Head and Neck Flashcards
Where does sternocleidomastoid attach?
From lateral mastoid process to anterior manubrium of sternum and to superior aspect of medial clavicle
What nerve innervates sternocleidomastoid and trapezius?
Spinal accessory nerve CN XI
What are the borders of the posterior triangle?
Anterior - Posterior border of sternocleidomastoid Posterior - Anterior border of trapezius Inferior - medial third of the clavicle Floor - paravertebral fascia Roof - investing fascia
What are the main contents of the posterior triangle?
Accessory nerve
External jugular vein
Subclavian artery and vein
Transverse cervical artery and vein
What are the subdivisions of the posterior triangle?
Inferior head of omohyoid muscle splits it into Occipital triangle superiorly and subclavian triangle inferiorly
What are the borders of the anterior triangle?
Superior - inferior border of madible
Lateral - Medial border of SCM
Medial - midline of neck
What are the different subdivisions of the anterior triangle?
Carotid, submandibular, submental, muscular
What are the borders of the carotid triangle?
Superior - Posterior belly of digastric muscle
Inferior- Superior belly of omohyoid muscle
Lateral - Medial border of SCM
What are the borders of the submental triangle?
Floor - Mylohyoid bone
Lateral - Anterior belly of digastric muscle
Medial - midline of neck
Inferior - hyoid bone
What are the borders of the submandibular triangle?
Anterior - anterior belly of digastric muscle
Posteriorly - Posterior belly of digastric muscle
Superior - body of mandible
What are the borders of the muscular triangle?
Superolateral - Superior belly of omohyoid muslce
Inferolateral - Medial SCM
Superior - Hyoid bone
Medial - midline of neck
What are the different divisions of the deep fascia of the neck?
Prevertebral, pretracheal and investing
What is contained in the carotid sheath?
Internal jugular vein Common carotid then internal carotid artery Vagus nerve Deep cervical lymph nodes Carotid sinus nerve Sympathetic nerve fibres
If there’s infection in the retropharyngeal space, where can it spread to?
Down into thorax and mediastinum
At what vertebral level does the common carotid artery bifurcate?
C4
What are the names of the 4 suprahyoid muscles and what are their actions?
Digastric - (facial) elevates and steadies the hyoid
Stylohyoid (facial) elevates and retracts hyoid
Geniohyoid (hypoglossal) Widens pharynx. pulls hyoid anterosuperiorly
Mylohyoid (nerve to) Elevates hyoid, tongue and floor of mouth
What are the 4 infrahyoid muscles and what are their actions?
Omohyoid (C1-C3) Depresses, retracts and steadies hyoid
Sternohyoid (C1-C3) Depresses hyoid after elevation
Thyrohyoid (hypoglossal) depresses hyoid and raises larynx
Sternothyroid (C2, C3) Depresses hyoid and larynx
What are the four main layers of the neck?
Skin
Superficial fascia
Platysma muscle (anteriorly)
Deep cervical fascia
What is contained in the superficial fascia?
Fatty connective tissue Cutaneous nerves Vasculature Lymphatic vessels Platysma
What are the three layers of the deep cervical fascia?
Investing
Pre tracheal
Pre vertebral
What does the investing layer of fascia in the neck contain?
Encloses sternocleidomastoid and trapezius muscles.
Contains parotid and submandibular salivary glands
What are the attachments of the investing layer of fascia in the neck?
Ligamentum nuchae Mastoid process Zygomatic arches Inferior mandible Hyoid bone Spinous process of C7 vertebrae
Where is the investing layer of fascia, in relation to the platysma muscle?
Posterior
Where does the pretracheal layer of fascia in the neck run from and to?
From inferior hyoid bone to the superior thorax where it fuses with the pericardium
What does the pretracheal layer of fascia in the neck contain?
Visceral part contains the trachea, thyroid gland and oesophagus.
Muscular part encloses the infrahyoid muscles
What’s the purpose of the thickenings of the pretracheal fascial layer in the neck?
Thickens to form a trochlea through which the intermediate tendon of the digastric muscle can pass and suspend the hyoid bone.
Tethers the omohyoid muscle
Where does the prevertebral fascial layer in the neck run from and to?
From the cranial base and then down to where it fuses with the endothoracic fascia peripherally and with the anterior longitudinal ligament at the level of T3, centrally
What does the prevertebral fascial layer extend laterally to form?
Axillary sheath, containing axillary vessels and the brachial plexus.
Where does the carotid sheath fuse with other fascial layers?
Anteriorly with the investing and pretracheal fascial layers and posteriorly with the prevertebral layer
What structures does the carotid sheath communicate with, inferiorly and superiorly?
Along with the pretracheal fascia, communicates superiorly with the cranial cavity and inferiorly with the mediastinum. This is important in the spread of infections and blood.
What is the retropharyngeal space?
Potential space between the prevertebral and visceral pretracheal fascial layers in the neck.
What is the alar fascia?
A subdivision of the retropharyngeal space. Runs from the cranium to C7 and extends laterally to the carotid sheath.
What is the purpose of the retropharyngeal fascia?
To allow movement of viscera, relative to the vertebral column on swallowing.
Where does the retropharyngeal space open?
Into the superior mediastinum
From where do most infections in the retropharyngeal space originate?
Nasopharyngeal lymph nodes, especially in children
Where is the parapharyngeal space?
Lateral to the pharynx, anterior to the carotid sheath and medial to the parotid gland
From where do infections in the parapharyngeal space most often originate?
The teeth or parotid gland. Spread to the mediastinum
From where does the right common carotid artery originate?
From the right brachiocephalic trunk
Where do the common carotids bifurcate?
At superior border of the thyroid cartilage, roughly level with C4
Where does the internal carotid artery enter the cranium?
At the carotid canal, anterior to the jugular foramen
Where is the thyrocervical trunk?
Arises from the subclavian artery, distal to the vertebral artery. Arises near the anterior border of the anterior scalene muscle
What are the four branches of the thyrocervical trunk?
Inferior thyroid
Ascending cervical
Transverse cervical
Suprascapular
What does the inferior thyroid artery innervate?
Larynx, trachea, oesophagus, thyroid, parathyroids, and their accompanying muscles.
What does the suprascapular artery supply?
Minor supply to sternocleidomastoid
Subclavius muscle
What’s an anatomical variant of place of origin of the suprascapular artery?
From thyrocervical trunk or direct from the subclavian artery
What does the transverse cervical artery supply?
Sternocleidomastoid
Trapezius
Vasovasorum of brachial plexus nerves after branching into superficial cervical artery and dorsal scapular artery
What does the ascending cervical artery supply?
Upper lateral muscles of the neck
SOme branches to intervertebral foramina
Where do the vertebral arteries originate?
From subclavian artery, medial to anterior scalene muscle.
Where do the vertebral arteries travel from their origin?
Up the back of the neck, through the transverse foramina of C6-C1 and then enter the cranial cavity through the foramen magnum. They then merge to form the basilar artery
What are the main branches of the external carotid artery?
Superior thyroid Occipital Maxillary Facial Lingual Ascending pharyngeal SUperficial temporal Posterior auricular
What happens if there’s a rupture of the middle meningeal artery due to a pterion fracture?
Can cause an extradural haemorrhage
What’s the embryological origin of muscles of facial expression?
Second pharyngeal arch
What cranial nerve supplies the muscles of facial expression?
Facial - CN VII and its branches: temporal, zygomatic, buccal, marginal mandibular and cervical
What’s the only muscle in the epicranial group of muscles of facial expression?
Occipitofrontalis. Flat digastric muscle with two bellies joined by epicranial aponeurosis
What’s the action of occipitofrontalis?
Raises eyebrows and wrinkles forehead
What are the muscles in the orbital group of muscles of facial expression?
Orbicularis oculi
Corrugator supercilii
What are the divisions of orbicularis oculi?
Orbital group more peripheral and thicker. Closes eyelids firmly and is under voluntary control
Palpebral portion is more central and thinner. Closes eyelids gently and isn’t under voluntary control
Lacrimal portion compresses lacrimal sac to aid the passing of tears
What’s the function of corrugator supercilii?
Draws eyebrows infermedially
What are the main nasal muscles of facial expression?
Nasalis
Procerus
Levator labii superioris alaeque nasi
What’s the main function of the nasal muscles of facial expression?
Flare nostrils.
Procerus also lowers eyebrows
What muscles are in the oral group of muscles of facial expression?
Buccinator Obicularis oris Mentalis Zygomaticus major and minor Risorius Depressor anguli oris Platysma
What’s the action of the buccinator muscle?
Presses cheeks against molar teeth and resists distension when blowing.
What’s the action of obicularis oris?
Oral sphincter. Purses lips and provides attachment for various muscles.
What’s the action of zygomaticus major and minor?
