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Spinal Cord, Human Reflex

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Presentation on theme: "Spinal Cord, Human Reflex"— Presentation transcript:

1 Spinal Cord, Human Reflex
For tracts and nerves use bundles of spaghetti.

2 Gross Anatomy of the Adult Spinal Cord

3 Anatomy of the Spinal Cord
Extends from the foramen magnum to L1 or L2 Conus medularis - it is the end of the spinal cord Denticulate ligaments – pia mater attaching the spinal cord t the vertebral wall Filum terminale – pia mater extension from the conus medularis to the coccix

4 Anatomy of the Spinal Cord
Lumbar tap – removal of CSF from the vertebral canal bellow L3 Cervical and lumbar enlargements 31 pairs of spinal nerves leave the spinal cord Cauda equina – collection of spinal nerves at the end of the spinal cord

5 The Spinal Cord and Spinal Meninges

6 Spinal meninges Three layers Dura mater Single layer
Epidural space – between the vertebra and dura. Filled with fat and blood vessels Arachnoid Subarachnoid space – between arachnoid and pia. Filled with CSF Pia mater

7 The Spinal Cord and Spinal Meninges

8 Sectional Organization of the Spinal Cord

9 Structures of the spinal cord
Gray Matter Cell bodies, unmyelinated axons, dendrites and neuroglia Posterior or dorsal horns – interneurons and sensory fibers coming from the dorsal root ganglion Anterior or ventral horns – cell bodies of the somatic motor neurons that send their axons to the ventral root

10 Gray matter Lateral gray horns contain visceral motor neurons
Gray commissures contain axons that cross from one side to the other Central canal – filled with CSF

11 White matter Divided into six columns (funiculi) containing tracts
Posterior funiculi Posterior median sulcus Anterior funiculi Anterior median fissure Lateral funiculi

12 Spinal Nerves

13 31 pairs of spinal nerves (mixed)
8 pairs of cervical Above C7 all nerves emerge above the corresponding vertebra C8 emerge between C7 and T1 12 pairs of thoracic 5 pairs of lumbar 5 pairs of sacral I pair of coccygeal

14 Spinal nerves Origin Dorsal root and dorsal root ganglion Ventral root
Dorsal ramus sensory and motor innervation to the skin and muscles of the back

15 Spinal nerves Ventral ramus
sensory and motor to the ventrolateral body surface, body wall and limbs T2 – T12 form intercostal nerves All other will form plexuses

16 Nerve plexus Complex interwoven network of nerves Four large plexuses
Cervical plexus Brachial plexus Lumbar plexus Sacral plexus

17 Peripheral Nerves and Nerve Plexus

18 The Cervical Plexus Ventral rami of spinal nerves C1 to C5
Innervate muscles of the neck Innervate the diaphragm Phrenic nerve (C3, C4,C5)

19 Cervical Plexus

20 Brachial Plexus

21 Brachial Plexus

22 The Brachial Plexus Axillary nerve Shoulder Musculocutaneous nerve
Anterior brachial area

23 The Brachial Plexus Radial nerve Posterior arm and hand Median nerve
Anterior antebrachial area

24 The Brachial Plexus Ulnar nerve Anterior antebrachial area

25 The Lumbar and Sacral Plexuses

26 Lumbar Plexus

27 The Lumbar Plexus Lower abdominopelvic region and the anterior thigh
L1 – L4 Femoral Nerve Anterior muscles of femoral area Obturator Nerve Adductors of leg

28 The Sacral Plexus Posterior thigh, gluteal region, leg and foot
L4 – S4 Sciatic nerve Tibial nerve Common fibular nerve Pudendal nerve Muscles and skin of perineum

29 Spinal Reflexes Reflexes are rapid and predictable automatic responses to stimuli Neural reflex involves sensory fibers to CNS and motor fibers to effectors

30 Reflex arc Five components Receptor – it is the site of the stimulus
Sensory neuron – transmits the stimulus Integration Center Monosynaptic reflex Polysynaptic reflex Motor neuron - conducts the impulse to the effector Effector – muscle or gland

31 Arc Reflex Components

32 Reflex classification
Somatic Reflexes Spinal Reflexes Patellar (knee-jerk) Achilles Triceps Biceps etc.

33 The Babinski Reflexes

34 Reflex classification
Superficial reflexes Plantar reflex Normal response – curling the toe Abnormal response – Babisnki’s sign Corneal reflex - Cranial nerve V Gag reflex Cranial nerves IX and X

35 Reflex classification
Autonomic Reflexes Pupillary reflex Ipsilateral constriction of the pupil Consensual reflex Contralateral constriction of the pupil Ciliospinal reflex Pupil dilation when pinching the neck Salivary reflex


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