Cranial and Peripheral Nerves - Martin.pdf

PERIPHERAL NERVOUS SYSTEM:
CRANIAL AND PERIPHERAL NERVES
Preceptors:
Dr. Maria Vanessa Cristi
Dr. Ceres Laud
Dr. Christian Jefferson Diego

PERIPHERAL NERVOUS SYSTEM
• Nerves and ganglia outside the brain and spinal cord
• Connects the CNS to limbs and organs
• Somatic Nervous System – voluntary movements
• Autonomic Nervous System – involuntary
movements
• Sympathetic Nervous System
• Parasympathetic Nervous System

CRANIAL NERVES
➢ 12 pairs
➢ Exits skull through the foramina
➢ Mainly innervate the head and neck
➢ 3 groups:
➢ Sensory
➢ Motor
➢ Mixed

CRANIAL NERVES: OLFACTORY NERVE (I)
➢ First and shortest cranial nerve
➢ Transmits information relating to SMELL
➢ Special visceral afferent nerve
➢ Fibers of the olfactory nerve are the
central processes of the olfactory cells

CRANIAL NERVES: OLFACTORY NERVE (I)
➢ Sense smell detected by olfactory receptors at the
nasal epithelium
➢ Signal is sent through the filia olfactoria
➢ Synapse with the Mitral Cells
➢ Pass on the second order neurons to the primary
olfactory cortex

CRANIAL NERVES: OPTIC NERVE (II)
➢ Nerve of Vision
➢ Developed from the optic vesicle, an out
pocketing of the fore brain
➢ Devoid of neurilemmal sheath
➢ Surrounded by the extension of the
meninges and subarachnoid space

CRANIAL NERVES: OPTIC NERVE (II)
➢ Carries afferent impulses for vison
➢ Convergence of axons from the retinal ganglion
➢ Enter the optic canal and converge at the optic
chiasm
➢ Left optic tract – contains fibers from left temporal
(lateral) retina and right nasal (medial) retina
➢ Right optic tract – contains fibers from right
temporal (lateral) retina and left nasal (medial)
retina

CRANIAL NERVES: OCULOMOTOR (III)
➢ Motor
➢ Extraocular muscles of the eye (levator
palpebrae superioris, superior rectus, inferior
rectus, medial rectus and inferior oblique)
➢ Parasympathetic
➢ Sphincter pupillae and the ciliary muscles of
the eye

CRANIAL NERVES: OCULOMOTOR (III)
➢ Originates from the oculomotor nucleus
➢ Emerge at the anterior aspect of the midbrain
➢ Pierces the dura mater and enters the
cavernous sinus
➢ Leaves the cranial cavity via superior orbital
fissure
➢ Superior branch
➢ Inferior branch

CRANIAL NERVES: TROCHLEAR (IV)
➢ Smallest cranial nerve but with the longest
intracranial course
➢ Purely a motor
➢ supplies the superior oblique
➢ Arise from the trochlear nucleus and emerged
on the posterior surface of the midbrain
➢ Passes through the cranial middle fossa
➢ Enters the orbit to superior orbital fissure

CRANIAL NERVES: TROCHLEAR (IV)
➢ Motor innervation to the superior oblique
➢ Moves eye downward and laterally
➢ A lesion of the trochlear nerve results in
paralysis of the superior oblique muscle with
the result that diplopia occurs when the patient
attempts to turn the eye downwards and
laterally.

CRANIAL NERVES: TRIGEMINAL (V)
➢ Largest cranial nerve
➢ Principal sensory nerve of the face, orbit, nose
and mouth, and because its branches are
eminently suitable for accurate anesthetic
blockade

➢ Leaves the anterior aspect of the pons as a
small motor root and a large sensory root
➢ Passes forward out of the posterior cranial
fossa and rest on the apex of the middle
cranial fossa
➢ In the middle cranial fossa
➢ Sensory root expands into 3 trigeminal
ganglion supplying 3 facial division
➢ Motor root supplies the mandibular
division