Dilators of the mouth that elevate the lip. If bilateral, helps produce a smile. If unilateral, produces a sneer
What’s the purpose of risorius?
Retracts the angle of the mouth to help with smiling.
Where does the risorius muscle arise?
From fascia covering the parotid gland
What’s the action of depressor anguli oris?
Dilator of the mouth that pulls the corners of the lips down
What’s the action of the mentalis muscle?
Protrudes the lower lip. Also wrinkles chin skin.
What’s the action of platysma?
Depresses and tenses the skin of the lower face and mouth. Aids in depression of the mandible.
Which muscles lie under the prevertebral fascia to form the floor of the posterior triangle of the neck?
Anterior, middle and inferior scalene muscles
Splenius capitis
Levator scapulae
Which vessels form the external jugular vein?
Retromandibular and posterior auricular veins
Where in the posterior triangle do the suprascapular and transverse cervical arteries run?
Along the base of the triangle
What happens if the external jugular vein is ligated?
Its lumen is kept patent by the thick, tough layer of investing fascia. Air is drawn into the vein so this can form a froth and therefore cause central cyanosis. To prevent this, pressure must be applied to the vein.
Where does the accessory nerve lie in the posterior triangle?
After innervating sternocleidomastoid, it crosses the traingle in an oblique, inferoposterior direction, within the investing layer of fascia. Therefore it is relatively superficial and prone to injury.
Where in the neck does the phrenic nerve pass?
Part of the cervical plexus which forms within the muscles of the floor of the posterior triangle. Arises from C3-C5 and then travels down the neck, within the prevertebral fascia, to innervate the diaphragm.
How is a cervical plexus nerve block performed?
Performed to numb the neck. Anaesthesia is injected along the posterior border of sternocleidomastoid, at the junction between it’s superior and middle thirds, as this is where the cutaneous branches of the cervical plexus emerge. (nerve point)
In what group of people should a cervical plexus nerve block not be performed?
In patients with cardiac or pulmonary problems as the block damages the phrenic nerve
What are the contents of the anterior triangle?
Infrahyoid muscles Supra hyoid muscles Common carotid artery and bifurcation into external and internal carotids Internal jugular vein Facial nerve (VII) Glossopharyngeal nerve (IX) Vagus nerve (X) Accessory nerve (XI) Hypoglossal nerve (XII)
What are the main contents of the carotid triangle?
Common carotid artery and bifurcation into internal and external carotids Internal jugular vein Vagus nerve (X) Hypoglossal nerve (XII)
What forms the base of the submental triangle?
Mylohyoid muscle. Runs from hyoid bone to body of mandible
What are the contents of the submandibular triangle?
Submandibular salivary gland
Submandibular lymph nodes
Facial artery
Facial vein
What are the contents of the muscular triangle?
Infrahyoid muscles
Pharynx
Thyroid gland
Parathyroid glands
What kind of connective tissue are deep and superficial fascia?
Superficial is loose connective tissue
Deep fascia is dense irregular connective tissue
What are the purposes of fascial planes?
Division into compartments
Ease of movement against other structures eg in swallowing
Forms natural planes
Determines spread of infection
Where do the heads of the platysma muscle originate?
Pectoralis major and deltoid muscle. Meet in midline and fuse with facial muscles
What are the attachments of the investing layer of fascia?
Superior - External occipital protuberance, superior nuchal line
Inferior - Spine of scapular, acromion, manubrium, clavicle
Lateral - Mastoid process, zygomatic arch
What other fascial layer helps to contribute to the posterior portion of the muscular pretracheal fascia layer?
Buccopharyngeal fascia
What are the attachments of the prevertebral layer of fascia?
Anteriorly attaches to vertebral bodies and transverse processes of cervical vertebrae
Posteriorly, attaches along the ligamentum nuchae
What stops a superficial skin abscess of the neck spreading further into the neck?
The investing layer of fascia
What are the two main locations, deep to investing fascia where an infection could be particularly problematic?
Posterior to the prevertebral fascia.This can errode through the prevertebral fascia, into the retropharyngeal space. This extends into the thorax so the drainage of pus can lead to infection of mediastinal contents.
Between investing fascia and visceral pretracheal. Infections can spread into the chest, causing infection anterior to the pericardium
What are the four suprahyoid muscles?
Mylohyoid
Geniohyoid
Digastric
Stylohyoid
What are the attachments of stylohyoid?
From styloid process of temporal bone to lateral side of hyoid bone
What innervates stylohyoid?
Facial nerve (CN VII)
What are the actions of stylohyoid?
Initiates swallowing by pulling the hyoid posteriorly and superiorly
What are the attachements of digastric?
Anterior belly originates from the digastric fossa of the mandible
Posterior belly originates from mastoid process. Both are joined by a tendon that’s attached to the hyoid bone
What innervates diagastric?
Anterior belly innervated by trigeminal nerve (CN V)
Posterior belly innervated by facial nerve
What are the actions of digastric?
Depresses mandible and elevates hyoid
What are attachments of mylohyoid?
Mylohyoid line of mandible to hyoid bone
What is mylohyoid innervated by?
Trigeminal nerve
What are the actions of mylohyoid?
Elevates the floor of the mouth and the hyoid bone
What are the attachments of geniohyoid?
Inferior mental spine of mandible to the hyoid.
What is geniohyoid innervated by?
C1 roots that run with the hypoglossal nerve
What are the actions of geniohyoid?
Depresses mandible and elevates hyoid
What are the four infrahyoid muscles?
Omohyoid
Sternohyoid
Sternothyroid
Thyrohyoid
Which two infrahyoid muscles are deeper?
Thyrohyoid and sternothyroid
What are the attachments of sternohyoid?
Sternum and sternoclavicular joint to hyoid bone
What are the actions of the infrahyoid muscles?
All act to depress the hyoid. If the hyoid is fixed, then thyrohyoid can also elevate the larynx
What supplies the infrahyoid muscles?
All supplied by the anterior rami of C1-C3, carried by a branch of ansa cervicalis
EXCEPT for thyrohyoid. This is supplied by anterior ramus of C1, carried within the hypoglossal nerve
What are the attachments of omohyoid?
Inferior belly arises at scapula. Superior belly attaches to hyoid. Joint in the middle by a tendon which is attached to clavicle by the deep cervical fascia, deep to sternocleidomastoid
What are the attachments of thyrohyoid?
Thyroid cartilage to hyoid bone
What are the attachments of sternothyroid?
Manubrium of sternum to thyroid cartilage
What is the function of the skull?
To enclose and protect the brain and special sense organs
Site of attachment for muscles and meninges
What kind of joints are the sutures of the skull?
Fibrous
What is the structure of cranial bones?
Two layers of compact bone surrounding a spongy diploe
How can the cranium be subdivided?
Calvaria which covers the cranial cavity that contains the brain
Cranial base
Facial skeleton
What are the main components of the calvaria?
Parietal Frontal Temporal Occipital Ethmoid
What are the main components of the cranial base?
Spenoid
Temporal
Occipital
What are the main facial bones?
Maxilla Nasal Lacrimal Palatine Zygomatic Inferior nasal conchae Vomer
What is the glabella?
Depression between the two superciliary arches of the frontal bone
Where is the supraorbital foramen?
The medial part of the superior orbital rim, formed by the frontal bone
What separates the paired nasal bones?
The naison
What is the piriform aperture?
Large opening in the nasal region
What structures can be visualised through the piriform aperture?
Nasal crests which end anteriorly as the anterior nasal spine
What’s the name of the inferior part of the maxilla, where teeth start?
Alveolar process
Where is the infraorbital foramina? m
Just below the inferior rim of the orbit, in the maxillary bone
What is the mental protuberance?
A midline swelling of the base of the mandible
Where are the mental tubercles?
Just lateral to the mental protuberance of the mandible
Where does the mandible articulate with the rest of the skull? ?
At the temporomandibular joint.
Coronoid process of mandible comes into contact with zygomatic bone
Which parts of the mandible unite at the angle of the mandible?
Anterior body and posterior ramus
What is the oblique line of the mandible?
A ridge that runs from the front of the ramus to the body for muscle attachment
What are some notable features of the ethmoid bone?
Horizontal cribriform plate with crista galli perpendicular to this. Also has oblique plate containing ethoid sinuses/ air cells and a perpendicular plate
What are some notable features of the sphenoid?
Has lesser wings superiorly and greater wings inferiorly. Point where these meet is a supraorbital fissure.
Also has downward projecting pterygoid process
What features are found on the internal surface of the parietal bone?
Groove for middle meningeal artery
Sagittal sulcus
Granular pits for CSF valves
Grooves for sigmoid sinus
What are some notable features of the temporal bone?
