Head and neck Flashcards
what bones me up the Calvarium?
Frontal,occipital and two parietal bones
What bones make up the Cranial base?
The frontal,occipital,sphenoid, ethmoid, parietal and temporal bones
What bones form the bones of the face? (14)
Zygomatic(2), maxilla(2), nasal(2), lacrimal(2) and mandible, vomer, inferior nasal conchae(2) and palatine(2) bones.
what type of joint are skull sutures?
fibrous- Synarthroses.
what three main sutures form the ‘H’ on the neurocranium?
Coronal, sagittal and lamboid sutures.
What are the two main fontanelles, and where are they located?
Frontal (the junction of the coronal and sagittal sutures) and occipital (the junction of the sagittal and lambed sutures)
What are the four main points of weakness in the skull?
the pterion, anterior cranial fossa, middle cranial fossa and posterior cranial fossa.
If a person receives a blow to the pterion, what may be damaged?
the underlying middle meningeal artery, which can lead to an extradural haematoma.
What are the four main types of skull fractures and their causes?
- Linear-most common, full thickness fracture with radiating, satellite fractures away from the site of impact.
- Depressed- fracture with depression inwards, they result due to a direct blow.
- basal skull-affects the base of the skull. They present with bruising behind the ears (mastoid ecchymosis) or the eyes (racoon eye’s)
- Diastatic- a fracture along a suture line, they are more common in children.
What are the four parts of the temporal bone?
Squamous, pteromastoid, zygomatic, tympanic and styloid process.
What structures form the external nasal skeleton?
Nasal bone, maxilla, septal cartilages, lateral cartilages, major alar cartilages,minor alar cartilages and fibro-fatty tissue.
What structures form the internal nasal skeleton?
Paired bones- nasal, maxillary and palatine bones
Unpaired bones- Ethmoid and vomer bones.
What are the three bony articulations of the TMJ?
The mandibular fossa, articular tubercle and mandibular head.
What are the three ligaments in the TMJ and what do they do?
- Lateral ligament- prevents posterior dislocation.
- Sphenomandibular ligament
- Stylomandibular ligament- supports the weight of the jaw with the facial muscles.
What muscles cause protrusion and retraction of the jaw?
Protrusion- lateral pterygoid muscle.
Retraction-geinohyoid and digastric muscles
What muscles are responsible for elevation and depression of the jaw?
Depression- mainly caused by gravity, but against resistance, the digastric, geniohyoid and mylohyoid muscles assist.
Elevation- temporalis, masseter, and medial pterygoid muscles.
Describe briefly what occurs in a dislocation of the TMJ?
Usually occurs via a blow to the side of the face, yawning or taking a large bite. The head of the mandible slips out of the mandibular fossa and is pulled anteriorly. The facial and auriculotemporal nerves run close to the joint and can be damaged. Posterior dislocations are rare.
There are many foramina in the cribriform plate, what are the three main ones and what do they transmit?
- Olfactory nerve fibres (CNI) intot he nasal cavity.
- Anterior ethmoidal foramen- anterior ethmoidal artery, nerve and vein.
- Posterior ethmoidal foramen- posterior ethmoidal artery, nerve and vein.
Why does the cribriform plate fracture easily and what are the two main symptoms of such a fracture?
it’s the thinnest part of the anterior cranial fossa.
Anosmia- the olfactory nerve fibres can be sheared, resulting in a loss of smell.
CSF rhinorrhoea- fragments of bone can tear the meningeal coverings causing leakage of CSF into the nasal cavity.
What is the Chiasmatic sulcus?
A groove running between the right and left optic canals
where in the sphenoid does the pituitary gland sit?
in the middle of the Sella trucica is a depression called the hypophyseal fossa.
What do the optic canals transmit and where are they located?
Transmit the optic nerves (CNII) and ophthalmic arteries into he orbital cavities. They are situated anteriorly in the middle cranial fossa.
what are the four foramina which lie laterally to the central part of the middle cranial fossa?
(6-1-2-3)
- Superior orbital fissure- opens anteriorly into he orbit. oculor motor nerve, trochlear nerve, ophthalmic branch of the trigeminal nerve, abducens nerve, ophthalmic veins and sympathetic fibres.
- Foramen rotundum- opens into he pterygopalatine fossa. maxillary branch of the trigeminal nerve.
- the foramen oval- opens into he infra temporal fossa. mandibular branch of the trigeminal nerve and accessory meningeal arteries.
- The foramen spinosum- opens into the infra temporal fossa. middle meningeal artery, middle meningeal vein and a meningeal branch of the trigeminal nerve.
What are the three major foramina in the temporal bone?
- Hiatus of the greater petrosal nerve- greater petrosal nerve (branch of the facial nerve), and the petrosal branch of the middle meningeal artery.
- hiatus of the lesser petrosal nerve-transmits the lesser petrosal nerve (a branch of the glossopharyngeal nerve).
- Carotid canal- transversed by the internal carotid artery and deep petrosal nerve.
What is the internal acoustic meatus?
oval opening in the posterior aspect of the petrous part of the temporal bone. It transmits the facial nerve, vestibulocochlear nerve and labyrinthine artery.
What’s transmitted through the foramen magnum? (7)
the medulla of the brain,meninges, vertebral arteries, spinal accessory nerve (ascending), dural veins, anterior and posterior spinal arteries.
What passes through the jugular foramina? (7)
Each transmits the glossopharyngeal nerve, vagus nerves, spinal accessory nerve (descending), internal jugular vein, inferior petrosal sinus, sigmoid sinus and meningial branches of the ascending pharyngeal and occipital arteries.
