Flashcards in Sensory Deck (171):
What bones make up the anterior skull?
What bones make up the lateral skull?
Where do the different sutures occur on the skull?
The coronal suture is the articulation by frontal and parietal
Saggital is between the two parietals
Lamboid is between parietals and occipital
Squamous is between temporal and parietal
Sphenoparietal is between sphenoid and parietal bones
Occipitomastoid is between Temporal and occipital
What is the pterion and why is it important?
It's the articulation between the frontal, parietal, temporal and sphenoid bones. It is the weakest part of the skull, and covers the anterior middle meningeal artery. This is a major site of extradural hematoma.
It can also compress CIII, and cause herniation into the brain base.
It's difficult to determine its location, and there are different frequencies depending on ethnicity.
It also may encapsulate the middle meningeal artery, rather than simply cover it. It lies within a 1cm circle 2cm behind and 1cm above the posterolateral margin of the frontozygomatic suture.
What bones make up the base of the skull?
The maxilla, hard palate, zygomatic, sphenoid, vomer, temporal and occipital bones.
What are the paired bony prominences of the skull?
The mastoid processes, occipital condyles and styloid processes.
What are the main foraminae of the skull and what passes through them?
Incisive foramen: nasopalatine nerves, sphenopalatine vessels
Greater palatine foramen
Foramen ovale (V2)
Foramen spinosum: middle meningeal artery
Carotid canal: int. carotid artery
Jugular foramen: C IX, X, XI, int. jugular vein
Foramen magnum: spinal cord and vertebral arteries
What foramen can you not see in a live skull, but can see in a live skull?
Foramen lacerum: it is filled with cartilage in life.
What bones make up the anterior fossa of the skull?
Body and lesser wings of sphenoid bone
What bones make up the middle fossa?
Chiasmatic sulcus of body of sphenoid bone and greater winds of sphenoid
Posterior edges of dorsum sellae of sphenoid, petrous part of temporal bone
What bones make up the posterior fossa?
Sorsum sellae of sigmoid, squamous part of occipital bone
Sup petrous temporal bones, parietal bones
What are the main intracranial foraminae of the skull?
Inf accoustic meatus
Sup orbital fissure
What are the sinuses of the skull and what is their function?
These lighten the face, humidify and head inspired air, and increase the resonance of speech
What are the bones that make up the orbit?
(make up the medial wall)
Maxilla (makes up the floor)
Zygomatic (makes up the lateral wall)
Frontal (makes up the roof)
What are the layers of the eyelid? (From superficial to deep)
What is orbiculus oculi?
A nerve that allows us to forcefully shut our eyes. It is supplied by CNVII. It has two parts- the orbital and palpebral parts.
What is the orbital septum?
An extension of the periosteum. It is an attachment point for the tarsus, levator palpebrae superioris, and the superior tarsal muscle.
What is the tarsus?
A plate of dense connective tissue, which protects the eye and has glands to help moisten the eye itself.
What is the blood and nervous supply to the eyelid?
Opthalmic, facial and superior temporal arteries
Sensory nerves are the opthalmic and maxillary
Motor is sympathetics, CNIII and CNVII
Describe the conjunctiva
It is a thin cell layer running around from the skin to the eye surface. It is very vascular, and is responsible for eye redness when injured.
Describe raccoon eyes
The skin and subcutaneous tissue of the eyelid is a potential space, which accumulates blood after injury to the eyes. It can also be due to extradural hematoma, where the blood escapes from the dura elsewhere, and ends up in the eyes even if this is not the site of injury
Describe the muscles that raise the eyelid
Two muscles raise it: Levator palpebral superioris and superior tarsal muscle. They are innervated by CNIII and the sympathetic nervous system, respectively
Loss of function as in horner's syndrome can cause drooping of the upper eyelid, called ptosis.
What are the three points at which structures enter and leave the orbit?
Superior orbital fissure
Inferior orbital fissure
What structures travel through the optic canal?
What structures travel through the superior orbital fissure?
Superior opthalmic vein
Frontal nerve (CV1)
Nasocilliary nerve (CV1)
CIII (inf ans sup)
Lacrimal nerve (CV1)
What structures travel through the inferior orbital fissure?
Inferior opthalmic vein
Infra orbital vein
Infra orbital artery
Name the extra-ocular muscles and their nerve supply
Superior, inferior and medial rectus, inf. oblique (CNIII)
Lateral rectus muscle (CNVI)
Sup oblique (CNIV)
Levator palpebrae superioris (CNVII)
What is the common tendinous ring?
A thickening of the periorbita in the posterior part of the orbit, around the orbit and central superior orbital fissure. It is the origin of the extraocular muscles.
How does the lacrimal apparatus work?
Lacrimal gland secretes tear film onto the eye, which then enters the canaliculi, lacrimal sac, and nasolacrimal duct to be excreted from the nose. If you have a closed sac, this can lead to an inability to remove tears
Where does the opthalmic artery arise from?
It comes from the internal carotid artery, wihc then gives off the opthalmic artery before it runs through the optic canal
What veins drain the orbital cavity?