V1 OPHTHALMIC NERVE
➢ First division of the CN V and is entirely sensory
➢ Innervates skin and mucous membrane of:
➢ Forehead, scalp, frontal and ethmoid sinus,
upper eyelid and its conjunctiva, cornea and
dorsum of the nose
➢ Provides parasympathetic supply to:
➢ Lacrimal gland

V2 MAXILLARY NERVE
➢ Second division of the trigeminal nerve,
entirely sensory
➢ Innervates the skin, mucous membrane and
sinuses of:
➢ Lower eyelid and its conjunctiva, cheeks
and maxillary sinus nasal cavity and
lateral nose, upper lip upper molar,
incisor and canine and associated
gingiva, superior palate
➢ Provides parasympathetic supply to:
➢ Lacrimal gland and nasal gland

CRANIAL NERVES: TRIGEMINAL(V)
V3 MANDIBULAR NERVE
➢ Sensory supply: mucous membrane and floor of the oral
cavity, external ear, lower lip, chin, anterior 2/3 of
tongue, lower molar, incisor and canine teeth and the
associated ganglia
➢ Motor supply: muscle of mastication (medial pterygoid,
masseter, temporalis), Anterior belly of the digastric
muscle and the mylohyoid muscle (these are suprahyoid
muscle), Tensor veli palatini, Tensor tympani
➢ Parasympathetic supply: submandibular, sublingual and
parotid

TRIGEMINAL NERVE BLOCK
Indication: Trigeminal neuralgia, intractable facial cancer,
cluster headache
Target: Depending on the site of pain
➢ Gasserian Ganglion Block
➢ Maxillary Nerve Block
➢ Mandibular Nerve Block
➢ Inferior Alveolar Nerve Block

SEMILUNAR (GASSERIAN) NERVE BLOCK
➢ Most comprehensive blockade of the trigeminal nerve
➢ Performed under fluoroscopic guidance
➢ Injection site: posterior 1/3 of the zygomatic bone, opposite the
second upper molar tooth

MAXILLARY NERVE BLOCK
➢ Maxillary nerve block is performed for acute or
chronic herpetic neuralgia, trigeminal neuralgia and
cancer pain.
➢ Injection site: pterygopalatine fossa after emerging
from the foramen rotundum.
➢ It is reached by inserting a needle through the mid-
point of the coronoid notch beneath the zygomatic
arch.

➢ MANDIBULAR NERVE BLOCK
➢ Indication: dental and maxillary surgery, for
inferior dental pain, trigeminal neuralgia on
the third branch, Temporomandibular
junction dysfunction
➢ Needle inserted midpoint of the coronoid
process beneath the zygomatic arch
➢ Target: muscles of mastication, lower jaw,
the side of the tongue and the skin overlying
the mandible

➢ INFERIOR ALVEOLAR NERVE BLOCK
➢ Injection site: medial to the anterior border
of the mandibular ramus
➢ Anaesthesia of the lower teeth, the skin and
mucosa of the lower lip
➢ Loss of sensation of the side of the tongue
owing to involvement of the lingual nerve

CRANIAL NERVES: ABDUCENS (VI)
➢ Purely somatic motor nerve supplying the Lateral
Rectus
➢ Arises from the abducens nucleus in the pons
➢ Exits at the junction of the pons and medulla
➢ Passes through the cavernous sinus, lying below
and lateral to the internal carotid artery
➢ Enters the orbit through the superior orbital
fissure
➢ When damaged, it gives rise to diplopia and a
convergent squint

CRANIAL NERVES: FACIAL NERVE (VII)
➢ The facial nerve supplies the muscles of facial expression, conveys secretomotor fibers to the
lacrimal gland, and to the submandibular and sublingual salivary glands, and transmits taste
fibers from the anterior two-thirds of the tongue.

