Spinal Cord, Spinal Nerves, and Reflexes Flashcards
Anterior boundary of vertebral canal
vertebral bodies, intervertebral discs, and posterior longitudinal ligament
Posterior boundary of the vertebral canal
vertebral laminae and the ligamentum flavum
Lateral boundaries of the vertebral canal
vertebral pedicles and the intervertebral foramina
Contents of the vertebral canal
the canal contains neural tissue and other structures associated with the protection and metabolic support of the neural tissue
What does the spinal cord include?
gray and white matter
What type of spinal nerve rootlets/roots are there?
left and right, dorsal and ventral
Spinal meninges are separated into 3 parts
pia mater, arachnoid mater, and dura mater
What other contents are found in the vertebral canal?
epidural fat, cerebrospinal fluid, and blood vessels
Superior end of spinal cord
ends at foramen magnum, continous with brainstem
Inferior end of spinal cord
conus medullaris, L1-2 in adults, L3-4 in newborn, 18in long
Shape of spinal cord
irregularly cylindrical
Cervical enlargement
supplies upper limbs, spinal cord segments C5-T1
Lumbosacral enlargement
supplies lower limbs, spinal cord segments L1-S3
Longitudinal grooves
help to delineate left, right, and column sections
Ventral (anterior) median fissure
wide groove on the anterior midline
Dorsal (posterior) median sulcus
narrow groove on the posterior midline
Ventral lateral sulci and dorsal lateral sulci
lateral grooves at site of respective rootlet attachments (dorsal more prominent)
White matter is primarily formed by _____with minimal cell bodies. The _____are bundled to form _____.
axons, axons, tracts
Tracts are organized within 3 columns
dorsal, lateral, and ventral columns that are delineated by the external longitudinal grooves
Ascending tracts relay information where?
the brain
Descending tracts relay information where?
inferiorly, the periphery
Dorsal columns are formed by which fibers and transmit what?
formed by primary ascending fibers and transmit ipsilateral fine touch and proprioception
fasciculus gracilis
subset of dorsal column, carries lower body information
fasciculus cuneatus
subset of dorsal column, carries upper body info (only found in upper spinal cord, more lateral)
Where does the dorsal column synapse?
synapse with secondary fibers within nuclei of medulla, which then cross the midline (decussate) and ascend as the medial lemniscus to the third order neurons in the thalamus and eventually terminate in the contralateral brain
Where is the spinothalamic tract found and what forms it?
found in both the lateral and ventral columns of white matter, formed by secondary ascending fibers
Peripheral primary sensory fibers synapse on the secondary cells where?
the dorsal gray horn, ipsilaterally
Where does secondary fibers cross?
the midline, then ascend within the tract
What does the lateral tract of the spinothalamic tract transmit?
contralateral pain and temperature !!!
What does the anterior tract of the spinothalamic tract transmit?
crude touch and pressure
Where is the lateral corticospinal (pyramidal) tract found and what forms it?
found in the lateral column of white matter and formed by descending upper motor neurons which originate in the motor cortices of the crebrum (brain)
Where do upper motor neurons cross?
they cross the midline in the medulla at the pyramids, thus run contralaterally in the spinal cord
Where does the lateral corticospinal tract synapse with the lower motor neurons?
in the ventral gray horn for eventual distribution to skeletal muscle for voluntary motor control
Gray matter is formed by what?
neural cell bodies, axon terminal branches and dendrites
Ventral horns
cut surface of ventral columns of gray matter, found at all levels of spinal cord, contains somatic motor neuron cell bodies, aka LMN, that innervate skeletal muscle
Dorsal horns
cut surface of dorsal columns of gray matter, found at all levels of spinal cord, contains central processes of sensory neuron axons and interneurons which integrate various sensory and motor neurons
Lateral horns
found only at spinal cord segments T1 to L2, contains preganglionic sympathetic neuron cell bodies (general visceral efferent)
Gray commissure
found at all levels of spinal cord, deepest/central region of spinal cord, contains central canal, connects to the left and right gray columns