Blood Supply of Spinal Cord by Dr. Rabia Inam Gandapore.pptx

Neuroanatomy

1. Blood Supply of Spinal Cord & Clinical Correlation Dr. Rabia Inam Gandapore Assistant Professor Head of Department Anatomy (Dentistry-BKCD) B.D.S (SBDC), M.Phil. Anatomy (KMU), Dip. Implant (Sharjah, Bangkok, ACHERS) , CHPE (KMU),CHR (KMU), Dip. Arts (Florence, Italy )

2. Teaching Methodology LGF (Long Group Format) SGF (Short Group Format) LGD (Long Group Discussion, Interactive discussion with the use of models or diagrams) SGD (Short Group) SDL (Self-Directed Learning) DSL (Directed-Self Learning) PBL (Problem- Based Learning) Online Teaching Method Role Play Demonstrations Laboratory Museum Library (Computed Assisted Learning or E-Learning) Assignments Video tutorial method

3. Goal/Aim (main objective) To help/facilitate/augment the students about the: Explain the Blood Supply of the spinal cord . Enumerate clinical problems of spinal cord.

4. Specific Learning Objectives (cognitive) At the end of the lecture the student will able to: Explain the Blood Supply of the spinal cord . Enumerate clinical problems of spinal cord.

5. Psychomotor Objective: (Guided response) A student to draw labelled diagram of Blood supply of Spinal cord

6. Affective domain To be able to display a good code of conduct and moral values in the class. To cooperate with the teacher and in groups with the colleagues. To demonstrate a responsible behavior in the class and be punctual, regular, attentive and on time in the class. To be able to perform well in the class under the guidance and supervision of the teacher. Study the topic before entering the class. Discuss among colleagues the topic under discussion in SGDs. Participate in group activities and museum classes and follow the rules. Volunteer to participate in psychomotor activities. Listen to the teacher's instructions carefully and follow the guidelines. Ask questions in the class by raising hand and avoid creating a disturbance. To be able to submit all assignments on time and get your sketch logbooks checked.

7. Lesson contents Clinical chair side question: Students will be asked if they know what is the function of Outline: Activity 1 The facilitator will explain the student's about the blood supply of spinal cord Activity 2 The facilitator will ask the students to make a labeled diagram of blood supply of Spinal Cord Activity 3 The facilitator will ask the students a few Multiple Choice Questions related to it with flashcards.

8. Recommendations Students assessment: MCQs, Flashcards, Diagrams labeling. Learning resources: Langman’s T.W. Sadler, Laiq Hussain Siddiqui, Snell Clinical Anatomy , Netter’s Atlas , BD Chaurasia’s Human anatomy, Internet sources links.

9. Blood Supply of Brain & Spinal Cord Heart produce 5L blood in Left Ventricles 15% /5L of resting cardiac output go to CNS Carotid (Anterior) System : Internal Carotid Artery (Origin: Common carotid artery) Vertebro Basilar (Posterior) System : Vertebral Artery (Origin: Subclavian artery)

10. Cerebrovascular accidents (stroke) is third leading cause of morbidity (USA) I nternal capsule contains major ascending & descending pathways to cerebral cortex is disrupted by arterial hemorrhage or thrombosis .

11. CNS is supplied by : a. 2 internal carotid Arteries b. 2 vertebral arteries . F our arteries lie within the subarachnoid space & their branches anastomose on the inferior surface of brain to form circle of Willis .

12. The distributing arteries arise from circle of Willis pass over outer surface of brain & anastomose with one another are: 1. Anterior Cerebral Arteries 2. Middle Cerebral Arteries 2. Posterior C erebral Arteries They give rise to branches that penetrate brain at right angles. In brain substance, further branching occurs, but no further anastomoses take place. Its anastomoses on brain surface that provide vital collateral circulation should one of arteries be occluded by disease. C erebrovascular disease is responsible for 50 % of all adult neurologic hospital admissions.

13. 1. Vertebro -Basilar System Vertebral Artery & Branches

14. 1 . Vertebral Artery B ranch of first part of subclavian artery , ascends the neck by passing through foramina in transverse processes of upper six cervical vertebrae. E nters skull through foramen magnum & pierces dura mater & arachnoid to enter the subarachnoid space . Then passes upward, forward & medially on medulla oblongata . At lower border of pons , it joins vessel of opposite side to form basilar artery .

