Extra-cranial arteries and veins Flashcards
What is the major vasculature of the neck?
- The major vasculature of the neck has anatomical relations to the following palpable landmarks:
○ Suprasternal Notch
○ Sterno-clavicular Joint
○ Clavicle
○ Sternocleidomastoid Muscle
○ Anterior Scalene Muscle
○ Thyroid Cartilage
○ Mandible
What are the major blood vessels of the neck?
○ Arterial supply to the Head & Neck Region originates from the arch of the
○ aorta
○ The anatomical plane that defines the
○ level of the arch of the aorta is known as the Sternal Angle or Sternal Angle of Louis
○ There is left-right asymmetry in the distribution of arterial supply from the arch of the aorta
○ Brachiocephalic Artery
§ Ends by bifurcating at the sternoclavicular joint
§ Giving rise to: the Right Common Carotid Artery and the Right Subclavian Artery
○ Left Common carotid Artery
§ Starts at the arch of the aorta
○ Left subclavian Artery
§ Starts at the arch of the aorta
Tell me about the subclavian artery.
- Left subclavian artery begins at the arch of aorta and will provide blood to the left side of the body
- Right subclavian artery begins at the brachiocephalic artery. The brachiocephalic artery begins at the arch of aorta and bifurcates ta the level of the sternoclavicular joint into the right subclavian artery and the right common carotid artery.
- The right subclavian artery provides blood to the right side of the heart
What are the branches of the subclavian artery?
The subclavian has 3 anatomical parts in respect of the major scalene muscle
Its first gives rise to major arterial branches to the head and region in the following order: vertebral artery and thyrocervical trunk
Tell me about the vertebral arteries
- Arise as the first branches of subclavian arteries, one on each side of the body
- Enter the neck deep to the transverse process at the level of the 6th cervical vertebrae (C6)
- They then course superiorly, in the transverse foramen of each cervical vertebra.
- Once they have passed through the transverse foramen of C1, the vertebral arteries travel across the posterior arch of C1 and through the suboccipital triangle before entering the foramen magnum.
- Inside the skull, the two vertebral arteries join to form the basilar artery at the base of the Pons (Pontomedullary Junction)
Tell me about the thyrocervical trunk
- artery that gives rise to three branches: Inferior thyroid Artery, Suprascapular Artery and Transverse cervical Artery
- This is only true in 30% of the population as its branches are extremely variable
- It is a wide vessel that arises from the first segment of the subclavian artery.
- It has a relatively short course in the anterior portion of the neck.
- It has a wide arterial territory
- it vascularizes the thyroid and parathyroid glands, larynx, pharynx, brachial plexus, cervical and shoulder muscles and the adjacent skin
Tell me about the common carotid arteries.
right common carotid rises from the bifurcation of the right brachiocephalic artery from behind the sternoclavicular joint
* The left common carotid arises from the arch of aorta as the third branch
* This means that the carotid has a 2cm path in the mediastinum before entering the neck
* Cervical portions of the common carotid arteries are about 8.5 cm long (Left & Right)
* They have no collateral branches
* They both terminate by divide into the internal and external ceratoid artery at the level of the upper border of the thyroid cartilage (C4 Vertebra - less reliable landmark)
* The Common carotid artery terminates by diving into: External Carotid Artery & Internal Carotid Artery
What are the arteries of the carotid line?
- The course of the common carotid artery is defined by a line between palpable anatomical landmarks of the head and neck as follows:
- This line:
○ Begins- Level of the sternoclavicular joint
○ Ends- Midway between the angle of the mandible and the mastoid process of the temporal bone. - This line is known as the Carotid Line
- there are 2 arteries along the carotid line
- Upper border of the thyroid cartilage forms the boundary between arteries of the carotid line
- Common carotid artery from the sternoclavicular joint to the upper border of the thyroid cartilage
- External carotid artery above the upper border of the thyroid cartilage
- This line:
Tell me about the internal carotid arteries
- Internal carotids have no branches in the neck but continue within the carotid sheath, in company with the internal jugular vein, to the base of the skull where they enter the cranium
- They continue within the carotid sheath
- Within the sheath, they are accompanied by the internal jugular vein & lymph nodes
- They continue to the base of the skull where they enter the cranium
- They enter the cranium via the carotid canal
Tell me about the blood supply to the intercranial compartment
- There are two separate but convergent arterial sources as follows:
- The left & right internal carotids
- The left and right vertebral arteries
- These arterial systems connect to form an arterial anastomosis
Arterial anastomosis of the brain.