CRANIAL NERVES: FACIAL NERVE (VII)
➢ Damage to the facial nerve or its central pathway results
in facial palsy
➢ Both nuclear and infranuclear palsies – complete facial
paralysis involving all facial muscles on one side
➢ Supranuclear palsies – no involvement of the muscles
above the palpebral fissure

CRANIAL NERVES: VESTIBULOCOCHLEAR
NERVE (VIII)
➢ COCHLEAR FIBERS – concerned with hearing
➢ Arises from the ventral and dorsal
cochlear nuclei in the inferior
cerebellar peduncle
➢ VESTIBULAR FIBER – concerned with
balance
➢ Arises from the vestibular nuclei
complex in the pons and medulla

CRANIAL NERVES: VESTIBULOCOCHLEAR
NERVE (VIII)
➢ Lesions of the vestibular division of the labyrinth or of
the vestibulocerebellar pathway result in vertigo,
ataxia and nystagmus
➢ Lesions of the cochlear division result in deafness that
may or may not be accompanied by tinnitus
➢ Temporal lobe tumors may give rise to auditory
hallucinations if they encroach upon the auditory
radiation or superior temporal gyrus.

CRANIAL NERVES: GLOSSOPHARYNGEAL
NERVE (IX)
➢ Leaves the anterolateral surface of the upper part of the
medulla oblongata as several rootlets
➢ Leaves the cranial cavity via the jugular foramen
➢ Superior and inferior glossopharyngeal sensory
ganglia
➢ Give rise to carotid sinus nerve

NERVE (IX)
➢ Sensory: Innervates the oropharynx, carotid body and
sinus, posterior 1/3 of the tongue, middle ear cavity and
Eustachian tube.
➢ Special sensory: Provides taste sensation to the
posterior 1/3 of the tongue.
➢ Parasympathetic: Provides parasympathetic innervation
to the parotid gland.
➢ Motor: Innervates the stylopharyngeus muscle of the
pharynx.

NERVE (IX)
GLOSSOPHARYNGEAL NERVE BLOCK
➢ Indication: glossopharyngeal neuralgia,
palliative care for patients with head and neck
malignancy
➢ Injection site: midpoint through mastoid
process and angle of mandible
➢ Targets the nerve as it emerges the
jugular foramen
➢ Anesthesia may spread to CN X (Vagus), XI
(Accessory) and XII (Hypoglossal)

CRANIAL NERVES: VAGUS NERVE (X)
➢ Largest and most widely distributed of the
cranial nerves
➢ Originates from the medulla of the brainstem
➢ Exits through the jugular foramen after giving off
the auricular branch

CRANIAL NERVES: VAGUS NERVE (X)
➢ Sensory: skin of the external acoustic meatus, internal
surfaces of the laryngopharynx and larynx, visceral sensation
to the heart and abdominal viscera
➢ Special Sensory: taste sensation to the epiglottis and root of
the tongue
➢ Motor: majority of the muscles of the pharynx, soft palate
and larynx
➢ Parasympathetic: smooth muscle of the trachea, bronchi
and gastro-intestinal tract and regulates heart rhythm

CRANIAL NERVES: ACCESSORY NERVE (XI)
➢ Purely somatic nerve that provides motor innervation
to the sternocleidomastoid and trapezius muscle
➢ Cranial Component – arise from the lateral aspect of
the medulla oblongata
➢ Exits through the jugular foramen
➢ Combines with the Vagus Nerve

➢ Spinal Component – arise from the neurons of
the upper spinal cord (C1 – C5/6)
➢ Runs superiorly and enter the foramen
magnum
➢ Exits through the jugular foramen
➢ Descend along the internal carotid artery to
the sternocleidomastoid and moves to the
trapezius
CRANIAL NERVES: ACCESSORY NERVE (XI)

CRANIAL NERVES: HYPOGLOSSAL NERVE (XII)
➢ Supplies all intrinsic and extrinsic muscle of the
tongue except the palatoglossus
➢ Arise from the hypoglossal nucleus of the
medulla oblongata of the brainstem
➢ Exits the cranium via the hypoglossal canal
➢ Travels along with branches from the cervical
plexus, C1/C2 spinal nerve root
➢ Pass inferiorly to the angle of the mandible and
moves to the direction of the tongue

