Major Vessels Flashcards
(36 cards)
What level does the common carotid artery bifurcate at? What is the clinical significance of this?
Superior border of thyroid cartilage (C4)
THEREFORE THE COMMON CAROTID ARTERY GIVES OFF NO BRANCHES IN THE NECK!!!
Carotid sinus in region of bifurcation —> carotid sinus massage to reduce BP (reversal of SVT) by activating baroreceptors
Common site of atheroma formation —> stenosis —> bruit
+ risk of rupturing clot —> embolism —> TIA (check for bruit before performing carotid sinus massage)
What are the main arteries branching off from the thyrocervical trunk?
Suprascapular artery —> scapular region
Transverse cervical artery —> neck
Ascending cervical artery —> neck
Inferior thyroid artery (posterior to common carotid artery) —> lower pole of thyroid gland
What are the major vessels of the head and neck?
Arteries arising from arch of the aorta:
RIGHT LEFT
Brachiocephalic trunk Left common carotid Left subclavian
- brachiocephalic gives off right subclavian and right common carotid arteries
- right subclavian artery gives off: internal thoracic, thyrocervical, and vertebral arteries
- common carotid arteries split into internal and external carotid arteries (left and right)
Veins: left and right internal and external jugular veins
- internal jugular vein deep to sternocleidomastoid, lateral to common carotid artery
- external jugular vein superficial to sternocleidomastoid
note: JVP is the right internal jugular vein (indicates pressure in right atrium, as there are no valves so a column of blood can form)
Outline the course and branches of the maxillary artery.
Terminal branch of external carotid artery
Originates adjacent to the neck of the mandible and passes through the infratemporal fossa and into the pterygopalatine fossa
Branches:
- posterior superior alveolar artery
- infra-orbital artery
- greater palatine artery
- pharyngeal branch
- sphenopalatine artery
- artery of pterygoid region
What are the branches of the external carotid artery?
- superior thyroid artery
- lingual artery
- facial artery
- ascending pharyngeal artery
- occipital artery
- posterior auricular artery
- superficial temporal artery (terminal branch)
- maxillary artery (terminal branch)
What is the arterial blood supply of the scalp? Which arteries are branches of the internal carotid artery, and which are branches of the external carotid artery?
Anterior & Superior scalp: supraorbital & supratrochlear arteries
Posterior to ear: posterior auricular artery
Posterior scalp: occipital artery
Lateral scalp: superficial temporal artery
Internal carotid artery —> ophthalmic artery —>
- –> supraorbital artery
- –> supratrochlear artery
External carotid artery —>
- –> superficial temporal artery
- –> posterior auricular artery
- –> occipital artery
What are the different layers of the scalp? Which layer contains the blood vessels supplying the scalp?
SCALP =
Skin Connective tissue (dense) (contains vessels of scalp) Aponeurosis (epicranial) Loose connective tissue Periosteum
note: fluid collecting in the dense connective tissue layer tracks forward into the orbital region because:
- the epicranial aponeurosis is continuous with the temporal fascia attached to the zygomatic arches (therefore does not move into
subtemporal region)
- occipitalis muscle attached to occipital bone & mastoid process (therefore does not move into occipital region)
- frontalis muscle inserts into skin/subcutaneous tissue, not bone (therefore fluid can move into the upper eyelids)
What are some factors which mean that the scalp bleeds profusely? Can loss of blood supply to the scalp lead to necrosis of the underlying bone?
Walls of arteries are closely attached to the connective tissue (limited constriction)
Numerous anastomoses (therefore little point in compressing inferior parts of arteries to try and stem bleeding)
Occipitofrontalis has opposing pull which keeps lacerations involving the epicranial aponeurosis open
Scalp and skull blood supplies are different, so loss of the scalp does not lead to underlying bone necrosis
What is the venous drainage of the scalp? Which parts of the scalp does each vein drain?
Anterior scalp: supratrochlear and supraorbital veins
Lateral scalp: superficial temporal veins
Posterior to ear: posterior auricular vein
Posterior scalp: occipital vein
Superficial veins accompany arteries:
- superficial temporal vein
- occipital vein
- posterior auricular vein
Supraorbital and supratrochlear veins join at medial angle of eye —> angular vein —> facial vein
Some deep parts of scalp in temporal region have veins draining into the pterygoid venous plexus
note: veins of the scalp —> diploic veins —> emissary veins —> dural venous sinus (veins are valveless, so infection of scalp can spread to meninges)
How is the blood supply preserved when the cranial cavity needs to be accessed?
Craniotomy = bone and scalp flap reflected inferiorly
Superficial temporal artery and middle meningeal artery kept intact
What is the main arterial supply of the skull and dura mater?
Middle meningeal artery (branch of maxillary artery)
Outline the arterial blood supply to the brain.
Left and right vertebral arteries (from left and right subclavian arteries) ascend through the transverse foramina of the cervical vertebrae (6)
—–> enter cranial cavity through foramen magnum —> fuse to form the basilar trunk —> posterior cerebral arteries
Internal carotid arteries enter the skull through carotid canals
—> anterior and middle cerebral arteries, ophthalmic artery, posterior communicating artery
Vertebral arteries and internal carotid arteries connect to form the cerebral arterial circle (of Willis):
- anterior communicating artery connects left and right anterior cerebral a arteries
- two posterior communicating arteries (left and right?) connect internal carotid arteries to posterior cerebral artery
Outline the venous drainage of the brain.
