The Spinal Cord and
Spinal Nerves
Chapter 12
THE SPINAL CORD
Spinal Cord Anatomy
Spinal Cord Anatomy
Spinal Cord Anatomy
Spinal Cord Anatomy
Spinal Cord Anatomy
Spinal Cord Anatomy
Spinal Cord Anatomy
THE SPINAL NERVES
Spinal Nerve Anatomy
Spinal Nerve Anatomy
Spinal Nerve Distribution
Spinal Nerves of the Body
The Cervical Plexus
The Cervical Plexus
Cervical Plexus
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Most branches are cutaneous nerves that
supply sensory impulses from the skin of
the neck, ear, back of the head and
shoulders
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Other branches innervate the muscles of
the anterior neck
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Phrenic nerve = sole motor nerve supply
to the diaphragm for breathing
The Brachial Plexus
The Brachial Plexus
The Brachial Plexus
The Brachial Plexus
o
Median nerve: Flexor muscles of the
anterior forearm and intrinsic muscles in
palm; pronates the forearm, flex the wrist
and fingers, and oppose the thumb
o
Radial nerve: largest branch; posterior
muscles of the arm and forearm; innervates
all the extensor muscles for elbow, wrist, and
finger extension, forearm supination, and
thumb abduction
The Brachial Plexus
o
Ulnar nerve: produces wrist and finger
flexion and adduction as well as abduction
of the medial fingers
o
Suprascapular nerve: innervates the
supraspinatus and infraspinatus muscles
for movement of the shoulder
Intercostal Nerves
The Lumbar Plexus
The Lumbar Plexus
The Lumbar Plexus
The Lumbar Plexus
o
Femoral nerve: the largest terminal nerve
of this plexus and innervates the anterior
muscles of the thigh (thigh flexors and
knee extensors). Branches to form the
saphenous nerve on the medial thigh and
knee extending to the foot.
o
Obturator nerve: innervates the adductor
muscles of the leg.
The Sacral Plexus
The Sacral Plexus
The Sacral Plexus
The Sacral Plexus
o
Sciatic nerve: which supplies the entire
lower limb (leg) except the anteromedial
thigh.
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Tibial nerve – flexors of the knee and
extensors of the ankle, flexors of the toes,
and plantar surface of the foot.
Fibular nerve. – biceps femoris muscle
and tibialis anterior muscle; extensors of
the toes, surface of the leg and dorsal
surface of the foot.
The Sacral Plexus
o
Pudendal nerve - innervates muscles of the
perineum, urogenital diaphragm and external
anal and urethral sphincter muscles; skin of
the genitalia.
REFLEXES
NEURAL CIRCUITS
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Divergence
Parallel
Serial
Convergence
Reverberation
Neural Circuits
Neural Circuits
Neural Circuits
Neural Circuits
Neural Circuits
Neural Circuits
Steps of the Reflex Arc
Classification of Reflexes
Classification of Reflexes
Monosynaptic Reflexes
Polysynaptic Reflexes
Types of Reflexes
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Stretch
Flexor reflex
Crossed extensor reflex
Stretch Reflex
Flexor Reflex
Crossed Extensor Reflex
Reflexes Used in
Diagnostic Testing
Reflexes Used in
Diagnostic Testing