➢ Division of the hypoglossal nerve, or lesions involving its nucleus, result in ipsilateral paralysis
and wasting of the muscles of the tongue.
➢ This is detected clinically by deviation of the protruded tongue to the affected side.
CRANIAL NERVES: HYPOGLOSSAL NERVE (XII)

SPINAL NERVES
➢ 31 Pairs
➢ 8 Cervical
➢ 12 Thoracic
➢ 5 Lumbar
➢ 5 Sacral
➢ 1 Coccygeal
➢ Pass through the Intervetebral Foramina
➢ Divides into Branches or Rami
➢ Posterior Ramus
➢ Anterior Ramus

SPINAL NERVES
➢ Dorsal (Posterior) Root
➢ Afferent (Sensory) Fibers
➢ Ventral (Anterior) Root
➢ Efferent (Motor) Fibers
➢ Mixed Spinal Nerve
➢ Anterior Ramus
➢ Posterior Ramus
Afferent fibers Arrive - SENSORY
Efferent fibers Exit - MOTOR

SPINAL NERVES
➢ Paravertebral Space
➢ A potential space along the outside of the vertebral
canal
➢ Filled with loose fat and areolar tissue
➢ Contains the nerve roots issuing from the spinal cord
and blood vessels
➢ Allows access for blocking the nerve without invading
the epidural or subarachnoid space
➢ Provide unilateral nerve blocks extending two to four
segments

SPINAL NERVES
➢ Nerve Plexus
➢ A network of intersecting nerve serving
the same part of the body
➢ Composed of afferent and efferent fibers
that arise from the merging of anterior
rami of spinal nerves
➢ Nerve Plexuses except in the thoracic region
➢ Cervical Plexus
➢ Brachial Plexus
➢ Lumbar Plexus
➢ Sacral and Coccygeal Plexus

➢ Myotome
➢ Specific muscle/s supplied by motor
innervation
➢ Dermatome
➢ Specific area of the skin supplied by sensory
innervation
SPINAL NERVES

SPINAL NERVES: CERVICAL PLEXUS
➢ Formed by the upper four Cervical Nerves, C1 – C4
➢ Provides innervation to skin and muscles of the neck
and the diaphragm
➢ Located on the posterior triangle of the neck
➢ Divided into two groups:
➢ Deep Muscular Branch
➢ Sensory Superficial Branch

➢ Deep Muscular Branch
➢ Nerve Root: C1
➢ Nerves to geniohyoid and
thyrohyoid
➢ Travels along with the hypoglossal
nerve
➢ Ansa Cervicalis (C1 – C3)
➢ Give off four branches to the
infrahyoid muscles
➢ Phrenic Nerve (C3 – C5)
➢ Motor innervation to the diaphragm

➢ Sensory Branches
➢ Greater Auricular Nerve (C2 – C3)
➢ External ear, skin over the parotid gland
➢ Largest ascending plexus branch
➢ Transverse Cervical Nerve(C2 – C3)
➢ Sensation to the anterior neck
➢ Lesser Occipital Nerve (C2, contribution from C3)
➢ Posterosuperior scalp
➢ Supraclavicular Nerve (C3 – C4)
➢ Skin overlying the supraclavicular fossa,
upper thoracic region, sternoclavicular joint

➢ SUPERFICIAL AND DEEP CERVICAL NERVE BLOCK
➢ Indication: provides regional anesthesia for
neck surgery (e.g. carotid endarectomy,
thyroidectomy, and cervical lymph node
dissection)
➢ Superficial plexus: behind the posterior
border of the middle portion of the
sternocleidomastoid
➢ Deep Plexus: transverse process of the 2nd, 3rd
and 4th cervical vertebrae

➢ OCCIPITAL NERVE BLOCK
➢ Indication: Diagnostic step in evaluating head
and neck pain
➢ Complications: rare, intravascular injection

SPINAL NERVES: BRACHIAL PLEXUS
➢ Provides motor innervation and nearly all sensory supply of the upper limb

