Unit 3: PNS - Spinal Nerves + Plexi of the Body

All of the nervous tissue structures except the brain and spinal cord

What does the PNS include?

Bone

What is most of the PNS not protected by?

12

How many pairs of Cranial Nerves are in the Peripheral Nervous System?

31

How many pairs of Spinal Nerves are in the Peripheral Nervous System?

Brain

Where do cranial nerves arise directly from?

Spinal Cord

Where do spinal nerves arise directly from?

Vertebral Canal of the Spinal Column

Where does the spinal cord pass through?

Dorsal and Ventral rootlets

What emerges from the spinal cord on both left and right sides?

Sensory neurons

What do Dorsal roots carry?

Motor neurons

What do Ventral roots carry?

spinal nerves

What do dorsal and ventral roots form when they converge together?

1-5 mm

How long can spinal nerves be?

intervertebral foramina

What do spinal nerves transverse?

8

How many pairs of cervical spinal nerves are there?

intervertebral foramina of the cervical vertebrae

Where do the Cervical Spinal Nerves transverse?

Above the Atlas

Where does the 1st cervical spinal nerve emerge?

Beneath

Each subsequent cervical spinal nerve corresponds numerically to the which vertebrae?

12

How many pairs of Thoracic Spinal Nerves are there?

intervertebral foramina of the thoracic vertebrae

Where do the Thoracic Spinal Nerves transverse?

above

Each thoracic spinal nerve corresponds numerically to which vertebrae?

5

How many pairs of Lumbar Spinal Nerves are there?

intervertebral foramina of the lumbar vertebrae

Where do the Lumbar Spinal nerves transverse?

above

Each lumbar spinal nerve corresponds numerically to the which vertebrae?

Pelvic and Dorsal sacral foramina, sacral hiatus of the sacrum

Where do the Sacral Spinal Nerves emerge?

5

How many pairs of Sacral Spinal Nerves are there?

1

How many pairs of Coccygeal Spinal Nerves are there?

Sacral Hiatus above the coccyx

Where do the Coccygeal Spinal Nerves emerge?

Back

What does the Dorsal Rami supply?

small

What size are the branches of Dorsal Rami?

Deep back muscles, skin of the back

What specific regions do the Dorsal Rami innervate?

front of the torso, extremities

Where does the Ventral Rami supply?

large

What size are the branches of the Ventral Rami?

cutaneous innervation of the skin, motor innervation to skeletal muscles

What are dorsal and ventral rami responsible for?

Nerve Plexus

A braiding or twining together of nervous tissue

4

How many major plexus systems are there?

Cervical, brachial, lumbar, sacral

What are the major plexus systems?

C1, C2, C3, C4

What is the Cervical Plexus derived from?

Motor innervation to some muscles in the neck region

What does the Cervical Plexus supply?

cutaneous innervation to the skin of the neck and sides of the head

What is the Cervical Plexus responsible for?

Phrenic Nerves

What innervates the diaphragm (the primary muscle involved in respiration)?

C3, C4, C5

What are the Phrenic Nerves derived from?

Ventral Rami of C5, C6, C7, C8, T1

What nerves is the brachial plexus comprised of?

3 trunks (superior, middle, inferior)

What do the 5 roots (Ventral Rami) combine together to form?

3 Anterior, 3 Posterior divisions

Each of the 3 trunks divides laterally to form what?

3 Cords (lateral, posterior, medial)

What do the divisions merge to form?

musculature of the entire upper limb

What does the brachial plexus supply?

Trapezius, Levator Scapula

What does the brachial plexus not supply?

cutaneous innervation to the majority of the upper limb

What does else does the brachial plexus supply?

skin over the upper medial portion of the arm, part of the upper shoulder

Where does the brachial plexus not supply cutaneous innervation?

16

How many nerves does the brachial plexus give off?

musculature of the superficial back, pectoral region, shoulder

Where do the majority of the Brachial Plexus nerves innervate?

terminal branches

Innervation to the muscles of the arm, forearm, and hand are derived from what part of brachial plexus?

Musculocutaneous, Radial, Median, Ulnar

What are the terminal branches?

Ventral Rami of C5-C7

What nerves form the Musculocutaneus nerve?

Lateral cord of the brachial plexus

Where is the Musculocutaneous nerve derived from?

anterior arm

Where does the Musculocutaneous nerve innervate?