The superior and inferior opthalmic veins
What is the danger triangle of the face?
The sommissures of the mouth to the naison- this is be cause the opthalmic vein communicates with the facial vein at this point, allowing infections to spread from the face to the cranial cavity.
What are the features of the different meninges of the cranium?
The dura mater is the outermost layer. There is a periosteal layer and an inner meningeal layer. The two separate to form intracranial venous structures and the spinal cord
The arachnoid mater is thin and avascular, and doesn't enter any grooves of the brain save for the longitudinal fissure
The pia mater is a thin membrane that invests in all of the brain's grooves.
Describe the spinal cord - cranial meninge transition
The meningieal layer of the dura extends down to form the dura mater of the spinal cord, while the periosteal layer ends at the foramen magnum.
Describe the arterial supply of the meninges
The ant, post and middle meningeal arteries, of which the middle is most crucial.
This enters through the foramen spinosum and travels just deep to the pterion. It has ant and post divisions.
Describe the venous drainage of the brain
Cerebellar veins drain into venous sinuses, and eventually to the internal jugular veins.
Diploic veins run between the internal and external bone, and emissary veins run from outside to inside the skull (important for infection)
Describe the sinus dranage of the brain
The sup sagittal sinus runs aong the falx cerebri, and drains into the straight sinus with the inf sagittal sinus. This then drains into the confluence of sinuses, to the Left and right trasverse (along with the sigmoid), and then to the sup. petrosal sinus, and then into the cavernous sinuses either side of the pituitary gland. These then drain into the internal jugular vein, and leave the brain.
What are the paired structures in the cavernous sinus, and do they run in the sinus itself or the walls?
In the sinus are the internal carotid artery and the abducent nerve
In the walls are the trochlear nerve, the maxillary nerve, the occulomotor nerve and the opthalmic nerve.
This means that thrombosis in the cavernous sinus is crucial due to the structures needing to be preserved. Fluid buildup here can crush the nerves and carotid artery
What are the partitions of the brain made by the dura mater?
The falx cerebri (separates hemispheres)
Tendorium cerebellum (separates cortex from cerebellum)
Falx cerebelli (separates halves of the cerebellum)
How can you tell what is causing a haemorrhage based on its location?
An extradural haemorrhave appears between the dura and the calvarium, and appears lemon shaped. It is classical from a torn middle meningeal artery, assoc. with skull fracture
A subdural haemorrhage forms between the layers of the dura, and is assoc with cerebral veins, particularly in those with atrophy or on anticoagulants
A subarachnoid haemorrhage is a bleed into the subarachnoid space, usually from a ruptured cerebral artery aneurysm of the circle of willis.
Describe the protective features of the eye
It is set in a socket for protection. It is in between bones for growth and development and entry and exit of structures
Has lacrimal glands to flush out water, and is surrounded by fat
The tear film also keeps the eye moist
What are the components of the tear film?
It has the eye epithelium, then mucosa secreted by lacrimal glands, aqueous part secreted by lacrimal glands, and finally oil secreted by meibomian glands
What is subconjunctival haemorrhage?
Common condition, mostly after severe coughing, sneezing or vomiting. Rarely seen with anticoagluants or blood pressure
What is ptosis?
Dysfunction of levator palpebrae superioris. Can be congenital, involuntary, mechanical, myogenic, traumatic or neurogenic- ie due to CNIII palsy or horners syndrome
What are some common refractive errors in the cornea?
Can be myopia- image focussed in front of retina (eye too long)
Can be hyperopia- image focussed behind retina (eye too short)
Can be stigmatism: 2 different planes of focus between horizontal and vertical
What is the cornea and what is its function?
It's the refractive surface of fixed power, for clarity, protection, ocular rigidity. It does 2/3 of the light focussing. It also sees the image upside down
What is the lens and what is its function?
It's the refractive surface of variable power, and has a smooth interface with the aqueous part. It's almost completely made of fibre cells, and has an inner nucleus in the middle. The fibres are laid down in layers after birth, allowing development of sight. It can have cataracts form on the nucleus or the cortex
What is the ciliary body/epithelium and what is its function?
It is used for lens attachment, production of aqueous humour. The ciliary body surrounds the lens, and can contract, causing the lens to thin.
Where does aqueous humour flow in the eye?
It flows through the angle of the eye between the ciliary body and lens to the trabecular network in the anterior chamber. It can get blocked, which causes a spike in ntraocular pressure.
What is an orbital haemorrhage?
Bleeding behind the orbital septum, which increases pressure and can block the orbital nerve
What are some signs of blowout fracture?
Black eye, infraorbital nerve anaesthesia. Can't fully look up or down
Describe thyroid eye disease
Lid changes- lag, retraction, lagopthalms
- Coular surface inflammation
- Optic neuropathy
How is light and colour received by the eye?
Light enters the eye and hits the fovea and macula. Light is detected by rods (night vision) and cones (colour vision), These then transfer info to connecting and processing cells, and then to ganglion cells in the brain
Where is the blind spot of the eye?
