Head And Neck Session 2 Flashcards
Which blood vessel is used to measure right atrial pressure and why?
Internal jugular vein as it is straighter therefore gives a better indication
Which jugular vein is more visible?
External
What is the difference in position of the internal and external jugular veins in relation to SCM?
External is superficial, internal is deep to SCM
How is jugular venous pressure calculated?
Height from sternal angle +5 cm
What structure gives the level of the bifurcation of the CCA?
Superior border of the thyroid cartilage
Which branches does the subclavian artery give rise to?
Thyrocervical trunk
Vertebral artery
Internal thoracic artery
What are the branches of the aorta in the neck?
Brachiocephalic trunk –> subclavian and common carotid
Describe the passage of vertebral arteries from the subclavian artery to the brain.
Ascend through L&R transverse foramina of C6-1 to anastomose with the internal carotid artery to form basilar arteries
Which branch of the CCA does not have any branches in the neck?
Internal
Describe the path of the internal carotid artery.
Through carotid canal to anastomose in the circle of Willis
What is the carotid sinus?
Swelling at the region of the carotid bifurcation where baroreceptors are located
What is a carotid body?
Peripheral chemoceptor with rich vascular supply that can detect arterial pO2
Why is the CCA bifurcation a common site for atheroma formation?
Turbulent flow occurs here
What percentage occlusion of the carotid artery must be achieved before it becomes symptomatic?
> 70%
What is the clinical importance of the carotid triangle of the neck?
Pulse point
Surgical access to carotid artery, IJV, vagus and hypoglossal nerves
Carotid sinus massage in SVT pts
Which are the terminal branches of the external carotid artery?
Superficial temporal and maxillary
What are the branches of the external carotid artery?
Maxillary Facial Lingual Superior thyroid Ascending pharyngeal Occipital Posterior auricular Superficial temporal
What are the two branches of the superficial temporal artery?
Frontal and parietal
What are the layers of the scalp?
Skin Dense CT Aponeurosis Loose CT Periosteum
In which layer of the scalp do the blood vessels lie?
Dense CT
Which arteries supply the scalp?
Superficial temporal Occipital Posterior auricular Supratrochlear Supraorbital
What are the supraorbital and supratrochlear arteries branches of?
Ophthalmic artery, a branch of the ICA
Why does the scalp bleed profusely if damaged?
Close attachment of artery walls to dense CT limits constriction
Numerous anastomoses
How can a deep laceration to the scalp cause profuse bleeding?
Opposing pull of occipitofrontalis via the epicranial aponeurosis holds arteries open
Why does loss of scalp not lead to bone necrosis?
Blood supply to the skull is mostly via the middle meningeal artery so this will be maintained
What forms the angular vein at the medial angle of the eye to empty into the facial vein?
Supraorbital and supratrochlear veins
Where do the veins in the deep part of the scalp empty?
Pterygoid venous plexus
Why can infection in the scalp spread to the cranial cavity and meninges?
Veins of scalp connect to diploid veins through several valveless emissary veins and thus to dural venous sinuses
What forms a groove near the coronal suture that is visible on internal view of the skull?
Anterior branch of middle meningeal artery
What is the pterion?
Relatively weak area of skull formed by fusion of temporal, frontal, sphenoid and parietal bones
Why can fracture of the pterion cause extradural/epidural haemorrhage?
Can rupture middle meningeal artery (especially anterior branch)
How is blood supply to the dura and skull preserved during craniotomy?
Reflect bone and scalp flap inferiorly to preserve MMA and superficial temporal artery
Where do the superficial arteries of the face arise from?
All from ECA except supraorbital and supratrochlear from the ICA
Where can the facial artery pulse be felt?
Inferior border of mandible, anterior to masseter
Which is the major branch of the maxillary artery?
MMA
What are the branches of the facial artery?
Superior and inferior labial
Lateral nasal
Angular
What is the danger triangle of the face?
Area between bridge of nose and corners of the mouth that allows retrograde infection from the nasal area to the brain
What can be the result of retrograde infection in the danger triangle of the face?
Cavernous sinus thrombosis
Meningitis
Brain abscess
What are dural venous sinuses?
Endothelium-lined spaces between the periosteal and meningeal layers of dura formed at dural septae that receive blood from large veins draining the brain
How many dural venous sinuses are there?
5
What are the names of the dural venous sinuses that converge at the posterior of the skull?
Superior sagittal Inferior sagittal Transverse Cavernous Sigmoid
Where does the sigmoid sinus empty into?
IJV to leave skull through the jugular foramina
What is the cavernous sinus?
Plexus of extremely thin-walled veins on the upper surface of sphenoid
What are the contents of the cavernous sinus?
ICA
CN: II-oculomotor, IV-trochlear, VI-abducent and 2 branches of the trigemnial V1-ophthalmic and V2-maxillary
Do veins in the face have valves?
No
What does the facial vein communicate with at the medial angle of the eye to empty into the cavernous sinus?
Superior ophthalmic
Where do the deep facial veins drain into?
Pterygoid venous plexus
How is the internal jugular vein positioned in relation to the other carotid sheath structures?
Deep to SCM and lateral to CCA, deep cervical lymph nodes and the vagus nerve
What is the lymphatic system?