What is cerebral herniation?
The downward displacement of the cerebellar tonsils through the foramen magnum.
It’s produced by raised inter cranial pressure.
It results in the compression the pons and medulla, which contain the cardiac and respiratory centres and ultimately results in death from cardiorespiratory arrest.
When is the eustachian tube open?
On swallowing
Which layer can the muscles of facial expression be found?
Subcutaneous tissue
What’s special about the insertion of the facial muscles?
They are the only muscles that insert into skin.
What’s the embryonic origin of the facial muscles?
2nd pharangeal arch
What are the two muscles in the orbital group of the muscles of facial expressions and their actions?
- Orbicularis Oculi- palpebral part= gentle closure of the eyes, orbital portion= forceful closure.
- Corrugator Supercilii- draws the eyebrows together.
What happens in an orbital muscle paralysis to the eye?
The lower eyelid droops (ectropion), and the lacrimal fluid can’t be spread over the surface of the eye. This can result in a failure to remove debris, and ulceration of the corneal surface. Exposure keratitis too.
What are the three nasal muscles of facial expression, and their actions?
- Nasalis- transvers= compresses the nares, Alar= opens the nares.
- Procerus- pulls the eyebrows downward to produce transverse wrinkles over the nose.
- Depressor Septi Nasi- Pulls the nose inferiorly, opening the nares.
What are the two main oral muscles and their actions?
- Orbicularis oris- purses the lips
- Buccinator- pulls the cheeks inwards against the teeth, preventing accumulation of food in that area.
What are the two groups of minor oral muscles?
- Lower group- depressor angel kris, depressor labii inferiors and the mentalis.
- Upper group- risers, zygomaticus major, zygomaticus minor, elevator labii superioris, levator superiors ileac nasa and elevator anguli oris.
What are the main symptoms of paralysis of the oral muscles?
- Difficulty eating
- Tissue around the mouth and cheeks sag.
- Skin is drawn to the opposite side when smiling
Where do the muscles of mastication originate from (embryologically)?
1st pharyngeal arch
what are the muscles of mastication innervated by?
Branch of the Trigeminal nerve
What are the three (4) muscles of mastication and their actions?
- Masseter- elevates the mandible, closing the mouth.
- Temporalis-elevates and retracts the mandible
- Medial Pterygoid- elevates the mouth
- Lateral Pterygoid- acting bilaterally, they protract the mandible, pushing the jaw forward. Unilateral action produces the ‘side to side’ movement of the jaw.
What are the four muscles of the tongue?
Geniohyoidus, Genioglossus, hyloglossus and styloglossus.
What is the anterior 2/3 of the tongue innervated by?
- touch- A branch of the trigeminal nerve, the anterior lingual nerve.
- taste- A branch of the facial nerve, the chorda tympani.
What is the posterior 1/3 of the tongue innervated by?
both touch and taste are supplied by the glossopharyngeal nerve
What nerve supplies the motor control of the tongue?
The hypoglossal nerve except the palatoglossus, which is supplied by the vagus nerve.
What is the blood supply to the tongue?
the lingual artery, and a branch from the facial artery- the tonsillar artery.
Through what vein is the tongue drained via?
The lingual vein.
At what levels do the brachiocephalic trunk and common carotid split?
- Brachiocephalic trunk- right strenoclavicular joint
- common carotid- thyroid cartilage (C4) in the carotid triangle.
Where does the external carotid artery end and what are it’s terminal branches
Parotid gland
-superficial temporal and maxillary artery
Before terminating, what are the six branches the external carotid gives off?
- Superior thyroid artery
- Lingual artery
- Facial artery
- Ascending pharyngeal artery
- Occipital artery
- Posterior auricular artery
What are the arteries that supply the scalp and what are they branches of?
- Posterior auricular, occipital and superficial temopral arterier- all branches of the external carotid.
- Supra-orbital and supratrochlear arteries- all branches of the internal carotid artery.
What features of the scalp make a laceration bleed excessively?
- The walls of the arteries are tightly bound to the underlying connective tissue, preventing them from constricting to limit blood loss.
- there are numerous anastomoses
- deep lacerations involve the epicranial aponeurosis, which is worsened by the opposing pulls of the occipital and frontal muscles.
Why does the bony cranium not undergo a vascular necrosis?
it receives it’s blood supply from the middle meningeal artery, which scalp lacerations don’t interfere with.
What structures does the middle meningeal artery supply and what happens if it’s lacerated?
- supplies the skull and the dura mater.
- in an injury to the pterion can lacerate the MMA, causing blood to accumulate between the dura mater and the skull- an extradural haematoma.
- treated by diuretics in minor cases and drilling burr holes in extreme heamorrhages.
Through what structure does the internal carotid enter the cranial cavity?
The carotid canal in the petrous part of the temporal bone.
What structures does the internal carotid artery supply?
- The brain
- The eyes
- The forehead
Where do the vertebral arteries arise from?
Subclavian arteries, medial to the anterior scalene muscles.
What structures in the cervical vertebrae do the vertebral arteries pass up through?
Foramen transversarium
Through what structures do the vertebral arteries enter the cranial cavity?
foramen magnum
What do the vertebral arteries become and what do they supply?
Basilar arteries which supply the brain.
From which artery do the thyrocervical trunk originate?
The right and left subclavian arteries
What are the branches of the thyrocervical trunk and what do they supply?
- inferior thyroid, thyroid gland–> ascending cervical, the posterior prevertebral muscles.
