Head & Neck Flashcards
What are the 3 layers of Deep Cervical Fascia?
Investing, Pretracheal + Prevertebral
What is contained within the Investing layer of deep cervical fascia?
This is the most superficial layer surrounding the entire deep neck, it splits in two where it meets the trapezius and the sternocleidomastoid completely surrounding them
Whats contained in the Pretracheal layer of deep cervical fascia?
Situated anteriorly in the neck it spans the hyoid bone to where it blends into the pericardium. It contains the trachea, oesophagus, thyroid gland and infrahyoid muscles
Describe the prevertebral layer of deep cervical fascia
The prevertebral layer surrounds the vertebral column from the base of the skull to the endothoracic fascia of the ribcage at T3, it also extends laterally as the axillary sheath
What is contained within the Carotid Sheaths?
Common carotid artery, Internal Jugular Vein, Vagus nerve, Cervical Lymph nodes
What is the Retropharyngeal space (danger space) and why is it dangerous?
Potential space between the pretracheal and prevertebral fascial layers, it allows movement of structures in the neck while swallowing. There is a risk of mediastinitis which is due to the face that infections can track all the way down into the chest cavity, this is normal caused by upper respiratory tract infections
What is the Parapharyngeal space and why can it be dangerous?
Found parallel to the pharynx infections of this space can lead to damage to the carotids, infections don’t tend to track down as far as in the retropharyngeal space. Can be caused by very bad tonsillitis or poor dental hygiene.
Name the 4 Suprahyoid muscles and their innervation
Geniohyoid (hypoglossal) Mylohyoid (Mandibular) Digastric (Mandibular) Stylohyoid (Mandibular)
Name the 4 Infrahyoid muscles and their innervation
Sternohyoid (Ansa Cervicalis C1-C3) Omohyoid (Ansa Cervicalis C1-C3) Thyrohyoid (C1 on Hypoglossal nerve) Sternothyroid (Ansa Cervicalis C1-C3)
Name the 4 muscles of Mastication and their innervation
Masseter Temporalis Medial Pterygoid Lateral Pterygoid All innervated by the mandibular nerve
What are two muscles of the orbital group of muscles of facial expression and what are their actions?
Obicularis Oculi - closes eye Corrugator Supercilii - draws eyebrows together
What are the two parts of Obicularis Oculi and what is the risk of damage to the facial nerve?
Outer orbital and inner palpebral parts Patients with damage to facial nerve can’t close their eyes which can lead to exposure keratitis
Name two muscles of the nasal group of muscles of facial expression and name their actions
Nasalis - Transverse part compresses the nares and Alar part opens them Procerus - Pulls eyebrows downwards to wrinkle nose
Name two muscle son the oral group of muscles of facial expression and name their actions
Obicularis Oris - Purses the lips Buccinator - Pulls cheek inwards against the teeth preventing the build up of food in this area
Name the superior, lateral and medial boarder of the anterior triangle of the neck
Superior - Inferior boarder of mandible Lateral - Medial boarder of sternocleidomastoid Medial - Imaginary line down middle of neck
What are the contents of the anterior triangle of the neck?
Supra and infrahyoid muscles Common carotid bifurcates within the triangle Internal jugular vein Cranial nerves; Facial (VII), Glossopharyngeal (IX), Vagus (X), + Hypoglossal (XII)
What are the superior, lateral and inferior borders of the carotid triangle?
Superior - Posterior belly of digastric Lateral - Medial boarder of sternocleidomastoid Inferior - Superior belly of omohyoid
What are the contents of the carotid triangle?
Bifurcation of the common carotid Carotid sinus Internal jugular vein (JVP) Hypoglossal and vagus nerves
Name the anterior, posterior and inferior borders of the posterior triangle
Anterior - Posterior boarder of SCM Posterior - Anterior boarder of trapezius Inferior - Middle 1/3 of clavicle
What are the contents of the posterior triangle?