Network of drainage vessels throughout the body with a series of nodes that return lymph to the blood circulation
Where are lymph vessels not found?
Avascular areas
Is the lymphatic system present in the CNS?
Yes
Why does a small amount of fluid remain in the intersticium during tissue fluid formation?
High hydrostatic pressure at arteriole end pushes out small proteins that cannot move back at the venule end as the oncotic pressure is not small enough
How much lymph is formed per day?
3-4 l
Why is lymph needed?
To prevent development of oedema due to the accumulation of small proteins as net filtration is not equal to net reabsorption
What is tissue fluid In a lymphatic capillary called?
Lymph
What does lymph contain?
Depends on location: damaged cells, bacteria, cancer cells, chylomicrons
How does the flow of lymph compare to that of blood?
Much lower, 2-3 ml vs 5000 ml per minute
Describe the order of lymphatic flow.
Tissue fluid –> lymphatic capillary –> lymphatic vessels –> lymph nodes –> lymphatic vessel –> lymphatic trunks –> thoracic/R lymphatic ducts
Which duct drains the majority of lymph in the body?
Thoracic
How many lymphatic vessels enter and exit each lymph node?
Several afferent enter but only one efferent exits
How is the one-directional flow, low pressure system with no central pump able to achieve return of tissue fluid to blood circulation?
Valves, passive constriction by muscles and arteries and intrinsic constriction by reflexively contracting smooth muscle cells
What is lymphoedema?
Chronic condition of fluid retention and tissue swelling due to compromise of the lymphatic system
What can cause lymphoedema?
Removal/enlargement of lymph nodes Infection e.g. Parasites Damage to system e.g. Cancer (itself or Tx) Lack of limb movement Congenital
Describe the tissue structure of a lymph node.
Tough fibrous outer capsule with reticular CT inside
What do lymph nodes contain large numbers of?
Lymphocytes and macrophages
How do lymph nodes play a key role in immune defence?
Physical filter
Phagocytic filter
Lymphocytes for immune surveillance
What size can a lymph node normally be?
Anywhere from microscopic to 2.5 cm
What shape are lymph nodes normally?
Bean
What can cause swollen lymph nodes?
Infection or malignancy
How can a swollen lymph node to due infection be differentiated from one due to malignancy?
Infection: tender, firm and mobile
Malignancy: hard, matted and non-tender
What does presentation with a swollen lymph node require?
Comprehensive history
Examination of area drained by node
Examine other lymph nodes and body systems if cancer is suspected
How are lymph nodes organised?
Regional/superficial nodes that are readily palpable drain specific areas and empty into terminal/deep nodes that receive lymph from multiple regional nodes
Where are superficial lymph nodes palpable?
Neck Armpit Abdomen Pelvis Groin
How many lymph nodes are there in the neck?
300
What is the most common cause of swelling in the neck?
Enlarged cervical lymph nodes
What separates cervical lymph nodes into superficial and deep?
Investing layer of deep cervical fascia
Where are most of the deep cervical lymph nodes found?
In the carotid sheath associated with the IJV
What are the 8 groups of superficial cervical lymph nodes?
Submental Submandibular Preauricular Postauricular Occipital Superficial (EJV) Posterior cervical Anterior cervical
What are the three groups of deep cervical lymph nodes?
Jugulo-digastric (tonsillar)
Jugulo-omohyoid
Supraclavicular
Which muscle are the deep cervical lymph nodes deep to?
SCM
Where do the L&R supraclavicular lymph nodes receive lymph from?
R: mid-section chest, oesophagus, lungs
L: abdomen and thorax
What is the alternative name for the left supraclavicular node?
Virchow’s node
What areas of the face do the submandibular lymph nodes receive drainage from?
Upper lip and teeth Lateral lower lip Most of face Anterior nasal cavity Cheeks Middle tongue Submental and lingual glands
Which areas of the face do the submental nodes receive drainage from?
Lower lip and teeth
Anterior chin
Tip of tongue
Floor of mouth
Which areas of the head do the preauricular lymph nodes receive drainage from?
Middle posterior scalp
Skin of lateral ear
Parotid gland
Which areas of the head do the postauricular lymph nodes receive drainage from?
Posterior scalp
Cranial surface of pinna
Back of external acoustic meatus
Which region of the head do the occipital lymph nodes receive drainage from?
Posterior scalp and neck
Where do the superficial cervical (including anterior and posterior) lymph nodes receive drainage from?
Skin of neck
Preauricular, postauricular and occipital nodes
Where do the entire head and neck superficial lymph nodes drain into?
Deep cervical nodes
Where do the jugulo-digastric nodes receive drainage from?
Palatine tonsil and posterior 1/3 of tongue
Where do the jugulo-omohyoid nodes receive their drainage from?
Anterior 2/3 tongue, oral cavity, trachea, larynx, oesophagus and thyroid gland
What is Waldeyer’s ring?
Ring of lymphoid tissue in the naso- and oropharynx consisting of pharyngeal tonsils, 2 eustaschian tonsils, 2 palatine tonsils, 1 or more lingual tonsils and lots of MALT
Why is the lymphoid tissue in Waldeyer’s ring considered tissue instead of nodes?
Lack fibrous CT surrounding them