- connects separate arteries that supply the brain
- The pattern of connection between these arteries has a tendency towards forming a what is
- effectively a closed, circular arterial network- allows blood to be supplied to all areas of the brain (even if one is blocked)
- This circular arterial anastomosis is known as The Circle of Willis
- It has a closed circular formation
- This circumvents the end-artery problem of perfusion of structures of the brain
- This design should make development of strokes a nullity
- VERY LITTLE PEOPLE HAVE A FULL CIRCLE OF WILIS SO STROKES STILL HAPPEN
Tell me about the external carotid arteries
It arises from bifurcation of the common carotid artery
Ascends from the arch of aorta giving numerous branches to supply the head and neck
We are required to know each of the major
branches of the external carotid artery and what structures they supply
Tell me about the branches of the external carotid arteries
- In total the ECA has 8 branches that are divisible into 2 categories
- Branches – n=6
- Terminal Branches- n=2
- Mnemonic for all branches of the ECA is: SALFOP
○ Superior Thyroid Artery
○ Ascending pharyngeal Artery
○ Lingual Artery
○ Facial Artery
○ Occipital Artery
○ Maxillary Artery
○ Posterior Auricular Artery
○ Superficial Temporal Artery - Some of these branches are more important than others for various reasons
Tell me about the maxillary artery
t is the largest terminal branch of the external carotid artery
* It arises from just deep and posterior to the neck of the mandible
* It then travels through the substance of the parotid gland
* The facial nerve also travels through the substance of the parotid gland without innervating it
* It then passes forwards between the sphenomandibualr ligament and ramus of the mandible
* It gives rise to a lot of deep arterial branches that supply various portions of the head
* Most Important Branch
* Middle meningeal – supplying the meninges and related to pterion and so Epidural haematomas
What is the anatomical course of the maxillary artery
- At its origin, the maxillary artery is embedded in the parotid gland
- After exiting the gland, it runs through the infratemporal fossa and enters the pterygopalatine
- fossa via the pterygomaxillary fissure
- While passing through the pterygopalatine fossa, the maxillary artery divides into four branches, and
- gives off several side branches
- Topographically the maxillary artery can be divided into three portions namely:
○ Mandibular part
○ Pterygoid part
○ Pterygopalatine part
What statues are supplied by the maxillary artery
- It supplies deep structures of the face that include the:
○ Mandible
○ Maxilla
○ Teeth
○ Muscles of mastication
○ Palate
○ Nose
○ Part of the cranial dura mater
Tell me about the facial artery
- It is a branch of the external carotid artery
- It supplies structures of the superficial face.
- It arises from the carotid triangle which is formed by the superior belly of the omohyoid muscle, the sternocleidomastoid, and the posterior belly of the digastric.
- It originates deep to the platysma and quickly becomes superficial.
- It is characterised by a tortuous course that allows for more stretch during facial actions such as mastication.
- It travels deep to the posterior belly of the digastric and stylohyoid muscles
- It then continues along the posterior surface of the submandibular gland
- It then curves upward over the body of the mandible and courses along the anteroinferior border of the masseter
- It then continues superiorly at an oblique angle across the cheek towards the oral commissure then ascends along the side of the nose terminating at the medial canthus of the eye as the angular artery
- its pulse is palpable as it crosses the mandible
What is the blood supply to the scalp?
- Supplied by an anastomosis of the superficial temporal, posterior auricular & occipital arteries
- Also has some supply from the ICA in the form of supratrochlear & supraorbital supplying forehead
ECA Targets in Some Detail
- Ear
○ Outer ear supplied by posterior auricular and superficial temporal- Nose
○ External nose is facial artery with lateral nasal and angular artery
○ Internal cavity is supplied by Ophthalmic artery giving anterior and posterior ethmoid
○ Maxillary gives spehnopalatine & greater ethmoid
○ Facial giving superior labile
○ Anastomase to make Kiesselbach area
- Nose
What is the blood supply to the mouth?
- Facial, Maxillary and lingual anastomose in the mouth
- Facial supplies the lips via superior and inferior labile
- Maxillary supplies the mucosa, teeth, gingivae and palate and muscles of mastication
- Inferior alveolar artery of maxillary supplies mandibular teeth and chin
Lingual supplies the tongue and floor of mouth
Give me an overview of venous drainage
- The face region is drained by both the internal jugular vein and external jugular vein
- The facial vein (or anterior facial vein) is a relatively large vein in the human face
- It commences at the side of the root of the nose and is adirect continuation of the angular vein
- It receives blood from the external palatine vein before it either joins the anterior branch of the retromandibular vein to form the common facial vein, or drains directly into the internal jugular vein.
- A common misconception states that the facial vein has no valves, but this has been contradicted by recent studies.
What is the triangle of danger?
- also known as the Naso-Labial Triangle
- Venous drainage from this territory can reach the Cavernous sinus
- Superior and Inferior Ophthalmic Vein provide most of the conduit for this communication with the cavernous sinus