Cerebral and cerebellum veins drain into dural venous sinuses = endothelium-lined spaces between periosteal and meningeal layers of the dura (form at dural septae)
Includes:
- superior and inferior sagittal sinuses
- sigmoid sinus
- transverse sinus
- confluence of sinuses
- cavernous sinus
etc.
Dural venous sinuses drain into the internal jugular veins
Outline the superficial arterial supply of the face. Which arteries are branches of the internal carotid artery, and which are branches of the external carotid arteries?
Internal carotid artery —> ophthalmic artery
- –> supraorbital artery
- –> supratrochlear artery
External carotid artery —>
- –> angular artery
- –> lateral nasal artery
- –> superior and inferior labial arteries
- –> facial artery
- –> maxillary artery
- –> transverse facial artery
note: pulse of facial artery can be felt at inferior border of the mandible, anterior to the masseter muscle
Outline the venous drainage of the face.
Facial vein communicates with:
- ophthalmic veins at medial angle of eye (via angular vein) —> cavernous sinus
- pterygoid venous plexus (via deep facial veins)
Therefore infection can spread to intracranial sinuses (veins are valveless so infection can go backwards) e.g. thrombophlebitis of facial vein can travel to intracranial venous system
Supraorbital & supratrochlear veins —> angular vein —> superior & inferior labial veins —> facial vein —> common facial vein
What are the contents of the cavernous sinus?
Cavernous sinus = plexus of extremely thin-walled veins on upper surface of sphenoid bone
O TOM CAT
- oculomotor nerve (CNIII)
- trochlear nerve (CNIV)
- ophthalmic branch of trigeminal nerve (CNV1)
- maxillary branch of trigeminal nerve (CNV2)
- internal carotid artery
- abducent nerve (CNVI)
- trochlear nerve (CNIV)
+ pituitary gland?
What is the danger triangle of the face, and what is its clinical significance?
Site where infection of the face can spread from the facial vein to the cavernous sinus (and other dural venous sinuses), causing meningitis/brain abscesses/thrombosis)
Triangle constructed from corners of the mouth and the bridge of the nose.
What is a lymphatic system? What areas of the body do not have lymphatics present? Why is the lymphatic system important?
System of vessels and lymphoid organs that drain tissue fluid from the extracellular component to the circulatory (venous) system
Absent in the CNS, eyeballs, inner ear, avascular planes of cartilage, bone
- major constituent of immune system
- fluid balance/determination of cell volume (blockage —> lymphoedema)
- absorbs/transports fats from digestive system
- conduit for spread of infection/cancer (primary and secondary)
- assists capillaries in returning plasma proteins (which leak into the ECF)
- assists transport of cellular debris which does not use the circulatory system
What is lymph composed of? What function does it serve? How much is produced per day?
Transudative fluid, alkaline, transparent, yellowish (although this depends on the location in the body)
- 96% water (exerts an osmotic effect)
- 4% solutes: electrolytes (osmotic effect), 2%-6% proteins (oncotic effect), 5%-15% lipids, glucose
- cells (mainly lymphocytes)
Lymph formed when water leaves blood and enters the extracellular compartment (via Starling’s forces) - ~10% of blood volume which passes through the tissues returns via lymphatics, not venous system
Bathes all cells of the body (most widely distributed tissue in body)
Low pressure; movement driven by breathing and muscle contraction.
3-4l of lymph produced per day (at rest) = ~120ml/hr flow (100ml through thoracic duct, 20ml through right lymphatic duct)
note: chyle = lymph produced by small intestines
What are the components of a lymph channel? How does lymph drain in general?
Lymphatic capillaries (microscopic) —> Lymphatic vessels (lymphangions) —> Lymph node —> Collecting trunks —> Lymphatic ducts (right lymph duct or thoracic duct) —> Subclavian vein
Afferent lymphatics —> Follicles (of lymph node) —> Efferent lymphatics
Superficial lymph vessels drain the skin and follow venous drainage
Superficial lymph vessels drain into deep lymph vessels
Deep lymph vessels tend to accompany arteries (except head and neck deep lymphatics, which follow veins)
What are the main organs of the lymphatic system?
Tonsils Lymph nodes & lymphatic vessels Thymus Spleen Peyer's patches Appendix Bone marrow
What quadrant of the body does the right lymphatic duct drain? Where does the right lymphatic duct drain into the venous system?
Drainage of upper right quadrant (right side of face, neck, and thorax, and right arm)
Enters venous system at right venous angle (union of right internal jugular vein and right subclavian vein)
What quadrant of the body does the thoracic lymphatic duct drain? Where does the thoracic lymphatic duct drain into the venous system?
Drains all three quadrants of the body apart from the right side of the head, neck, and thorax, and the right arm (right lymphatic duct)
Enters venous system via left venous angle (union of left internal jugular vein and left subclavian vein)
note: thoracic duct originates from cisterna chyli in the abdomen (dilatation of duct due to entry of chyle) and ascends through the aortic hiatus of the diaphragm
note: thoracic duct runs just right of the midline until T5 (sternal angle/mediastinum), then it crosses to the left side above T5
Contrast the different ways of classifying different lymph nodes.
Regional v.s. Terminal:
- regional lymph nodes drain specific anatomical regions
- terminal lymph nodes are the point of confluence of lymph drainage of many regional lymph nodes
Horizontal v.s. Vertical:
- horizontal: clusters of lymph nodes which occur on a horizontal plane (irrespective of depth; can be high, intermediate, or low)
- vertical: lymph nodes which occur on a vertical plane (following the course of the internal jugular vein; difficult to palpate due to depth)
