalmic artery and infraorbital artery
Transverse facial artery is from superficial temporal artery and runs between the zygoma and parotid duct
Arterial supply to the face
Describe the branches of the maxillary artery that supply the face. Which plane are they in?
Arterial supply to the face
Branches of the maxillary artery from ECA:
-infraorbital artery that emerges from infraorbital foramen with nerve. In plane 4. This supplies the lower eyelid and upper lip.
-buccal artery that emerges on top of the buccinator muscle in layer 2.
-mental artery that emerges from mental foramen. This supplies the muscles in the chin
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Filler in nasolabial fold
Why is this dangerous? In what plane should you inject filler into?
Facial artery here runs superficial hence you need to inject deep to the piriform fossa
Arterial supply to the face
Describe the branches of the opthalmic artery that supply the face.
Opthalmic artery arises from the internal carotid artery. It gives off a few branches:
-supratrochlear and supraorbital artery
-zygomatofacial and zygomatotemporal artery that emerge from foramina and supply the area of the face over the zygomatic bone
-dorsal nasal artery that lies on the top of the nose bridge. This anastamoses with the angular artery
Why is glabellar filler dangerous? What are potential complications?
Describe the route of the supratrochlear and supraorbital artery? What plane are they in (to avoid injecting in area)? How many mm away from midline
Glabellar filler is dangerous due to risk of retrograde embolus in opthalmic artery-> travelling to central retinal artery. Blood supply is made of branches from opthalmic artery
Other serious complications include skin necrosis
Supratrochlear artery arise from superomedial aspect of supraorbital rim, 15-20mm away from midline. It is found in level 2- subcutaneous fat
Supraorbital artery arises from supraorbital notch (1/3 of eyebrow). It is also found in level 2
