The Nervous System

授課老師 : 解剖學科 白滿惠學校分機:3262 Email:pai0507@tmu.edu.tw

本章重點:•神經系統的基本功能、發育與組成

•中樞神經系統的組成與功能•週邊神經系統的組成與功能

神經系統

Nervous system

The Control CenterIntegrating system

Thought, behavior,emotion, memory,

Physical responses ….

神經系統

Basic function of Nervous systemstimulus wave of excitation

(nerve impulse)

•analyze sensory information•make decisions regarding

appropriate behaviors

(CNS)

Sensory 感覺

IntegrationMotor 運動

感覺

感受體內與體外的變化，經分析整理之後，傳出訊息，控制肌肉收縮或腺體分泌，以維持身體的恒定。

Functional divisions of Nervous system

Structural divisions of Nervous system

1. Central nervous system(CNS)

- Brain : is housed within theskull

- Spinal cord : is encircledby the vertebral column

2. Peripheral nervous system(PNS; outside of the CNS)

- Nerves : cranial nerve(12)and spinal nerve (31)

中樞神經系統

神經

Summary of nervous system organization

Neurons 神經元- structural and functionalunits- Cell body (perikaryon) 細胞本體andprocesses細胞突起 (axon and dendrite)

1. Cell body-A single nucleus with a centralnucleolus 核仁

-Nissl bodies尼氏體 : contains rER &free ribosomes for protein synthesis-neurofibrils (a bundles of neurofilament 神

經絲), mictrotubules and actin : givecell shape and support, and transportmaterial-Pigaments : lipofuscin pigment脂褐質

(contain lysosome) or melanin

(Cytoskeleton)

2. Dendrites 樹突

•is the receptive portion•conducts impulses to the

cell body(將神經衝動傳向細胞本體)

•typically short, highlybranched & unmyelinated

•contains neurofibrils &Nissl bodies

3. Axon 軸突

–conduct impulses away from thecell body

- Axon hillock (lack of Nissl body)

- Initial segment (impulses arise )- Telodendria (Axon terminals)- Synaptic knobs (boutons)

(conductive portion)

1. unipolar neuron (or

pseudounipolar neuron) : oneprocess only (developsfrom a bipolar); are alwayssensory neurons cell type

2. bipolar neuron : one maindendrite & one axon(found in retina, inner ear& olfactory epithelium )

3. multipolar neuron : severaldendrites & one axon(most common)

Structural Classification of Neurons(Based on number of processes found on cell body)

Functional classification of Neurons1. Sensory (afferent) neurons感覺神經元

–transport sensory information from skin, muscles,joints, sense organs & viscera to CNS

2. Motor (efferent) neurons運動神經元

–send motor nerve impulses to muscles & glands3. Interneurons (association) neurons連絡神經元; 中間神經元

–transmit impulses from one neuron to another–90% of neurons in the body

Peripheral nervoussystem (PNS)

本章節重點 :

1.周邊神經系統的位置、基本組成與分布

2.12對腦神經的構成與功能

3.31對脊神經的構成與功能

4.神經叢的構成與功能

5.神經叢的主要神經分支

6.皮節定義

授課老師: 解剖學科 白滿惠分機:3262 email:pai0507@tmu.edu.tw

周邊神經系統

Peripheral nervoussystem (PNS)周邊神經系統

Cranial nervespinal nerve

Gangliaperipheral nerves

12 pairs ofCranial nerves

31 pairs ofSpinal nerves

Functional Organization of the PNS

Autonomic nervous system

Somatic nervous system (SNS) 體壁神經系統

Cranial Nerves

- originate from the brain-12 pairs of cranial nerves-most innervate the head and neck

CN I - Olfactory Nerve

•Extends fromolfactory mucosaof nasal cavity toolfactory bulb

•Sense of smell•purely sensory

•Connects to retinasupplying vision

•Optic chiasma

CN II - Optic Nerve(purely sensory)

CN II - Optic Nerve

•Extend from ventral midbrain to eye•Levator palpebrae提上眼瞼肌 raises eyelid (ptosis 眼瞼下垂)•4 extrinsic eye muscles

- superior, inferior, medial rectus and inferior oblique muscles•2 intrinsic eye muscles (Ciliary muscles and sphincter pupillae)

–accomodation for near vision (changing shape of lens during reading)–constriction of pupil

CN III - Oculomotor Nerve

CN IV - Trochlear Nerve

•Emerge from dorsal midbrain andenter orbit along with CN III

•Supply the Superior oblique muscle

Trigeminal Nerve (CN V )- The largest cranial nerve- from pons- the principal generalsensory nerve for the head

- innervate the muscles ofmastication and TensorTympani, Tensor Velipalatine

- 3 divisions : ophthalmic ,maxillary and mandibular br.

