Head And Neck Week 3 Flashcards
What are the major vessels in the neck?
Jugular veins
Carotid arteries
Which arteries arise from the subclavian artery at the base of the neck?
Internal thoracic, thyrocervical and vertebral arteries
What is similar about the internal carotid artery and the vertebral artery
They both supply the brain
Give off no branches in the neck
Does the common carotid artery give off branches in the neck?
No
Which arteries branch off from the thyrocervical trunk?
Suprascapular
Ascending cervical
Transverse cervical
Inferior thyroid
Where do the vertebral arteries arise from?
Subclavian artery
Describe the path of the vertebral arteries
Originate from the subclavian artery
Ascends through the transverse foramina of the cervical vertebrae 6-1
And enters the subarachnoid space just between the atlas and the occipital bone
Passes through foramen magnum
Curves around the medulla
Meets the other vertebral artery to form the basilar artery (circle of Willis) - runs along the anterior aspect of the brainstem
Which artery does the right common carotid originate from and where?
The brachiocephalic
Behind the right sternoclavicular joint
Where does the left common carotid originate?
Arch of the aorta
Which common carotid artery is longer?
The left because it arises from arch of aorta - courses for about 2cm through the superior mediastinum before entering the neck
What are the common carotid arteries enclosed in in the neck?
Carotid sheath
What are the contents of the carotid sheath?
Carotid artery
IJV
Vagus nerve
Deep cervical lymph nodes
Where is the carotid sheath found?
Deep to the sternocleidomastoid muscle
What forms the carotid sheath?
Prevertebral layer of cervical fascia - posteriorly
Pretracheal layer - anteromedially
Investing layer - anterolaterally
How does the carotid sheath differ over the artery and over the vein?
Thicker over the artery compared to the vein
Where does the sympathetic trunk lie in relation to the carotid sheath?
Posteromedially
How do the contents lie in the carotid sheath?
Artery medially
Vein laterally
Nerve posteriorly and between the vessels
At what point do the common carotid arteries bifurcate?
The superior surface of thyroid cartilage
What does the common carotid artery divide into?
External carotid
Internal carotid
What important structures are located at the bifurcation of the common carotid artery?
Carotid sinus (Baroreceptors) Carotid body (O2 peripheral chemoreceptors)
What is the clinical important of the carotid sinus?
Carotid massage can help to alleviate supra-ventricular tacchycardia
Why should you not attempt a carotid massage on healthy individuals?
Can cause bradycardia and a severe drop in blood pressure
Which artery is the major blood supply to the extra-cranial structures of the head and neck?
External carotid artery
What are the names of the terminal branches of the external carotid artery?
Maxillary artery
Superficial temporal artery
Where does the external carotid artery become the maxillary artery and superficial temporal?
Behind the neck of the mandible
In the parotid gland
What are the branches of the external carotid artery?
Some Anatomists Like Freaking Out Poor Medical Students S- Superior thyroid artery A - Ascending pharyngeal artery L- Lingual artery F - Facial artery O- Occipital artery P - Posterior auricular artery M - Maxillary artery S- Superficial temporal artery
The bifurcation of the common carotid artery is a common site for what pathology?
Atheroma formation
Causes narrowing - stenosis of the artery
Limit blood supply to the brain
The circle of Willis allows the other common carotid artery to compensate
Therefore may be no symptoms
Why do atheromas tend to form at the bifurcation of the common carotid artery?
Bifurcation causes turbulent flow
Damages endothelium
Leads to atherosclerotic changes
What may result from atherosclerosis of the common carotid artery?
Rupture of the clot –> embolus
Can become lodged in a cerebral artery
Leading to TIA or stroke
What are the boundaries of the carotid triangle?
Superior - Posterior belly of digastric muscle
Lateral - Anterior border of sternocleidomastoid
Medial - Superior belly of omohyoid
What is the carotid triangle?
A subdivision of the anterior triangle of the neck
What are the contents of the carotid triangle?
Internal jugular vein
Bifurcation of common carotid artery
Why is the carotid triangle important clinically?
