How does the formation of the spinal nerve work?
spinal nerve is formed from an anterior (efferent fibers) + posterior (afferent) spinal root
—> the 2 roots fuse and leave the vertebral canal through the intervertebral foramen
—> outside the vertebral canal the spinal nerve divides into posterior branch + anterior branch + communicating branch
Where in the spinal nerve do we find the spinal ganglion?
the posterior root of the spinal nerve contains the spinal ganglion
—> spinal ganglion contains the cell bodies of the afferent nerves entering the spinal cord
Which structures are generally supplied by the posterior branch of the spinal nerve?
motor fibers
deep muscles (epaxial muscles) of the back
sensory fibers
skin areas of the back + buttock
What is the segmental organisation of the posterior branch of the spinal nerve?
Suboccipital nerve (C1)
Greater occipital nerve (C2)
third occipital nerve (C3)
superior clunial nerves ( L1 - L3)
middle clunial nerves (S1-S3)
Which structures are supplied by the anterior branch of the spinal nerve?
muscles of anterior + lateral walls of the trunk
muscles of the limbs
to corresponding skin areas
Which plexi are formed from the anterior branch of the spinal nerve?
cervical plexus
brachial plexus
thoracic nerves (segmental organisation)
lumbar plexus
sacral plexus
coccygeal plexus
What is the structure of the communicating branch of the spinal nerve?
it connects with the sympathetic chain ganglion
it usually forms 2 indipendent branches —> white + gray
Which structures pass through the white + gray branches of the communicating branches of the spinal nerve?
White branch
visceromotor fibers pass via white branch to sympathetic chain ganglion —> there they are relayed to neurons
Gray Branch
axons of the neurons partly reenter the spinal nerve as postganglionic fibers via the gray branch
how many pairs of spinal nerves do we have?
31 pairs
What are the 31 pairs of spinal nerves?
Cervical Nerves (8) —> innervate skin + muzscles of upper limbs, head, neck (C1-C8)
Thoracic nerves (12) —> innervate intercostal muscles, skin + muscles of back + thorax (T1-T12)
Lumbar Nerves (5) —> innervate muscles + skin of abdomen, thighs, skin of genital organs (L1-L5)
Sacral Nerves (5) —> innervate skin + muscles of lower extremities (S1-S5)
Coccygeal Nerves (1) —> rudimentary in humans
What is a “Dermatome”?
is an area of skin innervated by a posterior root of a single spinal nerve
—> area radicularis sensoria
adjacent dermatomes may overlap but never cross the midline of the body
dematomes retain segmental organisation on the thorax, abdomen + are arrenged longitudinally along the long axes of the limbs
What is a “Myotome”?
group of muscles innervated by an anterior root of a single spinal nerve
—> area radicularis motorica
What are “Peripheral nerve fields”?
refers to the structure innervated by a single peripheral nerve
Which 2 types of peripheral nerve fields do we recognize?
Peripheral skin nerve field (area nervina sensoria)
area of skin innervated by a single peripheral nerve
Peripheral muscle nerve field (area nervina motorica)
group of muscles innervated by a single peripheral nerve
How does the sensory cutaneous innervation of the face work?
by branches of the trigeminal nerve —> each division passes out of the cranial cavity to innervate part of the face
—> all face covered except from the part of the ear
Which nerves are responsible for the cutaneous innervation of the face?
Opthalmic nerve —> supraorbital nerve
Maxillary nerve —> infraorbital nerve
Mandibular nerve —> mental nerve
Which nerves are responsible for the sensory (cutaneous) innervation of the head?
Upper part:
opthalmic nerve
Middle-posterior part —> posterior branches of spinal nerves
greater occipital nerve
third occipital nerve
Latero-Posterior parts:
lesser occipital nerve (cervical plexus)
Which nerves are responsible for the sensory /cutaneous innervation of the neck?
Anterior Part:
transverse cervical nerve (cervical plexus)
Posterior Part:
posterior branches of spinal nerves
Lateral Parts
great auricular nerve (cervical plecus)
Which nerve is responsible for the sensory / cutaneous innervation of the shoulder?