It covers the exit point of the optic nerve, as no photoreceptors overlie it.
Optic neuropathy with specific axonal loss, associated with increased intraoptic pressure. It usually presents with upper and lower eye being lost first
You can have closed angle, where the angle of the eye is closed by the iris, or open angle, with a predisposition to reduced drainage
95% of glaucoma is open angle, so you can see it using gonioscopy. Half of the nerve may be lost before symptom development
Can be associated with diabetes and macular degeneration
What are the layers of the cornea?
Stroma (collagen lamellae)
It's avascular unles pathological, but the most highly innervated structure in the body
The stroma is regularly spaced, and has an endothelial pump to remove water- this prevents oedma
What is Keratoconus?
Multifactorial but partly genetic, partly environmental aetiology. Causes a steep, thin cornea, usually in late puberty. It can have rapid, gradual or intermittent progression.
What are some common diseases of the lens?
Phacodoneis- wobbly lens and capsule
Cateracts- less opacity and acuity of cornea (can be age, congenital, metabolic, traumatic, toxic causes)
What are zonules?
Microfibres connecting the lens with the ciliary muscle.
What are the five fascias held within the posterior triangle of the neck?
Superficial fascia- fatty tissue with platysma muscle (CVII)
- Investing layer. Surrounds neck like a stocking, holding the peripheral muscles around the neck
- Pretracheal layer- engloses the thyroid, larynx/trachea and pharynx/oesophagus. Called buccopharyngeal in the posterior aspect
- Prevertebral: Encompasses the vertebral column and paravertebral muscles. Forms 2 layers with a potential space between them in the anterior aspect
- Carotid sheath- surrounds internal carotid artery, jugular vein and vagus nerve. Made up of the other fascias.
What are the three cervical spaces of the posterior triangle of the neck?
- Pretracheal space is the region between investing and pretracheal layer. It enxtends down from the pharynx/larynx to the ant. mediastinum
-Retropharyngeal space is post- to pharynx oesophagus and ant to prevertebral layer. Extends inferiorly from base of skull to post mediastinum
- Prevertebral space- space between layers of the prevertebral fascia, running from the base of the skull to the diaphragm.
You only see these on MRI when there is a pathology (eg. infection)
What are the boundaries of the posterior triangle of the neck?
Ant: Post border of sternocleidomastoid
Post: ant border of trapezius
Base: Middle third of clavicle
Apex: Base of skull on sup. nuchal line
Roof: Investing deep fascia
Floor: Prevertebral fascia covering semispinalis capitis, spenius capitis, levator scapulae, and scalenus post and med
What are the contents of the post triangle of the neck?
- Occipital artery and greater occipital nerve
- Lymph nodes
- Accessory nerve (about 1.5 cm deep to greater auricular nerve)
- Cutaneous branches of cervical plexus (C1-4)
- Omohyoid muscle
- Transverse cervical and supraclavicular arteries
- Third part of subclavian artery
- Ext. jugular vein
- Some brachial plexus
How does the posterior triangle help in central venous catheterization?
- Catheters may be used for central venous pressure monitoring, administering irritant or chemotherapy or for long term venous access. They are inserted in the internal jugular, subclavian or their junction. The patient is in the trendelenburg position with contralateral head rotation, to dilate the internal jugular. The point where the vein crosses the post sternocleidomastoid is a key landmark
Why do we need to ultrasound the accessory nerve before surgery?
It is easy to damage it especially in lymph node biopsy, and there is a lot of variation between patients
Patients may be left with the inability to rotate their heads or lift their arms up.
What are the components of the external ear?
The auricle is the visible part, and consists of the helix (outer rim), antihelix (inner rim), tragus (pointy cartilage), antitragul, and lobule.
The external acoustic meatus extends between the deepest part of the concha and the tympanic membrane, but not in a straight course.
Its lateral third is cartilaginous, while its inner 2/3s are bony.
What is the innervation of the external ear?
The auricle is innervated superficially by the cervical plexus and V3, and the deeper parts by VII and X
The external acoustic meatus is innervated by V3, X and VII
The tympanic membrane's outer surface is innervated by V3, VII, IX and X, while its inner surface is by IX
What are some issues that can arise with the external ear? How do you view it using otoscopy?
Swimmers ear is an infection of the external acoustic meatus
Surfers ear is cole water in the ear, making the bony part grow
Otoscopy required us to pull the ear back and up to straighten the EAM
In babies, we pull the ear downwards
What are the 6 boundaries of the middle ear?
- Jugular wall (floor)
- Membranous wall (lateral)
- Mastoid wall (posterior)
- Carotid wall (anterior)
- Labyrinthine wall (medial)
- Tegmental wall (roof)
Describe the tegmental wall of the middle ear
Separates the middle ear from the middle cranial fossa
Describe the jugular wall of the middle ear
Separates the middle ear from the internal jugular vein. A branch of IX nerve enters the middle ear on its medial border.