Important for surgical approach to the carotid arteries or internal jugular vein - e.g. Carotid endarterectomy
Can access vagus and hypoglossal nerves
Carotid pulse can be palpated - but usually use more inferior pulses - Note: Dont feel for both carotid pulses at the same time, check for stenosis in both arteries before palpating
Carotid sinus massage - revert SVT
Draw and label a diagram showing the distribution of the external carotid artery and its branches
Check lecture
Which arteries supply the scalp?
Branches of internal carotid: Supraorbital Supratrochlear Branches of external carotid: Superficial temporal Posterior auricular Occipital
Which artery supplies the skull and dura?
Middle meningeal artery
How many layers of dura mater are there intracranially?
Two:
Outer endosteal layer - continuous with periosteum
Inner meningeal layer - continuous inferiorly with theca of spinal cord
Where do the dural venous sinuses lie?
In between the periosteum layer and meningeal layer of dura mater
Why is the bone reflected with its overlying muscle and skin during a craniotomy?
To preserve its blood supply during the surgery and after repositioning - reintegration is more successful this way
Adult pericranium has poor osteogenic properties - little regeneration occurs after bone loss
Which arteries supply the face? Draw and label their distribution
Supraorbital and supratrochlear from internal carotid artery Transverse facial artery Angular artery Lateral nasal artery Maxillary artery Superior and inferior labial artery Facial artery
Where can the facial artery pulse be felt?
At the inferior border of the mandible anterior to the masseter muscle
From what artery does the middle meningeal artery originate ?
Maxillary artery
What are the dural venous sinuses?
Endothelium-lined spaces between periosteal and meningeal layers of dura
Form at dural septae
Receive blood from large veins draining the brain (cerebral veins)
Connect to the scalp veins via emissary veins
Name some of the dural venous sinuses. Draw and label their positioning on a skull
Superior sagittal Inferior sagittal Cavernous Sigmoid Transverse sinus
What does the sigmoid sinus continue as ?
Continues as internal jugular vein
Leaves skull through jugular foramen
Which veins drain the face?
Follow the arterial vessels (same names)
What is the cavernous sinus?
A plexus of extremely thin-walled veins ont he upper surface of the sphenoid
What other structures lie in the cavernous sinus?
Internal carotid artery CN III oculomotor CN IV trochlear CN VI abducent CNV 1 ophthalmic and CNV2 maxillary branches of trigeminal nerve (CNV)
How do the facial veins communicate with the dural venous sinuses?
Superior ophthalmic vein and inferior ophthalmic vein drain into cavernous sinus
Inferior ophthalmic vein and the deep facial veins drain into the pterygoid venous plexus
What is the clinical relevance of the connections between the facial veins and the dural venous sinuses?
Infection from facial vein can spread to dural venous sinuses
Thrombophlebitis - infected clot can travel to intracranial venous system - can spread to other important intracranial structures
What is the danger triangle of the face? Draw it
High risk for infections from this area to spread to the cavernous sinus causing thrombosis, meningitis and brain abscesses
Which jugular vein is the best indication of right atrial pressure?
The right IJV
How do we measure JVP?
Lie the patient at 45 degrees
Tell them to turn to face the left
Measure the distance between the highest point of visible pulsation and the sternal angle
Add 5 cm
What is the difference between jugular vein pulsations and carotid artery pulsations?
Carotid artery has one pulsation per heartbeat whereas the jugular vein has two in sinus rhythm
Carotid artery pulsation is a rapid outward movement where as the jugular vein is a rapid inward movement
Carotid artery pulsation is palpable whereas the jugular pulsation is not
Carotid artery pulsation is independent of respiration where as jugular pulsation in a healthy heart shows decreased JVP on inspiration whereas unhealthy heart shows increased JVP on inspiration
Carotid artery pulsation is unaffected by position of patient whereas jugular pulsation is affected
Carotid artery pulsation is unaffected with hepatojugular reflex (pressing on the abdomen) whereas the jugular pulsation is affected (height increased)
Carotid artery pulsation is non-compressible whereas jugular pulsation is compressible
What are the branches of the internal jugular vein?
