Session 2- Blood Supply ( workbook section in quizlet ) Flashcards
Describe the bifurcations of the main aorta and what vessels arise from those bifurcations
Aorta splits into the brachiocephalic trunk, left subclavian, left common carotid
On right, common carotid and right subclavian both branch off of the brachiocephalic trunk
Vertebral arteries and thyrocervical trunk branch off subclavian
What are the 3 branches of the thyrocervical trunk and what do they supply
Ascending and transverse- neck
Suprascapular- shoulder
Inferior thyroid- lower thyroid
At what level does the common carotid bifurcate
C4- also level of superior part of thyroid cartilage
What are the anatomical relations around the common carotid
Under SCM muscle and is medial to the IJV (IJV is lateral to common carotid)
Borders of carotid triangle and relevance
Part of the anterior triangle
Upper belly of omohyoid
Posterior belly of digastric
Anterior border of SCM
Where bifurcation of common carotid occur
Why is the carotid artery a common place for atheroma to form and what can occur due to it
Lots of turbulence at bifurcation causing sheer stress and eventual build up of plaque
Can cause TIA due to limited blood supply to brain (can travel to circle of Willis and block brain blood supply)
What is the carotid sinus, what important features does it have and what is it’s relation to SVT
Carotid sinus is the bulge before the bifurcation which houses baroreceptors for detecting changes in BP
Where is the carotid body and what is its importance
Houses chemoreceptors which detect arterial oxygen
Located next to carotid sinus
What is the carotid sinus innervated by
Branch of the glosopharngeal
What is the clinical significance of the carotid triangle
Gives surgical approach to carotid , IJV and vagus via carotid triangle
Can feel pulse below bifurcation and can perform carotid sinus massage
Path of internal carotid artery
Goes through Peterous part of temporal bone and turns to enter the cranial cavity, bends (s shape) and goes through cavernous sinus
What is the cavernous sinus’s, its clinical relevance and contents
What gland sits superiorly
Plexus of thin walled veins on upper surface of sphenoid
ICA, branches of trigeminal and many other important nerves so swelling here dangerous
Pit gland sits on top
What are the important bifurcations of the ophthalmic artery and where is the opthalmic originally from
From the ICA
Supraorbital and supratrochlear supply eye
Ethmoidal supply nose
What are the 6 branches of the ECA and its 2 terminal branches
What do they mostly supply
Mostly supply skin and scalp
Superior thyroid Lingual Facial occipital Ascending pharyngeal Posterior auricular Maxillary (terminal) Superficial temporal (terminal)
What arteries form both internal and external carotids supply the scalp
External
- superficial temporal
- occipital
- posterior auricular
Internal
- supra orbital (opthalmic branch)
- supra trochlear (ophthalmic branch)
What are the layers of the scalp and what layer d the vessels lay in and what is the clinical relevance
Skin Dense connective tissue Aponeurosis Loose connective tissue Periosteum
Lie in subcutaneous connective tissue layer
Means walls of arteries attached to CM limiting constriction, if lacerated can get profuse bleeding
Why do deep lacerations of the epicranial aponeurosis cause profuse bleeding
Cuz of opposing pull of occipofrontalis
What artery supplies most of the scalps blood
Middle meningeal from maxillary
Why does loss of scalp not result in bone necrosis
Because scalp get separate blood from face
What are the superficial arteries of the face
Ones branching off of external carotid and 2 from internal
What are some important branches of the maxillary artery
What do the maxillary branches supply
Middle meningeal - meninges
Sphenopalatine - nose (by joining other arteries)
Deep structures in face
What is the blood supply to the nasal septum
Anastomoses of arteries in kiesselbach area 9castle back)
Sphenopalatine (septal branch)
Anterior ethmoidal arteries (form opthalmic)
What is the most common area for nose bleeds
Kiesselbach cuz of anastomoses
What supples the dura and why is this artery particularly vulnerable to damage
The middle meningeal
Because it foes through pterion to meet dura which is the thinnes part of the skull so common site of rupture is here
What artery forms the grooves seen on the internal view of the skull cap (calvaria)
The anterior branch of the middle meningeal artery
What does the middle meningeal artery supply
Skull and dura
What occurs as a consequence of a pterion fracture and what does it form (/ show on CT)
Extramural haemorrhage which can incr cranial pressure
Forms a convex haematoma outside of the dura
In a craniotomy why is the bone and skull flap reflected inferiorly
To preserve blood supply
What is special about the venous drainage of the supraorbital and supratrochlear veins
Unlike the rest, they unite at the medial angle of the eye and form the angular vein which drains into the facial vein instead of going back to the cranial cavity
Describe the connection between venous drainage of scalp and rural venous sinuses
Why is this important
Veins of scalp connect to diploic veins through emissary veins, which drain into dural venous sinuses
Infection from scalp can spread to cranial cavity and affect meninges
Describe the connection of the facial veins with the cavernous sinus and the pterygoid venous plexus
Give an example
The facial vein meets superior opthalmic at angle of eye and drains into the cavernous sinus
DEEP facial veins drain into pterygoid venous plexus meaning infection from facial vein can spread to dural venous sinuses
Thrombophlebitis of facial vein where infected clot travel to intracranial venous system
VEINS IN THE FACE ARE VALVELESS
K
What is the danger triangle of the face
Infections in the middle part of the face (nose, top lip to t zone) can spread through venous system to dural venous sinuses
List 3 examples of dural venous sinuses
Superior Sagittarius sinus
Cavernous
Sigmoid (leaves skull through jugular foramina as a continuation of the IJV)
What is the IJV an indication of and how do you measure JVP
Right atrial pressure
Measure by using RIGHT IJV as its a direct connection to atrium
- head slightly left, patient at 45 degree angle
- see pulsation through muscle
- measure height from sternal angle and add 5 cm
