S3 Major Blood Vessels of the Head and Neck Flashcards
on the right side, where do the subclavian and common carotid arteries arise from ?
brachiocephalic trunk
where do the vertebral, internal thoracic and thyrocervical arteries arise from ?
subclavian in the base of the neck
where does the CCA bifurcates from ?
around C4
describe route of vertebral artery
ascend in the neck through transverse foramina in cervical vertebrae 6-1 and pass through the foramen magnum
vertebral arteries supply the brain along with ICA
describe route of Internal carotid artery
gives no branches off in neck
enters skull through carotid canal
what are the borders of carotid triangle ?
Superior - posterior belly of digastric
Lateral - Anterior Sternocleidomastoid
Medial - superior belly of omohyoid
what are the contents of the carotid triangle ?
Internal jugular vein
bifurcation of CCA at C4
what is the carotid triangles clinical significance ?
surgical approach to CA or IJV, can access CN X and CN XII via this triangle, can palpate carotid pulse here, carotid sinus massage can lower heart rate
where is clinical significance of the bifurcation of CCA ?
common site of atheroma formation
causes narrowing of the artery (stenosis)
rupture of the clot can cause an embolus to travel to brain causing TIA or stroke
what is the carotid sinus ?
swelling at bifurcation ( internal CA) and also the location of baroreceptors for detecting changes in arterial BP
what is the carotid body ?
peripheral chemoreceptors which detect arterial 02, massage in supraventricular tachycardia to stimulate baroreceptors to reduce BP. A hypersensitive carotid sinus may cause fainting upon pressure here.
common site of atherome due to turbulence
describe route of ICA
enters skull through carotid canal in petrous part of temporal bone
turns medially and horizontally
enters cranial cavity the makes s- shaped bend
courses through the carvenous sinus
what is the carvenous
sinus and what are its contents ?
plexus of extremely thin-walled veins on upper surface of sphenoid
Contents –> O TOM CAT
O- Oculomotor nerve
T- Trochlear nerve
O- Ophthalmic branch
M- Maxillary branch
C- Carotid artery
A- Abducens nerve
Lateral wall (S to I) : Oculomotor, Trochlear, ICA, Abducens
Transversing trigeminal branches : Ophthalmic (CNV1), Maxillary (CN V2)
what is the route of the Ophthalmic artery ?
ICA – > Ophthalmic artery —–> Supra-orbital artery
what are the branches of the external carotid artery ?
Six branches : SALFOPMS Super Angry Lady Figured Out Post Menopausal Syndrome Superior Thyroid Ascending Pharyngeal Lingual Facial Occipital Posterior Auricular Maxillary (terminal) Superficial Temporal(terminal)
describe the blood supply to the scalp
rich blood supply with many anastomoses
largely branches of external carotid artery ( superficial temporal, posterior auricular, and occipital arteries) except supratrochlear and supraorbital arteries( branches of the ophthalmic artery) which arises from the ICA
what is the clinical significance of blood supply to the scalp ?
Walls of arteries closely attached to connective tissue in scalp, limits constriction - can get profuse bleeding
Deep lacerations involve epicranial aponeurosis cause profuse bleeding because of opposing pull of occipitofrontalis
NOTE : BLOOD SUPPLY TO SKULL IS MIDDLE MENINGEAL ARTERY SO LOSS OF SCALP DOES NOT LEAD TO BONE NECROSIS
where can facial artery pulse be felt ?
inferior border of mandible, anterior to the masseter muscle
where do the superficial arteries of the face ?
all arise from the ECA except supra-orbital and supratrochlear from ICA (via ophthalmic)
give examples of branches of the maxillary artery
many branches of supplying muscles and deeper structures in face - middle meningeal , sphenopalatine
what is the blood supply to the Dura and Skull and its clinical significance?
Middle meningeal artery enters via the foramen spinosum and supplies skull and dura. Fracture of skull at pterion can rupture the middle meningeal artery - extradural haemorrhage, blood collects outside the dura
Describe the superficial vein drainage of the scalp
superficial veins generally accompany arteries
- superficial temporal veins
- occipital veins
- posterior auricular veins
Supraorbital veins and supra trochlear veins united at medial angle of eye to form angular vein which drains into the facial vein
Describe the deep venous drainage of the scalp
some deep parts of the scalp in temporal region have veins which drain into the pterygoid venous plexus
- veins of scalp connect to diploic veins of skull through several emissary veins and thus to dural venous sinuses
- emissary veins are valve less. infection from scalp can spread to the cranial cavity and affect meninges
Describe the connection of facial veins with carvenous sinus and pterygoid venous plexus
veins of the face are valveless. at medial angle of eye , facial vein communicates with superior ophthalmic drains into carvernous sinus
deep facial veins drain into pterygoid venous plexus. Infection from facial vein can spread to dural venous sinuses.