Flat squamous part superiorly, articulates with parietal bone
Zygomatic process that projects out laterally and articulates with temporal process of zygomatic bone
Styloid process projecting inferiorly
Mastoid part articulates with parietal and occipital bones. Mastoid process projects inferiorly from mastoid part
Tympanic part is immediately below origin of zygomatic process and has external acoustic opening
What are some notable features of the occipital bone?
Flat squamous part.
Superior and inferior nuchal lines either side of the external occipital crest.
Occipital condyles surrounding the foramen magnum with hypoglossal canal lateral to these condyles
What is the purpose of the cranial floor foramina?
TO reduce skull weight
To allow passage of vessels
Weaken cranial floor
What structures enter through the cranial floor foramina?
Arteries
Sensory nerves
Sympathetic fibres
(infections)
What structures leave through the cranial floor foramina
Cranial motor nerves Parasympathetic outflow Veins Lymphatics (Infections)
Where is the transverse suture?
Between the hard palate of the maxilla and the hard palate of the palatine bone
Where is the sagittal suture?
Between two parietal bones
Where is the coronal suture?
Between the frontal and parietal bones
Where is the pterion?
Point where greater wing of sphenoid, parietal, temporal and frontal bones meet
Where is the lamboid suture?
Between the parietal and occipital bones
Where is the parietotemporal suture?
Also squamous suture. Between parietal bone and squamous part of temporal bone
What is the bregma?
Point where the coronal and sagittal sutures meet
What is the lamba?
Point where sagittal and lamboid sutures meet
What are the remnants of the anterior and posterior fontanelles?
Anterior becomes bregma
Posterior becomes lambda
What is the purpose of fontanelles in newborns?
Points where sutures haven’t fully close. Adjacent bones are held together by a thick, membranous connective tissue matrix. They allow for the cranial bones to be pushed together and interlock via their serrated edges in labour, to protect the brain. Can be too wide to interlock in preterm births, however.
What are some of the typical features of a cervical vertebra?
Bifid spinous process
Transverse foramina for passage of vertebral arteries
Pedicle joining transverse process to body
Which cervical vertebrae are atypical?
C1 - has no spinous process of body
C2 - has large odontoid peg for articulation with C1
C7 - prominent, non bifid spinous process
large transverse process.
Where is the lacrimal bone?
Anteromedial wall of orbit
What are the two surfaces of the lacrimal bone?
orbital surface
Nasal surface
What are some notable features of the lacrimal bone?
On orbital surface has a vertical lacrimal crest with a lacrimal sulcus that runs anterior. The sulcus is continuous with the frontal process of the maxilla and this forms the lacrimal fossa where the lacrimal sac is found
Where is the palatine bone?
At posterior nasal cavity between the maxilla and the pterygoid process of sphenoid
Where is the skull vulnerable to fracture?
Squamous parts of temporal and parietal bones
Foramen magnum and inner sphenoid wing
Middle cranial fossa
Posterior cranial fossa
What is a depressed fracture?
A local indentation due to a sever localised blow. Bone fragment may compress or injure underlying brain
What is a linear fracture?
Fracture lines radiating away from point of impact in more than two directions. Often due to skull vault trauma
What is a comminuted fracture?
Where bone is broken into several pieces
What is a counterblow fracture?
Where fracture occurs at the opposite side of the cranium
What is a simple fracture?
Where there’s a break in the bone but no break in the skin
What is a compound fracture?
Where there’s break in or loss of skin and splintering of the bone. Accompanied by brain injury and bleeding
What is a basillar fracture?
Fracture of base of skull which can cause extravasation of blood along the path of the posterior auricular artery so presentation may be with battle’s sign/ mastoid ecchymosis
What are some symptoms of skull fracture?
Bleeding from wound, nose, ears of eyes COnfusion Dizziness Drowsiness Convulsions Bruising Draining of CSF from nose or ears Balance difficulties Headache Loss of consciousness Nausea/vomiting Visual disturbances Stiff neck Slurred speech
How can infections from scalp cause osteomyelitis?
Can spread through emissary and diploic veins
What are facial fractures most commonly caused by?
Car accidents, fist fights and falls
What is the most common facial fracture?
Of nasal bones
What can happen if there’s a hard blow to the lower jaw?
Neck of mandible can fracture with dislocation from the temporomandibular joint
What causes a black eye?
Skin bruising around orbit and accumulation of blood and tissue fluid in the surrounding connective tissue
What is malar flush?
Reddening of the skin over the zygomatic bones
What is a burst fracture?
Fracture of arches of C1. Often due to head first fall from a height
What is a hangmans fracture?
Fracture of C2 due to hyperextension of the head
What can happen as a result of a dens fracture?
If it’s displaced then may injure the spinal cord, causing quadriplegia or, if it damages brain stem, will be fatal
Why are cervical vertebrae prone to dislocation?
Due to the way that they are stacked on top of one another, can easily slip out of position.
Why may dislocation of cervical vertebrae not necessarily damage spinal cord?
Due to the large cervical canal, there’s room for manoeuvre
What changes to cervical vertebrae occur with age?
Intervertebral foramina narrow
What can happen if there’s hyperflexion of the neck?
Rupture of the lower cervical intevertebral discs, resulting in nerve root compression so can cause neck, should, arm and hand pain
What can happen if there’s hyperextension of the neck?
Can tear the anterior and posterior longitudinal ligaments, fracture of spinous processes, disc rupture and injury of muscles and blood vessels.
Where are the zygopophyseal joints?
Between articular facets of vertebrae
What can happen if there’s arthritis in zygopophyseal joints?
May be osteophyte formation. Osteophytes may affect spinal nerves, causing pain along their dermatomes and muscle spasm of corresponding myotome
What are the most common sites of cervical spine injury?
C2, C6, C7
Injuries at which spinal levels may be fatal?
C1-2
Which vessels make up the upper systemic vascular loop?
Common carotid arteries
Vertebral arteries
Internal, external and anterior jugular veins
What’s the arrangement of the main structures within the carotid sheath?
Internal jugular vein lies lateral to the common carotid artery
Vagus nerve lies posterior to both
What structure lies posteromedial to the carotid sheath?
The sympathetic trunk
Behind which anatomical structure does the right common carotid artery originate?
From brachiocephalic trunk, behind the right sternoclavicular joint
Between which anatomical structures do the common carotids bifurcate?
Midway between the angle of the mandible and the mastoid process of the temporal bone. Good landmark is the upper border of the thyroid cartilage (C4)
What bifurcation occurs within the parotid gland?
That of the external carotid artery into the maxillary artery and the superficial temporal artery
What structures run through the parotid gland?
External carotid into superficial temporal and maxillary
Retromandibular vein
Facial nerve
What are the different layers of the scalp?
Skin Loose connective tissue Aponeurosis Loose connective tissue Periosteum
Why can a laceration to the epicranial aponeurosis cause profuse bleeding?
Joins two bellies of occipitofrontalis which will then pull in opposing directions and form a gaping wound
What is the arterial supply to the dura mater and the skull?
Both supplied by middle meningeal artery via the maxillary artery
What is the distribution of the facial artery?
Supplies muscles of facial expression and the face
What is the distribution of the superior labial artery?
Supplies upper lip and the ala and septum of the nose
What is the distribution of the inferior labial artery?
Lower lip
What is the distribution of the maxillary artery?
Deep structures of the face
What is the distribution of the lateral nasal artery?
Skin of the ala and bridge of nose
What is the distribution of the angular artery?
Superior cheek and inferior eyelid
What is the distribution of the transverse facial artery?
Facial muscles and skin of temporal and frontal regions
What is the distribution of the supratrochlear and supraorbital arteries?
Muscles and skin of forehead
Scalp
Superior conjunctivae
What are the 8 main branches of the external carotid artery?
Ascending laryngeal Superior thyroid Occipital Maxillary Superficial temporal Facial Lingual Posterior auricular
What veins unite to form the external jugular vein?
Occipital
Retromandibular
Superficial temporal
Posterior auricular
Where does the formation of the external jugular vein occur?
Just posterior to the angle of the mandible and inferior to external ear
How can infections of scalp cause meningitis?
Veins in scalp connect to diploic veins via valveless emissary veins. Diploic veins drain into dural venous sinuses so infection can easily spread
What are dural venous sinuses?
Endothelium lined spaces between the periosteal and meningeal layers of the dura. Form at dural septae and receive blood from large veins draining the brain
What are the main dural venous sinuses?
Sigmoid
Inferior and superior sagittal sinuses
Cavernous sinus
Transverse sinus
What is the cavernous sinus?
A plexus of extremely thin walled veins on the supper surface of the sphenoid bone.
What is also located in the space where the cavernous sinus is located?
Internal carotid artery
Cranial nerves 3,4,6 and 5a and b
Where is the pterygoid plexus?
Between temporalis and lateral pterygoid and partly between the two pterygoid muscles
What is the function of secondary lymphoid organs?