- transverse cervical artery, crosses the base of the carotid triangle, and supplies the trapezius and rhomboid muscles.
- suprascapular- posterior shoulder area.
How can the venous drainage of the head be split and what are the main vessels that do this?
- Brain and meninges- dural venous sinuses
- Scalp and face- internal and external jugular veins
- Neck- anterior jugular veins
The union of what two veins form the external jugular veins?
- Posterior auricular vein- superior scalp and posterior to the outer ear.
- retromandibular vein- formed by the maxillary and superficial temporal veins which drain the face.
Where do the posterior auricular and retromandibular veins combine?
immediately posterior to the angle of the mandible, and inferior to the outer ear.
Describe the anatomical relationship of the external jugular veins to the sternocleidomastoid.
It runs anteriorly to the SCM, crossing it in oblique, posterior and inferior direction.
Does the external jugular vein pass superior or inferiorly to the clavicle?
Inferiorly.
As the external jugular vein passes down the neck, what tributary veins does it receive? (3)
- Posterior external jugular vein
- transverse cervical
- suprascapular veins
What happens when the external jugular vein is severed?
the lumen is held open due to the thick layer of investing fascia. Air is drawn in, producing cyanosis and can eventually stop the blood flow to the right atrium. Pressure can be applied, stopping the bleeding and the entry of air.
What area does the anterior jugular vein drain?
The anterior aspect of the neck.
What’s the communication between the anterior jugular veins called?
The jugular venous arch.
Where does the internal jugular vein originate?
In the cranial cavity, as a continuation of the sigmoid sinus. It starts as a dilation, called the superior bulb.
Through what structure does the internal jugular vein exit the skull via?
the jugular foramen
Describe the anatomical relationship of the internal jugular vein to the carotid sheath, the SCM and common carotid arteries.
- within the carotid sheath
- deep to the SCM
- lateral to the common carotid artery
Where does the IJV combine with the subclavian vein?
posterior to the sternal end of the clavicle.
Where is the inferior bulb of the IJV and why is it important?
Immediately before it’s termination, it has a valve to stop back flow of blood.
During it’s descent, what veins join onto the IJV? (5)
- Fascial
- lingual
- occipital
- superior thyroid
- middle thyroid
What general structures drain into the IJV? (6)
- anterior face
- trachea
- thyroid
- oesophagus
- larynx
- muscles of the neck
What are dural venous sinuses and their role?
Spaces between the periosteal and meningeal layers of the dura mater which are lined by endothelial cells. They collect venous blood from the veins that drain the brain and bony skull, and drain into the IJV.
where are the cavernous sinuses located?
the lateral aspect of the body of the sphenoid bone.
from what structures do the cavernous sinus receive blood from? (3)
- Superior and inferior ophthalmic veins
- middle superficial cerebral veins
- the sphenoparietal sinus
What vessels pass throught the cavernous sinus? (2)
- Internal carotid artery (cools blood before it supplies the brain)
- Abducens nerve
Which nerves are located in the wall of each sinus, and why is this of clinical importance?
- Oculomotor
-Trochlear
-Ophthalmic (V1)
-Maxillary (V2)
they are at risk if the sinus becomes infected.
How is the facial vein connected to the cavernous sinus and why is this of clinical importance?
Via the superior ophthalmic vein, the vein is valveless so blood can reverse its direction and flow from the facial vein to the cavernous sinus. This provides a pathway from which a facial infection can spread to the venous sinuses.
How many cervical vertebrae are there?
7
What are the three characteristic features of cervical vertebrae?
- Triangular vertebral foramen
- Transverse foramen (transmit the vertebral artery, vein and sympathetic nerves)
- Bifid spinous process
How does the C1 Atlas differ from the other cervical vertebrae? (4)
- no vertebral body/ spinous process
- articular facet anteriorly which articulates with the dens of the axis.
- lateral masses on either side of the vertebral arch, which provide an attachment for the transverse ligament of the atlas.
- posterior arch has a groove for the vertebral artery and C1 spinal nerve.
What feature makes the C2 Axis easily identifiable?
Its dens (odontoid process), which articulates with the articular facet of the atlas, creating the medial atlanto-axial joint, which allows for rotation of the head (no).
What are the two types of joint unique to the cervical spine?
- Lateral atlanto-axial joints- articulation between the inferior facets of the lateral masses of C1 and the superior facets of C2. Plane type synovial joints.
- Medial atlanto-axial joint- articulation of the dens of the C2 with the articular facet of c1. Pivot type synovial joint.
What is the joint between the spine and cranium?
atlanto-occipital joints. between the superior facets of the lateral masses of the atlas and the occipital condyles at the base of the cranium. Condyloid type synovial joints, allow flexion at the head (yes).
What are the two joints that are present throughout the whole vertebral column?
- vertebral bodies, a symphyses joint joints by the intervertebral disks.
- vertebral arches, formed by the superior and inferior articular processes of adjacent vertebrae, a plane type synovial joint.
What’s significant about the relationship between the vertebral artery and C7?
it runs around the vertebra, instead of passing through the transverse foramen. The vertebral vein and sympathetic plexus still run in the foramen.
What’s significant about the vertebral artery and the Atlas?
it runs along the groove for the vertebral artery instead of the transverse foramen.
The 7 cervical vertebrae have 8 sets of paired nerves, how does this happen?
The C7 vertebrae has a set of nerves extending from above (C7) and below (C8).
What are the four common types of cervical injury?
- Jeffersons fracture of the atlas
- Hyperextension injury
- Hangman’s fracturs
- Dens Fracture
Describe a Jefferson fracture of the atlas.