Describe the membranous wall of the middle ear
Separates the middle ear from the EAM and almost entirely made up of the tympanic membrane (but upper part is epitympanic recess)
Describe the mastoid wall of the middle ear
Separates the middle ear from the mastoid air cells inferiorly and continuous with the mastoid antrum via the auditus superiorly. The tendon of stapedius and a branch of VII (corda tympani) enter through here
Describe the carotid wall of the middle ear
Separates the middle ear from the internal carotid artery inferiorly. Allows eustachian tube and tensor tympani to eneter superiorly. Branches from int carotid plexus enter here, cordae tympani exits here
Describe the labyrinthine wall of the middle ear
Separates the middle and inner ears. Assoc with the promontory covered by mucous membrane, which contains the tympanic plexus (IX and caroticotympanic nerves). Holds the oval and round windows, and the lesser petrosal nerve, which leaves to run into the middle cranial fossa to the otic ganglion
What structures run within the middle ear?
The prominence of the facial canal, cordae tympani, the tendons of stapedius and tensor tympani, the lesser petrosal nerve, eustachian tube, CIX
What is the neurovascular supply of the middle ear?
Innervated by the tympanic plexus
Blood supply from tympanic branch of the maxillary artery, mastoid branch of occipital or posterior auricular arteries
Venous drainage is pterygoid plexus of veins to sup. petrosal sinus
Describe the parts of the tympanic membrane
There are three dips (sup is called the pars flaccida). The cone of light can also be seen
You can see the handle of the malleus running down the middle, with the umbo inferiorly, and the lateral process of the malleus superiorly. The posterior and anterior malleolar folds extend away from this.
What is mastoiditis and why is it important?
It occurs when infection spreads from the middle ear into the mastoid antrum, which may lead to meningitis. It requires emergency surgery
Why are the facial nerve and chordae tympani important in terms of the middle ear?
The facial nerves enters medioposteriorly, before circling the top of the tympanic membrane.
The chorda tympani may come with it- although 15% branch after the facial nerve has left the skull
It is responsible for submandibular and sublingual salivary function and taste to the ant. 2/3 of the tongue. It can be damaged in tympanic membrane perforation or middle ear surgery
What are the boundaries of the anterior triangle of the neck?
Anterior border of sternocleidomastoid forms the lateral border
Inferior border of the mandible forms the superior border
Midline of the neck forms the medial border
Describe the muscles of the ant triangle of the neck
the suprahyoid muscles run from the hyoid bone up. They include stylohyoid (most superfical and lateral), digastric (has ant and post bellies, seen first in the midline), mylohyoid (lateral deep) and geniohyoid (behind digastric and mylohyoid)
The infrahyoid muscles run from the hyoid bone down
They include sternohyoid (most superficial, clavicle head to hyoid), omohyoid (lateral, shoulder to hyoid), thyrohyoid (thyroid to hyoid) and sternothyroid (sternum to thyroid).
Before ossification of the hyoid, thyrohyoid and geniohyoid were the same muscle
Describe the innervation of the anterior triangle muscles
Suprahyoid: Post digastric and stylohyoid are innervated by the facial nerve. Ant digastric and mylohyoid are innervated by V3 Geniohyoid is innervated by C1.
Both thyrohyoid and geniohyoid are unnervated by the superior root (C1) of the ansa cervicalis. The rest of the muscles are innervated by the inferior root from C2-3
Describe erb's point
A spot on the posterior border of sternocleidomastoid where the lesser occipital, greater auricular, transverse cervical and supraclavicular nerves leave the plexus
Describe the internal and external carotid arteries as they are in the neck
The internal carotid has no branches in the neck, and supplies the ipsilateral cerebral hemisphere
The external carotid gives off branches immediatesly after bifurcation of the common carotid, the first of which is the sup thyroid artery
Describe the various jugular veins as they are in the neck
It originates as a continuation of the sigmoid sinus in the skull
The anterior jugular vein is very superficial around the zygomatic process
The posterior auricular and retromandibular vein combine to form the external jugular
Describe the glossopharyngeal nerve's course in the neck
Leaves the skull via the jugular foramen and lies deep to the styloid process. Runs between the int and ext carotid arteries, around lateral stylopharyngeus, and continues to the base of the tongue
Describe the course of the vagus nerve in the neck
Leaves the skull via the jugular foramen and travels down in the carotid sheath. Passes in front of the subclavian artery and behind the subclavian vein to enter the mediastinum
Describe the course of the hypoglossal nerve in the neck
Leaves the skull via the hypoglossal foramen, passing between internal carotid artery and internal jugular vein.