To maintain lymphocytes
Involved in adaptive immune response
What are the main secondary lymphoid organs?
Tonsils
Spleen
Lymph nodes
MALT
Where do lymphatic vessels join the systemic circulation?
At right or left subclavian vein
Where in the body are the highest densities of lymphatic structures?
Groin
Head and neck
Axilla
What are the two main ducts that lymph nodes drain into?
Right lymphatic duct drains right side of head, neck, arm and trunk.
Thoracic duct drains rest of the body
Where does the thoracic duct arise?
From cisterna chyli on the right of L2. Then crosses the midline at T5
What does intestinal lymph do?
AKA chyle. Carries fat absorbed from the digestive tract to the cisterna chyli
What can cause swelling of lymph nodes?
Physiological response to infection
Lodging and proliferation of cancerous cells
What is lymphoma?
Cancer of lymphocytes or immune cells
What are the 13 main regional groups of lymph nodes in the head and neck?
occipital Post auricular Pre auricular Anterior cervical Posterior cervical Submental Submandibular Parotid Buccal Laryngeal Tracheal Sublingual Retropharyngeal
What is the terminal group that lymph nodes of the head and neck drain into?
Deep cervical. Closely related to carotid sheath
What would be the consequence of removing spinal accessory lymph nodes?
Closely related to spinal accessory nerve so can be damaged in surgery, causing weakness of trapezius and sternocleidomastoid
Which lymph node is commonly enlarged in oral cancer?
Jugulo-omohyoid
Where is virchow’s node and what is its relevance?
Left supraclavicular node - often swollen in gastric cancer
If there’s cancer in cervical lymph nodes, what structures are removed in surgery?
Lymph nodes
Internal jugular vein
Submandibular salivary gland
What are the boundaries of the temporal fossa?
Posterior and superior - temporal lines of skull
Anterior - Frontal and zygomatic bones
Inferior - Infratemporal crest
Lateral - zygomatic arch
What bones form the floor of the temporal fossa?
Greater wing of sphenoid
Frontal
Temporal
Parietal
What is contained within the temporal fossa?
Superior part of temporalis muscle
What are the boundaries of the infratemporal fossa?
Superior - Infratemporal surface of greater wing of sphenoid
Inferior - Attachment of medial pterygoid to the mandible, near it’s angle
Lateral - Ramus of mandible
Medial - Lateral pterygoid plate of sphenoid
Anterior - Posterior aspect of maxilla
Posterior - Tympanic plate, mastoid and styloid processes of temporal bone
What is contained within the infratemporal fossa?
Inferior part of temporalis
Maxillary artery
Inferior medial and inferior lateral pterygoids
Pterygoid venous plexus
Otic ganglion
Mandibular, inferior alveolar, lingual, buccal and chorda tympani nerves
What arteries can be found in the infratemporal region?
Maxillary
Superficial temporal
Middle meningeal
What veins can be found in the infratemporal region?
Maxillary
Middle meningeal
What are some openings of the infratemporal fossa?
Foramen ovale for mandibular nerve Foramen spinosum for middle meningeal artery Alveolar canal Inferior orbital fissure Pterygomaxillary fissure
What is involved in a mandibular nerve block?
Anaesthesia is injected near to foramen ovale of infratemporal fossa, near where mandibular nerve enters. Affects inferior alveolar, lingual, buccal and auriculotemporal nerves
What is involved in an inferior alveolar nerve block?
Anaesthesia is injected near to the mandibular foramen. Anaesthetises all mandibular teeth of that side Skin and mucous membranes of lower lip Labial alveolar mucosa Gingivae Skin
What kind of joint is the temporomandibular joint?
Modified hinge synovial joint
What is unique about the structure of the TMJ, compared to other synovial joints?
Has an articular disk which splits synovial cavity into two. This means that the articulating bones never come into contact with each other. Bones are also covered in fibrocartilage, rather than hyaline.
What are the articulating surfaces of the TMJ?
Head of mandible Mandibular fossa (posterior) Articular tubercle (anterior)
What is involved in elevation of the TMJ (closing the mouth)?
There’s retraction of the mandible (uses superior compartment) by action of posterior part of temporalis)
Elevation of the mandible which uses the rest of temporalis, masseter and medial pterygoid muscles
What is involved in depression of the TMJ (opening the mouth)
Condyles are pushed forward using lateral pterygoid muscle/
Chin is moved down and back which mostly uses gravity, however, if there’s resistance, uses digastric, geniohyoid and mylohyoid.
What’s involved in gliding movements of the TMJ?
Uses superior compartment
Protrusion uses lateral pterygoid, medial pterygoid and masseter
Retrusion uses temporal and masseter muscles
What’s involved in rotation movements of the TMJ?
Occurs in inferior compartment
Uses ipsilateral temporalis
Contralateral pterygoids
Masseter muscle
What are the attachments of the TMJ capsule?
Attaches superiorly to mandibular fossa and articular tubercle
Infeirorly to neck of condyle of mandible
What are the main 3 extracapsular ligaments of the TMJ?
Lateral temporomandibular ligament which blends with the joint capsule
Stylomandibular ligament is thickening of parotid fascia. Runs from styloid process to angle of mandible
Sphenomandibular ligament from spine of sphenoid to lingula of mandible.
What stops the TMJ from dislocating posteriorly?
The laterla extracapsular ligament
What supports the weight of the the TMJ?
Facial muscle and stylomandibular ligament.
How can yawning cause dislocation of TMJ?
Wide opening can cause excessive contraction of the pterygoids so that the head of the mandible is dislocated anteriorly to in front of articular tubercles
What nerves are vulnerable to injury in a neck of mandible fracture?
Facial and auriculotemporal nerves
What are the different classifications of cranial nerves?
General somatic efferent General somatic afferent General visceral efferent General visceral afferent Special visceral efferent Special visceral afferent Special somatic afferent
What do special visceral efferent nerves do?
Supply muscles derived from branchial arches. Supplied by Cn V, VII, IX, X
What do special visceral afferent nerves do?
Taste
What do special somatic afferents do?
Equilibration, hearing and sight
Where does parasympathetic outflow come from?
Cranial nerves III, VII, IX, X
S2-S4
At which ganglion does the oculomotor nerve terminate at?
Ciliary ganglion
Where is the ciliary ganglion?
Located in orbital cavity, just lateral to the optic nerve
Where does the ciliary ganglion get its sympathetic fibres from?
Superior cervical ganglion via a plexus on opthalmic artery
What do sympathetic fibres of ciliary ganglion go on to innervate?
Eye. Sensory fibres from eyeball then go to nasociliary nerve
Which ganglia does the facial nerve terminate at?
Pterygoplatine ganglion via greater pertrosal nerve
Submandibular ganglion via branch of chorda tympani
Where is the pterygopalatine ganglion?
Within pterygopalatine fossa
Where does the pterygopalatine ganglion get its sympathetic fibres from?
Superior cervical ganglion via plexus on internal carotid artery
What do sympathetic fibres from pterygopalatine ganglion go on to innervate?
Nose
Palate
Nasopharynx
Sensory fibres from these go via CNVii
Where is the submandibular ganglion?
Suspended from the lingual nerve
Where does the submandibular ganglion get its sympathetic fibres from?
Superior cervical ganglion via branches along the facial artery
What do sympathetic fibres from submandibular ganglion go on to innervate?
Glands in the floor of the oral cavity
Where are neurons of the vagus nerve found?
Preganglionic neurones start at the dorsal vagal motor nucleus. Then synapse in the walls of their target organs at laryngopharynx, larynx, oesophagus, trachea
Where do sympathetic nerves originate?
T1-L2
Where do preganglionic sympathetic neurones synapse?
Mostly in paravertebral chain but may be at prevertebral chain
Where is the prevertebral chain?
Anterior to the vertebral bodies, either near to abdominal aorta at point on mesenteric arteries, or carotids
What is the distribution of sympathetic ganglia?
2/3 cervical
11 thoracic
4 lumbar
4 sacral
Along which kind of nerves do sympathetic nerves to somatic targets follow?
Along segmental nerves
Along what, do sympathetic nerves to visceral targets follow?
Along ganglionated trunks
Where does the head and neck get its sympathetic supply from?
Sympathetic trunk which runs anterolateral to the vertebral column, within the prevertebral fascia and deep to carotid sheath. This then synapses as 3 cervical ganglions
Where does the superior cervical ganglion run?
Along internal and external carotid arteries and their brances to C1-C4, pharyngeal plexus and along a cardiac branch to a cardiac plexus
What does the superior cervical ganglion go on to supply?
Somatic supply of sweat glands
Visceral supply to dilator pupillae, smooth muscle part of levator palpebrae superioris, nasal glands, salivatory glands
Where does the middle cervical ganglion run?