- Vertecal fall onto extended neck (diving into a shallow pool)
- compression of the lateral masses of the atlas between the occipital condyles and the axis. Driving them apart, and potentially fracturing the anterior/posterior arches (polo).
- The transverse ligament of the atlas may also be ruptured.
- unlikely there will be any damage to the C1 level as the foramen is large.
Describe a hyperextension injury.
- rear end traffic collision
- anterior longitudinal ligament of the spine is damaged.
- in more severe cases, fractures can occur to any of the cervical vertebrae as they are suddenly compressed.
- the vertebral foramen is large so spinal chord damage is common.
- The worst case scenario- dislocation/subluxation at the C2. C2 moves anteriorly to C3. This can lead to quadriplegia and death.
- More commonly , subluxation occurs at the C6/C7 in 50% of cases.
Describe a hangmans fracture.
Fracture of the pars interarticularis, which is the bony column between the superior and inferior articular facets of the axis.
-likely to be lethal as the fracture fragments or force are likely to rupture the spinal chord.
Describe a Dens fracture.
- 40% of the fractures of the axis
- commonly caused by traffic collisions and falls
- unstable
- high risk of a vascular necrosis and take a long time to heal
Name the four suprahyoid muscles
- stylohyoid
- digastric
- mylohyoid
- geniohyoid
what is the action and innervation of the stylohyoid?
- Initiates a swallowing action by pulling the hyoid bone in a posterior and superior direction.
- Facial nerve (VII)
what is the action and innervation of the digastric?
- It has two muscular bellies, connected by a tendon.
- depresses the mandible and elevates the hyoid
- the anterior belly is innervated by the trigeminal nerve
- the posterior belly is innervated by the facial nerve.
what is the action and innervation of the mylohyoid?
- firms the floor of the oral cavity
- elevates the floor of the mouth and the hyoid bone.
- trigeminal nerve.
what is the action and innervation of the geniohyoid?
- deep to the myohyoid
- depresses the mandible and elevates the hyoid bone
- C1 roots that run within the hypoglossal nerve.
What are the four infrahyoid muscles and what two divisions can they be split into?
- superficial plane- sternohyoid, omohyoid
- deep plane- sternothyroid, thyrohyoid
what is the action and innervation of the sternohyoid?
- depresses the hyoid bone
- anterior rami of C1-3, carried by a branch of the ansa cervicalis.
what is the action and innervation of the omohyoid?
- split into two bellies connected by a muscular tendon.
- depresses the hyoid bone
- anterior rami of C1-3, carried by a branch of the nasa cervicalis.
what is the action and innervation of the sternothyroid?
- depresses the thyroid cartilage
- anterior rami of C1-3, carried by a branch of the nasa cervicalis.
what is the action and innervation of the thyrohyoid?
- continuation of the sternothyroid muscle.
- depresses the hyoid, and raises the larynx if the hyoid is fixed.
- anterior rami of C1, carried within the hypoglossal nerve.
What are the boundaries of the anterior triangle?
- Superior- inferior border of the mandible
- laterally- medial border of the SCM.
- medially- imaginary sagittal line down the midline of the body.
What structures are found in the anterior triangle? (9)
- suprahyoid muscles (4)
- infrahyoid muscles (4)
- carotid artery which bifurcates within it
- IJV
- facial nerve
- glossopharyngeal nerve
- vegas nerve
- accessory nerve
- hypoglossal nerve
What divisions can the anterior triangle be split into?
- carotid triangle
- submental triangle
- submandibular triangle
- muscular triangle
What are the borders of the carotid triangle?
- superior- posterior belly of the digastric muscle
- lateral- medial border of the SCM
- inferior- superior body of the omohyoid
What can be located in the carotid triangle?
- Common carotid artery, which bifurcates in this space
- IJV
- Hypoglossal and vegas nerves
What are the border of the submental triangle?
- inferior- hyoid bone
- medially- imaginary sagittal midline of the neck
- laterally- anterior belly of the digastric bone
- base- myohyoid muscle
What are the borders of the submandibular triangle?
- superiorly- body of the mandible
- anteriorly- anterior body of the digastric
- posteriorly- posterior belly of the digastric muscle.
What can be found in the submandibular triangle?
- submandibular gland
- lymphnodes
what are the boundaries of the muscular triangle?
p.s. it’s all a lie, its not even a triangle !
- superiorly- the hyoid bone
- medially- midline of the neck
- superio-laterally- superior body of the omohyoid muscle
- inferior-laterally- inferior portion of the SCM
What structures lie within the muscular triangle?
- infrahyoid muscles
- pharynx
- thyroid gland
- parathyroid glands
What are the borders of the Posterior triangle?
Anterior: posterior border of the SCM Posterior: anterior border of the trapezius inferior: middle 1/3 of the clavicle roof: investing layer of fascia floor: pre-vertebral fascia
what muscles are contained in the posterior triangle?
- the omohyoid (inferior belly) splits the triangle in half
- splenius captitis
- levator scapulae
- anterior, middle and posterior scalene
what key blood vessels are contained in the posterior triangle?
- external jugular vein
- transverse cervical artery
- subclavian artery
- subclavian vein
- suprascapular artery
- transverse cervical artery
What happens when the external jugular vein is ligated?
It’s lumen is maintained by the investing fascia, so air is drawn into the vein. This causes the right atrium to fill with froth, producing central cyanosis.
How can a severed external jugular vein be stopped from drawing air into the right atrium?
firm pressure must be applied to stop bleeding and entry of air.
which nerves can be found in the posterior triangle?