Supraclavicular nerves (cervical plexus)
which 4 nerves are responsible for the sensory/cutaneous innervation of the arm?
all from brachial plexus
Axillary Nerve —> superior lateral cutaneous nerve of arm
Radial Nerve —> inferior lateral cutaneous nerve of arm
Medial Cutaneous Nerve of Arm —> innervation of the medial aspect of arm
Intercostal Nerves (thoracic nerves) —> innervate a little axillary part of the arm
Which 4 nerves are responsible for the cutaneous innervation of the forearm?
Medial Cutaneous Nerve of Forearm —> medial part
Musculocutaneous Nerve —> lateral part
Radial Nerve —> posterior part
Articular Branch of Ulnar Nerve —> sensory innervation of elbow joint
Which 3 nerves are responsible for the sensory / cutaneous innervation of the hand?
ULNAR NERVE
dorsal branch —> 4th + 5th fingers and ulnar side of 3rd finger
superficial branch —> 5th finger + ulnar side 4th finger
RADIAL NERVE
superficial branch —> 1st + 2nd finger and radial sode of 3rd finger (only proximal + middle phalanges)
MEDIAN NERVE
Palmar branch —> skin of thenar eminence
common palmar digital nerves —> 1st, 2nd, 3rd fingers + radial side of the 4th digit and distal phalanges on both palmar + dorsal sides
Which nerves are responsible for the sensory/cutaneous innervation of the thigh + gluteal region and from which plexi are the originating from?
Ilioinguinal Nerve (lumbar plexus)
Genitofemoral nerve (lumbar plexus)
lateral cutaneous nerve of thigh (lumbar plexus)
femoral nerve (sacral plexus)
Obturator nerve (lumbar plexus)
posterior cutaneous nerve of thigh (sacral plexus)
Which structures are innervated by the ilioinguinal nerve?
root of penis/mons pubis
anterior 1/3 of the scrotum/labia majora
superomedial part of thigh
Which structures are innervated from the genitofemoral nerve?
medial side of thigh
which structures are innervated by the lateral cutaneous nerve of the thigh
anterolateral side of thigh
Which 2 branches does the femoral nerve has + which structures are innervated by them?
Anterior cutaneous branches —> anterior side of thigh
Saphenous nerve
infrapatellar branch -> skin inferior to patella
medial cutaneous nerve of leg —> medial part of lower leg
Which structures are innervated by the obturator nerve?
medial thigh
which structures are innervated by the branches of the posterior cutaneous nerve of the thigh?
Inferior clunial nerve —> distal part of gluteal region
Perineal branches —> perineal skin
Which nerve is responsible for the innervation of the lower leg + dorsum of the foot and what are its branches?
Sciatic Nerve (SP)
common fibular nerve
tibial nerve
what are the 3 branches of the common fibular nerve?
Lateral Sural Cutaneous nerve —> lateral calf
Superficial Fibular nerve
medial dorsal cutaneous nerve —> medial side of 1st-3td toe and lateral side of 2nd toe
intermedial dorsal cutaneous nerve —> lateral 3rd. whole 4th and medial 5th toe
Deep fibular nerve
lateral dorsal digital nerve of toe —> lateral side 1st toe
medial dorsal digital nerve of toe —> medial side 2nd toe
What are the 3 branches of the tibial nerve?
Medial sural cutaneous nerve
Sural nerve —> calf + lateral side of heel
Medial plantar nerve
proper plantar digital nerve of toe —> medial side of 1st toe
common plantar digital nerves —> lateral side of 1st toe, both sides 2nd-3rd toe, medial side 4th toe
Lateral plantar nerve:
superficial branch: lateral side of 4th toe + whole 5th toe
Which 4 nerves are responsible for the sensory/cutaneous innervation of the trunk?
Supraclavicular nerves (CP)
Thoracis nerves (intercostal nerbes)
Iliohypogastric nerve (LP)
Posterior branches of the spinal nerves
What are the 3 branches of the supraclavicular nerves?
Medial supraclavicular nerves —> skin over manubrium
Intermediate …. —> infraclavicular region
Lateral … —> acrominal region
What are the 2 branches of the thoracic nerves?
lateral cutaneous branches —> lateral part of the mammary + inframammary regions of abdomen
aterior cutaneous branches —> medial parts ….
What are the 2 branches of the iliohypogastric nerve?
lateral cutaneous branch —> lateral abdomen
anterior cutaneous branch —> around superficial inguinal ring
what are the 2 branches of the posterior branches of the spinal nerves?
Medial cutaneous branches
Lateral cutaneous branches
superior + middle clunial nerve
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