It crosses the occipital, external carotid and lingual arteries deep to post digastric into the tongue. A branch from the ant rami of C1 hitchhikes with it to innervate thyrohyoid and geniohyoid
Describe the thyroid gland and how it develops
It is a structure in the anterior neck, below and lateral to the thyroid cartilage. It has two lobes connected by an isthmus, which crosses the ant surface of tracheal cartilage 2 and 3
It grows down from the foramen caecum at the base of the tongue, as the thyroglossal duct. It travels down and passes the hyoid before reaching the trachea. This thyroglossal duct usually disappears early in development, but cysts, fistulae or ectopic thyroid tissue can stay, and move with swallowing or tongue protrusion
This can stop in the tongue (lingual thyroid), above the hyoid (accessory thyroid), below the hyoid (cervical thyroid) or over top of the thyroid (pyramidal thyroid)
Describe the blood supply of the thyroid
It is suppled by two major arteries: The superior thyroid from the external carotid, and the inferior thyroid from the thyrocervical trunk (from subclavian artery
Th ima artery supplies the isthmus (from the arch of the aorta)
Describe the venous and lymphatic drainage of the thyroid
Drained by the sup, middle thyroid veins (to internal jugular) and inf thyroid vein (to brachiocephalic veins)
Lymph drains to paratracheal and deep cervical nodes
Describe the innervation of the thyroid
Receives parasymp from the vagus nerve via the recurrent laryngeal, and sympathetic from sup, mid and inf cervical sympathetic ganglua. This comes from T1-L2 via the chain
What structres surround the thyroid?
strap muscles are anterior, trachea and oesophagus are posterior
It is medial to the carotid sheaths, as well as the recurrent laryngeal nerves
What are the layers of the scalp?
Upper layer is skin, then connective tissue (dense), aponeurotic layer, loose connective tissue and pericranium (remember SCALP)
What are some of the features of the scalp?
- First three layers tightly anchored together
- Dense connective tissue contains neurovascular structures
- Loose connective tissue allows it to move over the calvaria. It is also responsible for much of the infection due to its consistency
What is the blood supply and lymphatic drainage of the scalp?
Supplied mainly by external carotid and opthalmic artery (from supratrochlear or supraorbital branches)
Venous drainage is equivalent
Lymph drainage drains to occiptial nodes etc.
Describe the innervation of the scalp. How should it be anaesthetised?
Innervated by CNV anteriorly and and rami of C2-4 posteriorly- includes greater auricular nerve, and lesser, greater and third occipital nerves
- Occipitofrontalis muscle is for facial expression, innervated by CNVII
- Anaesthetic should be given to the proximal part of the nerve, so that the distal flow-on is covered
What are the muscles of facial expression and what is their innervation?
There are several groups:
- Orbital muscles (orbicularis oculi which shuts the eye),nasal (nasalis), oral (buccinator, raise and lower lips), auricular (anterior, superior and posterior division) and other groups (platysma, occipitofrontalis (long aponeurosis over the calvarium to give and and post bellies).
All are innervated by CNVII
Describe the parotid gland
The largest of the salivary glands, wrapped around the mandible, anteroinferior to the ear. The parotid duct leaves the and border of the gland, transversing the face over the masseter muscle. At its anterior border, the duct pierces the buccinator fat and muscle, opening into the oral cavity by the second upper molar.
it sits on the ramus of the mandible, with the deep part flicking behind it.
Describe the structures deep to the parotid gland
Parotid gland is most superficial. Then mastication muscles, fat pads and facial muscles
Describe the innervation of the parotid gland
Innervated by the auriculotemporal nerve (CNV3) for sensation. The parotid fascia is innervated by C2 Secretomotor fibres from CNV3 and CNIX also innervate it.
Sympathetic stimulation comes from the superior cervical ganglia
Describe the course of the facial nerve in the head
Exits the skull via the stylomastoid foramen and gives off the post. auricular nerve, which suplies the occipital part of occipitofrontalis
- Gives off next branch to supply post digastric and stylohyoid
- Enters parotid gland and gives off temporozygomatic and cervicofacial branches.
What are the five nerve branches arising out of the parotid gland?
What do the parotid gland nerve emergents supply?
- Temporal: Ant and sup auricularis muscle, frontalis
- Zygomatic: Frontalis, orbicularis oculi
- Buccal: Buccinator, muscles of upper lip
- Marginal mandibular: Muscles of lower lip
- Cervical: Platysma
What do each of the branches of V3 supply?
Opthalmic nerve gives:
Supraorbital, supratrochlear, lacrimal, infratrochlear and external nasal nerves. They supply upper 1/3 orbit and frontalis
Maxillary gives infraorbital, zygomaticofacial and zygomaticotemporal nerves. Innervate middle 1/3- skin covering maxilla
Mandibular gives mental, buccal, auriculotemporal branches to supply the lower 1/3 of skin covering the mandible
What structures is the facial nerve close to? Why is it important to locate?
It is near the structures of the parotid gland, as it travels directly through the superfical and deep parts. It crosses superfically to the retromandibular vein, external carotid, mandible and masseter muscle.
It is important to locate for lacerations, reconstructions, and in diagnosis of duct injury to reduce cysts etc.
Describe the surface anatomy of the parotid duct and why this is important
It is important for assessing facial laceration, and facial reconstruction surger.
It is mostly located in the middle half of a line between the tragus and cheilion, within 1.5cm superior or inferior.
