Spinal Cord & Spinal Nerves Flashcards
The ___ is nerve tissue continuous with that of the brain, extending inferiorly from the brain at the level of the foramen magnum.
spinal cord
The bony covering of the spinal cord is formed by the ____. The spinal cord lies within the spinal cavity formed by the vertebral foramina of the stacked vertebrae.
vertebral column.
The outermost of three membranous coverings, or meninges (singular, meninx), of the spinal cord is the tough, skin-like ___.
dura mater
The ___ are continuous with the meninges surrounding the brain.
spinal meninges
Categories under meninges
Dura mater
Arachnoid mater
Subarachnoid space
Pia mater
Deep to the dura mater is a much thinner meninx, the spidery ___.
arachnoid mater
The space deep to the arachnoid, the ___, is filled with circulating cerebrospinal fluid (CSF) in life. The CS has been drained from your specimen.
subarachnoid space
The deepest meninx, the delicate ___, is a thin, vascular membrane adhering to the surface of the spinal cord.
pia mater
The ____ is a deep groove on the anterior surface of the human spinal cord (along the midline). This fissure is analogous to that on the ventral surface of the ox spinal cord.
anterior median fissur
The ___ is a somewhat shallower groove along the dorsal surface of the spinal cord.
posterior median sulcus
A ____ is seen in the C5 to Tl segments of the spinal cord, and a similar ____ is found in the L2 to S3 segments.
cervical enlargement, lumbar enlargement
Inferior to the lumbar enlargement, the spinal cord tapers to a cone-shaped end called the
conus medullaris.
TRUE or FALSE
The spinal cord proper does not extend below the L1 vertebra.
True
This group of spinal nerve roots, resembling a horse’s tail, is called the
cauda equina
Spinal cord extends from the foramen magnum at the base of the skull to the ___ lumbar vertebra;
Spinal cord protected by vertebral column; its inferior end where the spinal nerves exit is called ___ (resembles a horse’s tail)
cauda equina
occurs when there is dysfunction of multiple lumbar and sacral nerve roots of the cauda equina.
Most commonly results from a massive herniated disc in the lumbar region. A single excessive strain or injury may cause a herniated disc, however, many disc herniations do not necessarily have an
identified cause.
Cauda equina syndrome
•Spinal lesions and tumors
•Spinal infections or inflammation
•Lumbar spinal stenosis
•Violent injuries to the lower back (gunshots, falls, auto
accidents)
•Birth abnormalities
•Spinal arteriovenous malformations (AVMs)
•Spinal hemorrhages (subarachnoid, subdural, epidural)
•Postoperative lumbar spine surgery complications
•Spinal anesthesia
Potential Causes of CES
Tests that May be Helpful in Diagnosing CES
Extremely important to assess for cauda equina syndrome.
Patient history and physical exam
Tests that May be Helpful in Diagnosing CES
A diagnostic test that produces three-dimensional images of body structures using magnetic fields and computer technology. ___ produces images of the spinal cord, nerve roots and surrounding areas.
Magnetic resonance imaging (MRI)
An x-ray of the spinal canal that gives good definition of the bone. If CES is
secondary to bone collapse from trauma or cancer, this study can help define that.
Visualization of the discs are not as easily seen on ___ scan. If no MRI is available, this study can give information helpful to evaluate the anatomy of the region, particularly if done in combination with a myelogram described below.
CT Scan
An X-ray of the spinal canal following injection of a contrast material into
the surrounding cerebrospinal fluid spaces; can show displacement on the spinal cord or spinal nerves due to herniated discs, bone spurs, tumors, etc.
Myleogram
Mainly collection of cell bodies at the center of spinal cord that is shaped like letter H or butterfly; consists of four structures
Gray Matter
contain axons which synapse with interneurons
Posterior Horns
contains cell bodies of pseudounipolar sensory neurons & axons that originate in the periphery of the body; passes through spinal nerves & dorsal roots of this horn
Dorsal Root Ganglion
contain somatic neurons
o Anterior Horns
contain autonomic neurons
o Lateral Horns
fluid-filled space in the center of the cord
o Central Canal
located at the superficial portion; each half is organized into three columns: dorsal / posterior, ventral / anterior, and lateral columns. Each column contains two nerve tracts/pathways
White Matter
consist of axons that conduct action
potentials toward the brain
o Ascending Tracts
consist of axons that conduct action
potentials away from the brain
o Descending Tracts
arise along spinal cord from union of dorsal & ventral roots.
All contain axons from both sensory and somatic motor neurons (mixed nerves)
Categorized by region of vertebral column from which they emerge – cervical (C1 to C8), thoracic (T1 to T12), lumbar (L1 to L5), sacral (S1 to S5), and
coccygeal (Co) – ___ pairs in total
Spinal nerves
31
area of skin supplied with sensory innervation by a pair of spinal nerves; each spinal nerves has specific cutaneous sensory distribution
(except C1)
Dermatome
area where neurons of spinal nerves come together & intermingle
Plexus
Arise along the lateral side of the vertebra
Formed by union of dorsal and ventral roots
Spinal nerve
TRUE or FALSE
All spinal nerves are mixed (both sensory and motor) in function
True
Most of the spinal nerves are organized in groups “PLEXUSES”
- Cervical Plexuses
- Brachial Plexuses
- Lumbosacral Plexuses
Arises from spinal nerves C1-C4
Innervates several muscles on the neck
Innervates the ___ nerve
Cervical plexus
Phrenic
- Arises from spinal nerves C5-T1
- Forms 5 major nerve of the upper extremities
Brachial plexus
Shoulder muscle
Axillary nerve
All muscles of the posterior arm and forearm
Radial nerve
Anterior muscle of the arm
Musculocutaneous nerve
2 forearm muscles and the intrinsic muscle of the hand
Ulnar nerve
Muscles of the anterior forearm
Median nerve
Axillary nerve
Radial nerve
Musculocutaneous nerve
Ulnar nerve
Median nerve
Brachial plexus
- Arises from spinal nerves L1-S4
Lumbosacral plexus
Innervate the muscles of the inner thigh and skin
Obturator nerve
Muscles of the anterior thigh and skin (+skin of medial side of the leg)
Femoral nerve
Posterior thigh muscles, anterior and posterior leg muscles, and most of intrinsic foot muscle
Tibial nerve
Innervate the muscles of the inner thigh and skin
Common fibular nerve
the largest nerve in the body, running from the lower back down the back of each leg
Sciatic nerve
Combination of common fibular and tibial nerve
Sciatic nerve