➢ Pass through the anterior and medial scalene muscles
➢ Covered sheaths of fibrous tissue
➢ Upper Trunk – root of C5 and C6
➢ Middle trunk – C7
➢ Lower Trunk – root of C8 and T1

➢ Lateral border of the first rib
➢ 3 Anterior Division
➢ 3 Posterior Division
➢ Leave through the posterior triangle and
pass into the axilla

➢ Enter the apex of the axilla
➢ Grouped together:
➢ Medial Cords
➢ Lateral Cords
➢ Posterior Cords

BRACHIAL PLEXUS : MAJOR BRANCHES
MUSCULOCUTANEOUS NERVE
• Roots: C5, C6, C7.
• Motor Functions: Innervates the brachialis,
biceps brachii and coracobrachialis muscles.
• Sensory Functions: Gives off the lateral
cutaneous branch of the forearm, which
innervates the lateral half of the anterior
forearm, and a small lateral portion of the
posterior forearm.

AXILLARY NERVE
• Roots: C5 and C6.
• Motor Functions: Innervates the teres minor
and deltoid muscles.
• Sensory Functions: Gives off the superior
lateral cutaneous nerve of arm, which
innervates the inferior region of the deltoid
(“regimental badge area”).

RADIAL NERVE
• Nerve roots – C5-T1.
• Sensory – Innervates most of the skin of the
posterior forearm, the lateral aspect of the
dorsum of the hand, and the dorsal surface of
the lateral three and a half digits.
• Motor – Innervates the triceps brachii and the
extensor muscles in the forearm.

MEDIAN NERVE
• Nerve roots: C6 – T1 (may contain C5 fibers)
• Motor functions: Innervates the flexor and
pronator muscles; thenar muscles and lateral two
lumbricals in the hand
• Sensory functions:
palmar cutaneous branch – lateral aspect of
the palm
digital cutaneous branch – lateral three and
a half fingers on the anterior (palmar)
surface of the hand.

• ULNAR NERVE
• Spinal roots: C8-T1.
• Motor functions:
• Two muscles of the anterior forearm – flexor carpi
ulnaris and medial half of flexor digitorum
profundus
• Intrinsic muscles of the hand (apart from the
thenar muscles and two lateral lumbricals)
• Sensory functions: Medial one and half fingers and the
associated palm area.

BRACHIAL PLEXUS NERVE BLOCK
INTERSCALENE NERVE BLOCK
➢ procedure of upper arm and shoulder.
SUBCLAVIAN NERVE BLOCK
➢ Procedure at the distal elbow
INFRACLAVICULAR NERVE BLOCK
➢ Procedure at the distal elbow
AXILLARY NERVE BLOCK
➢ Procedure at elbow, forearm and hand

AXILLARY BRACHIAL PLEXUS BLOCK
➢Indication: for procedures of the elbow,
forearm and hand
➢ Targets the Ulnar, Radial, and Median
Nerve

MEDIAN NERVE BLOCK
• Indication: for injuries requiring procedure on the
radial side of the palm, palmar surface and tip of
the thumb, index, middle and ring finger

ULNAR BLOCK
• Indication: for rescue analgesia or surgical
anesthesia for surgery on the fifth digit

SPINAL NERVES: THORACIC NERVE
➢12 pairs of thoracic anterior primary rami
➢11 intercostal nerve
➢1 subcostal nerve
➢Nerve Root: T1 – T12
➢Motor: muscles of the intercostal space, anterior abdominal wall
➢Sensory: skin of the medial aspect of the upper arm, anterior
and lateral aspects of the trunk from the level of the angle of
Louis to just above the groin

➢Intercostal nerve travels together with the ribs on the
inferior aspect
➢Between intercostal muscle and innermost intercostal
muscle
➢Sensory innervation to the parietal pleura

➢Motor and sensory functions - determined by its
vertebral level
➢T1 and T2 - top of the chest, arm and hand
➢T3, T4, and T5 - chest wall and aid in breathing
➢T6, T7, and T8 - chest and/or down into the abdomen
➢T9, T10, T11, and T12 - abdomen and/or lower in the
back

INTERCOSTAL NERVE BLOCK
➢Indication: for relief of pain associated with
rib fractures, herpes zoster, and cancer
➢ Targeted to the various vertebral level that
correspond to the area of the body wall to
be anesthetized
➢Complication: intravascular local injection,
pneumothorax.