What are the borders of the oral cavity?
The roof, floor and lateral walls
Ant opens to the oral fissure
Post opens to the oropharyngeal isthmus
What muscles form the floor of the oral cavity>
- Paired mylohyoid muscle, connected in the midline by the raphe
- Paired geniohyoid muscles
- Tongue (external and intrinsic muscles
What are the extrinsic and intrinsic muscles of the tongue, and how are the innervated?
Extrinsic: Palatoglossus (from palatine bones), styloglossus (from styloid process), hyoglossis (from hyoid bone) and genioglossus (from geniohyoid)
Intrinsic: Sup longitudinal, vertical, transverse and inf longitudinal
All innervated by the hypoglossal nerve except palatoglossus (CX)
What structures other than muscles can be found in the tongue?
Lingual veins are on its inf surface
Lingual artery and nerve run nearby
Sublingual folds over the sublingual glands
Sublinqual openings and submandibular openings are at the base of the frenulum- the membrane from the floor of the mouth to the tongue
Describe the submandibular gland
A hook shaped gland with smaller and larger arms. Layers needing to be dissected to reach the gland are the skin, subcutaneous fat, platysma and investing layer of the deep cervical fascia.
The submandibular duct exits the deeper arm. The gland is wrapped around the free edge of mylohyoid
What are the three muscles and nerves lying around the submandibular gland?
Muscles are the mylohyoid, hypoglossus, and the posterior belly of digastric
The marginal mandibular branch of the facial nerve, lingual nerve, and hypoglossal nerve are also near.
What are the two potential spaces of the mouth, and what structures run through them?
First potential space is the triangular apterture- formed by mylohyoid, sup constrictor and med constrictor. The hypoglossal nerve enters the tongue here, as does the lingual nerve, but from a superior plane.
The lingual artery enters the escond potential space, between hyoglossus and genioglossus
What is the consequence of damage to the marginal mandibular nerve?
Lip depressors move upwards
Describe the innervation of the tongue
Taste from the anterior two thirds is taken by the chorda tympani (VII)
Taste from the post 1/3 is taken by the glossopharyngeal (IX)
Sensation is innervated by CNV3
Describe the roof of the oral cavity
Anterior hard palate and a posterior soft palate. The hard palate is covered by mucosa, and formed by the palatine process of the maxillae (ant 3/4) and the horizontal plates of the palatine bones (post 1/4)
Describe the soft palate
This hangs off the posterior edge of the hard palate. Its bulk is formed from mucous and serous glands within the mucous membrane. It has an aponeurosis and five pairs of muscles, acting like a valve during swallowing to prevent reflux into the nasopharynx
What are the muscles of the soft palate and what is their innervation?
- Tensor veli palatini
- Levator veli palatini (apex of petrous temp bone to palatine aponeurosis
- Palatopharyngeus (sup palatine aponeurosis, hard palate to inner pharynx- elevates larynx and pharynx during swallowing, narrows oropharyngeal isthmus)
- Musculus uvulae
All innervated by CNX except for tensor veli palatini (CNV3)
Supplied by greater and lesser palatine arteries, from the facial arteries
Describe the lateral walls of the oral cavity
Fascia, a thin layer of skeletal muscle (buccinator) between skin and oral mucosa. Innervated by CNVII
What is the surface anatomy of the soft palate?
You can see the uvula hanging down
Palatoglossal arch externally
Palatopharyngeal arch internally
Palatine tonsil between the two
Foramen cecum where the two tonsils meet (it is here that the thyroid develops
What are the different tastebuds?
Fungiform and foliate papillae (ant 2/3)
Circumvallate (post 2/3)
What are the regions of the nasal cavity?
Nasal vestibule- small dilated space lined by skin and hair
Respiratory region- largest part with a rich neurovascular supply. Lined by respiratory epithelium
Olfactory region- small part of the apex of the cavity, lined by olfactory epithelium and receptors
What structures form the external nose?
Bony and cartilaginous parts. The cartilaginous parts are what is manipulated in nasal surgery. If damaged in infancy, the nose may not grow
The cartilage consists of major and minor alar cartilages, as well as the lateral process of the septal cartilage. Some of these function as growth plates
What are the bones that contribute to the skeletal framework of the nose?
The unpaired ethmoid, the sphenoid (and sinus), frontal and vomer bones
The paired nasal, maxillary, palatine and lacrimal bones, as well as the inferior conchae
What are the components making up the borders of the nasal cavity?
Describe the floor of the nasal cavity
Palatine process of the maxilla
Nasal crest running between the two
Describe the roof of the nasal cavity
Nasal bone anteriorly, most common to fracture
Frontal bone with a nasal spine
Cribiform plate and crista galli from the ethmoid bone
Describe the medial wall of the nasal cavity
Septal cartilage (important for trauma)
Perpendicular plate of the ethmoid bone
Vomer articulating with cartilage and bone, as well as the nasal crest of the maxillary and palatine parts
Describe the lateral wall of the nasal cavity
Superior and middle conchae formed by the ethmoid bone
Inferior concha is separate
Frontal process of the maxilla
Perpendicular plate of the palatine
Lateral process of septal cartilage
Medial pterygoid plate of the sphenoid
Describe the parts of the ethmoid bone that contribute to the nasal cavity
The superior and middle conchae
Perpendicular plate (greatest fracture risk)
Infundibuli communicating with the nasal cavity
Describe the paranasal sinuses
- Ethmoidal cells (innervated by CNV1 and V2)
- Sphenoidal (innervated by CNV1 and V2).