15. Clinical Relevance Berry Aneurysm: Intra-cranial Aneurysm (90%) of Cerebral aneurysm i.e. ballooning arise from weakened area in the walls of blood vessels of brain (Circle of Willis). T hey rupture and produce hemorrhage in the subarachnoid space . The main arteries in subarachnoid space than gives branches to the brain substance.

16. Posterior cerebral artery Basilar artery divides into terminal braches posteriorly called Posterior Cerebral Artery below the Occulomotor Nuclei (Nerve) It curves laterally & backward around midbrain & is joined by posterior communicating branch of internal carotid artery. Cortical branches supply inferolateral & medial surfaces of temporal lobe & lateral + medial surfaces of occipital lobe. Thus, posterior cerebral artery supplies visual cortex . Central branches pierce the brain substance & supply parts of thalamus, lentiform nucleus, midbrain, pineal & medial geniculate bodies. C horoidal branch enters inferior horn of lateral ventricle supplies the choroid plexus & supplies choroid plexus of third ventricle.

17. Branches of Cranial Portion M eningeal branches are small & supply bone & dura in posterior cranial fossa .

18. 2. Posterior spinal artery: Arise: from vertebral artery or posterior inferior cerebellar artery (PICA) . Descends: on posterior surface of spinal cord close to posterior roots of spinal nerves . The branches are reinforced by radicular arteries that enter the vertebral canal through the intervertebral foramina .

19. 3. Anterior spinal artery is formed from a contributory branch from each vertebral artery near its termination . The single artery descends on the anterior surface of the medulla oblongata and spinal cord and is embedded in the pia mater along the anterior median fissure. The artery is reinforced by radicular arteries that enter the vertebral canal through the intervertebral foramina .

20. Clinical Relevance If anterior Spinal artery blocked than 2/3 rd of spinal cord will undergo infarction (Necrosis). If its severe will lead to death of that part of spinal cord. (Anterior Spinal cord doesnot get enough blood supply from ASA and hence reinforced by the segmental arteries at multiple levels of spinal cord. T4 & L1 chance of infaction (Anterior Spinal Artery) T1, T2 & T3 chance of infaction (Posterior Spinal Artery)

21. S egmental artery divides into: 1. Anterior Division= Anterior Radical Artery , reinforce blood supply of Anterior spinal artery (origin: vertebral artery) 2. Posterior Division= Posterior Radical Artery , reinforce blood supply of Posterior spinal arteries (origin: Vertebral artery or Indirectly from PICA) Hence there are one Anterior spinal artery and 2 Posterior Spinal Artery. Segmental arteries at every level of spinal cord dividies to enter the intervertebral foramina & gives many types of arteries, Most important: 1. Deep Cervical Artery 2. Intercoastal Artery 3. Lumbar Artery 4. One large and important feeder artery: Great Medullary artery of Adam Kiewicz ( origin: enters spinal cord via left side of aorta in lower thoracic or upper lumbar vertebral levels; its unilateral in majority of persons , if blocked cause infraction of lower 2/3 of spinal cord)

22. 4. Posterior inferior cerebellar artery (PICA) : largest branch of vertebral artery , passes on an irregular course between medulla & cerebellum . S upplies inferior surface of the vermis , central nuclei of cerebellum & undersurface of cerebellar hemisphere ; it also supplies the medulla oblongata & choroid plexus of fourth ventricle .

23. Medullary arteries: small branches distributed to medulla oblongata.

24. Basilar Artery formed by union of two vertebral arteries , ascends in a groove on anterior surface of pons . At the upper border of pons, it divides into two posterior cerebral arteries .

25. Branches P ontine arteries: small vessels, enter substance of pons Labyrinthine artery: long , narrow artery that accompanies facial & vestibulocochlear nerves into internal acoustic meatus & supplies internal ear . It arises as a branch of anterior inferior cerebellar artery .

26. 1. Posterior cerebral artery Basilar artery divides into terminal braches posteriorly called Posterior Cerebral Artery below the Occulomotor Nuclei (Nerve) It curves laterally & backward around midbrain & is joined by posterior communicating branch of internal carotid artery. Cortical branches supply inferolateral & medial surfaces of temporal lobe & lateral + medial surfaces of occipital lobe. Thus, posterior cerebral artery supplies visual cortex . Central branches pierce the brain substance & supply parts of thalamus, lentiform nucleus, midbrain, pineal & medial geniculate bodies. C horoidal branch enters inferior horn of lateral ventricle supplies the choroid plexus & supplies choroid plexus of third ventricle.

27. 2. Anterior inferior cerebellar artery (AICA) passes posteriorly & laterally and supplies the anterior and inferior parts of the cerebellum . A few branches pass to pons & upper part of medulla oblongata .