The sigmoid sinuses continue as the internal jugular veins, leaving the skull through the jugular foramen
what is the purpose of the lymphatic system ?
remove tissue fluid from the extracellular space back into blood circulation, return small proteins/fluids that leaked from capillaries, remove excess fluid from interstitial space, big role in immune defence and surveillance
how does tissue fluid form ?
at the arteriole end, hydrostatic pressure> oncotic pressure and at the venule end oncotic pressure stays the same but the hydrostatic pressure has fallen, therefore there is a higher pull in than push out.
Net filitration of fluid is not equal to net reabsorption of fluid. As some very small proteins also get pushed into the interstitium, but are not absorbed at the venule end so residual fluid remains
Describe lymph fluid formation
Tissue fluid in interstitium enter lymphatic capillary to form lymph, combined with small proteins, lipids, damaged cells , bacteria and cancer cells. 3-4 litres per day. System is low pressure, there is no central pump. One directional flow.
How lymph fluid form ?
Lymph vessels run closely to blood vessels and muscles, so they get pressed on contractions, pushing the fluid in one direction - passive constriction
How does lymphatic system drains lymph into venous circulation
Right side down to diaphragm drains to right lymphatic duct which goes into right subclavian veins, left side and right side below diaphragm drains into thoracic duct which goes into left subclavian vein
What is a lymphoedema and it’s causes ?
A chronic condition involving an abnormal collection of protein rich fluid causing tissue swelling due to a compromised lymphatic system. Non - pitting
Causes : removal or enlarged LN, damaged to lymphatic system (e.g radiotherapy causing fibrosis of LN), lack of limb movement ( doesn’t cause but wont allow it to get better) congenital (e.g Milroy’s syndrome)
Describe lymph nodes
- connective tissue structures with fibrous outer capsule and reticular connective tissue inside
- highly organised centres of immune cells - lymphocytes (B AND T) and macrophages. B cell proliferation on infection causes LN enlargement
- Lymph draining into lymph nodes may contain pathogens (e.g from an infected area of tissue)
- all substances transported in lymph pass through > 1 lymph node, which act as a physical and phagocytic filter and are full of lymphocytes that activate and proliferate in response to antigens
Describe lymphadenopathy
Enlarged LN, infection most common cause (tender and mobile) also from malignancy ( hard and non- tender)
How are lymph nodes organised
Superficial (drain specific superficial areas and are usually more superficial)
Deep ( receive drainage from number of regional nodes)
Regional and terminal separated by investing layer of deep cervical fascia. Regions where lymph nodes may be palpable
What are the superficial lymph nodes ?
submental submandibular preauricular postauricular occipital superficial cervical lymph nodes
what are the cervical lymph nodes ?
Superifical cervical lymph nodes : superficial to External Jugular vein
Posterior cervical lymph nodes : posterior to external jugular vein
Anterior cervical lymph nodes : Anterior jugular vein
are the superficial nodes palpable ?
may be readily palpable even if slightly enlarged
what is the waldeyers ring ?
annular collection of lymphatic tissue (nodules) surrounding the entrance to the aerodigestive tracts. Responds to pathogens that may be ingested or inhaled. Consists of the tonsils : Pharyngeal tonsil (adenoids) Tubal tonsils Palatine tonsils Lingual tonsils
what are the deep (terminal) cervical lymph nodes ?
lymph drains from superficial lymph nodes into the deep lymph nodes thus some diseases ( inflammation/ malignancy) may enlarge superficial or deep (main) cervical lymph nodes
Deep to SCM
closely related to IJV and carotid sheath
9. Jugulo-digastric
10. Jugulo-omohyoid
11. Supraclavicular lymph nodes (within supraclavicular fossa)
describe the nature of supraclavicular lymph nodes
oversee transport of lymph from thoracic activity and abdomen
Left node : drains abdomen and thorax - Virchow’s Node (for GI malignancy)
Right node : drains mid-section chest, oesophagus and lungs
describe the nature of deep cervical lymph nodes
deep cervical lymph nodes are found in close relation to the IJV within the carotid sheath. Lymph fluid passing through the deep cervical lymph nodes drains into the subclavian vein
