SPINAL CORD AND NERVES

Outline Spinal cord - General considerations - Gray matter: arc reflex - White matter: Sensory and motor tracts Nerves - Cranial nerves - Spinal nerves

Outline Spinal cord - General considerations - Gray matter: arc reflex - White matter: Sensory and motor tracts Nerves - Cranial nerves - Spinal nerves

Spinal cord Continuation of medulla oblongata From C1 to L1-l2 Surrounded by meninges dura mater, arachnoid and pia mater) Cerebrospinal fluid surrounding it Epidural space: between vertebra and dura mater (fatty tissue + blood vessels) Lumbar puncture between L2-L3 or L3-L4

Spinal cord

Spinal cord Internal gray matter: presence of neurons relaying and integrating motor/sensory impulses Fiber tracts: sensory and motor

Outline Spinal cord - General considerations - Gray matter: arc reflex - White matter: Sensory and motor tracts Nerves - Cranial nerves - Spinal nerves

Arc reflex Arc reflex (fast and involuntary)

Outline Spinal cord - General considerations - Gray matter: arc reflex - White matter: Sensory and motor tracts Nerves - Cranial nerves - Spinal nerves

Sensory tracts

Motor tracts

Outline Spinal cord - General considerations - Gray matter: arc reflex - White matter: Sensory and motor tracts Nerves - Cranial nerves - Spinal nerves

Cranial nerves

Cranial nerves I - Olfactory II - Optic III - Oculomotor IV - Trochlear V - Trigeminal VI - Abducens VII - Facial VIII - Auditory IX - Glossopharyngeal X - Vagus XI - Accessory XII - Hypoglassal

Olfactory nerve

Optic nerve

Oculomotor nerve

trochlear

Trigeminal nerve Motor and sensory

shingles

Abducens nerve

Facial nerve Motor and sensory

Bell’s palsy

Vestibulocochlear nerve

Vagus nerve Sensory Motor 75% autonomic

Accessory nerve

Accessory nerve

Hypoglossal nerve

Outline Spinal cord - General considerations - Gray natter: arc reflex - White matter: Sensory and motor tracts Nerves - Cranial nerves - Spinal nerves

Spinal nerves Originate at the root between each vertebra 31 pairs Formed by the fusion of the sensory and motor roots Organized into cervical, thoracic, lumbar, sacral and coccygeal nerves

Spinal nerves

Spinal nerve structure

Dermatomes

Spastic paralysis The upper motor neuron, located in the motor cortex has been destroyed (by a stroke, for example) the lower motor neuron can still be stimulated by reflex arc and trigger movements (which are involuntary and spastic)

Flaccid paralysis The lower motor neuron located in the anterior horn of the spinal cord is damaged  no impulse can reach the muscle fibers  no contraction