Inferior belly of omohyoid divides it into the occipital and subclavian triangles. External jugular vein Subclavian artery and vein Accessory nerve (CN XI) Cervical plexus Phrenic nerve (innervates diaphragm)
Which two structures can be found at the bifurcation of the external carotid artery?
Carotid Sinus Carotid Bodies
Name the 8 main arteries which arise from the external carotid
- Superior Thyroid - Lingual - Facial - Ascending Pharyngeal - Occipital - Posterior Auricular - Maxillary - Superficial Temporal
Which arteries supply the scalp?
Occipital Posterior Auricular Superficial Temporal Supraorbital + Supratrochlear of the Internal Carotid
What 3 reasons can help to cause heavy bleeding from scalp injuries?
- Walls of the arteries are tightly bound to underlying connective tissue preventing it from constricting to limit blood loss after laceration. 2. Numerous anastomoses form a densely vascularised area. 3. Deep lacerations can involve the epicranial aponeurosis which is worsened by the opposing pulls of the occipital and frontal muscles.
Where is the Middle Meningeal artery at risk of laceration?
Pterion
What is the laceration of the middle meningeal artery called? How would it present?
- Extradural haematoma - Increased intracranial pressure causing vomiting, seizures, bradycardia ect.
Why are you at higher risk of atheroma formation in the internal carotid artery? What can it lead to?
- Carotid sinus causes turbulent flow - Can lead to TIA’s and Strokes
Where does the internal carotid artery enter the skull?
Through the carotid canal in the petrous part of the temporal bone
Describe the path of the Vertebral arteries. What do they give rise to?
Arise from subclavian arteries and ascend up the posterior side of the neck through the foramen transversarium of cervical vertebrae. Give rise to the basilar arteries which supply the brain.
Which 4 arteries arise from the thyrocervical trunk?
- Suprascapular 2. Transverse Cervical 3. Inferior Thyroid 4. Ascending Cervical
Where do you find the dural venous sinuses? Where do they collect venous blood from?
- Between the periosteal and meningeal layers of dura matter. - Collect blood from the brain, skull and scalp.
How does blood pass from the scalp to the dural venous sinuses? Why can this be dangerous?
Through emissary veins which can provide a path of infection from the scalp to the meninges.
From where does the internal jugular vein arise and leave the skull?
Continues from the sigmoid sinus leaving the skull through the jugular foramina.
Which veins of the face can provide a route for infection into the skull? And why?
Superior and inferior ophthalmic veins and the facial vein are all valveless allowing easy flow between them and the cavernous sinus.
Where do the deep facial veins drain?
Pterygoid venous plexus
What is contained within the cavernous sinus?
- Internal Carotid - Oculomotor Nerve (CN III) - Trochlear Nerve (CN IV) - Abducent Nerve (CN VI) - Ophthalmic and Maxillary branch of Trigeminal
What is the danger triangle of the face?
From the corners of the mouth to the bridge of the nose the facial vein and cavernous sinus can communicate which can be a path for infection into the brain
What are the 3 features that distinguish cervical vertebrae from thoracic vertebrae?
- Triangular vertebral foramen 2. Bifid spinous process 3. Transverse foramina for the passage of the vertebral arteries
What are the 3 unique features of the Atlas (C1)?
- No vertebral body 2. No spinous process 3. Articular facet to articulate with the dens of the axis (C2)
What is the distinguishable feature of the Axis (C2)?
Dens which articulates with the facet on the atlas (C1)
What causes a Jefferson (burst) fracture of the Atlas?
Vertical fall onto extended neck causing lateral masses of the atlas to be driven apart. Unlikely to have involvement of the spinal cord due to wide vertebral foramen.
Which bones make up the Calvarium?
Frontal, Parietal and Occipital bones
Which 6 bones make up the Cranial Base?
- Frontal 2. Ethmoidal 3. Sphenoid 4. Temporal 5. Parietal 6. Occipital
Whats the name of the 3 fibrous joints of the cranium?