SPINAL NERVES: CERVICOTHORACIC BLOCK
➢ STELLATE GANGLION BLOCK
➢ Combined structure of the inferior cervical
sympathetic and the first thoracic ganglion
➢ Indications:
➢ Pain syndrome (refractory angina pectoris,
phantom limb, etc)
➢ Vascular insufficiency in the arm
➢ Adequate block develops Horner’s Syndrome

SPINAL NERVES: LUMBAR PLEXUS
➢Nerve Root: L1, L2, L3, L4 (contribution from L4)
➢Divide into several cords to form six major
peripheral branches:
1. Iliohypogastric
2. Ilioinguinal
3. Genitofemoral
4. Dorsal division:
1. Lateral cutaneous nerve
2. Femoral nerve
5. Ventral Division
1. obturator nerve
2. accessory obturator nerve

LUMBAR PLEXUS: MAJOR BRANCHES
ILIOHYPOGASTRIC NERVE
• Roots: L1 (with contributions from T12)
• Motor Functions: Innervates the internal oblique
and transversus abdominis
• Sensory functions: innervates the posterolateral
gluteal skin in the pubic region

ILIOINGUINAL NERVE
• Roots: L1
• Motor Functions: Innervates the internal oblique
and transversus abdominis.
• Sensory Functions: Innervates the skin on the
superior antero-medial thigh.
• Males - over the root of the penis and anterior
scrotum
• Females - skin over mons pubis and labia
majora

GENITOFEMORAL NERVE
• Roots: L1, L2
• Motor Functions: The genital branch innervates the
cremasteric muscle.
• Sensory Functions:
• genital branch innervates the skin of the
anterior scrotum (in males) or the skin over
mons pubis and labia majora (in females)
• femoral branch innervates the skin on the
upper anterior thigh.

LATERAL CUTANEOUS NERVE
• Roots: L2, L3
• Sensory Functions: Innervates the anterior and
lateral thigh down to the level of the knee.
• Anterior branch – skin over the anterolateral
aspect of the thigh down to the knee
• Posterior branch – lateral aspect of the leg from
the greater trochanter to the mid-thigh

FEMORAL NERVE
• Roots: L2, L3, L4.
• Motor Functions: Innervates the muscles of the
anterior thigh – the illiacus, pectineus, sartorius
and quadriceps femoris.
anterior thigh and the medial leg.

OBTURATOR NERVE
• Roots: L2, L3, L4
• Motor Functions: Innervates the muscles of the
medial thigh – the obturator externus, adductor
longus, adductor brevis, adductor magnus and
gracilis.
• Sensory Functions: Innervates the skin over the
medial thigh.

LUMBAR PLEXUS BLOCK
LUMBAR PLEXUS NERVE BLOCK
➢ Indication: hip surgery and for intermittent or continuous
analgesia in selected patients
➢ Blocks the femoral, obturator and lateral cutaneous nerve
of the thigh

LUMBAR PLEXUS BLOCK
FEMORAL NERVE BLOCK
➢ Indication: provide postoperative analgesia for hip, thigh,
knee, and ankle (for the saphenous nerve) procedures
➢ Blocks the entire anterior thigh and most of the femur and
knee joint, skin on the medial aspect of the leg below the
knee joint

LUMBAR PLEXUS BLOCK
OBTURATOR NERVE BLOCK
➢ Indication: hip joint pain, relief of adductor muscle
spasm associated with hemi- or paraplegia
➢ Anesthesia of the adductor muscles and knee

SACRAL AND COCCYGEAL PLEXUSES
SACRAL PLEXUS
➢Nerve Root: L5 – S3, contributions from L4 and
S4
COCCYGEAL PLEXUS
➢Nerve Root: S4, S5 and anterior primary ramus
of the coccygeal nerve

SACRAL PLEXUS: MAJOR BRANCHES
SUPERIOR GLUTEAL NERVE
• Roots: L4, L5, S1
• Motor Functions: Innervates the gluteus minimus,
gluteus medius and tensor fascia lata.