- accessory nerve
- cervical plexus–> phrenic nerve
- cutaneous innervation to neck and scalp
- trunks of the brachial plexus cross it
where is a cervical plexus nerve block performed? and what is the relevant muscle?
Anaesthetic is injected along the posterior border of the SCM, concentrating on the junction of its superior and middle thirds.
Why, in a cervical plexus nerve block, do you concentrate on the junction of the superior and middle 1/3s of the SCM?
It’s where the cutaneous branches of the cervical plexus emerge, it’s known as the nerve point of the neck.
When would you not carry out a cervical nerve plexus block? and why?
On patients with respiratory or cardiac problems as it can damage the phrenic nerve.
What are the two divisions of the posterior triangle? and what divides them?
the inferior belly of the omohyoid splits it into the occipital triangle and the subclavian triangle.
What is fascia?
A layer of fibrous tissue that surrounds muscles, vessels and nerves.
What is contained within the superficial facia of the neck?
- neurovascular supply to the skin
- superficial veins e.g. external jugular vein
- superficial lymph nodes
- fat
- platysmus muscle
how many heads does the platysmus muscle have
2
what nerve provides the motor innervation to the platysmus muscle?
cervical branch of the facial nerve
where does the deep cervical fascia lie?
underneath the superficial fascia
how many layers of deep fascia are there, and what are they called?
4
- investing layer
- pretracheal layer
- prevertebral layer
- carotid sheaths
what is the most superficial of the deep cervical fascia?
the investing layer
what muscles can be found within the investing layer?
-SCM and trapezius
between which structures does the pretracheal fascia run?
the hyoid bone and thorax, where it fuses with the pericardium
what structures are enclosed within the pretracheal fascia?
trachea, oesophagus, thyroid gland and infrahyoid muscles
what can the pre tracheal fascia be divided into and what is contained in each division?
- visceral- thyroid gland, trachea and oesophagus
- muscular- infrahyoid muscles
what structures does the prevertebral fascia enclose?
vertebral column, scalene, and deep muscles of the back
what are the contents of the carotid sheath(s)?
- common carotid artery (bifurcates within the sheath)
- internal jugular vein
- vagus nerve
- cervical lymph nodes
infection can spread downward in the retropharyngeal space to what structure?
the diaphragm and mediastinum
which fascia surrounds the brachial plexus and subclavian artery, forming the axillary sheath?
prevertebral layer
which cranial nerves are associated with the four nuclei ?
- occulomotor
- facial
- glossopharangeal
- vagus
what are the four parasympathetic ganglia located in the head?
- ciliary
- otic
- pterygopalatine
- submandibular
where is the ciliary ganglion located?
in the bony orbit, anteriorly to the superior orbital fissure, between the lateral rectus muscle and the optic nerve.
which nerve fibres pass through the ciliary ganglion without synapsing, and what do they innervate??
- sympathetic nerves from the internal carotid plexus- innervate the dilator papillae
- sensory fibres from the nasociliary nerve (a division of the trigeminal nerve)- innervate the cornea, ciliary body and iris
what structures do the post-ganglionic fibres from the ciliary body innervate?
- sphincter papillae-contracts the pupil
- ciliary muscle-accommodates for near vision
which is the largest of the parasympathetic ganglia?
pterygopalatine
where is the ptegyropalatine ganglia located?
ptegyropalatine fossa- a space inferior to the base of the skull, and posteriorly to the maxilla.
what are the target organs of the post synaptic fibres from the ptegyropalatine ganglia?
- secretory motor innervation to the lacrimal gland
- mucous glands of the posterior nasal cavity.
- nasopharynx
- palate
what nucleus provides the pre-ganglionic fibres to the ptegyropalatine ganglia?
superior salivatory nucleus (fascial nerve)
describe the path of the ptegyropalatine nerve before it reaches the ganglia.
the fibres travel within the greater petrosal nerve and the nerve the pterygoid canal to reach the ganglion.
describe the path of the ptegyropalatine nerve after it leaves the ganglia.
the parasympathetic fibres leave the ganglion by hitch-hiking on branches of the maxillary nerve
which nerve fibres pass through the ptegyropalatine ganglion without synapsing?
- sympsthetic fibres from the internal carotid plexus
- sensory fibres from the maxillary nerve
describe the path of the ptegyropalatine nerve before it reaches the ganglia.
the fibres travel within the greater petrosal nerve and the nerve the pterygoid canal to reach the ganglion.
describe the path of the ptegyropalatine nerve fibres after they leave the ganglia.
the parasympathetic fibres leave the ganglion by hitch-hiking on branches of the maxillary nerve
what are the target organs of the submandibular ganglion nerve fires?
-secretory motor innervation to the submandibular and sublingual salivary glands.
describe the path of the submandibular ganglia fibres before they leave the ganglia.
the fibres are carried within a branch of the facial nerve, the chorda tympani. The nerve hitch-hikes along the inguinal branch of the mandibular nerve to reach the ganglion
what are the target organs of the submandibular ganglion nerve fires?
-secretory motor innervation to the submandibular and sublingual salivary glands.
where is the otic ganglion located?
-inferiorly to the foramen oval, within the infra temporal fossa. Medial to the mandibular branch of the trigeminal nerve.
describe the path of the otic ganglion nerve fibres before they enter the ganglia.
the parasympathetic nerve fibres travel within a branch of the glossopharyngeal nerve, the lesser petrosal nerve, to reach to otic ganglion.
describe the path of the otic ganglion nerve fibres after they leave the ganglia.
the parasympathetic fibres hitch-hike along the auriculotemporal nerve (from the mandibular nerve) to provide secretory motor innervation to the parotid gland.
what are the target organs of the otic ganglion nerve fires?
innervation to the parotid gland
which nerves pass through the otic ganglion but don’t synapse?