- Coronal Suture 2. Sagital Suture 3. Lambdoid Suture
If you have incomplete fusion it leaves 2 membranous gaps in the skull, what are they called?
- Frontal Fontanelle 2. Occipital Fontanelle
Whats the purpose of the serrated edges of the cranial bones? Whats the risk of premature birth?
- During birthing the serrated edges interlock protecting the brain from any injury. 2. Cranial sutures are wide in pre-term development which means the edges don’t interlock and can cause brain damage from trauma of birthing process.
Name the 12 cranial nerves
CN I - Olfactory CN II - Optic CN III - Oculomotor CN IV - Trochlear CN V - Trigeminal CN VI - Abducens CN VII - Facial CN VIII - Vestibulocochlear CN IX - Glossopharyngeal CN X - Vagus CN XI - Accessory CN XII - Hypoglossal
Which 4 cranial nerves have autonomic innervation?
CN III - Oculomotor CN VII - Facial CN IX - Glossopharyngeal CN X - Vagus
What is the main function of the Olfactory nerve? What can damage to the Olfactory nerve lead to?
- Responsible for olfaction - Anosmia (loss of smell) due to nerve damage as they pass through the cribriform plate
What is the path of the Optic nerve? What is a common cause of damage to the Optic nerve and how would it present?
- Transmits special sensory information from the retina through the optic canal of the bony orbit, fibres from the medial half of each retina cross over at the optic chiasm. They then travel to the primary visual cortex in the occipital lobe via the optic tract. - Pituitary tumours press on the optic chiasm causing bitemporal hemianopia
What is the path of the Oculomotor nerve? Which muscles does it innervate?
- Arises from the oculomotor nucleus in the midbrain passing through the cavernous sinus leaving the skull through the superior orbital fissure - Superior, inferior and medial Rectus muscles, Inferior Oblique and Levitator Palpabrae Superioris
What is the route of the parasympathetic fibres? What are the two parasympathetic functions of the Oculomotor nerve?
- Travel in the inferior branch of the oculomotor nerve, branch off within the orbit to join the ciliary ganglion. 1. Constriction of pupil by the Sphincter pupillae 2. Contraction of the lens by the Ciliary muscles causing the lens to become more spherical and adapted to short sight
What are the three main causes of Oculomotor damage? What does this damage cause?
- Increased intracranial pressure, Aneurysm of posterior cerebral artery + cavernous sinus infection or trauma - Down and out pupil, Ptosis (drooping eyelid) + dilated pupil due to unopposed action of the Dilator Pupillae muscle
What is the path of the Trochlear nerve? Which muscle does it innervate?
- Arises from the trochlear nucleus on the posterior aspect of the midbrain passing through the cavernous sinus before exiting through the superior orbital fissure - Innervates the superior oblique muscle
What can cause damage to the Trochlear nerve? How does it present?
- Damage to the cavernous sinus and raised intracranial pressure - Diplopia when looking down and in, may have sore neck from tilting their head to the side to accommodate
What is the route of the Trigeminal nerve and where do the three divisions leave the cranial cavity? Whats its main motor function?
Arises from the trigeminal sensory nuclei in the pons and travels to the trigeminal ganglion where it splits into the three branches. - Ophthalmic division passes through the superior orbital fissure - Maxillary division passes through foramen rotundum - Mandibular division passes through the foramen ovale - Provides innervation for muscles of mastication
What are the 3 branches of the Ophthalmic nerve? What does it innervate? How can it be tested?
- Frontal, Lacrimal and Nasociliary - Forehead, scalp, frontal and ethmoid sinuses, upper eyelid, cornea and dorsum of nose - Corneal reflex
What does the maxillary nerve innervate?
Lower eyelid, cheeks and maxillary sinus, nasal cavity and lateral nose, upper lip, upper teeth and their gingiva and superior palate of the mouth
What does the mandibular nerve innervate?
