Lecture 4: Head and Neck Vasculature II: Arterial Supply Flashcards
(51 cards)
What is Subclavian Steal Syndrome?
- Obstruction of the subclavian artery proximal to vertebral artery
- Episodic increase in peripheral circulatory demand in associated extremity causes shunting of blood from the vertebro-basilar circulation through vertebral artery into distal subclavian artery
- Causes vertebro-basilar insufficiency
The decrease in blood flow to the brain (vertebro-basilar insufficiency) may cause what serious problems?
- Coma
- Quadriplegia
- Numerous CN abnormalities
- Transient or permanent neurologic damage
The second part of the subclavian artery is found where; gives off what branches?
- Immediately posterior to the anterior scalene muscle
- Costocervical Trunk (2 major branches):
a) Deep Cervical artery
b) Superior Intercostal artery
What supplies 20% of the blood to the brain and what does it terminate as?
- Vertebral artery from Subclavian artery
- Terminates as the Basilar artery
Changes in cerebral blood are auto-regulated to a degree, why is this clinically significant?
- Significant shunting of blood from one region of circulation to another (i.e., anterior –> posterior) may result in:
- Hyperperfusion
- Cerebral edema
How is the blood supply to the brain maintained by the internal carotids and vertebral arteries; what does each supply?
Internal Carotids: supply 80% of the blood to the Circle of Willis
- Anterior circulation
- Most of cerebral hemispheres, upper brainstem
Vertebral artery: supply 20% of the blood
- Posterior circulation
- Brainstem, Cerebellum, Occipital lobe
One each side of the pituitary gland through the thin bony wall lies what artery; what must be clamped to stop blood flow if this artery is compromised?
- The internal carotid artery
- Must open the neck and clamp the common carotid artery
What provides blood supply to the anterior aspect of larynx; what membrane does it pierce?
- Superior Laryngeal artery a branch of the Superior Thyroid artery
- Superior Laryngeal artery piercs the thyrohyoid membrane and provides blood to the anterior aspect of the larynx
How do the common carotids differ in their origin?
- Right common carotid begins at bifurcation of the brachiocephalic trunk just posterior to the right sternoclavicular joint
- Left common carotid arises from the apex of the aortic arch, and passes through the superior mediastinum to enter the neck just posterior to the left sternoclavicular joint
Facial artery passes through where and terminate as?
- Passes through the submandibular triangle, DEEP to the submandibular gland
- Gives off 3 branches in the face before terminating as the angular artery at the medial angle of the orbit
What are the 5 branches of the Mandibular Portion (1st) of the Maxillary Artery?
1) Deep Auricular
2) Anterior Tympanic
3) Middle Meningeal
4) Accessory Meningeal
5) Inferior Alveolar
What occurs if the middle meningeal artery is ruptured with head trauma?
- Hemorrhaging separates the endocranium and dura mater and creates a rapidly expanding blood clot in epidural space
- Epidural Hematoma
What is the route of the middle meningeal artery after branching from Maxillary artery; what nerve does it travel with; what does it split into and supply?
- Splits the auriculotemporal nerve before passing through the foramen spinosum along with the recurrent meningeal branch of V3.
- At level of the pterion, splits into anterior and posterior branches to supply most of the dura mater and endocranium
After branching from the maxillary artery, the Inferior Alveolar artery gives off what artery, passes through where to supply what; what does it terminate as?
- Gives off the small mylohyoid artery prior to passing through the mandibular foramen
- Within the lower jaw, supplies the: mandible, teeth and gingivae
- Terminates as the mental artery at the mental foramen
What are the branches of the Pterygoid portion (2nd) of the Maxillary Artery?
- Deep Temporal a.
- Pterygoid Branches
- Masseteric a.
- Buccal a.; runs with Buccal N. (CN V)
What are the 2 branches of the Sphenopalantine Portion (3rd) of the Maxillary artery that are lateral to the pterygomaxillary fissue; what does each supply?
1) Posterior Superior Alveolar artery: penetrates the posterior surface of the maxilla and supplies the molar teet and gingiva of the upper half of jaw
2) Infraorbital artery: courses through the infraorbital fissue and canal. In the canal gives off the anterior superior alveolar artery, which supplies anterior upper half of jaw. Distal to the infraorbital foramen, it anastomoses with branches of the facial artery
What are the 2 main branches of the Sphenopalantine Portion (3rd) of the Maxillary artery that are within the Sphenopalantine fossa; what does each supply?
1) Descending Palatine artery: divides into the lesser and greater palatine arteries at the level of the hard palate. Supplies the soft and hard palate, respectively
2) Sphenopalantine artery: the terminal branch of the maxillary. It is the MAJOR ARTERIAL SUPPLY to the posterior nasal cavity, through its 2 major branches: Posterior Lateral Nasal and Posterior Septal as.
Wha is the significance of the carotid sinus; what provides the innervation?
- Acts as baroreceptors innervated by Glossopharyngeal N (CN IX)
- Indirectly modulates parasympathetic and sympathetic response to blood pressue
At a regional cerebral blood flow of 10-20 mL/100 gm/min what occurs to the watershed region? (this is important)
- The watershed region of the cerebral cortex is too ischemic to function, yet critically viable. Stroke therapy is directed at rescuing this ischemic penumbra by improving tissue acidosis and oxygen delivery
- Neurons in this region require blood supply from both of the major cerebral arteries (MCA and ACA). Obstruction causes hyperperfusion to try and fix the problem, but just ends up leading to edema
- Autoregulation dysfunction and edema due to ischemic tissue acidosis, and resultant “luxury perfusion” of adjacent normal tissue
Regional or focal ischemia is characteristically seen in athero-cerebral infarction (stroke) where there is an occulsion of a large nutrient artery, what does it lead to?
Neuronal injury or necrosis to the central core territory of arterial supply, and varying degrees of dysfunction to the potentially viable tissue in the surrounding marginal territory (ischemia penumbra)
The internal carotid and vertebral arteries pierce the ______, and course in the _______ along with their many branches for a variable distance.
The internal carotid and vertebral arteries pierce the dura, and course in the subarachnoid space along with their many branches for a variable distance.
As the branches of the internal carotid and vertebral arteries penetrate into the substance of the brain they are progressively surrounded by the tapered?
Perivascular space (Virchow-Robin space) and the pia mater or blood-brain barrier
The posterior communicating artery (PCoA) is located between; what do its ganglionic or penetrating branches supply?
- The ICA and the posterior cerebral arteries
- Supply the internal capsule and the basal ganglia
What areas of the brain and particular neuronal populations are consistently damaged in severe ischemic injury?
Pyramidal cells of the hippocampus especially the CA1 or Sommer’s sector