- sympathetic fibres from the superior cervical chain
- they travel with the middle meningeal artery to the parotid gland
which nerves pass through the otic ganglion but don’t synapse?
- sympathetic fibres from the superior cervical chain
- they travel with the middle meningeal artery to the parotid gland
what is Adie’s pupil and what are some potential causes of it?
- damage to the ciliary ganglion causes a loss of innervation to the sphincter papillae, leading to a permanently dilated pupil.
- it’s thought to result from inflammation caused by a viral or bacterial infection.
what is Adie’s pupil and what are some potential causes of it?
- damage to the ciliary ganglion causes a loss of innervation to the sphincter papillae, leading to a permanently dilated pupil.
- it’s thought to result from inflammation caused by a viral or bacterial infection.
where is the superior cervical ganglion located?
posteriorly to the carotid artery, and anterior to the C1-C4 vertebrae.
where is the middle cervical ganglion located?
- it is absent in some individuals
- it’s located anteriorly to the inferior thyroid artery and the C6 vertebra.
what postganglionic nerve fibres originate from the superior cervical ganglion?
- internal carotid nerve
- external carotid nerve
- nerve to pharyngeal plexus
- superior cardiac branch
- nerves to cranial nerves II,III,IV,VI and IX
- grey rami communicantes- anterior rami of C1-C4
what postganglionic nerve fibres originate from the middle cervical ganglion?
- grey rami communicantes- sympathetic fibres to the anterior rami of C5 and C6
- thyroid branches
- middle cardiac branch
where is the inferior cervical ganglion located?
anteriorly tot he C7 vertebra, occasionally fused with the first thoracic vertebrae, forming the cervicothoracic ganglion.
what postganglionic nerve fibres originate from the inferior cervical ganglion?
- grey rami communicantes- sympathetic fibres to the anterior rami of C7, C8 and T1
- branches to the subclavian and vertebral arteries
- inferior cardiac nerve
what are the three characteristic symptoms of Horner’s syndrome?
- partial ptosis- due to paralysis of the superior tarsal muscle
- miosis- paralysis of dilator papillae
- anhydrosis- due to a loss of innervation of the facial sweat glands
list some causes of Horner’s syndrome.
- spinal chord lesions
- traumatic injury
- pancoast tumor (tutor of the apex of the lung)
what are the cranial nerves from 1-12? and the mnemonic that’s good to use
Oh Oh Oh To Touch And Feel A Girls Vagina, So Hot. CN I – Olfactory CN II – Optic CN III – Oculomotor CN IV – Trochlear CN V (1,2,3) – Trigeminal CN VI – Abducens CN VII – Facial CN VIII –Auditory (Vestibulocochlear) CN IX – Glossopharyngeal CN X – Vagus CN XI – Accessory CN XII – Hypoglossal
Which never provide sensory, motor or both fibres? and the handy mnemonic?
Some Say Marry Money But My Brother Says Big Boobs Matter More. CN I – Olfactory-sensory CN II – Optic- sensory CN III – Oculomotor- motor CN IV – Trochlear- motor CN V (1,2,3) – Trigeminal- both CN VI – Abducens- motor CN VII – Facial- both CN VIII –Auditory (Vestibulocochlear)- sensory CN IX – Glossopharyngeal -both CN X – Vagus- both CN XI – Accessory- motor CN XII – Hypoglossal- motor
which is the shortest cranial nerve?
olfactory
what does the olfactory nerve do?
-transmits the special sensory information for the sense of smell
which two nerves do not join the brain stem?
optic and olfactory
is the olfactory nerve myelinated or unmyelinated?
unmyelinated
what are the two processes that make up the olfactory nerve?
- peripheral olfactory processes (receptors) in the olfactory mucosa
- central processes that return the information tot he brain
what type of epithelia makes up the olfactory mucosa?
pseudo stratified columnar epithelia
what four specialist cells can be found in olfactory mucosa?
- basal cells- form the new stem cells for olfactory cells to develop from
- sustentacular cells- tall cells for structural support
- olfactory receptor cells- bipolar neurones
- bowmans glands- secrete mucus
what four specialist cells can be found in olfactory mucosa?
- basal cells- form the new stem cells for olfactory cells to develop from
- sustentacular cells- tall cells for structural support
- olfactory receptor cells- bipolar neurones
- bowmans glands- secrete mucus
describe the anatomical path of the olfactory nerve from the mucosa to the olfactory tract.
-the axon penetratesthrought he basement membrane
-joins other non-myelinated processes to form the film olfactory.
-enters the cranial cavity through the cribriform plate
-the fibres enter the olfactory bulb, in the olfactory groove within the anterior cranial fossa.
the nerves then pass posteriorly into the olfactory tract
what is the olfactory bulb and what happens to the nerves there?
- ovioid structure containing mitral cells.
- the olfactory nerve fibres synapse with the mitral cells, forming synaptic glomeruli
where is the olfactory tract?
it runs inferiorly to the frontal lobe
what does the olfactory tract divide into?
- lateral stria carries the axons to the olfactory area of the cerebral cortex
- medial stria carries the axons across the medial plane of the anterior commissar where they meet the olfactory bulb of the opposite side.
what are some causes of temporary anosmia?
infection or local disorders of the nose
what are some permanent causes of anosmia?
head injury, or tutors in the olfactory groove
how would you test the olfactory nerve?