- Maxillary sinus (CNV2)
- Frontal sinus (CNV1)
- All are lined by respiratory mucosa and open into the nasal cavity
- Frontal, ant/mid ethmoidal and maxillary open into the lateral wall of the middle meatus (behind the concha)
- Post ethmoidal cells open onto the sup nasal meatus (behind the concha)
- Sphenoidal open into the roof of the nasal cavity (sphenoethmoidal recess)
What are the four routes through which structures enter and leave the nasal cavity?
- Cribiform plate: CN1, ant. ethmoidal nerve of CNV1, nasal veins to sup sagittal sinus
- Sphenopalatine foramen: Sphenopalatine branch of maxillary artery, nasopalatine branch of CNV2, sup nasalbranches of CNV1
- Incisive canal: Nasopalatine nerve, terminal part of the greater palatine artery
- Small foramina in the lateral wall: Branch of infraorbital nerve (CNV2), branch of the greater palatine nerve (CNV2)
What is the blood supply of the nasal cavity
Main artery is the sphenopalatine. This anastomoses with the septal branch of the superior labial, and ascending branch of the greater palatine, forming Kieselbach's plexus
Ant and post ethmoidal arteries supply the roof and anterolateral part of the wall
Veins drain to the pterygoid plexus, including the facial, opthalmic, and inf cerebral vein
Little's area in the ant cavity is the most prone to nosebleeds, as they sit just on the cartilage
What is the nervous supply of the nasal cavity?
Olfactory area is supplied by olfactory receptors, from the olfactory nerve
Vestibular area is supplied by the infraorbital nerve
Respiratory area is supplied via ant ethmoidal and ant sup alveolar nerves, and posteriorly via pterygopalatine ganglion, and greater palatine nerve.
What are the three regions of the pharynx?
What muscles make up the pharyngeal wall?
Three constrictor muscles: Superior, middle and inferior
Three longitudinal muscles: Salpingopharyngeus, palatopharyngeus and stylopharyngeus
How are the constrictor muscles of the pharyngeal wall attached?
The superior constrictor is attached to the base of the skull, forming the nasopharynx
The middle is attached to the stylohyoid ligament, the lesser and greater horns of the hyoid bone
The inferior is attached to the oblique line of the thyroid cartilage as well as the fascia of the corticothyroid muscle
They have anterior and inferior gaps in their surfaces
Where does the pharynx end?
What is the function of the vertical pharyngeal muscles?
They support and reinforce the circular muscles, elevate and assist in swallowing, help with peristalsis
What is the innervation of the pharyngeal muscles?
All but stylopharyngeus are innervated by CX, (SP is innervated by IX)
Sensory from V2 (nasopharynx), IX (glossopharynx) and CX (laryngopharynx)
What structures pass between the superior and middle constrictors? (Oropharyngeal triangle)
Muscles nerves and vessels in and out of the oral cavity- stylopharyngeus muscle, glossopharyngeal nerve and lingual nerve and vessels
What structures pass between the middle and inferior constrictors?
Internal laryngeal vessels and nerve
What structures enter below the inferior constrictor muscle?
Recurrent laryngeal nerve and inferior laryngeal vessels
What structures form the boundaries of each component of the pharynx?
Nasopharynx: Pharyngeal tonsil superiorly (can get inflamed and block posterior nasal cavity in infection). Also eustachian tube, torus tubularis, salpingopharyngeal fold and pharyngeal inlet
Oropharynx: Palatoglossal arch, palatine tonsil and palatopharyngeal arch
Laryngopharynx: Laryngeal inlet
What is the blood and lymph of the pharynx?
Upper part is suppled by branches of ext carotid (lingual, maxillary, facial arteries)
Lower part is subclavian artery- inf thyroid
Palatine tonsil is facial artery
Drains to pterygoid plexus superiorly, int jugular and facial veins inferiorly
Lymph to deep cervical lymph nodes
What is the larynx and what are the main structures it is formed from?
Musculoligamentous structure with a cartilaginous framework located above the lower resp tract. It protects the airway, produces sounds.
Composed of cartilages, ligaments and msucles
What are the cartilages of the laryn?
Arytenoid- triangle at back
Thyorid- large middle part
(Cuneiform and corniculate- within fascia)
What are the features of the thyroid cartilage?
Superior and inferior thyroid notches
What are the membranes and ligaments of the pharynx?
