Anatomy of a Typical Spinal Nerve
What do nerves consist of?
collection of axons, Schwann cells, and connective tissue in PNS
What is the Endoneurium ?
delicate CT layer surrounding each axon, nerve fiber, and its Schwann cell sheath
What is continuous with the dura mater surrounding the CNS?
what is the analogy between the dura and the epineurium?
a coat and its sleeve
What is the perineurium?
a heavier CT layer that surrounds groups of axons to form nerve fascicles
what is the epineurium ?
a third layer of dense CT bind ti the nerve fascicles together to form a nerve
What is the outer most connective tissue of spinal nerve?
Humans have 31 spinal nerves.
Humans have 31 pairs of spinal nerves.
How many regions of the vertebral column do nerves emerge out of ?
what are the 5 regions of the vertebral column that nerves emerge.
Cervical, Thoracic, Lumbar, Sacral, Coccygeal
How many vertebrae are there in the spinal column
how many pairs of spinal nerves do humans have?
Between C-1 and C-8, ___ pairs of nerves are associated with the first cervical vertebra
Between what two places does the 1st pair of cervical nerves exit the spinal cord?
Skull and first vertebral column
the 2nd pair of cervical nerves exit through what, and between what two vertebra ?
exit through intervertebral foramina between the first and second cervical vertebra
How many nerves does the sacrum have?
Where do the cervical nerves supply to?
muscles of head, neck, shoulder, and upper limbs
Where does the thoracic nerves supply?
muscles of upper limbs, thorax, vertebral column, hips, and lower limbs.
The sacral nerves supply the muscles of the lower limbs.
each of the spinal nerves especially C-1 has a specific cutaneous sensory distribution.
What is a dermatome?
area of skin supplied with sensory innervation by a pair of spinal nerves
What kind of map shows the distribution of all the dermatomes?
Where do spinal nerves arise from spinal cord?
Rootlets combine to form what?
ventral and dorsal roots
What do the ventral and dorsal roots combine to become?
The spinal nerves divide to form branches, what are these branches called?
Each spinal nerve have a dorsal and ventral ramus.
What do the dorsal rami innervate most?
deep muscles of dorsal trunk responsible for movement of the vertebral column, also innervate the CT and skin near the midline of the back.
How many ways does the ventral rami distribute into?
In the thoracic region, ventral rami form what?
In the thoracic region, ventral rami form intercostal nerves, which extend where?
along inferior margin of each rib and innervate the intercostal muscles and the skin over the thorax
The ventral rami of what regions of spinal nerves form plexus?
cervical, lumbar, sacral, and coccygeal
What does plexus mean?
braided and describes the organization produced by the intermingling of nerves
The Brachial Plexus originate from what spinal nerves?
C5 - L2
In Brachial Plexus, the ventral rami of the spinal nerves are called what?
roots of plexus
In Brachial Plexus, how many roots join to form three trunks?
In Brachial Plexus, how many divisions are there ?
In Brachial Plexus, how many major branches are there?
what are the five major nerves in Brachial Plexus ?
axillary, radial, musculocutaneous, ulnar, and median nerves
what do the five major nerves in the brachial plexus supply?
Where do the cervical plexus originate?
C1 - C4
branches derive from the cervical plexus innervate what?
superficial neck structures: including several of the muscle attached to hyoid bone
The cervical plexus innervate what?
skin of neck, and posterior portion of head.
Where does the phrenic nerve originate?
C3 - C5
where does the phrenic nerve derive from?
both cervical and brachial plexus
why is the phrenic nerve so important?
it controls breathing
Where does the phrenic nerve reach?
The Lumbar plexus originates from what vertebra ?
L1 - L4
the sacral plexus originates from what vertebra?
L4 - S4
the lumbar and sacral plexuses are often considered what?
what four major nerves exit the lumbosacral plexus and enter lower limb?
obturator, femoral, tibial, and common fibular nerves
where does the Lumbosacral plexus supply?
lower back, hips, and lower abdomen and the skin of the hip and thigh
What is the largest peripheral nerve in the body ?
Where does the coccygeal plexus originate from?
S5 - Co
Where does the coccygeal plexus supply to?
pelvic floor and skin over coccyx
The dorsal rami of coccygeal nerves also innervate some skin over coccyx.