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Chapter 13. Spinal Cord, and the Autonomic Nervous System. Gross Anatomy of the Adult Spinal Cord. Anatomy of the Spinal Cord. Extends from the foramen magnum to L1 or L2 Conus medularis - it is the end of the spinal cord
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Chapter 13 Spinal Cord, and the Autonomic Nervous System
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
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
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
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
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
White matter • Divided into six columns (funiculi) containing tracts • Posterior funiculi • Posterior median sulcus • Anterior funiculi • Anterior median fissure • Lateral funiculi
White Matter • Spinal cord tracts • axons with the same origin, terminus and function • Ascending or sensory tracts • Anterior spinothalamic • Lateral spinothalamic • Fasciculus gracilis • Fasciculus cuneatus • Anterior spinocerebellar • Posterior spinocerebellar
White Matter • Descending or motor tracts • Direct or pyramidal • Lateral corticospinal • Anterior corticospinal • Indirect or extrapyramidal • Rubrospinal • Tectospinal • Vestibulospinal • Reticulospinal
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
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
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
Nerve plexus • Complex interwoven network of nerves • Four large plexuses • Cervical plexus • Brachial plexus • Lumbar plexus • Sacral plexus
The Cervical Plexus • Ventral rami of spinal nerves C1 to C5 • Innervate muscles of the neck • Innervate the diaphragm • Phrenic nerve(C3, C4,C5)
The Brachial Plexus • Axillary nerve • Shoulder • Musculocutaneous nerve • Anterior brachial area
The Brachial Plexus • Radial nerve • Posterior arm and hand • Median nerve • Anterior antebrachial area
The Brachial Plexus • Ulnar nerve • Anterior antebrachial area
The Lumbar Plexus • Lower abdominopelvic region and the anterior thigh • L1 – L4 • Femoral Nerve • Anterior muscles of femoral area • Obturator Nerve • Adductors of leg
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
The Autonomic Nervous System (ANS) • Parasympathetic is the “resting and digesting” division • Sympathetic is the “fight or flight” division • Sympathetic chain ganglia