Yuniarti

Anatomy DepartmentFaculty of Medicine

UNISBA

• Structurally : - CNS (Central Nervous System) * Brain * Spinal cord - PNS (Peripheral Nervous System)The PNS consists of nerves and ganglia. * Cranial nerve * Spinal nerve* A collection of neuron cell bodies outside the CNS is a ganglion motoric and sensory ganglia.

• Functionally : - SNS ( Somatic Nervous System ) - ANS ( Autonomic Nervous System)

• Peripheral nerve consist : - a bundle peripheral nerve fibers - the connective tissue - the blood vessels

•Peripheral nerve fibers consist : - Axon - Neurolemma - Endoneurium

• Peripheral nerve covering : - Endoneurium - Perineurium - Epineurium

1. Somatic fibers - General sensory fibers / General somatic afferent (GSA) fibers transmit sensations from the body to the CNS - Somatic motor fibers / General somatic efferent (GSE) fibers transmit impulses to skeletal (voluntary) muscle

2. Visceral fibers - Visceral sensory fibers / General visceral afferent (GVA) fibers transmit pain or subconscious visceral reflex sensations ( ex: blood gas & blood pressure levels) - Visceral motor fibers / General visceral efferent (GVE) fibers transmit impulses to smooth (involuntary) muscle & glandular tissue

•Two varieties of visceral motor fibers :

- Presynaptic /preganglionic fibers emerge from the synapse outside the CNS in a parasymphatetic ganglion

- Postsynaptic / postganglionic fibers continue to innervate muscles & glands

**Work together to conduct impluses from CNS to smooth muscle or glands

•Spinal nerves initially arise from the spinal cord as rootlets.

•The rootlets converge to form two nerve roots :1.An anterior (ventral) nerve root, consisting of motor (efferent) fibers passing from nerve cell bodies in the anterior horn of spinal cord gray matter to effector organs located peripherally.

2.A posterior (dorsal) nerve root, consisting of sensory (afferent) fibers from cell bodies in the spinal sensory or posterior (dorsal) root ganglion (“DRG”) that extend peripherally to sensory endings and centrally to the posterior horn of spinal cord gray matter.

•The posterior and anterior nerve roots unite, within or just proximal to the intervertebral foramen, to form a mixed (both motor and sensory) spinal nerve, which immediately divides into two rami ):1.a posterior (dorsal) ramus 2.an anterior (ventral) ramus

In addition to posterior & anterior rami, spinal nerves also give off :

• Meningeal branch Supplies the vertebrae, vertebra ligament, blood vessels of spinal cord & meninges

• Rami communicantes component of the autonomic nervous system

Posterior rami, supplying nerve fibers to : -The synovial joint of the vertebral column-Deep muscle of the back-The overlying skin in a segmental pattern

Anterior rami, supplying nerve fibers to :-Anterior region of the trunk-Lateral region of the trunk-Upper limb-Lower limb

Anterior rami merge with all or portions of one or moreadjacent anterior rami, forming nerve plexuses

Posterior rami and the anterior rami of spinal nerves T2-T12 generally do not merge with the rami of adjacent spinal nerves to form plexuses.

INTERCOSTAL or THORACIC NERVE

Anterior ramiNerve T2 innervates the intercostal muscle, axilla & posteromedial aspect of the arm

Nerve T3-T6 innervates the intercostal muscle & abdominal muscle & the overlying skin

Posterior ramiInnervates the deep back muscle & skin of the posterior aspect of thorax

•The unilateral area of skin innervated by the sensory fibers of a single spinal nerve is called a dermatome

•The unilateral muscle mass receiving innervation from the fibers conveyed by a single spinal nerve is a myotome

Important to distinguish between the distribution of the fibers carried by spinal nerves (segmental innervation or distribution—i.e., dermatomes and myotomes labeled with a letter and a number, such as “T4”) and of the fibers carried by branches of a plexus (peripheral nerve innervation or distribution, labeled with the names of peripheral nerves, such as “the median nerve”)

Nerve Origin Distribution

Superficial(sensory)branches

-Lesser occipital C2 Skin of scalp posterior and superior to ear

-Great auricular C2-C3 Skin anterior,inferior&over ear and over parotid glands

-Transverse cervical C2-C3 Skin over anterior aspect of neck

-Supraclavicular C3-C4 Skin over superior portion of chest and shoulder

Deep(largerly motor) branches

-Ansa cervicalis *superior root *inferior root

C1C2-C3

*infrahyoid & geniohyoid muscles of neck*infrahyoid muscles of neck

-Phrenic C3-C5 Diaphragm

-Segmental branches C1-C5 Prevertebral (deep) muscles of neck, levator scapulae, and middle scalene muscles