Thyrohyoid membrane (between thyroid cartilage and hyoid bone)- has an aperture for internal branch of superior laryngeal nerve and its artery (from superior thyroid artery)
- Vocal ligament- thickened part of the cricothyroid membrane, which forms the ability for phonation
Vestibular ligament from the quadrangular membrane, which is more lateral and not a true vocal ligament
What are the important muscles of the larynx?
Posterior crico-arytenoid- only one that opens the vocal cords, allowing air in and out. Innervated by recurrent laryngeal nerves
- Vocalis mvoes the vocal cords
- Cricothyroid is an extrinsic muscle
What can happen if the posterior crico-arytenoid/recurent laryngeal nerve is damaged?
I side leads to hoarseness
2 sides leads to asphyxiation
What are the parts of the larynx that can be seen on endoscope?
Either side of the laryngeal inlet are the piriform recesses. These are medially bounded by aryepiglottic folds and laterally by thyroid cartilage- food is likely to get stuck here
Vocal cords are in the middle, forming a V. The rima glottidis is the space between the two true vocal cords
The adjacent vestibular folds (false cords) have the rima vestibuli between the (sup to rima glottidis) forming a V shape
How does swallowing occur?
Rima glottidis, rimavestibuli and vestibule close, with the larynx moving up and forwards, causing the epiglottis to swing downwards and narrow the laryngeal inlet and open the oesophagus
What is the blood supply of the larynx?
Superior and inferior laryngeal arteries, from the superior and inferior thyroid arteries (This means you ahve to be careful when removing the thyroid not to ligate these
They drain to sup laryngeal and inf laryngeal veins, to sup thyroid and left brachiocephalic veins, respectively
What is the innervation of the larynx?
Sensory and motor from branches of the vagus- superior and recurrent laryngeal nerves
Recurrent laryngeal goes to all intrinsic muscles (except cricothyroid) and sensory below the vocal folds
Superior laryngeal divides into internal and external laryngeal
External innervates cricothyroid and internal is sensory, supplying the laryngeal cavity above the vocal folds
What are the borders of the infratemporal fossa?
Medial: Lateral plate of the pterygoid process, pharynxm muscles of the pharynx- tenso veli palatine and levator veli palatine
Lateral: Medial surface of the ramus of the mandible
Anterior: Posterior surface of the maxilla
Roof: Inferior surface of the greater wing of the sphenoid and temporal bone
What are the movements of the jaw and what are the muscles responsible for elevation and depression?
Depression: Digastric, geniohyoid, mylohyoid
Elevation: Temporalis, masseter
Describe the temporomandibular joint
Abnormal synovial joint, covered with a cartilage articulation
Thickening of the capsule laterally forms the lateral ligament and stylomandibular ligament
Contains an articular disc and an attachment site for muscles
What are the major contents of the infratemporal fossa?
Sphenomandibular ligament, latera and medial pterygoid muscles, maxillary artery, mandibylar nerve, pterygoid venous plexus, glosspharyngeal nerve and branches of the facial nerve.
Describe the branches of the mandibular nerve in the infratemporal fossa
It divides into two trunks.
The posterior trunk gives rise to the lingual nerve, joined in the fossa by chordae tympani, responsible for the ant 2/3 of tasts, as well as into the inferior alveolar
The anterior trunk gives the buccal nerve, responsible for sensation in the lower 1/2 of the cheek, and the auricolotemporal nerve.
The lesser petrosal nerve, which travels with the auriculotemporal nerve, is responsible for parasymp to the parotid
Describe the branching of the maxillary artery in the infratemporal fossa
Gives off the middle meningeal and inferior alveolar arteries.
Describe the veins contributing to the pterygoid plexus
Inferior alveolar veins
These drain via emissaries to the cavernous sinus, and so are a potential route for infection
Describe the borders of the pterygopalatine fossa
Lies directly behind the maxilla and orbit, below the middle cranial fossa. lateral to the posterior nassal cavity
Bordered by palatine bone medially, maxilla anteriorly, and sphenoid bone on the roof
What are the contents of the pterygopalatine fossa?
Maxillary division of CNV
Maxillary artery continuation
Autonomic nerves from the pterygoid canal, forming the pterygoid ganglion.
Describe how CNV2 branches in the pterygopalatine fossa
Purely sensory nerve, entering through the foramen rotundum. Gives off zygomatic nerve to the face and temple skin, post sup alveolar for upper molar teeth, gums and maxillary sinus
Describe other nerves in the pterygopalatine fossa
Greater petrosal from facial, gives parasymp supply to nasal cavity and lacrimal glands
Deep petrosal nerve from superior cervical ganglion runs with the internal carotid and gives symp supply to the middle face and orbital cavity. Forms part of the pterygopalatine ganglion
Describe the pterygopalatine ganglion
Gives hay fever symptoms. Located in the pterygopalatine fossa. Made up of greater petrosal and deep petrosal nerves
What is the blood supply within the pterygopalatine fossa?
Maxillary artery enters through the pterygomaxillary fissue, after running through the infratemporal fossa. Gives off sphenopalatine artery, which runs into nasal cavity and is responsible for posterior nasal bleeds