• There is a pair of spinal nerves at the level of each
vertebrae for a total of 31 pairs
• Spinal nerves are named for the region from which they
• Spinal nerves are formed by the combination of the ventral
and dorsal roots of the spinal nerve.
• Spinal nerves soon divide into ventral and dorsal rami
(branches = rami )according to the area it supplies.
• The ventral rami in four regions unite to form plexuses
(cervical ,brachial , lumber and sacral plexuses).
in the adult, the spinal cord is in the upper two thirds
of the spinal canal of the vertebral column.
On transverse section, the spinal cord has an oval
shape, and the internal gray matter has the appearance
of a butterﬂy or letter “H.”
The dorsal horns contain the IA neurons and receive
information from dorsal root and other connecting
The ventral horns contain the output association
neurons and lower motor neurons that leave the cord
by the ventral roots.
Thirty-two pairs (or 31) of spinal nerves(i.e., 8
cervical, 12 thoracic, 5 lumbar, 5 sacral, and 2
or more coccygeal) are present.
Each pair communicates with it corresponding
The spinal nerves and the blood vessels that
supply the spinal cord enter the spinal canal
through an intervertebral foramen.
After entering the foramen, they divide into two branches,
or roots :
1. one of which enters the dorsolateral surface of the cord
(i.e., dorsal root), carrying the axons of afferent neurons
into the CNS.
2. Other root leaves the ventrolateral surface of the cord
(i.e., ventral root), carrying the axons of efferent neurons
into the periphery.
These two roots fuse at the intervertebral
foramen, forming the mixed spinal nerve.
Cross-section of vertebral column at the level
of the third thoracic vertebra, showing the meninges, the spinal
cord, and the origin of a spinal nerve and its branches or rami.
The Autonomic Nervous
(ANS) regulates, adjusts, and coordinates the
of the body.
The ANS, which is divided into the sympathetic
and parasympathetic systems, is an efferent
system .It receives its afferent input from
visceral afferent neurons.
The ANS has central nervous system and
peripheral nervous system components.
Spinal cord injuries (SCIs)
• Damage to the spinal cord ranges from transient
concussion (patient recovers fully), to contusion,
laceration, and compression of the cord substance
• are a major health problem.
• Most SCIs result from motor vehicle crashes.
Types and Classiﬁcation of Spinal Cord
• Alterations in body function that result from
SCI depend on :
the level of injury (Tetra………)
the amount of cord involvement (complete or in..)
The consequences of SCI depend on the type and level of injury of the cord.
The neurologic level refers to the lowest level at which sensory
and motor functions are normal. Signs and symptoms
• Total sensory and motor paralysis below the neurologic level.
• Loss of bladder and bowel control (usually with urinary
retention and bladder distention).
• Loss of sweating and vasomotor tone.
• Marked reduction of BP from loss of peripheral vascular
• If conscious, patient reports acute pain in back or neck;
patient may speak of fear that the neck or back is broken.
• Related to compromised respiratory function;
depends on level of injury.
• Acute respiratory failure is the leading cause of
high cervical cord injury.
Assessment and Diagnostic
• Detailed neurologic examination, x-ray
• cervical spine x-rays), computed tomography
• resonance imaging (MRI), and ECG (bradycardia
• are common in acute spinal injuries) are common
• and diagnostic methods.
the level of injuryAS
A. Tetraplegia=sometimes referred quadriplegia
• impairment or loss of
motor or sensory
function (or both) after
damage to neural
• the cervical segments of
the spinal cord.
• It results in impairment
of function in the arms,
trunk, legs, and pelvic
• refers to impairment or loss of
motor or sensory function
(orboth) from damage of neural
elements in the spinal
• canal in the thoracic, lumbar,
or sacral segments of the
spinal cord. With paraplegia,
arm functioning is spared, but
depending on the level of
injury, functioning of the
• trunk, legs, and pelvic organs
may be impaired.
• Paraplegia includes conus
medullaris and cauda