Anterior to inferior thyroid artery to C5-C6, a cardiac branch to cardiac plexus
What does the middle cervical ganglion go on to supply?
Lower larynx
Trachea
Hypopharynx
Upper oesophagus
Where does the inferior cervical ganglion run?
Passes with vertebral artery to C7-C8 and a cardiac branch to cardiac plexus. Also, in 80% of people, it combines with the thoracic ganglion to form the stellate ganglion
What forms the internal carotid plexus?
Internal carotid nerve that ascends along the internal carotid artery, alongside the superior cervical ganglion
What is supplied by sympathetic outflow from the internal carotid plexus?
Pterygopalantine ganglion CNVI CNIX CNIII CN IV Opthalmic nerve Vessels from internal carotid artery
What causes horner’s syndrome?
Injury to the sympathetic trunk so sympathetic outflow is interrupted
What are the symptoms of horner’s syndrome?
Miosis due to unopposed parasympathetic innervation of sphincter pupillae
Ptosis due to paralysis of the superior tarsal muscle, which is made up of smooth muscle fibres from levator palpebrae superioris
Vasodilatation causing reddening and increased temperature of the face due to loss of sympathetic tone
Anhydrosis due to lack of innervation of sweat glands
What drives the formation of the neural tube?
Notochord drives thickening of the ectoderm overlying it
What are pharyngeal arches?
System of mesenchymal proliferation that forms in the neck region of the embryo
What are the derivatives of the first pharyngeal arch?
Muscles of mastication Mylohyoid Anterior belly of digastric Tensor tympani Tensor veli paltine
What cranial nerve is associated with the first pharyngeal arch?
CNV - trigeminal.
What cartilage system derives from the first pharyngeal arch?
Meckel’s cartilage. Gives rise to malleus and incus bones and the sphenomandibular ligament.
Also provides the template for the mandible which later forms through membranous ossification
What is the blood supply to the first pharyngeal arch?
Common, external and internal carotids and their branches
What are the derivatives of the second pharyngeal arch?
Muscles of facial expression
Posterior belly of digastric
Stapedius
Stylohyoid
What cartilage system is derived from the second pharyngeal arch?
Reichert’s cartilage. Gives rise to lesser cornu and upper body of hyoid, stapes, styloid process, stylohyoid ligament
What cranial nerve is associated with the second pharyngeal arch?
CNVII - facial nerve
What are the derivatives of the third pharyngeal arch?
Stylopharyngeus
Greater cornu and lower body of hyoid
What cranial nerve is associated with the third pharyngeal arch?
CNIX - glossopharyngeal
What is the blood supply to the second pharyngeal arch?
Common, external and internal carotid arteries and their branches
What is the blood supply to the third pharyngeal arch?
Common, external and internal carotid arteries and their branches
What are the derivatives of the 4th pharyngeal arch?
Cricothyroid
Constrictor muscles of pharynx
Levator palatini
What cranial nerve is associated with the fourth pharyngeal arch?
CNX - vagus nerve. superior laryngeal branch.
What cranial nerve is associated with the sixth pharyngeal arch?
CNX - vagus nerve. recurrent laryngeal branch
What are the derivatives of the sixth pharyngeal arch?
Intrinsic muscles of larynx
What is the blood supply to the fourth pharyngeal arch?
Aortic arch and part of right subclavian artery
What is the blood supply to the sixth pharyngeal arch?
Pulmonary arteries
What are the cartilage derivatives of the fourth and sixth pharyngeal arches?
Combine to give rise to: Cricoid Arytenoid Thyroid cartilage Epiglottis
What are the nerves of the pharyngeal arches?
Cranial nerves with mixed sensory and motor functions that supply all derivatives of the pharyngeal arches
CNV, VII, IX, X
(CN XI and XII have some association)
What’s derived from the first pharyngeal pouch?
Eustachian tube
Middle ear cavity, especially tympanic cavity
Auditory tube
What’s derived from the second pharyngeal pouch?
Palatine tonsils?
What’s derived from the third pharyngeal pouch?
Dorsal component gives rise to inferior parathyroid glands
Ventral component gives rise to thymus gland
What’s derived from the fourth pharyngeal pouch
Dorsal component gives rise to superior parathyroids
Ventral component gives rise to ultimobranchial body which gives rise to C cells of the thyroid gland
What’s derived from the pharyngeal clefts?
2nd pharyngeal pouch overgrows all of the clefts, except for the first one. This gives rise to the external auditory meatus
What happens if the cervical sinus isn’t obliterated?
Cysts or fistulae can occur at any point along the anterior border of sternocleidomastoid
What is the development of the face driven by?
Need to separate the respiratory and GI tracts
Expansion of the cranial neural tube
Development of sense organs
Appearance of a complex tissue system that’s associated with the cranial gut tube and the outflow of the developing heart
What are neural crest cells?
Special population of cells that originate at the lateral border of neuroectoderm and then become displaced, enter the mesoderm and migrate to contribute to the formation of a wide range of head and neck structures
What are the derivatives of the frontonasal prominence?
Nose
Bridge of nose
Forehead
Philtrum
What are the derivatives of the maxillary prominence?
Lateral upper lip
Lateral upper jaw
Cheeks
What pharyngeal arch forms the facial skeleton?
First arch
What are the derivatives of the mandibular prominence?
Lower lip and jaw
What are nasal placodes?
Bilateral ectodermal thickenings that form on the frontonasal prominence
How are nasal pits formed?
Central invagination of nasal placodes
How is the nose formed?
Maxillary prominences grow medially which pushes the nasal prominences towards the midline. Medial nasal prominences fuse with each other in the midline and they also fuse with the maxillary prominences to form the intermaxillary segment
What does the intermaxillary segment give rise to?
Philtrum Primary palate (ie medial anterior part) 4 incisors (mid upper jaw)
How is the secondary palate form?
Mandible continues to grow and the tongue drops down, this allows for palatal shelves, derived from maxillary prominences, to grow and fuse together in the midline. The nasal septum also fuses with the maxillary prominences
What causes a cleft lip?
Failure of medial nasal prominences to fuse with the maxillary prominences
What causes a cleft lip and jaw?
Failure of medial nasal prominences to fuse with maxillary prominences,as well as failure of palatal shelve midline fusion
How are the eyes formed?
Outgrowths form either side of the diencephalon and theyse outgrowths are called optic vesicles. These release signalling molecules that stimulate thickening of the overlying ectoderm and this thickening forms lens placodes. These then invaginate to form closed vesicles that sink beneath the ectoderm layer.
Eyes are brought to midline by growth of maxillary prominences
What are the embryological origins of the lens?
Lens placode
What are the embryological origins of retina?
Diencephalon
What are the embryological origins of the cornea?
Ectoderm overlying sunken lens vesicles
What are the embryological origins of the optic muscles?
Somites
What are the embryological origins of the choroid and sclera?
Mesenchyme cells that arrange around the developing cells
What is anopthalmia?
The absence of one or both eyes
What is micropthalmia?
Abnormally small eyes
What forms the external ear?
External auditory meatus comes from first pharyngeal cleft
Auricles come from proliferation of first and second pharyngeal arches around the meatus
What leads to final position of ears?
Growth of mandible bring them up in line with they eyes
What are the main signs of foetal alcohol syndrome?
Indistinct philtrum Growth deficiency Small eyes and head Small facial features Thin upper lip Short nose Low nasal bridge
What are some distinctive markings on the dorsum of the tongue?
Convex sulcus terminalis with foramen cecum at its apex
What attaches the tongue to the floor of the oral cavity?
Lingual frenulum
What are the main lingual swellings that form, and what are their pharyngeal arch origins?
Lateral lingual swellings (Ph.A1)
Tuberculum Impar (Ph.A1)
Cupola (Ph.A.2,3, (4))
Epiglottal swelling (Ph.A.4)
How is the tongue formed from its lingual swellings?
Lateral lingual swellings over grow the tuberculum impar
PhA.3 overgrows PhA.2 contribution to cupola.
Extensive degeneration frees tongue from the floor of the oral cavity, except for by the lingual frenulum
Which pharyngeal arches form the anterior 2/3 of the tongue?
First and 3rd arches
What is the sensory innervation of the tongue?
General sensory to anterior 2/3 is CNV and CNIX
Special sensory to this area is CNVII via chorda tympani nerve
Special sensory to Posterior 2/3 is from CNX
Where does chorda tympani have to pass to innervate first pharyngeal structures after originating in second pharyngeal arch?
Through middle ear cavity ie first pharyngeal pouch
Where do the muscles of the tongue originate from and what is their innervation?
Occipital somite myogenic precusors. Innervated by CN XII
Where does thyroid originate and where does it descend?
Originates between tuberculum impar and copola at site of future foramen cecum. Then bifurcates and descends down the midline, attached to the tongue by the hypoglossal duct
What happens if the hypoglossal duct doesnt degenerate?