Cervicalis Plexus

Brachial plexus

Nerve Origin Distribution

Dorsal scapular C5 Levator scapula,rhomboid major,rhomboid minor muscles

Long thoracic C5-C7 Serratus anterior muscle

Subclavian C5-C6 Subclavius muscle

Suprascapular C5-C6 Supraspinatus&infraspinatus muscles

Musculocutaneous C5-C7 Coracobrachialis,biceps brachii & brachialis muscle

Lateral pectoral C5-C7 Pectoralis major muscle

Upper subscapular C5-C6 Subscapularis muscle

Thoracodorsal C6-C8 Latissimus dorsi muscle

Lower subscapular C5-C6 Subscapularis & teres major muscle

Axillary C5-C6 -Deltoid&teres minor muscle-Skin over deltoid-Superior posterior aspect of arm

Median C5-T1 -Flexor of forearm (except flexor carpi ulnaris) & some muscle of the hand-Skin of lateral two-thirds of palm of hand&fingers

Brachial plexus

Nerve Origin Distribution

Radial C5-T1 -Triceps brachii & other extensor muscle of arm & forearm-Skin of posterior arm&forearm, lateral two-third dorsum of hand &fingers and middle phalanges

Medial pectoral C8-T1 Pectoralis major & minor muscles

Medial cutaneous nerve of arm

C8-T1 Skin of medial & posterior aspects of distal third of arm

Medial cutaneous nerve of forearm

C8-T1 Skin of medial and posterior aspects of forearm

Ulnar C8-T1 -Flexor carpi ulnaris,Flexor digitorum profundus & most muscles of the hand-Skin of medial side of hand, little finger and medial half of ring finger

Nerve Origin Distribution

Illiohypogastric L1 -Muscles of anterolateral abdominal wall-Skin of inferior abdomen&buttock

Illioinguinal L1 -Muscle of anterolateral sbdominal wall-Skin of superior medial aspect of thigh, root of penis&scrotum, labia majora&mons pubis

Genitofemoral L1-L2 -Cremaster muscle-Skin over middle anterior surface of thigh, scrotum & labia majora

Lateral cutaneous nerve of thigh

L2-L3 Skin over lateral, anterior & posterior aspect of thigh

Obturator L2-L4 -Adductor muscles of leg-Skin over medial aspect of thigh

Femoral L2-L4 -Flexor muscles of thigh & extensor muscle of leg-Skin over anterior&medial aspect of thigh and medial side of leg & foot

Lumbar plexus

Nerve Origin Distribution

Superior gluteal L4-L5 and S1

Gluteus minimus ,gluteus medius and tensor fasciae latae

Inferior gluteal L5-S2 Gluteus maximus muscle

Nerve to piriformis S1-S2 Piriformis muscle

Nerve to quadratus femoris & inferior gamellus

L4-L5 and S1

Quadratus femoris & inferior gamellus muscles

Nerve to obturator internus & superior gamellus

L5-S2 Obturator internus & superior gamellus muscles

Perforating cutaneous

S2-S3 Skin over inferior medial aspect of buttock

Posterior cutaneous nerve of thigh

S1-S3 Skin over anal region, inferior lateral aspect of buttock, superiorposterior aspect of thigh, superior part of calf, scrotum in male,& labia majora

Pudendal S2-S4 -Muscle of perineum-Skin of penis&scrotum, clitoris,labia majora, labia minora and vagina

Sacral & cocxygeal plexus

Nerve Origin Distribution

Sciatic-Tibial

*Medial plantar

*Lateral plantar

-Common fibular * Superficial fibular * Deep fibular

L4-S3L4-S3

L4-S2

Gastrocnemius, plantaris, soleus, popliteus, tibialis posterior, flexor digitorum longus, & flexor hallucis longus muscle*Abductor hallucis, flexor digitorum brevis, and flexor hallucis brevis muscles; skin over medial two-third of plantar surface of foot*Remaining muscle of foot not supplied by medial plantar nerve; skin over lateral third of plantar surface of foot

*Fibularis longus and fibularis brevis muscles; skin over distal third of anterior aspect of leg and dorsum of foot

*Tibialis anterior, extensor hallucis longus, fibularis tertius, extensor digitorum longus & brevis muscles; skin on adjacent sides of great and second toes