- ask the patient if they have experienced andy change in food taste or smell.
- examining it involves testing each nostril in turn by asking them to identify certain smells e.g. peppermint and coffee
what embryological tissue does the olfactory nerve develop from?
otic placode, a thickening of the ectoderm
what embryological tissue does the optic nerve develop from?
optic vessel- and out pocketing of the forebrain
what tissue surrounds the optic nerve and why is this different to most nerves?
- cranial meninges
- not epi-, peri- and endoneurium like most other nerves
through what hole in the skull does the optic nerve enter and which bone is this in?
optic canal
sphenoid bone
why is the optical nerves close relationship to the pituitary gland clinically important ?
it runs along the surface of the middle cranial fossa in close proximity tot he pituitary gland, so can become compressed in the case of a pituitary tumor
what is the optic chiasm?
in the middle cranial fossa, where the optic nerves combine and switch fibres
what is the optic chiasm?
in the middle cranial fossa, where the optic nerves combine and switch fibres
how would you test the optic nerve?
acuity- senellen chart or magazine if not availible
Visual fields- wiggle finger test- REMEMBER to cover your eye
fundoscopy- learn exactly how in phase II
pupillary response- light reflex, look for constriction in both pupils when shone in one eye
pupillary response- accommodation- focus on finger while being moved to their nose
what structures does the Oculomotor nerve supply motor innervation to?
most of the extra ocular muscles
what structures does the Oculomotor nerve supply parasympathetic innervation to?
sphincter pupillae and the ciliary muscles of the eye
what structures does the Oculomotor nerve supply sympathetic innervation to?
none really, but sympathetic fibres run with the oculomotor nerve to innervate the superior tarsal muscle
where does the oculomotor nerve originate from?
anterior aspect of the midbrain
what are the vascular structures associated with the oculomotor nerve and where does this occur?
it exits the mid brain and then passes below the posterior cerebral artery, and above the superior cerebellar artery.
what fibres travel with the oculomotor nerve after they join it in the cavernous sinus?
sympathetic nerve fibres from the internal carotid plexus
what fibres travel with the oculomotor nerve after they join it in the cavernous sinus?
sympathetic nerve fibres from the internal carotid plexus
through what does the oculomotor nerve enter the cranial cavity?
superior orbital fissure
where does the oculomotor nerve split in two?
after it exits through the superior orbital fissure
what does the superior branch of the oculomotor nerve innervate?
- superior rectus and levator palpabrae superioris
- the sympathetic fibres run with it to supply the superior tarsal muscle
what does the inferior branch of the oculomotor nerve innervate?
- motor innervation to the inferior rectus, medial rectus and inferior oblique
- the parasympathetic fibres innervate the sphincter papillae and ciliary muscle (via the ciliary ganglion)
what’s the action of superior rectus?
elevates the eyeball
what’s the action of elevator palpable superioris?
raises the upper eyelid
what’s the action of the superior tarsal muscle?
keeps the eyelid raised after elevator palpable superioris has raised it
what’s the action of inferior rectus?
depresses the eyeball
what’s the action of medial rectus?
adducts the eyeball
what’s the action of inferior oblique?
elevates, abducts and laterally rotates the eye
which two structures in the eye receive parasympathetic innervation?
- sphincter pupillae- constricts the pupil
- cilliary muscles- contracts, causes the lens to become more spherical and more adapted to short range.
what are the three main causes of an oculomotor nerve lesion?
- increases inter cranial pressure- compresses the nerve against the temporal bone
- aneurysm of the posterior cerebral artery
- cavernous sinus infection or trauma
what are the three clinical signs of an oculomotor nerve palsy?
- ptosis- due to paralysis of elevator palpable superioris
- eyeball in ‘down and out’ position- paralysis of the superior, inferior and medial rectus and the inferior oblique.
- dilated pupil- due to unopposed action of the dilator papillae muscle
which cranial nerve has the longest anatomical path?
Trochlear
which part of the brain does the trochlear nerve originate from?
the trochlear nucleus of the brain, and emerges from the posterior aspect of the midbrain.
briefly describe the anatomical course of the trochlear nerve
- runs anteriorly and inferiorly within the subarachnoid space
- pierces the dura mater adjacent to the posterior clinoid process of the sphenoid bone.
- moves along the lateral wall of the cavernous sinus
- enters the orbit of the eye through the superior orbital fissure.
which muscle does the trochlear nerve innervate?
superior oblique
what structure does superior oblique attach to?
trochlear
how would you examine the trochlear nerve?
- in conjunction with the oculomotor and abducens nerves by testing the movements of the eye
- a target is moved in an ‘H-shape’ and the patient asked to follow it
what are some causes of trochlear nerve palsy?
- congenital fourth nerve palsy
- diabetic neuropathy
- thrombophlebitis of the cavernous sinus
- raised intracranial pressure
- rare for only the trochlear nerve to be affected
How will a patient with 4th nerve palsy present? Why?
Diplopia when looking down and in, such as when reading or going down the stairs.
paralysis of superior oblique, so one eye can’t look down and in and diplopia results.
How will a patient with 4th nerve palsy present? Why?
Diplopia when looking down and in, such as when reading or going down the stairs.
paralysis of superior oblique, so one eye can’t look down and in and diplopia results.
which paralegal arch is the 5th cranial nerve associated with?
1st pharyngeal arch
what’s the sensory function of the trigeminal nerve?
- skin
- mucous membranes
- sinuses of the face
which branch of the trigeminal nerve has motor function?