Can get hypoglossal fistulae or cysts at any point in midline down path of thyroid descension.
Where do parafollicular cells originate?
Ultimobranchial body from 4th pharyngeal pouch
What is first arch syndrome?
Spectrum of defects in the development of ears, eyes, madible and palate. Due to failure of colonisation of first pharyngeal arch with neural crest cells
What is treacher collins syndrome?
Type of first arch syndrome. There’s hypoplasia of mandible and facial bones and low set ears
What abnormalities are found in DiGeorge syndrome?
Cardiac abnormalities Abnormal facies Thymic aplasia Cleft palate Hypocalcaemia/hypoparathyroidism 22 chromosome mutation
What defects are found in Charge syndrome?
Colobome of iris Heart defects Choanal atresia Growth and development retardation Genital hypoplasia Ear defects
What is mutated in CHARGE syndrome and why is this important?
CHD7 - needed for expression of neural crest cells
What are the names of the 12 cranial nerves?
Olfactory Optic Oculomotor Trochlear Trigeminal Abducens Facial Vestibulocochlear Glossopharyngeal Vagus Spinal accessory Hypoglossal
From where do the cranial nerves originate?
CNI, CNII come from forebrain CNIII, CNIV come from midbrain CNV, VI, VII come from pons CN VIII, IX, X, XII come from medulla CNXI comes from spinal cord (C1-C5)
What is the function of CNI?
Special sense nerve providing sense of smell by acting at nasal mucosa at roof of nasal cavity, superior concha and sides of nasal septum
Where does CNI enter the cranial cavity?
Cribriform plate of ethmoid bone
What can the consequence be of a fracture to the cribriform plate?
Can damage olfactory nerve giving anosmia. Also directly below meninges so can give CSF rhinorrhoea
What is the function of CNII?
Special sense nerve giving sense of vision from stimuli from the retina
Where does CNII enter the cranial cavity?
Through optic canal of the spehnoid bone
What can the consequence be of raised intracranial pressure in terms of the eye and its innervation?
Can compress optic nerve. Central artery and vein of the retina also run through this nerve so the vein, especially, can easily be compressed in raised pressure, leading to reduced venous return and papilloedema
What is the function of CNIII?
Mixed nerve giving somatic motor innervation to inferior oblique, superior rectus, inferior rectus and medial rectus as well as to levator palpebrae superioris
Parasympathetic innervation to sphincter pupillae muscle to constrict pupil and ciliary muscles for accommodation
Where does parasympathetic outflow to the head and neck come from?
CN III, VII, IX
Where does the parasympathetic portion of CNIII synapse?
Originates at Edinger-Westphal nucleus and then synapses at the ciliary ganglion which is in orbital cavity, lateral to optic nerve.
Where does the oculomotor nerve exit the cranial cavity?
Through superior orbital fissure, between the greater and lesser wings of the sphenoid bone
What can the consequence of damage to the oculomotor be?
Ptosis (LPS denervation)
Dilated pupil (unopposed sympathetic action)
Eye looks down and out (unopposed lateral rectus and superior oblique action)
Diplopia
What is the function of CNIV?
Somatic motor to superior oblique muscle which depresses and abducts the eye
Where does the trochlear nerve exit the cranial cavity?
Through superior orbital fissure
What is the consequence of damage to the trochlear nerve?
Patient may tilt head to unaffected side as resting gaze of unaffected eye is superomedially. Struggle with convergent gaze eg walking downstairs so there will be diplopia
What are the branches of the trigeminal nerve and what types of nerves are they?
Vi - Opthalmic branch is sensory only
Vii - Maxillary branch is sensory only
Viii - Mandibular branch in sensory and motor
What is the function of CNVi?
Sensory innervation from derivatives of the frontal nasal prominence - forehead, scalp, upper eyelid, dorsum of nose. Also sensation from cornea giving rise to blink reflex, conjunctiva, lacrimal gland and muscosa of nasal cavity and paranasal sinuses
Where does CNVi exit the cranial cavity?
Through the superior orbital fissure
What is the function of CNVii?
Sensory innervation from derivatives of the maxillary prominence of the first pharyngeal arch - skin over the maxilla, upper teeth, upper lip, maxillary sinuses and palate
Where does CNVii leave the cranial cavity?
Through the foramen rotundum of the sphenoid bone
What is the function of CNViii?
Sensory innervation to derivatives of the mandibular prominence of the first pharyngeal arch - skin over temples, cheeks, chin, mucosa of mouth and the anterior 2/3 of the tongue
Motor innervation to muscle derivatives of the first pharyngeal arch - muscles of mastication, anterior belly of digastric, mylohyoid, tensor tympani and tensor veli palatini
Where does CNiii leave the cranial cavity?
Through the foramen ovale of the sphenoid bone
What are some important branches of CNViii?
Auriculotemporal
Buccal
Inferior alveolar
Lingual
What is the function of CNVI?
Motor nerve to lateral rectus muscle
Where does CNVI leave the cranial cavity?
Through the superior orbital fissure
What are the functions of CNVII?
Special sensory giving sense of taste to the anterior 2/3 of the tongue and modulatesamplitude of sound
Somatic motor to muscles of facial expression, stapedius, posterior belly of digastric, stylohyoid
Parasympathetic innervation to submandibular and sublingual salivary glands, lacrimal gland and glands of nose and palate
What is the path of the facial nerve through the bones of the skull?
Exits cavity through the internal acoustic meatus and enters facial canal. Then gives rise to the geniculate ganglion which gives off the greater petrosal nerve (to glands), the nerve to stapedius (to middle ear) and chorda tympani (to middles ear and then tongue). Leaves skull through the stylomastoid foramen of the temporal bone
What can the consequences be of a facial nerve palsy?
Drooping of mouth angle
Facial muscle paralysis
No wrinkling of forhead ability
Which nerve is vulnerable to damage in a forceps delivery?
Facial nerve - CNVII
What is the function of CNVIII?
Special sensory nerve. Vestibular nerves give sense of balance. Cochlear nerves give sense of hearing
Where does CNVIII enter the cranial cavity?
Through the internal acoustic meatus
What is the function of CNIX?
Mixed nerve.
Somatic motor innervation to stylopharyngeus to aid with swallowing
Parasympathetic innervation of the parotid gland
Special sensory innervation to posterior 1/3 of tongue giving sense of taste
Autonomic sensory innervation to parotid gland, carotid body and sinus, pharynx and middle ear
Somatic sensory innervation to external ear
Where does the glossopharyngeal nerve exit the cranial cavity?
Through the jugular foramen of the temporal bone
Where does the parasympathetic portion of the glossopharyngeal nerve synapse?
Arises at Inferior salivatory nucleus and gives off lesser petrosal branch. This synapses at the otic ganglion, before giving of the auriculotemporal nerve which innervates the parotid gland and oropharynx
Where do the parasympathetic portions of the facial nerve synapse?
Arise at superior salivatory nucleus. Greater petrosal branch synapses at pterygopalatine ganglion and innervates lacrimal gland and glands of nose and palate
Chorda tympani branch synapses at submandibular branch which innervates submandibular and sublingual salivary glands and mucous glands of the palate
What are the functions of CNX?
Mixed nerve
Somatic motor to muscles of pharynx (not stylopharyngeus), intrinsic muscles of larynx, muscles of palate and superior 2/3 of oesophagus
Somatic sensory from auricle and external acoustic meatus (ear cough reflex)
Parasympathetic motor to smooth muscle and glands of trachea, bronchi, digestive tract, coronary arteries and conductive nodes of heart
Autonomic sensory to base of tongue, larynx, pharynx, trachea, bronchi, heart, oesophagus and stomach
Special sensory to epiglottis and palate
Where does the vagus nerve exit the cranial cavity?
Through jugular foramen of temporal bone
What is the function of CNXI?
Motor nerve to sternocleidomastoid and trapezius muscles
What is the path of CNXI?
Arises from spinal cord. Enters cranial cavity through foramen magnum and leaves through the jugular foramen
What is the function of the hypoglossal nerve?
Somatic motor to intrinsic and extrinsic muscles of the tongue
Where does CNXII leave the cranial cavity?
Through hypoglossal canal of occipital bone
What is the consequence of damage to the hypoglossal nerve?
Wasting and deviation of the tongue towards the affected side. Will be dysarthria (speech problems)
What structures pass through the superior orbital fissure?
CN III, Vi, VI, IV. Opthalmic veins
What structures pass through the foramen magnum?
CN IX Medulla Vertebral arteries Meninges Dural veins Anterior and posterior spinal veins
What are the borders of the orbit?