Lateral Antebrachial Cutaneous nerve (LAC)

What does the musculocutaneus nerve change to when it courses lateral to the tendon of insertion of the biceps brachii muscle?

cutaneous innervation to the skin of the lateral forearm

What does the LAC nerve supply?

C5-T1

What nerves makes up the Median Nerve?

medial and lateral cords of the brachial plexus

What is the Median Nerve derived from? (cord)

medial surface of the arm within the neurovascular compartment

Where does the Median Nerve course?

anterior forearm

Where does the median nerve innervate?

portions of the hand

Where does the median nerve supply cutaneous innervation?

flexor retinaculum

The median nerve is the only nerve to pass deep to what?

carpal tunnel

Where does the Median nerve ultimately lie within in flexor retinaculum?

some small hand muscles and muscles within the thenar group

What do the terminal branches of the median nerve supply?

Lateral surface of the palm, distal ends of digits 1, 2, 3, lateral half of digit 4

Where do the cutaneous branches of the median nerve innervate?

Ventral Rami of C8 and T1

What nerves is the ulnar nerve derived from?

Medial cord of the brachial plexus

What is the Ulnar nerve a continuation of?

medial surface of the arm within the neurovascular compartment

Where does the ulnar nerve course?

1 1/2 muscles in the anterior forearm, majority of hand muscles

What does the ulnar nerve supply?

skin of the medial surface of the palm, dorsum of the hand, distal end of digit 5, medial half of digit 4

What does the Superficial Branch of the Ulnar nerve innervate?

Significant compression of the ulnar nerve against the medial epicondyle

What does Cubital Tunnel Syndrome result from?

Ventral Rami of C5-T1

What nerves is the Radial nerve derived from?

posterior cord of the brachial plexus

What is the Radial nerve a continuation of?

Posterior forearm muscles

What does the superficial and deep branches of the Radial nerve innervate?

skin on the lateral dorsal surface of the hand, lateral palmar surface of the thenar area

What does the superficial branch of the radial nerve innervate?

muscular and cutaneous innervation to the entire lower limb

What does the Lumbosacral Plexus supply?

Ventral rami of L1-S3

What forms the Lumbosacral Plexus?

Lumbar Plexus, Sacral Plexus

What is the lumbosacral plexus divided into?

Posterior wall of abdomen within Psoas Major

Where is the Lumbar Plexus location?

Tissue and musculature of the anterior, medial, lateral thigh

What does the Lumbar Plexus supply?

Ventral rami of L1, L2, L3, upper division of ventral ramus of L4

What forms the Lumbar Plexus?

Ventral rami of L2, L3, upper division of ventral ramus of L4

What is the Femoral Nerve derived from?

Iliopsoas, Satorius, Pectineus, Quadriceps Femoris

What is the muscular distribution of the Femoral nerve?

Ventral rami of L2, L3, upper division of ventral ramus of L4

What is the Obturator Nerve derived from?

Gracilis, Adductor Longus, Adductor Brevis, Adductor part of Adductor Magnus

What is the muscular distribution of the Obturator Nerve?

Lateral walls of the pelvis, medial to the piriformis muscle

Where is the Sacral plexus location

Tissues and musculature of the pelvis, gluteal region, posterior thigh, entire leg and foot

What does the sacral plexus supply?

Lower division of the ventral ramus of L4, ventral rami of L5, S1, S2, S3

What is the Sacral plexus derived from?

Lower division of the ventral ramus of L4, ventral rami of L5, S1

Where does the Superior Gluteal Nerve originate from?

Gluteus Medius, Gluteus Minimus, Tensor Fasciae Latae

What is the muscular distribution of the Superior Gluteal Nerve?

Ventral rami of L5, S1, S2

What does the Inferior Gluteal Nerve arise from?

Gluteus Maximus

What is the muscular distribution of the Inferior Gluteal Nerve?

Ventral ramus of S2

What does the nerve to Piriformis arise from?

Ventral rami of L5, S1, S2

What does the nerve to Superior Gemellus and Obturator Internus arise from?

Lower division of the ventral ramus of L4, ventral rami of L5, S1

What does the nerve to Inferior Gemellus and Quadratus Femoris arise from?

Ventral rami of S2, S3, S4

What is the Pudendal Nerve derived from?

male and female genitalia

What does the Pudendal nerve innervate?

Ventral rami of S1, S2, S3

What is the Posterior Femoral Cutaneous nerve derived from?