INFERIOR GLUTEAL NERVE
• Roots: L5, S1, S2.
• Motor Functions: Innervates gluteus maximus

POSTERIOR FEMORAL CUTANEOUS
(POSTERIOR CUTANEOUS NERVE OF THE THIGH)
• Roots: Roots: S1, S2, S3
posterior surface of the thigh and leg. Also
innervates the skin of the perineum.

PUDENDAL NERVE
• Roots: S2, S3, S4
• Motor Functions: Innervates the skeletal muscles in the
perineum, the external urethral sphincter, the external anal
sphincter, levator ani.
• Sensory Functions: Innervates the penis and the clitoris and
most of the skin of the perineum.

SCIATIC NERVE
• Roots: L4, L5, S1, S2, S3
• Largest peripheral nerve of the body
• Made up of two nerves: the tibial nerve and the
peroneal nerve

SCIATIC NERVE
The branches of the sciatic nerve can be grouped into
the following:
1. Muscular – semitendinous, semimembranous,
adductor magnus, biceps femoris
2. Articular to the hip joint
3. Terminal – common peroneal and tibial nerve

SCIATIC NERVE
• Motor Functions:
• Tibial portion – muscles in the posterior
compartment of the thigh, leg and sole of the
feet
• Common fibular portion – Short head of
biceps femoris, all muscles in the anterior and
lateral compartments of the leg and extensor
digitorum brevis.

SCIATIC NERVE
• Sensory Functions:
• Tibial portion: supplies the skin of the
posterolateral leg, lateral foot and the sole of
the foot.
• Common Peroneal portion: supplies the skin
of the lateral leg and the dorsum of the foot.

BRANCHES OF SCIATIC NERVE: TIBIAL NERVE
• Nerve roots: L4-S3
• Sensory: Innervates the skin of the posterolateral
leg, lateral foot and the sole of the foot.
• Motor: Innervates the posterior compartment of
the leg and the majority of the intrinsic foot
muscles.

BRANCHES OF SCIATIC NERVE: COMMON PERONEAL
NERVE
• Nerve roots: L4 – S2
• Motor: Innervates the short head of the biceps femoris
directly. Also supplies (via branches) the muscles in the
lateral and anterior compartments of the leg.
• Sensory: Innervates the skin of the lateral leg and the
dorsum of the foot.

BRANCHES OF SCIATIC NERVE: COMMON PERONEAL
NERVE
• Superficial Peroneal nerve: Innervates the muscles of
the lateral compartment of the leg; fibularis longus and
brevis.
• Deep Peroneal nerve: Innervates the muscles of the
anterior compartment of the leg; tibialis anterior,
extensor digitorum longus and extensor hallucis
longus.

SCIATIC NERVE BLOCK
➢ Indication: for surgical procedures involving the hip,
thigh, knee, lower leg, and foot
➢ Posterior approach – most popular and reliable
SPINAL NERVE: SACRAL PLEXUS BLOCK

PUDENDAL NERVE BLOCK
➢ Indication: for evaluating patients with perineal
somatosensory pain
➢ Numbness of the genitalia

NERVE BLOCKS TO THE ANKLE
➢ Five nerves pass the malleoli at the ankle:
➢ posterior tibial nerve,
➢ sural nerve
➢ deep peroneal nerve
➢ superficial peroneal nerve
➢ saphenous nerve

SPINAL NERVES: COCCYGEAL PLEXUS
• Nerve Root: part of S4, S5 and Co. 1
• Forms a single trunk – Anococcygeal Nerve
• Sensory Function: supply the skin over the coccyx

References:
• Barash Clinical Anesthesia 8th ed
• Anatomy for Anaesthetists 9th ed
• Snell’s Clinical Neuroanatomy 8th ed

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