UG02-AON-1015 Blood Supply to the Head and Venous Drainage PDF

Anatomy of the head and neck – Blood supply, venous drainage Anatomy of the Head & Neck Blood supply and venous drainage of the head and neck [email protected] ANATOMY 0 Lecture outcome Ø State the origins and course of the common, internal and external carotid arteries form both sides Ø Des...

Anatomy of the head and neck – Blood supply, venous drainage Anatomy of the Head & Neck Blood supply and venous drainage of the head and neck [email protected] ANATOMY 0 Lecture outcome Ø State the origins and course of the common, internal and external carotid arteries form both sides Ø Describe the course and distribution of the major branches of the external carotid Ø Summarize the importance of the anastomoses in the region Ø Describe the usual pattern of venous drainage and the major variations ANATOMY 1 Blood supply to the head!? Ø Arterial blood supply to the head may seem very intricate … ⁉ ANATOMY © Visible Body 2 Blood supply to the head Ø … But arterial blood supply to the head comes from four main arteries. These are: External caro,ds Internal carotids Vertebral Thyrocervical trunk Ø The first three supply the head, while the fourth is confined to the neck Ø The area each supplies do overlap, which allows for collateral blood to reach all areas even if any of these sources becomes compromised ANATOMY 3 Blood supply to the head – cont. Ø All of the mentioned vessels originally stem from the aorta (highlighted) Arch of the aorta ANATOMY © Visible Body 4 The arch of the aorta Ø The following slides will then look at the main branches out of the arch of aorta Ø This differs slightly between the left and right hand side ANATOMY 5 Common carotid and subclavian arteries Ø On the leG hand side, the common caro(d (highlighted) emerges directly from the aorta… Left common carotid ANATOMY © Visible Body 6 CC and subclavian arteries – cont. Ø … as does the subclavian artery (highlighted), so named as it travels under the clavicle (a.k.a. collar) bone to target primarily the arm LeG subclavian ANATOMY © Visible Body 7 CC and subclavian - 3 Ø On the right hand side, though, both the carotid and subclavian arteries arise instead from a common branch emerging from out of the aorta called brachiocephalic (highlighted) that, as the name indicates, is the source of blood to the arm (brachium) and head (cephalic) Brachiocephalic ANATOMY © Visible Body 8 The external and internal caro@d arteries Ø On either side of the head and close to the upper border of the thyroid carIlage, the common caroId (highlighted) splits, giving rise to the external and internal caro(ds (also highlighted) External carotid Internal carotid Thyroid cartilage Common carotid ANATOMY © Visible Body 9 External carotid Ø The external caroId provides several branches that target the face and neck Ø OGen memorised using the mnemonic : ‘Some Anatomists Like Freaking Out Poor Medical Students’ Superior thyroid artery Ascending pharyngeal artery Lingual artery Facial artery Occipital artery Posterior auricular artery Note: The external carotid provides a useful target to obtain the carotid pulse or to insert a line Maxillary artery ANATOMY Superficial temporal artery 10 External caro@d – cont. Ø The branches of the external carotid communicate between both sides of the head ANATOMY 11 Superior thyroid artery Ø The superior thyroid (highlighted) arises from just below the hyoid and descends to supply the thyroid gland External carotid Thyroid Superior thyroid ANATOMY © Visible Body 12 Posterior auricular, temporal and occipital arteries Posterior auricular Temporal Occipital ANATOMY © Visible Body 13 Lingual branches of the external carotid artery © Visible Body Facial External carotid ANATOMY Lingual 14 Branches of the maxillary artery Ø The maxillary runs deep to the zygomatic arch before branching to provide blood to the deep structures of the face – see previous lectures Maxillary ANATOMY © Visible Body 15 Internal caro@d Ø The internal carotid, which travels much deeper in the neck, has fewer branches Ø It contributes primarily towards supplying the brain, after travelling through the carotid canal (white dashed circle) at