Roof - frontal bone, lesser wing of sphenoid
Floor - Zygomatic, maxilla, palatine
Medial - lacrimal, ethmoid, maxilla, sphenoid
Lateral - Zygomatic, greater wing of sphenoid
Apex - Optic foramen
Base - Orbital rim
What are the contents of the orbit?
Eyeball Extraocular muscles Eyelids CN II, III, IV, Vi, VI Opthalmic artery Inferior and superior opthalmic veins
What triggers the blinking reflex?
Drying of cornea
Touching of cornea
Irritation to cornea
Sight of oncoming irritant
What nerve stimulates the blinking reflex?
CNV - facial nerve
What are the main openings of the orbit and what passes through them?
Optic canal - optic nerve (CNII) and opthalmic artery
Superior orbital fissure - CNIII, IV, Vi, VII, lacrimal nerve, frontal nerve, nasociliary nerve and superior opthalmic vein
Inferior orbital fissure - Infraorbital nerve and inferior opthalmic vein
What is the parasympathetic innervation of the lacrimal gland?
Facial nerve - greater petrosal nerve - pterygopalatine ganglion - lacrimal nerve
Describe the drainage of lacrimal fluid?
Fluid is moved from superiolateral (site of lacrimal gland) to medial aspect by blinking. Fluid accumulates medially at lacrimal lake (visible part is puncta) this then drains via canaliculi to lacrimal sac. Lacrimal sac is dilated by orbicularis oculi in drinking and drains into nasolacrimal duct where it enters nasal cavity and inferior nasal meatus and is then swallowed
What are the contents of lacrimal fluid?
Water
Bactericidal enzymes and antibodies
Oil
Mucins
Where are different components of lacrimal fluid produced?
Lacrimal gland secretes water and the bactericidal enzymes and antibodies
Mebomian glands secrete oil
Mucins are produced by conjunctival goblet cells
What are the components of the eyelid fold?
Skin Alveolar tissue Orbicularis oculi fibres Tarsal plate Orbital septum Tarsal glands Conjunctiva
Where do the extraocular muscles originate?
Recti muscles originate from common tendinous ring. Superior oblique originates from body of sphenoid and inferior oblique originates from the anterior orbital floor
What are the layers of the eye?
Outer fibrous layer
Middle vascular layer
Inner Retinal layer
What makes up the outer fibrous layer of the eyeball?
Cornea - Transparent and allows light to enter the lens
Sclera - covers 5/6 of posterior aspect
What makes up the middle vascular layer of the eyeball?
Choroid - vascular layer that lies between the sclera and the retina
Ciliary body - Runs between choroid and lens. Produces lens accommodation and secretes aqueous humour
Iris - controls amount of light passing through. Dilater pupillae under sympathetic control. Constrictor pupillae under parasympathetic control
Describe the inner retina layer
Two cellular layers.
Neural layer is made up of photoreceptors and is posterolateral in the eye
Pigmented layer is beneath the neural layer and attached to the choroid. Pigmented layer continues anteriorly but neural layer doesn’t. This layer is the ‘non-visual part’ and posterolateral aspect with both layers present is the visual part.
What’s the difference between open and closed angle glaucome?
In open angle glaucoma, the trabecular meshwork that normally drains aqueous humour is obstructed
In closed angle, the meshwork is functioning but fluid can’t get to it, either due to covering of the meshwork by the iris root or due to adhesions between the iris and the cornea
What are the features of the retina on fundoscopy?
Optic disk is where optic nerve enters
Dark spot is the macula lutea which has highester concentration of cone cells and so provides high resolution vision. In the centre of this is the fovea centralis and this provides high acuity vision
What happens in retinal detachment?
In general, neural layer becomes detached from pigmented layer as it’s not strongly fused as the pigmented is to the choroid. Patient may report of seeing flashing lights/floating specks
What happens in horner’s syndrome?
There’s damage to the sympathetic trunk in the neck so there’s partial ptosis, miosis and anhydrosis on ipsilateral side to damage
What is the difference between myopia, hyperopia and presbyopia?
Myopia is short sightedness
Hyperopia is long sightedness
Presbyopia is longsightedness due to age related changes to lens
What is mydriasis?
A blown/abnormally dilated pupil
What is coloboma?
Absence of a section of the iris
What’s the difference between a Meibomian cyst and a stye?
Meibomian cyst is obstruction of a tarsal gland behind eyelashes/
Stye is infection of a sebaceous gland
What is the blood supply to the auricle?
External auricular artery
What is the lymphatic drainage of the external ear?
Anterior aspect drains to parotid nodes.
Posterior aspect drains to mastoid nodes
What is the nerve supply to the external ear?
Superficial structures innvervated by Mandibular branch of trigeminal nerve
Rest innervated by great auricular nerve
What types of muscles are found in the auricle?
Extrinsic muscles run from scalp/skull and act to position the auricle
Intrinsic muscles run between cartilaginous parts and can alter the shape of the auricle
Where does the external auditory meatus run?
From deepest part of concha to the lateral surface of the tympanic membrane
How is ear wax made?
Cerumen secreted by epithelial cells of external auditory meatus. This combines with dead skin cells to make ear wax
What are the different layers of the tympanic membrane?
Lateral is made of keratinised stratified squamous epithelia
Middle layer is fibrous
Inner layer is respiratory epithelium
What is the sensory innervation of the tympanic membrane?
Lateral layer is innervated by the vagus nerve CNX
Medial layer is innervated by the glossopharyngeal nerve - CN IX
What are the borders of the middle ear?
Lateral - tympanic cavity Medial - Oval window Superior - Tegmen tympani Floor - jugular floor Anterior - Carotid wall Posterior - Mastoid air antrum
How can the middle ear be divided?
Into tympanic cavity and epitympanic recess. Epitympanic recess lies above the tympanic cavity
What are the contents of the middle ear?
Auditory ossicles Chorda tympani Stapedius Tensor tympani Tympanic nerve plexus
What are the actions of stapedius and tensor tympani and what are their innervations?
Both act to minimise loud sounds by reducing vibration of stapes and malleus respectively.
Tensor tympani runs from auditory tube to handle of malleus and brings it medially
Stapedius innervated by CNViii
Tensor tympani innervated by CNVII
What is the purpose of mastoid air cells?
Lie posterior to the epitympanic recess. Release air into the tympanic cavity if pressure falls too low
What are the main components of the inner ear?
Vestibule contains utricle and saccule which are sensitive to gravity and rotational acceleration
Semicircular ducts and canals communicate with vestibule and contain receptors that respond to rotational acceleration
Cochlea contains cochlear duct. Cochlear duct accommodates the spiral organ of Corti.
Organ of Corti contains the receptors of the auditory apparatus
What is tympanosclerosis?
Calcification of the tympanic membrane with formation of dense white plaques on the membrane
How does cauliflower ear occur?
If there’s trauma to the auricle and bleeding of the perichondrium, this impairs blood supply to auricular cartilage so if not treated, there’s fibrosis of the cartilage
What happens if stapedius is paralysed?
Hyperacusis - loud sounds appear louder than normal
What is choleasteatoma?
Growth of stratified squamous epithelium within the middle ear. Is destructive and can damage ossicles through increased pressure or release of osteolytic enzymes
What is meniere’s syndrome?
Triad of tinnitus, hearing loass and vertigo, together with a feeling of pressure in the ear and sound distortion. Due to blockage of the cochlear aqueduct
What makes up the ‘skeleton’ of the external nose?
2 nasal bones
1 septal cartilage
2 alar cartilages
2 lateral cartilages
What makes up the nasal septum?
Anteriorly - is cartilage
Middle - perpendicular plate of ethmoid bone
Posteriorly - Vomer bone
Floor - palatine and maxilla bones
What are the borders of the nasal cavity?
Roof - cribriform plate of the ethmoid bone
Floor - palatine process of maxilla and horizontal plate of palatine bone
Medial - nasal septum
Lateral - Nasal conchae
How is the nasal cavity divided?
Into vestibule at opening
respiratory region lined by respiratory mucosa
Olfactory region - lined by olfactory mucosa
What are the nasal conchae?
3 curved shelves of bone that create many pathways for air flow to increase surface area and turbidity of air
What air pathways do the conchae form?
Sphenoethoidal recess superoposterior to the superior concha
Superior meatus between superior and middle conchae
Middle meatus between middle and inferior conchae
Inferior meatus between inferior concha and the nasal cavity floor
What are the main openings of the nasal cavity and what drains into them?
Semilunar hiatus at middle for drainage of frontal, maxillary and anterior ethmoidal sinuses
Ethmoid bulla for drainage of posterior ethmoidal sinus (this is just posterior to semilunar hiatus)
Opening of sphenoid sinus at level of superior concha
Opening of eustachian tube - at level of inferior meatus
Opening of nasolacrimal duct in inferior meatus but anterior
What are the four main points of access to the nasal cavity for passage of vessels?