Floor of the oral cavity, external ear, lower lip, chin, general sensation of the anterior 2/3 of the tongue. Also supplies the muscles of mastication, anterior belly of digastric and mylohyoid muscles.
What can be caused by compression or damage to the trigeminal nerve?
Trigeminal neuralgia - severe facial pain described like an electric shock.
What is the path of the Abducens nerve? What does it innervate?
- Arises for the abducens nucleus of the pons and travels through the cavernous sinus before passing through the superior orbital fissure. - Innervates the Lateral rectus muscle
What is the path of the Facial nerve?
Arises from the pons and passes through the anterior acoustic meatus entering the facial canal. It then leaves the skull through the stylomastoid foramen
Name the 9 branches of the facial nerve. 1 in the facial canal, 3 between the stylomastoid foramen and the parotid and 5 in the parotid gland (To Zanzibar By Motor Car).
- Nerve to Stapedius - stapedius muscle in ear 2. Posterior auricular nerve - intrinsic and extrinsic muscles of the outer ear 3. Nerve to digastric - posterior belly of digastric muscle 4. Nerve to stylohyoid muscle - stylohyoid muscle 5. Temporal branch - Frontalis, obicularis oculi 6. Zygomatic branch - Obicularis oculi 7. Buccal branch - Obicularis oris, buccinator and zygomaticus muscles 8. Marginal Mandibular - Mentalis muscle 9. Cervical - Platysma
What is the sensory function of the Facial nerve?
The Chorda Tympani is responsible for the special taste innervation of the anterior 2/3 of the tongue
What is the parasympathetic function of the Facial nerve?
Innervation of the salivary and lacrimal glands
What is the difference between an intracranial and extracranial lesion of the facial nerve?
Extracranial lesions occur distal to the stylomastoid foramen and only effect motor function.
What is the route of the Vestibulocochlear nerve? Whats it responsible for?
- Vestibular component arises from the vestibular nuclei in the pons and medulla, Cochlear component arises from the cochlear nuclei, both fibres combine in the pons and exit the cranium through the internal acoustic meatus of the temporal bone. - Vestibular component responsible for balance, Cochlear component responsible for hearing
What is a Vestibular schwannoma and what problems can it cause?
Benign growth on the Vestibulocochlear nerve, can lead to hearing loss, tinnitus, balance issues.
What is the path of the Glossopharyngeal nerve? What is are the two nerves that arise from it and the 3 branches it terminates into? What do they innervate?
- Originates from the medulla and leaves the cranium through the jugular foramen 1. Tympanic nerve - Sensory innervation for middle ear, internal surface of tympanic membrane + eustachian tube. 2. Carotid sinus nerve - Innervates carotid sinus and body. 1. Pharyngeal branch - Innervates mucosa of oropharynx. 2. Lingual branch - General sensation to posterior 1/3 of the tongue. 3. Tonsillar branch - innervates palatine tonsils
What is the special sensory and parasympathetic function of the glossopharyngeal nerve?
- Taste sensation to posterior 1/3 of tongue - Parasympathetic innervation to the parotid gland
What are the two main parasympathetic functions of the Vagus nerve?
- Cardiac branches innervate the SAN and the AVN stimulating a reduction in heart rate - Innervates oesophagus, stomach and intestines up to the splenic flexure of the large colon, causes smooth muscle contraction and glandular secretion
What are the 5 main branches of the Vagus nerve?
- Pharyngeal Branches - Innervation to pharynx and soft palate. - Superior Laryngeal nerve - Internal and external branches, provide innervation to the larynx - Recurrent Laryngeal nerve - Hooks under right subclavian artery and innervates intrinsic muscles of larynx - Left Recurrent Laryngeal nerve - Hooks under arch of aorta and innervates intrinsic muscles of larynx - Cardiac branches - Regulate heart rate
What is the somatic and visceral innervation of the Vagus nerve?