the base of the skull Ø But also supplies the eyes, upper nose and forehead => ophthalmic arteries Internal carotid CaroId canal ANATOMY © Visible Body 16 Branches of the subclavian artery Ø The remaining two arteries of interest – vertebral and thyrocervical – arise from the first* part of the subclavian ANATOMY * The subclavian artery is divided into three parts, by the scalenus anterior. Most of the branches supplying the head and neck are branches of the first part 17 Vertebral artery Ø The vertebral artery originates from the subclavian and proceeds superiorly within the vertebrae, only providing small spinal arteries to supply surrounding structures Ø This vessel then enters the skull through the foramen magnum (dashed circle) Vertebral © Visible Body foramen magnum ANATOMY 18 Vertebral and internal carotid Ø Both vertebral arteries merge to form the basilar artery Ø The basilar and internal caroIds are the greatest contributors of blood to the brain, which is not done discretely Ø Instead both arteries form part of the circle of Willis (dashed line), a redundancy system of vessels that ensures that the brain receives adequate blood supply – cerebral perfusion – even if one of its elements becomes compromised, e.g. narrowed Circle of Willis Basilar ANATOMY Internal caroId 19 Thryocervical trunk Ø The thyrocervical trunk also originates from the subclavian Ø A very short, thick vessel that soon branches into supplying the thyroid gland and muscles of the neck: Inferior thyroid artery Ascending cervical artery Transverse cervical artery Suprascapular artery ANATOMY © Visible Body Thyroid gland Thyrocervical trunk 20 Branches of the thyrocervical trunk ANATOMY 21 Branches of the thyrocervical trunk – cont. Ø Inferior thyroid: as the name suggest this artery runs superiorly to supply the inferior aspect of the thyroid gland giving muscular branches as well as pharyngeal and inferior laryngeal branches Ø Ascending cervical: ascends between the anterior scalene and longus capiIs, sending small branches to supply the spinal cord and membranes, as well as the bodies of vertebrae Ø Transverse cervical: passes laterally in front of scalenus anterior and the brachial plexus to supply trapezius Ø Suprascapular: runs behind sternocleidomastoid (SMC) to the superior border of the scapula giving branches to the SCM as it passes ANATOMY 22 Blood drainage of brain is into venous sinuses Ø Superficial and deep cerebral veins drain the brain tissues into vessels either close to the surface or the great cerebral vein inferiorly ANATOMY Extra Dural23Vessel Venous sinuses 1. Sigmoid sinus 2. Superior petrosal sinus 3. Ophthalmic vein 4. Cavernous sinus 5. Superior petrosal sinus 6. Sigmoid sinus 7. Great cerebral vein 8. Confluence of sinuses 9. Straight sinus 10. Superior sagi9al sinus 11. Inferior sagi9al sinus ANATOMY 24 Venous sinuses exiting the skull Ø The network of sinuses drain into ever larger sized ones (in bold) which then ultimately drain into the sigmoid sinus (5) that exits through the jugular foramen and is then continuous with the internal jugular 1. Superior sagittal sinus 2. Sphenoparietal sinus 3. Cavernous sinus (see below) 4. Superior petrosal sinus 5. Sigmoid sinus 6. Great cerebral vein 7. Transverse sinus 8. Superior sagittal sinus 9. Transverse sinus 10. Superioro petrosal sinus ANATOMY 25 Venous drainage of the head and face Ø The veins of the face and scalp generally accompany the arteries and have the same name, e.g. facial artery and facial vein Ø The anterior aspect of face, including muscles is via a superficial network ulImately drains into the internal jugular vein, which also drains the brain Ø The side of the face and scalp in turn goes into the external jugular vein ANATOMY 26 Final stages of venous drainage: head, neck and brain Ø Ultimately, the internal and external jugular, as well as the vertebral veins descend towards the base of the neck whereby venous blood is delivered into the brachiocephalic vein Ø Unlike the case seen with arteries, there is a brachiocephalic vein on each side of the body ANATOMY 27 Rela@onship between the great veins of the neck and SMC ANATOMY 28 Questions? Email: [email protected] ANATOMY 29