28. Superior cerebellar artery: arises close to termination of basilar artery. It winds around the cerebral peduncle and supplies the superior surface of the cerebellum . I I t also supplies the pons (below oculomotor nerve) , pineal gland, midbrain & superior medullary velum.

29. Blood Supply of Spinal Cord

30. Arteries of Spinal Cord R eceives its arterial supply from 3 small arteries: two posterior spinal arteries One anterior spinal artery. These longitudinally running arteries are reinforced by small segmentally arranged arteries that arise from arteries outside the vertebral column and enter the vertebral canal through the intervertebral foramina. These vessels anastomose on the surface of the cord and send branches into the substance of the white and gray matter.

31. Posterior Spinal Arteries Arise either directly from vertebral arteries or indirectly from posterior inferior cerebellar arteries PICA . Each artery descends on the posterior surface of the spinal cord close to the posterior nerve roots and gives off branches that enter the substance of the cord. The posterior spinal arteries supply the posterior 1/3 rd of the spinal cord . The posterior spinal arteries are small in the upper thoracic region , and T1-T3 vulnerable to ischemia if segmental or radicular arteries occluded .

32. Anterior Spinal Artery A nterior spinal artery is formed by the union of two vertebral artery D escends on anterior surface of spinal cord within anterior median fissure . Branches from it supply the anterior two-thirds of the spinal cord . In u pper & lower thoracic segments of spinal cord, the anterior spinal artery may be extremely small. T4 & L1 segmental or radicular arteries if occluded are liable to ischemic necrosis.

33. Veins of the Spinal Cord D rain into six tortuous longitudinal channels that communicate superiorly within skull with the veins of brain & venous sinuses. They drain mainly into internal vertebral venous plexus .

34. Clinical Relevance

35. Cerebral Ischemia Unconsciousness occurs in 5 to 10 seconds = blood flow to brain is cut off. Irreversible brain damage rapidly follows complete arrest of cerebral blood flow. Cardiac arrest due to coronary thrombosis

36. Cerebral Artery Syndromes Anterior Cerebral Artery Occlusion is proximal to anterior communicating artery , the collateral circulation is usually adequate to preserve circulation . Occlusion distal to communicating artery may produce following signs & symptoms: Contralateral hemiparesis H emisensory loss involving mainly the leg and foot ( paracentral lobule of cortex) Inability to identify objects correctly, apathy & personality changes (frontal and parietal lobes)

37. 2. Middle Cerebral Artery Occlusion Occlusion produce following signs and symptoms: Contralateral hemiparesis H emisensory loss involving face & arm ( precentral and postcentral gyri ) Aphasia (unable to communicate) if the left hemisphere is affected (rarely if the right hemisphere is affected) Contralateral homonymous hemianopia (visual field loss= damage to the optic radiation ) Anosognosia (patient unaware of mental illness, dementia) if the right hemisphere is affected (rarely if the left hemisphere is affected )

38. Posterior Cerebral Artery Occlusion Occlusion p roduce following signs and symptoms: 1 . Contralateral homonymous hemianopia ( visual field loss= damage to the optic radiation ) with some degree of macular sparing (damage to the calcarine cortex, macular sparing due to the occipital pole receiving collateral blood supply from the middle cerebral artery) 2. Visual agnosia (unable to visually recognise object with clear vision- ischemia of the left occipital lobe) 3. Impairment of memory (possible damage to the medial aspect of the temporal lobe)

39. Internal Carotid Artery Occlusion Occur without causing symptoms or signs or can cause massive cerebral ischemia depending on the degree of collateral anastomoses. M iddle cerebral artery occlusion , including contralateral hemiparesis and hemianesthesia (loss of sensitivity to stimuli on one side of body) . P artial or complete loss of sight on same side , but permanent loss is rare (emboli dislodged from the internal carotid artery reach the retina through the ophthalmic artery).

40. Anterior spinal artery Occlusion p roduce signs and symptoms as: Loss of motor function (paraplegia ) due to bilateral damage to corticospinal tracts. Bilateral thermoanesthesia (loss of ability to differentiate between heat, cold, touch) & analgesia (inability to feel pain) due to bilateral damage to spinothalamic tracts. Weakness of the limb muscles due to damage of anterior gray horns in cervical or lumbar regions. Loss of bladder and bowel control due to damage of the descending autonomic tracts. Position sense, vibration, and light touch are normal because supplied by posterior spinal arteries.

41. Thank You Any Questions?