Somatic - External ear and auditory canal Viceral - Laryngopharynx - Superior aspect of larynx - Heart - GI tract
What is the motor function of the Vagus nerve?
Innervation to the majority of muscles of the pharynx, soft palate and larynx
How will damage to the Vagus nerve present?
- Lack of gag reflex and difficulty swallowing due to involvement of pharynx muscles - Deviation of the uvula away from the affected side
What is the route of the Accessory nerve? What does it innervate?
- Arises from C1-C5 spinal root nerves, passes up through the foramen magnum and then back out through the jugular foramen - Innervates SCM and Trapezius
Whats the route of the Hypoglossal nerve? What does it innervate? How does damage present?
- Arises from the medulla oblongata and exits through the hypoglossal canal - Innervates muscles of the tongue - Tongue deviates towards damaged side
Describe the route of sympathetic innervation
Sympathetic fibres arise from T1-6 and enter the sympathetic trunk, extending from base of skull to the coccyx. There are three main ganglia, superior, middle and inferior, which are related to specific arteries of the head and neck, the post ganglionic fibres then ‘hitch hike’ along these arteries to their target organs.
What can cause damage to sympathetic fibres in the head and neck?
Damage to artery walls they travel along can cause stretch and damage to the sympathetic fibres
Where is the Superior Cervical Ganglion located? What does it innervate?
- Posteriorly to the carotid artery and anterior to the C1-4 vertebrae. - Internal and external carotids, Sweat glands of trigeminal dermatomes, Dilator pupillae, SM of Levitator palpebrae superioris, Nasal and Salivary glands
Where is the Middle Cervical Ganglion located? What does it innervate?
- Anteriorly to the inferior thyroid artery and C6 Vertebrae. - Lower larynx, Trachea, Upper oesophagus and hypo-pharynx
Where is the Inferior Cervical Ganglion located? What does it innervate?
- Anteriorly to the C7 vertebrae. - Travel along vertebral arteries to innervate the subclavian arteries + contribute to the cardiac plexus
What is Horner’s syndrome and what causes it? What is the triad of symptoms?
- Damage to sympathetic fibres caused by spinal cord lesions, traumatic injury or tumour of lung apex. Triad of symptoms: 1. Partial ptosis - due to paralysis of superior tarsal muscle 2. Meiosis - constriction of pupil due to paralysis of dilator pupillae 3. Anhydrosis - decreased sweating due to loss of sweat gland innervation
Which 4 cranial nerves carry parasympathetic innervation?
- Oculomotor CN III 2. Facial CN VII 3. Glossopharyngeal CN IX 4. Vagus CN X
What are the 4 peripheral ganglions of the head and neck?
- Ciliary 2. Otic 3. Pterygopalatine 4. Submandibular
Where is the Ciliary ganglion located? Where does it receive its parasympathetic fibres from? What does it innervate?
- Within bony orbit - From the Edinger-Westphal nucleus (associated with oculomotor nerve) - Sphincter pupillae muscle (contraction of pupil) + ciliary muscles (contraction causes lens to relax for close sight)
Where is the Pterygopalatine ganglion located? Where does it receive its parasympathetic fibres from? What are the target organs?
- Pterygopalatine fossa inferior to base of skull - From the Facial nerve, postganglionic fibres hitch hike on maxillary nerve - Lacrimal gland, mucous glands of nasal cavity, nasopharynx and palate
Where is the Submandibular ganglion located? Where does it receive its parasympathetic fibres from? What are the target organs?
- Suspended from the lingual nerve - Facial nerve in Chorda Tympani (Taste ant 2/3 tongue) - Submandibular and sublingual salivary glands
Where is the Otic ganglion located? Where does it receive its parasympathetic fibres from? What is the target organ?
- Inferiorly to the foramen ovale - Glossopharyngeal nerve, then hitch hike along auriculotemporal nerve (Branch of mandibular) - Parotid gland