Inferior to superior: Middle thyroid vein Superior thyroid vein Lingual vein Facial vein Pharyngeal vein Inferior petrosal sinus
Where do the superior and inferior ophthalmic veins drain into?
Facial vein (as well as cavernous sinus, pterygoid venous plexus)
Describe the lymphatic system
Network of drainage vessels
Throughout the body - except eyeball (cornea, lens), inner ear, cartilage
Series of nodes (lymphoid organs) along the vessels
Filter the lymph
Return the lymph to the blood circulation
Does the CNS have a lymphatic system?
Recent evidence identifying small lymphatic vessels lining the dura
How is tissue fluid formed?
Hydrostatic pressure in the arteriole is greater than the oncotic pressure of the arteriole, forcing plasma (including small molecules - e.g. small proteins) out in the interstitium - ultrafiltration
Hydrostatic pressure in the venule is less than the oncotic pressure of the venule, drawing the tissue fluid back in (95% of it)
The net filtration of fluid is not equal to the net reabsorption of fluid
(5% drains into the lymphatic system)
Describe the constituents of lymph
Tissue fluid Small proteins Lipids (chylomicrons) Damaged cells Pathological state - bacteria/virus infected cells, cancer
How much lymph is produced per day?
3-4 L/day
120-180ml/hour or 2-3ml/min
What is the function of the lymphatic system?
Continuous removal of tissue fluid and macromolecules from interstitial space back to the blood circulation
Why is the lymphatic system important clinically?
Route for spread of infection and malignant disease
Outline the structures that lymph flows through from lymphatic capillary to duct
Lymphatic capillary Lymphatic vessels (afferent) Lymph nodes Lymphatic vessel (efferent) Lymphatic trunks Lymphatic ducts
How is the lymphatic system different to the circulatory system?
No central pump
Describe the mechanics of the lymphatic system
One directional flow
Low pressure
How many vessels drain into and out of a lymph node?
Several drain into the node and only one exits
What consequence does having several vessels entering the node and one vessel leaving have?
Increases the pressure and slows the flow to allow time for filtration
Name the two lymphatic ducts
Thoracic duct (left) Right lymphatic duct
What keeps the flow travelling in one direction in the lymphatic system?
Endothelial cells act like one way valve in lymphatic capillary
Valves along the vessels
Passive constriction - from the surrounding muscle contraction and pulsation of arteries
Intrinsic constriction - smooth muscle of larger lymphatic vessels enables them to constrict in response to stretch - autonomous
Which veins do the thoracic and right lymphatic ducts drain into?
Left and right subclavian respectively
Why does the lymphatic system drain into the subclavian veins?
The part of the CVS with the lowest pressure
Lymph from which parts of the body drain into the thoracic duct?
Left upper body (including head and neck) and all of the lower body (waist down)
Lymph from which parts of the body drains into the right lymphatic duct?
The right upper body (including head and neck)
What is lymphoedema?
An abnormal collection of protein-rich fluid causing tissue swelling due to a compromised lymphatic system
Chronic condition
What causes lymphoedema?
Removal or enlargement of lymph nodes e.g. As a result of surgery to remove cancerous nodes
Infections e.g. Parasites
Damage to lymphatic system e.g. Cancer treatment
Lack of limb movement (Doesn’t cause by itself but makes things worse)
Congenital e.g. Milroy’s syndrome (rare)
How can you tell the difference clinically, between lymphoedema and the oedema you would see in heart failure?
Lymphoedema is protein rich and is therefore non-pitting
Heart failure produces pitting oedema because the fluid is protein poor
Name some lymphoid organs
Spleen
Thymus
Tonsils
Lymph nodes
Describe the structure of a typical lymph node
Range from microscopic to 2.5cm in size
Tough fibrous outer capsule
Reticular connective tissue inside
Contain large collections of lymphocytes and macrophages
In what do lymph nodes play a key role?
Immune defence
How are lymph nodes suited to immune defence?
All substances transported in lymph pass through at least 1 lymph node
Physical filter created by reticular connective tissue
Phagocytic filter - macrophages
Full of lymphocytes - activate and proliferate in response to antigen
What causes lymph nodes to increase in size during an infection?