Cribriform plate for passage of olfactory nerve fibres and receptors
Incisive foramen for greater palatine artery and nasopalatine nerve
Foramen cecum for (in some) nasal veins to pass into superior sagittal sinus (infection spread)
Sphenopalatine foramen for passage to pterygopalatine fossa and entry of sphenopalatine artery
What’s the blood supply to the lateral wall of the nasal cavity?
Anterior and posterior ethmoidal arteries (branches of ICA)
Anastamose with lateral nasal branches of the facial artery at cavity opening
Spehnopalatine artery enters through sphenopalatine foramen
What’s the blood supply to the medial wall of the nasal cavity (septum)
Anterior and posterior ethmoidal arteries from ICA
Branch of sphenopalating artery
Greater palatine and superior labial arteries anastamose from inferior with the anterior ethoidal artery to form little’s area
What is the venous drainage of the nasal cavity?
Tends to follow arterial supply
Drains to facial vein
pterygoid plexus
or cavernous sinus
What’s the innervation of the nasal cavity?
Special sensory via CN1
General sensory from trigeminal nerve. Nasociliary nerve (branch of CNVi) supplies anteroposterior mucosa
External nasal from CNVi and infraorbital nerve from CNVii supply external skin
Nasopalatine nerve from CNVii supplies posteroinferior mucosa
Where is the maxillary sinus?
Inferolateral to maxillary sinus between floor of orbit and alveolar part of maxilla, in front of the pterygopalatine and infratemporal fossae
Where does the maxillary sinus drain to?
Through maxillary ostia to the semilunar hiatus of the nasal cavity
Where is the frontal sinus?
Found under the forehead, between the inner and outfer tables of the frontal bone, posterior to the superciliary arches and root of the nose
Which sinuses are present at birth?
Sphenoidal
Ethmoidal (not visible on x-ray until 8yrs)
Maxillary
All grow later
Where does the frontal sinus drain to?
Through frontonasal duct to the semilunar hiatus
Where do the 3 ethmoidal sinus drain into?
Anterior - semilunar hiatus
Middle - ethmoid bulla
Posterior - superior meatus
Where is the sphenoid sinus?
Lies in the body of the sphenoid but may extend into the wings of the bone. Lies at level of sphenoethmoidal recess
Where does sphenoid sinus drain into?
Into sphenoethmoidal recess
What structures is the spehnoid sinus in very close proximity to?
Pituitary gland
Internal carotid arteries
Optic nerves and chiasm
What are the ethmoidal sinuses?
Small invaginationg of mucous membranes of the superior and middle nasal recesses, into the ethmoid bone
Why can maxillary sinus pain be felt as toothache?
As maxillary molar teeth and maxillary sinus are both innervated by the superior alveolar branch of the maxillary brach of the trigeminal nerve
Where can infections of the nasal cavity spread to?
Paranasal sinuses
Middle ear
Lacrimal apparatus and conjunctiva
Anterior cranial fossa
How can infection of the ethmoidal recess lead to visual disturbances?
Can erode through to medial wall of the orbit which is in close proximity to the optic canal, which carries the optic nerve and opthalmic artery
What is rhinitis?
Inflammation of the mucosa of the nasal cavity leading to swelling and an increase in volume of secretions
What can cause rhinitis?
Allergic reaction
Nasal polyps
Viral infection (resp. syncytial virus, rhinovirus, adenovirus)
What is sinusitis?
Inflammation of the mucosa lining the paranasal sinuses. If more than one sinus is affected, its pansinusitis
What causes sinusitis?
Infection
Haemophilus influenzae
Streptococcus pneumoniae
What can nasal polyps cause?
Lie close to ostiomeatal complex of nasopharynx so can cause obstruction leading to snoring and obstructive sleep apnoea
Why are the maxillary sinuses the most commonly infected sinuses?
Have small openings that are very high and if head is erect, can’t drain unless full so can be stasis of contents, making them prone to infection. Small ostia are also very prone to congestion
What are some risk factors for epistaxis?
Trauma Tumours Mucosal drying Infections NSAIDs Granulomas Alcohol Coagulation defects
What are the most common origins of epistaxis?
Kiesselbach’s plexus anteriorly
Sphenopaltine artery posteriorly
What can cause damage to the oculomotor nerve?
Diabetes mellitus
Hypertension
Compression, ie in aneurysm
What are the main branches of the opthalmic nerve?
Supratrochlear Supraorbital Infratrochlear Lacrimal External nasal
What are the main branches of the maxillary nerve?
Zygomaticofacial
Zygomaticotemporal
Infraorbital
What are the main branches of the mandibular nerve?
Auriculotemporal
Buccal
Mental
What are the main branches of the facial nerve and where are they given off?
Within parotid gland - temporal, zygomatic, buccal, marginal mandibular, cervical
Other intracranial - Greater petrosal, chorda tympani, nerve to stapedius
Extracranial - Nerve to posterior belly of digastric and stylohyoid
Posterior auricular
How is it possible to distinguish between bell’s palsy and a stroke on examination?
Strokes tend to be forehead sparing whereas foreheads tend to be affected in Bell’s
What are the borders of the nasopharynx?
Roof - cranial base
Floor - soft palate
Posterior - nasopharyngeal tonsil and body of C1
Anterior Posterior nares
In what portion of the pharynx is the eustachian tube opening?
Nasopharynx
What are the boundaries of the oropharynx?
Superior - soft palate Inferior - Superior border of epiglottis Anterior - oral cavity Posterior - bodies of C2-C3 Lateral - palatoglossal and palatopharyngeal arches
What makes up the tonsillar fossa?
Anterior - palatoglossal arch
Posterior - palatopharyngeal arch
Floor - Superior constrictor muscle
What is the palatoglossal arch?
RUns from palate to tongue, fusing wit the lateral wall of the tongue. Acts as boundary between buccal cavity and oropharynx and contains the palatoglossus muscle
What is the palatopharyngeal arch?
Blends with wall of pharynx and contains the palatopharyngeus muscle
What are the boundaries of the laryngopharynx?
Superior - Superior border of epiglottis
Inferior - Inferior border of cricoid cartilage
Anterior - Larynx
Posterior - vertebral bodies of C4-C6
What is the motor innervation to the muscles of the larynx?
Vagus nerve (CNX) except for stylopharyngeus which is innervated by the glossopharyngeal nerve (CNIX) Also supply from facial nerve and hypoglossal nerve
What is the sensory innervation to the larynx?
Nasopharynx is CNVii
Oropharynx is CNIX
Laryngopharynx is CNX
What are the constrictor muscles of the pharynx and what is their function?
Superior, middle and inferior constrictor muscles sit on top of each other and constrict the pharynx to aid in swallowing
What are the different stages of swallowing?
Stage 1 is voluntary. Bolus is pushed against the palate and into the oropharynx
Stage 2 is involuntary. Soft palate elevates to close of the nasopharynx. Pharynx widens and shortens to accept the bolus. Suprahyoid and longitudinal pharyngeal muscles contract to elevate the hyoid and the larynx
Stage 3 is also involuntary. There’s sequential contraction of all 3 pharyngeal constrictor muscles with superior constricting the oropharynx and middle and inferior constricting the laryngopharynx. This passes the bolus into the oesophagus
How is the larynx protected in swallowing?
By overhanging tongue, the vocal cords and the epiglottis which diverts the bolus away from the opening
What are the longitudinal muscles of the pharynx?
Stylopharyngeus runs from styloid process to pharynx
Palatopharyngeus runs from palate to pharynx
Salpingopharyngeus runs from eustachian tube opening to pharynx. Also opens this tube in swallowing to equalise middle ear pressure
What is the blood supply to the pharynx?
Branches of the external carotid artery, particularly the ascending laryngeal, facial, maxillary and lingual arteries.
What does waldeyer’s ring consist of?
Nasopharyngeal tonsils
Palatine tonsils
Lingual tonsils
Tubal tonsils at opening of eustachian tube
What immunoglobulins are produced by nasopharyngeal tonsils?
G,A,M
What are some consequences of enlarged adenoids?
Nasal obstruction leading to hyponasal voice, mouth breathing, snoring, feeding difficulties, obstructive sleep apnoea
Eustachian tube obstruction leading to recurrent acute otitis media or chronic otitis media with effusion
How are adenoids treated?
Grommets if there’s acute otitis media
Curretage
Suction diathermy
When is a tonsillectomy carried out?
With recurrent tonsillitis (>5/year for at least 2 years)
Previous peritonsillar abscess/quinsy
Suspected cancer
Obstructive sleep apnoea
What is a pharyngeal pouch?
Posterior herniation of mucosa through wall of pharynx at point between inferior constrictor muscle and cricopharyngeus muscle
Occurs due to weakness, uncoordinated contraction and pharyngeal spasm
