Major Blood Vessels Session2 Flashcards
Where do the subclavian and common carotid arteries arise from?
Brachiocephalic trunk (directly from arch of aorta)
Look at slide 4 of lecture
Where do the vertebral, internal thoracic and thyrocervical arteries all arise from?
Subclavian artery in the base of the neck
Look at slide 4 in lecture
Branches of the thyrocervical trunk & where they supply (4)
Inferior to superior
Suprascapular-> shoulder
Transverse cervical &
Ascending cervical -> neck
(Most medial)
Inferior thyroid -> lower pole of thyroid gland
Route of the vertebral arteries
Arise from subclavian arteries
Ascend neck in transverse foramina of C1-6
Pass through foramen magnum base of skull
-> circle of Willis
Supply the brain along with internal carotid arteries
Course of the internal carotid artery from entering the skull?
Through the carotid canal (anterior to foramen magnum) in petrous part of temporal bone
Turns medially and horizontally
Enters the cranial cavity then makes S shaped bend
Courses through the cavernous sinus
Where in the neck is a common site for atheroma formation?
Bifurcation of the carotid artery -> stenosis -> rupture of the foot can cause embolus travel to the brain -> TIA or stroke
Where and what is the function of the carotid sinus and carotid body?
Carotid sinus - swelling at bifurcation CCA, baroreceptors detect changes in arterial BP -> carotid sinus N (branch of glossopharyngeal N) -> increase or decrease
(Heart contract/ speed, kidneys urine production, dilate veins/arteries)
Carotid body - peripheral chemoreceptors which detect arterial O2 - at bifurcation -> glossopharyngeal N
(Increase decrease ventilation rate)
What’s the operation to remove a plaque from the carotid bifurcation?
Carotid endarterectomy
What’s a carotid sinus massage?
Rub the carotidsinus -> increased parasympathetic output -> slow down heart
Helps with supraventricular tachycardia but can cause bradycardia in a healthy person
What is the cavernous sinus and what does it contain?
Dural venous sinus- plexus of extremely thin veins on upper surface of sphenoid
Internal carotid A, Cranial nerves: 3 (oculomotor), 4 (trochlear), 6 (abducent), 2 branches of the trigeminal (cranial nerve 1/ ophalmic and 2/ maxiallary)
Cranial nerves 1-6 minus 5
Main branches of ophthalmic artery
Posterior to superior
Anterior (part of kiesselbachs area along with septal branch of sphenopalatine) and posterior ethmoidal arteries (in canals in ethmoid bone)
Supratrochlear A
Supra-orbital A (in front of eye)
6 branches of external carotid artery and the 2 terminal branches
inferior to superior
Superior thyroid A - superior lobe Tg
Lingual A - tongue
Facial A
Ascending pharyngeal A - pharynx
Maxillary A (terminal) - chin
Occipital A -back head
Posterior auricular A - scalp behind ear
Superficial temporal A (terminal) - upper and lateral parts of the scalp
‘Some(t) long face arteries(p) make oral presentation(a) superficial(t)’
Scalp layers
Skin
Connective tissue (dense. Vessels lie in subcutaneous CT layer)
Aponeurosis
Loose Ct
Periosteum
Why can you get profuse bleeding in the scalp?
Occipitofrontalis has an occipital belly and a frontal belly. Between is the epicranial aponeurosis. Arteries lie close to CT which limits contraction. If deep lacerations involving epicrainial aponeurosis occur there is profuse bleeding bc of the opposing pull of occipitofrontalis.
Why does loss of scalp not lead to bone necrosis? What is the blood supply to the scalp and where is the most common point of rupture?
Skull has different blood supply - mostly middle meningeal artery
Anterior/ frontal branch (common site of rupture - thin bone of pterion can fracture -> extramural haemorrhage)
Posterior/ occipital branch
Also supply dura
Superficial arteries of the face
Superior to inferior
From ICA (via ophthalmic):
Supra-orbital a
Supratrochlear a
From ECA:
Angular a (ascending nose)
Lateral nasal a
Transverse facial a (more lateral in front of ears)
Maxillary a (more lateral, below TFA)
Superior and inferior labial a (lips)
Facial a (pulse felt inferior mandible, anterior to masseter)
Two main branches of maxillary artery
Middle meningeal -> skull and meninges
Sphenopalatine -> anastomoses on nasal septum (kiesselbachs area) common site for epistaxis
How is blood supply preserved in a craniotomy?
Bone and scalp flap reflected inferiorly
Venous drainage of the scalp
Supraorbital vein (above eyes) and supratrochlear vein (lateral scalp) at medial angle of eye drain into the angular vein (corner of eyes and top of nose) drains into the facial vein (runs down either side of lips) which drains into the IJV
Some deep parts in temporal region have veins which drain into the pterygoid venous plexus
Connection between venous drainage of scalp and dural venous sinuses and why is this a problem?
Veins of scalp -> emissary veins-> veins of skull (diploic)-> Dural venous sinuses
Emissary veins (valveless)
Infection can spread from scalp to cranial cavity and affect meninges
Veins of the face
Veins of the face are valveless
At medial angle of eye facial vein communicates with superior ophthalmic vein -> cavernous sinus
(Between temporalis and lateral pterygoid) Pterygoid venous plexus cavernous sinus (Dural venous sinus in skull)
How can infection spread from face to brain
Through cavernous sinusa dural venous sinus which superior and inferior ophthalmic veins drain into
If thrombophlebitis occurs of facial vein, infected clot can travel, to intracranial venous system
Especially in danger triangle of face (corners of mouth to bridges of nose)
Dural venous sinuses
Superior Sagittal sinus (top of head) -> transverse sinus -> sigmoid sinus -> IJV (through jugular foramen)
Also a inferior sagittal sinus and a cavernous sinus
Measuring JVP
Use the right internal jugular vein (direct connection to right atrium)
Patient at 45d angle - head slightly to left
Pulsation through sternocleidomastoid
Measured in cmH2O
Height from sterna, angle +5cm
