L3: major blood vessels of the head and neck Flashcards
What is the arterial supply of the head and neck?
Right and left common carotid arteries
Vertebral arteries
Describe the course of the vertebral arteries
The vertebral artery ascends through the transverse foramina of the cervical vertebrae and enters the subarachnoid space between the atlas and occipital bone
Passes up through the foramen magnum, curving around the medulla to join the vertebral artery from the other side = BASILAR ARTERY
Supplies the posterior neck and posterior parts of the brain
Where do the right and left common carotid artery arise from?
Right – originates from the brachiocephalic artery behind the sternoclavicular joint
Left – arises directly from the arch of the aorta
Therefore, LCCA is slightly longer
Describe the course of the common carotid arteries
Ascend through the neck enclosed within the carotid sheath
Terminate at the level of the upper border of the thyroid cartilage & divide into internal and external carotid arteries
-ICA is more bulbous due to present of the carotid sinus
Describe the importance of the carotid sinus
Rubbing this area firmly can alleviate supra-ventricular tachycardias
CAROTID MASSAGE
Describe the course of the internal carotid artery
Doesn’t give off any branches in the neck
Ascends through the base of the skull, through a bony canal called the carotid canal
Passes through the cavernous sinus
After it has exited the sinus, the ICA gives its branches which supply the brain and the eye
Describe the external carotid artery and list its branches
Major source of blood supply to extra-cranial structures Gives rise to eight branches -superior thyroid -ascending pharyngeal -lingual -facial -occipital -posterior auricular -maxillary -superficial temporal ‘some anatomists like freaking out poor medical students’
Describe the course of the maxillary and superficial temporal arteries
Considered the terminal branches of the ECA, arising at a level behind the neck of the mandible
Arise within and travel through the substance of the parotid gland & provide the gland its major source of blood
Maxillary artery – supplies deep tissue & bone structures of the face
-gives off a branch called the middle meningeal artery, which runs through the base of the skull to supply the meninges and skull bones
Superficial temporal artery – supplies tissue of the scalp
What is temporal arteritis?
Superficial temporal artery is affected -> a form of vasculitis involving small and medium size vessels
Serious condition, requiring urgent treatment -> can lose eyesight if not
Describe the course of the facial vein
Most of the structures of the face drain via the facial vein
Runs from the medial angle of the eye towards the inferior border of the mandible
Then joins the internal jugular vein
What is the clinical importance of the cavernous sinus?
The facial vein connects with both the superior and inferior ophthalmic veins – direct connection with the cavernous sinus
Cavernous sinus lies intra-cranially, therefore blood draining the face via the facial vein can drain intracranially (veins are valveless, blood can flow in either direction)
Implications for infections involving the face -> can spread to involve intracranial structures, making the infection immediately more concerning
-cavernous sinus thrombosis (extremely rare)
What are emissary veins?
Run through the skull and connect the veins of the scalp and intra-cranial venous sinuses
Provide a potential route for infection of the scalp to spread into the cranial cavity
What is the danger triangle?
Infections within the scalp or face can potentially track intra-cranially to involve the brain and/or its associated structures, becoming an immediately more serious infection
Area from the corners of the mouth to the bridge of the nose, including the nose and maxilla
Describe the course of the internal jugular vein
Arises as a continuation of a venous structure found within the skull, the sigmoid sinus
Runs the length of the neck within the carotid sheath
Throughout much of its course the SCM muscle covers it anteriorly, however toward the inferior end of the vein, the SCM muscle splits into its two heads forming a gap -> IJV can be readily accessed here
IJV ends by joining with the subclavian vein -> brachiocephalic vein -> superior vena cava -> right atrium
Describe the clinical importance of the internal jugular vein
Common site for the insertion of central venous catheters
Normal jugular venous pulsation can be seen -> gives an indication of the pressures within the venous circulation and right side of the heart
-right side is favoured, as the right has a straight, more vertical route into the right atrium -> better reflects pressures within the right side of the heart
