The gross anatomy of spinal cord
Prof. Dr. Ansari
For Dental students
A 19-year-old college student, was rock
climbing when he fell 30 feet to the ground
Paramedics arriving at the scene found him lying in the
supine position, unable to move any extremities and
complaining of neck pain. He was awake, alert, and
oriented to his current location, the date and day of the
week, and the details of his fall. His responses to
questioning were appropriate. He complained that he
could not feel his arms and legs. The paramedics applied
a cervical collar, placed him on a back board, immobilized
his head, and transported him to the trauma center by
helicopter. X-rays taken upon arrival revealed a fractured
fifth cervical vertebra.
The spinal cord is well protected in the vertebral column
The spinal cord begins as a continuation of the
medulla oblongata of the brain at the level of the
foramen magnum in the skull.
• Along its course, the spinal cord gives rise to 31
pairs of spinal nerves: 8 cervical, 12 thoracic,
5 lumbar, 5 sacral, and 1 coccygeal.
• The spinal cord terminates at the level of the first
or second lumbar vertebrae as the conus
• Caudal to the conus medullaris are the nerve
roots of the more caudal spinal nerves which are
collectively called, because of their appearance,
the cauda equina (horse's tail).
The spinal cord is shaped something like a
It has a cervical enlargement which begins at roughly C4
and extends to roughly T1 and a lumbar enlargement
that extends from roughly the T11 vertebra through the
L1 vertebral level.
• The cervical enlargement is the site of the cell bodies of
the motor neurons that innervate the upper limbs, as
well as the site where the sensory nerves from the
upper limbs synapse.
• The lumbar enlargement is the site of the cell bodies of
the motor neurons that innervate the lower limbs and
the site where the sensory nerves from the lower limbs
Meninges of spinal cord
The dura mater is strong, formed of elastic and fibrous tissue. It is the
outermost covering of the spinal cord and provides the external layer of
the dural sac. Superiorly it adheres to the margin of the foramen
magnum where it is in continuity with the cranial dura mater; inferiorly
it is anchored to the coccyx by the filum terminale.
The arachnoid mater lines the dural sac, separated from it by a
potential space, the subdural space. The arachnoid mater is a thin
avascular membrane that also ensheathes the spinal cord and the spinal
nerve roots. It is connected to the underlying pia mater by delicate
strands of connective tissue, the arachnoid trabeculae. Between the
arachnoid and the pia mater lies the subarachnoid space, which
contains the CSF.
• The pia mater is the innermost membrane covering
the spinal cord and adheres closely to it.
• The pia mater ensheathes the spinal nerve roots and
covers the spinal blood vessels.
• The spinal cord is suspended in the dural sac by pairs
of segmental denticulate ligaments, composed of pia
• There are 21 pairs of these ligaments, each arising
from the side of the spinal cord midway between the
dorsal and ventral nerve roots.
The white matter of spinal cord
There are ascending and descending tracts in the
white matter of spinal cord.
• The posterior funiculus has sensory tracts where as
mixed tracts run in anterior and lateral funiculi.
The grey matter of spinal cord
It is H-shaped mass of grey matter.
It has sensory, motor and interneuron.
Anterior horns have motor neurons.
Posterior horns have sensory neurons.
The interneuron's are connecting the sensory with
the other neurons.
• The motor neurons are the efferent neurons; the
afferent neurons are situated at the dorsal root
ganglia and posterior horns.
•Neck (cervical) injuries usually result in quadriplegia.
• People with injuries to the C1 - C4 level often require a
ventilator to breathe.
• Shoulder and biceps control can remain with C5 injuries,
however wrist and hand movements do not.
• C6 injuries can give wrist control but no hand function
•while at C7 and T1 individuals can straighten their arms but
may have dexterity problems with their hands and fingers.
• Spinal cord injuries to the thoracic level and below result in
paraplegia, where the hands are not affected.
• At T1 through to T8 there may be poor trunk control as a
result of the lack of abdominal muscle control.
• Lower injuries of T9 to T12 allow for good sitting balance
from abdominal muscle and trunk control while injuries to
the Lumbar and Sacral regions mean a decrease in control of
the hip flexors and legs
(spinal cord hemisection)
• Refers to injuries limited to one side of the
cord. People have weakness and loss of touch
sense in one leg but loss of pain and
temperature sensation in the other side.
Stephen Hawking (1946- )
British Physicist, suffering from Amyotrophic
• The disorder is
characterized by rapidly
muscle atrophy and
dysarthria, dysphagia, and
• It is a form of motor neuron
disease caused by the
degeneration of neurons
located in the ventral horn
of the spinal cord and the
cortical neurons that
provide their afferent input.
• It is a virus reactivation from
the dorsal root ganglia.
• There will be unilateral
vesicular eruption within a
• T3 to L3 dermatome lesions
• A patient complains of unsteadiness.
Examination shows a marked diminution of
position sense, vibration sense, and
stereognosis of all extremities. He is unable to
stand without wavering for more than a few
seconds when his eyes are closed. There are
no other abnormal findings. The lesion most
likely involves the:A.Lateral columns of the spinal cord, bilaterally
B. Inferior cerebellar peduncles, bilaterally *
C. Dorsal columns of the spinal cord, bilaterally
D. Spinothalamic tracts, bilaterally
E. Corticospinal tracts
Destruction of lateral spinothalamic tract result
in:• A. Ipsilateral loss of pain & temperature
• B. Contralateral loss of light touch & pressure
*C. Contralateral loss of the pain & temperature
• D. Contralateral loss of proprioceptive
• E. Balance is lost