The gross anatomy of spinal cord

1. The gross anatomy of spinal cord By Prof. Dr. Ansari For Dental students 4/27/2013 1

2. A 19-year-old college student, was rock climbing when he fell 30 feet to the ground Paramedics arriving at the scene found him lying in the supine position, unable to move any extremities and complaining of neck pain. He was awake, alert, and oriented to his current location, the date and day of the week, and the details of his fall. His responses to questioning were appropriate. He complained that he could not feel his arms and legs. The paramedics applied a cervical collar, placed him on a back board, immobilized his head, and transported him to the trauma center by helicopter. X-rays taken upon arrival revealed a fractured fifth cervical vertebra. 4/27/2013 2

3. 4/27/2013 3 The spinal cord is well protected in the vertebral column

4. The spinal cord begins as a continuation of the medulla oblongata of the brain at the level of the foramen magnum in the skull. Along its course, the spinal cord gives rise to 31 pairs of spinal nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal. The spinal cord terminates at the level of the first or second lumbar vertebrae as the conus medullaris. Caudal to the conus medullaris are the nerve roots of the more caudal spinal nerves which are collectively called, because of their appearance, the cauda equina (horse's tail). 4/27/2013 4

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10. The spinal cord is shaped something like a glass soda-bottle It has a cervical enlargement which begins at roughly C4 and extends to roughly T1 and a lumbar enlargement that extends from roughly the T11 vertebra through the L1 vertebral level. The cervical enlargement is the site of the cell bodies of the motor neurons that innervate the upper limbs, as well as the site where the sensory nerves from the upper limbs synapse. The lumbar enlargement is the site of the cell bodies of the motor neurons that innervate the lower limbs and the site where the sensory nerves from the lower limbs synapse. 4/27/2013 10

11. Meninges of spinal cord 4/27/2013 11 The dura mater is strong, formed of elastic and fibrous tissue. It is the outermost covering of the spinal cord and provides the external layer of the dural sac. Superiorly it adheres to the margin of the foramen magnum where it is in continuity with the cranial dura mater; inferiorly it is anchored to the coccyx by the filum terminale. The arachnoid mater lines the dural sac, separated from it by a potential space, the subdural space. The arachnoid mater is a thin avascular membrane that also ensheathes the spinal cord and the spinal nerve roots. It is connected to the underlying pia mater by delicate strands of connective tissue, the arachnoid trabeculae. Between the arachnoid and the pia mater lies the subarachnoid space, which contains the CSF.

12. Meninges The pia mater is the innermost membrane covering the spinal cord and adheres closely to it. The pia mater ensheathes the spinal nerve roots and covers the spinal blood vessels. The spinal cord is suspended in the dural sac by pairs of segmental denticulate ligaments, composed of pia mater. There are 21 pairs of these ligaments, each arising from the side of the spinal cord midway between the dorsal and ventral nerve roots. 4/27/2013 12

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14. The white matter of spinal cord Anterior funiculus Posterior funiculus Lateral funiculus There are ascending and descending tracts in the white matter of spinal cord. The posterior funiculus has sensory tracts where as mixed tracts run in anterior and lateral funiculi. 4/27/2013 14

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18. The grey matter of spinal cord It is H-shaped mass of grey matter. It has sensory, motor and interneuron. Anterior horns have motor neurons. Posterior horns have sensory neurons. The interneuron's are connecting the sensory with the other neurons. The motor neurons are the efferent neurons; the afferent neurons are situated at the dorsal root ganglia and posterior horns. 4/27/2013 18

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20. Lateral horns are seen in the first thoracic to second lumbar segments 4/27/2013 20

21. Segments of spinal cord 4/27/2013 21

22. APPLIED ANATOMY 4/27/2013 22

23. 4/27/2013 23 Neck ( cervical ) injuries usually result in quadriplegia. People with injuries to the C1 - C4 level often require a ventilator to breathe . Shoulder and biceps control can remain with C5 injuries, however wrist and hand movements do not.  C6 injuries can give wrist control but no hand function while at C7 and T1 individuals can straighten their arms but may have dexterity problems with their hands and fingers. Spinal cord injuries to the thoracic level and below result in paraplegia , where the hands are not affected.   At T1 through to T8 there may be poor trunk control as a result of the lack of abdominal muscle control. Lower injuries of T9 to T12 allow for good sitting balance from abdominal muscle and trunk control while injuries to the Lumbar and Sacral regions mean a decrease in control of the hip flexors and legs

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25. Brown-Sequard syndrome (spinal cord hemisection) Refers to injuries limited to one side of the cord.  People have weakness and loss of touch sense in one leg but loss of pain and temperature sensation in the other side. 4/27/2013 25

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28. Stephen Hawking (1946- ) British Physicist, suffering from Amyotrophic lateral sclerosis The disorder is characterized by rapidly progressive weakness , muscle atrophy and fasciculations , spasticity , dysarthria , dysphagia , and respiratory compromise. It is a form of motor neuron disease caused by the degeneration of neurons located in the ventral horn of the spinal cord and the cortical neurons that provide their afferent input. 4/27/2013 28

29. Herpes zoster It is a virus reactivation from the dorsal root ganglia. There will be unilateral vesicular eruption within a dermatome. T3 to L3 dermatome lesions are frequent. 4/27/2013 29

30. Herpes zoster ophthalmicus (ophthalmic division of trigeminal n., V1). 4/27/2013 30

31. Poliomyelitis (Infantile Paralysis) It is viral infection of lower motor neuron. LMN syndrome at the level of lesion. Sensations are not affected. 4/27/2013 31

32. References Clinically Oriented Anatomy-Keith Moore 6 th Edn. (pgs. 496-507) http://howmed.net/anatomy/gross-anatomy/spinal-cord-gross-anatomy-internal-structure / http:// vanat.cvm.umn.edu/neurLab2/SpCdGross.html http://academic.pgcc.edu/~ tpefok/NOTES/Spinal%20Cord.pdf http://apbrwww5.apsu.edu/thompsonj/Anatomy%20&% 20Physiology/2010/2010%20Exam%20Reviews/Exam%204%20Review/CH%2012%20Gross%20Anatomy%20of%20the%20Spinal%20Cord.htm 4/27/2013 32

33. SAMPLE MCQS A patient complains of unsteadiness. Examination shows a marked diminution of position sense, vibration sense, and stereognosis of all extremities. He is unable to stand without wavering for more than a few seconds when his eyes are closed. There are no other abnormal findings. The lesion most likely involves the :- 4/27/2013 33 A.Lateral columns of the spinal cord, bilaterally B. Inferior cerebellar peduncles, bilaterally * C. Dorsal columns of the spinal cord, bilaterally D. Spinothalamic tracts, bilaterally E. Corticospinal tracts

34. Sample MCQS Destruction of lateral spinothalamic tract result in:- A. Ipsilateral loss of pain & temperature B. Contralateral loss of light touch & pressure * C . Contralateral loss of the pain & temperature D. Contralateral loss of proprioceptive E. Balance is lost 4/27/2013 34

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