Spinal Cord and Reflexes

Fundamentals of Human Biology II

SCB 204

Overview

Meninges

Spinal Nerve Function

Spinal Cord Cross-Section

The total number of paired spinal nerves isa. 12b. 26c. 31d. 48

Dissected Ventral Surface

Ascending and Descending Tracts

Ascending Tracts

� Fascicular - touch, somesthesis� Spinocerebellar - Proprioception� Spinothalamic - pressure, pain, crude

touch

Descending Tracts

� Corticospinal - somatic motor function� Vestibulospinal - equilibrium� Tectospinal - reflex postural movements

in response to visual and auditory stimuli

� Rubrospinal - reduced function in humans. thought to control some gross action of flexors and extensors (walking)

Why is there no cerebellospinal pathway?

� A. the cerebellum does not have a motor function.

� B. it’s included with the cerebrospinal pathway

� C. it’s included with the tectospinal pathway

� D. both B and C

Which part of the brain is involved with somatic motor function?

� A. precentral gyrus� B. thalamus� C. cerebellum� D. all of these

Sensory Pathways

Somatic Reflex Arc

Ipsilateral andContralateral Reflexes

Types of Reflexes

Motor Integration

Sensory Endings

� Mechanoreceptors - � Thermoreceptors - � Photoreceptors - � Chemoreceptors -� Nociceptors -

Cutaneous Endings

Cutaneous Endings

Dermatomes

If a reflex involves your big toe, what is its pathway?

� A. brachial plexus and cervical cord� B. thoracic plexus and thoracic cord� C. lumbar plexus and lumbar cord� D. sacral plexus and sacral cord

Spinal Nerve Structure