The proliferation of lymphocytes
What is the clinical term for a swollen lymph node?
Lymphadenopathy
What can cause lymphadenopathy?
Cancer
Infection
How can we differentiate between lymphadenopathy caused by infection and that caused by cancer?
Infection - nodes are tender and mobile
Cancer - nodes are hard, matted and non-tender
What action is taken if a swollen lymph node is found?
Comprehensive history
Examine the area of tissue it drains
If malignancy suspected examine other lymph nodes and body systems
How can lymph nodes be classified?
Regional - drain specific areas - superficial to investing layer of deep cervical fascia - in the superficial cervical fascia
Terminal - receive drainage from number of regional nodes - deep to investing layer of deep cervical fascia
Give some examples of areas where lymph nodes may be palpable
Neck (Cervical) Arm pit (Axillary) Abdomen Diaphragm Spleen Pelvis Groin (Femoral)
How many lymph nodes are there?
Around 800 (300 in neck)
What is the most common cause of swelling in the neck?
Lymphadenopathy
How do superficial and deep nodes communicate?
Superficial nodes drain into deep nodes
Which type of node is more palpable?
Superficial :D
Draw and label a diagram, showing the positions of the superficial and deep lymph nodes
Look in lecture Superficial: Submental Submandibular Preauricular Post auricular (mastoid) Occipital Superficial cervical (superficial in relation to SCM) Anterior cervical Posterior cervical Deep: Jugulodigastric Juguloomohyoid Supraclavicular
What is Waldeyers ring?
Annular collection of lymphatic tissue (nodules - not nodes) Surrounding superior pharynx Consists of: Pharyngeal tonsil (adenoids) Palatine tonsil (2) Lingual tonsil (2)
Within what structure are most deep nodes found?
The carotid sheath
What is suggested by a swollen supraclavicular lymph node on the left v.s. right side
Left node - drains abdomen and thorax
Called Virchow’s node
Right node - drains midsection of the chest, oesophagus and lungs
Draw a diagram and shade the areas drained by each superficial lymph node
Check slide in lecture
Which deep cervical lymph node is most frequently enlarged?
Jugulo-digastric - drains the palatine tonsil, oral cavity, posterior 1/3 of tongue, pharynx and larynx
In what clinical condition is the jugulodigastric node often enlarged?
Tonsillitis (palatine tonsil drainage)
Which vessel are the deep cervical lymph nodes in close association with?
IJV
Which structures are drained by the juguloomohyoid node?
Tongue, oral cavity, trachea, oesophagus, thyroid gland
What is the difference between the terms Virchow’s node and Trosier’s sign?
Virchow’s node is a term used for an enlarged left supraclavicular node - not necessary pathological
Trosier’s sign is a term used for - enlarged, hard left supraclavicular node - sign of metastatic abdominal malignancy
What anatomical surface landmark is crossed by the arch of the aorta?
The angle of Louis
Why might you ask a patient to hold their breath during auscultation of the carotid arteries?
To prevent tracheal breath sounds being transmitted
Also might be able to identify systolic murmur (e.g. Aortic stenosis) easier because closure of the pulmonary valve is delayed due to more blood return to the right side of the heart
Why would you auscultate over the carotid arteries?
To identify carotid bruit or transmitted systolic murmurs created by aortic valve stenosis
Why might a patient with an infected lower lip present with lymphadenopathy of both the submental and submandibular lymph nodes?
Because the submental nodes drain into the submandibular nodes and therefore infection of areas drained by the submental nodes may reach the submandibular nodes
In a patient presenting with conjunctivitis, which lymph nodes are likely to be enlarged?
Pre auricular nodes
Through which structure does the ophthalmic artery pass when travelling extracranially?
Orbital canal - with the optic nerve
What are the important things to consider when examining a lump?
Size, texture, mobility, is it fluid filled (fluctuant, transilluminate)
What might be the consequence of a blockage of the ophthalmic artery?
Sudden, acute and painless vision loss