Only the mandibular branch
what muscles are innervated by the trigeminal nerve?
- the muscles of mastication: medial pterygoid, lateral pterygoid, masseter and temporalis
- also supplies other 1st pharyngeal arch derivatives: anterior belly of digastric, tensor veli palatini and tensor tympani.
what do the parasympathetic fibres of the trigeminal nerve innervate?
- post-ganglionic neurones of parasympathetic ganglia travel with branches of the trigeminal nerve.
- NOT part of the cranial outflow of PNS supply
what do the parasympathetic fibres of the trigeminal nerve innervate?
- post-ganglionic neurones of parasympathetic ganglia travel with branches of the trigeminal nerve.
- NOT part of the cranial outflow of PNS supply
where does the trigeminal nerve originate from?
- three sensory nuclei (mesencephalic, principal sensory, spinal nuclei of trigeminal nerve)
- one motor nucleus (motor nucleus of the trigeminal nerve)
- extending from the midbrain to the medulla
at what level do the sensory nuclei merge to form a sensory root
the level of the pons
What does the motor nucleus go on to form?
a motor root.
what are the motor nucleus and motor root analogous to?
the dorsal and ventral roots of the spinal cord.
where does the sensory root expand into the trigeminal ganglion?
middle cranial fossa
what is a ganglion?
a collection of the nerve cell bodies outside the central nervous system
where is the trigeminal ganglion located?
located lateral to the cavernous sinus, in a depression of the temporal bone, known as the trigeminal cave.
where is the trigeminal ganglion located?
located lateral to the cavernous sinus, in a depression of the temporal bone, known as the trigeminal cave.
what are the three divisions of the trigeminal nerve?
- ophthalmic (V1)
- maxillary (V2)
- mandibular (V3)
describe the path of the motor root in relation to the sensory root in the trigeminal nerve
motor root passes inferiorly to the sensory root, along the floor of the trigeminal cave. Its fibres are only distributed to the mandibular division
through what structure does the ophthalmic nerve exit the skull?
the superior orbital fissure
through what structure does the maxillary nerve exit the skull?
the foramen rotundum
where does the ophthalmic nerve and maxillary nerve travel in relation to the cavernous sinus
lateral
through which structure does the mandibular nerve pass into the infra temporal fossa
foramen ovale
what are the three terminal branches of the ophthalmic branch
frontal, lacrimal and nasociliary
what structures do the branches of the ophthalmic branch innervate?
- Forehead and scalp
- Frontal and ethmoidal sinus
- Upper eyelid and its conjunctiva
- Cornea
- Dorsum of the nose
what structures do the branches of the ophthalmic branch innervate?
- Forehead and scalp
- Frontal and ethmoidal sinus
- Upper eyelid and its conjunctiva
- Cornea
- Dorsum of the nose
what structure does the ophthalmic branch innervate?
Lacrimal gland
Post ganglionic fibres from the pterygopalatine ganglion (derived from the facial nerve), travel with the zygomatic branch of V2 and then join the lacrimal branch of V1. The fibres supply parasympathetic innervation to to the lacrimal gland.
what is the corneal reflex?
the involuntary blinking of the eyelids – stimulated by tactile, thermal or painful stimulation of the cornea.
describe the reflex arc which causes the corneal reflex.
the ophthalmic nerve acts as the afferent limb – detecting the stimuli. The facial nerve is the efferent limb, causing contraction of the orbicularis oculi muscle.
how many branches arise from the maxillary nerve?
14
what structures receive their innervation from the maxillary nerve?
the skin, mucous membranes and sinuses of derivatives of the maxillary prominence of the 1st pharyngeal arch:
- Lower eyelid and its conjunctiva
- Cheeks and maxillary sinus
- Nasal cavity and lateral nose
- Upper lip
- Upper molar, incisor and canine teeth and the associated gingiva
- Superior palate
what structures receive parasympathetic innervation via the maxillary nerve?
- Lacrimal gland: Post ganglionic fibres from the pterygopalatine ganglion (derived from the facial nerve), travel with the zygomatic branch of V2 and then join the lacrimal branch of V1. The fibres supply parasympathetic innervation to the lacrimal gland.
- Nasal glands: Parasympathetic fibres are also carried to the mucous glands of the nasal mucosa. Post-ganglionic fibres travel with the nasopalatine and greater palatine nerves (branches of V2)
what are the four branches of the mandibular nerve?
- buccal nerve
- inferior alveolar nerve
- auricotemporal nerve
- lingual nerve.
where does the mandibular nerve branch?
infratemporal fossa
what does the mandibular nerve provide sensory innervation to?
- Mucous membranes and floor of the oral cavity
- External ear
- Lower lip
- Chin
- Anterior 2/3 of the tongue (only general sensation; special taste sensation supplied by the chorda tympani, a branch of the facial nerve)
- Lower molar, incisor and canine teeth and the associated gingiva
what does the mandibular nerve provide motor innervation to?
- Muscles of mastication; medial pterygoid, lateral pterygoid, masseter, temporalis
- Anterior belly of the digastric muscle (part of the suprahyoid muscles)
- Tensor veli palatini
- Tensor tympani
what does the mandibular nerve provide parasympathetic innervation to?
- Submandibular and Sublingual glands: Post-ganglionic fibres from the submandibular ganglion (derived from the facial nerve), travel with the lingual nerve to innervate these glands.
- Parotid gland: Post-ganglionic fibres from the otic ganglion ganglion (derived from the glossopharyngeal nerve, CN IX), travel with the auricotemporal branch of the V3 to innervate the parotid gland.