Summary of Trigeminal Nerve

CN VI - Abducens Nerve

•Extend from inferior pons to eye•Supply the Lateral rectus muscle

The cranial nervesof control eye

movements

•Fibers issue from pons internalacoustic meatus內聽道stylomastoid foramen莖乳突孔•Motor portion

–facial muscles (facial expression)–salivary ,nasal and oral mucous

glands and tears•Sensory portion : taste buds onanterior 2/3 of tongue

5 branches

CN VII - Facial Nerve

CN VIII - Vestibulocochlear Nerve (purely sensory)

• Cochlear branch-耳蝸支 begins in medulla–receptors in cochlea (hearing)– if damaged deafness or tinnitus (ringing) is produced

• Vestibular branch前庭支 begins in pons–receptors in vestibular apparatus (sense of balance)–Vertigo暈眩 (feeling of rotation)–ataxia (lack of coordination)

CN IX - Glossopharyngeal Nerve

•Innervate part of tongue and pharynx (ex. Stylopharyngeus m. lifts throat during swallowing)•Secretions of parotid gland (motor; parasympathetic)•Somatic sensations & taste on posterior 1/3 of tongue

•The only cranial nerve to extendbeyond head and neck

•Receives sensations fromviscera

•Controls cardiac muscle andsmooth muscle of the viscera

•Controls secretion of digestivefluids and swallowing

CN X - Vagus Nerve

•are formed by union of a cranial and spinal portion1. Cranial portion (arises medulla; join vagus nerve) : supplyskeletal muscles of throat & soft palate

2.Spinal portion (arises cervical spinal cord) :sternocleidomastoid and trapezius mm.

CN XI - Spinal Accessory Nerve

CN XII - Hypoglossal Nerve

•Controls muscles of tongueduring speech andswallowing

•Injury deviates tongue toinjured side when protruded

•Mixed, primarily motor

Cranialnerves

Summary of Cranial Nerves

Spinal Nerves

•Multiple anterior rootlets a single anterior root (containmotor axons only)

•Multiple posterior rootlets a single posterior root (containsensory axons only)

•Each anterior root and posterior root unite within theintervertebral foramen to become a spinal nerve.

•A spinal nerve contains both motor and sensory axons.

Spinal nerves

•31 pairs of spinal nerves

Each side contains:

•Eight cervical nerves (C1-C8).

•Twelve thoracic nerves (T1-T12).

•Five lumbar nerves (L1-L5).

•Five sacral nerves (S1-S5)

•One coccygeal nerve (Co1)

•Spinal nerves form fromdorsal背根& ventral roots腹根

•Spinal nerves branch intodorsal背枝 & ventral rami腹枝

–dorsal rami supply skin &deep muscles of back

–ventral rami form plexusinnervates the anteriorand lateral portions of thetrunk and the upper andlower limbs

Branching ofSpinal Nerve

Nerve Plexus

•Joining of ventral rami ofspinal nerves to form nervenetworks or plexuses

•The principle plexuses are :cervical plexuses, brachialplexuses, lumbar plexuses,and sacral plexuses.

•No plexus in thoracicregion–intercostal n. innervate

intercostal spaces–T7 to T12 supply

abdominal wall as well

神經叢

Intercostal Nerves

- The anterior rami ofspinal nerves T1-T11

- travel in the intercostalspaces between adjacentribs

- Spinal nerve T12 is calleda subcostal nerve becauseit arises below the ribs

- the intercostal nerves donot form plexuses

- Only T1 forms part of thebrachial plexus

肋間神經

•Ventral rami of spinalnerves (C1 to C4)

•innervate the anterior neckmuscles and the skin of theneck ,head and shoulders

•Cutaneous branches :greater auricular, lesseroccipital, supraclavicular,and transverse cervicalnerves

頸神經叢

1. Phrenic nerve (C3-C5)-travels through the thoracic cavity to innervate thediaphragm

2. Ansa cervicalis innervates the infrahyoid m.

Cervical Plexus

Motor branches :

Cervical plexus (C2~C4)

Supraclavicular nerve (C3,C4)

- 4 Cutaneous nerves

Lesser occipital nerveGreat auricular nerve(C2,C3)

Transverse cervical n.(C2,C3)

Cervical Plexus

•Ventral rami from C5 to T1•Supplies shoulder & upperlimb

Brachial Plexus臂神經叢

1.The anterior rami of C5-T1 formthe roots of the brachial plexus.

2.The roots unite to form the:•Superior trunk-nerves C5 and C6•Middle trunk -nerve C7•Inferior trunk -nerves C8 and T13.Portions of each trunk divide

into and anterior division and aposterior division.

4.The anterior and posteriordivisions converge to form threecords: Posterior cord, Medialcord and Lateral cord

Brachial Plexus臂神經叢

Axillarynerve 腋神經

•Ventral rami from C5 to T1•Supplies shoulder & upper limb•Passes superior to 1st rib & under clavicle•5 terminal branches :Axillary n. to deltoid & teres m.Musculocutaneous n. to elbow flexorsRadial n. to shoulder & elbow extensorsMedian & ulnar n to flexors of wrist & hand

R1

Brachial Plexus臂神經叢

Clinical Correlations•Radial nerve injury

–improper deltoid injectionor tight cast

–wrist drop

•Median nerve injury–numb palm & fingers;

inability to pronate & flexfingers

•Ulnar nerve injury (clawhand)

–inability to adduct/abductfingers, atrophy ofinterosseus

•are formed from the Ventralrami of L1 to L4

•is subdivided into an anteriordivision and a posteriordivision.

•The main nerve of theposterior division is thefemoral nerve.

•The main nerve of theanterior division is theobturator nerve.

•Supplies abdominal wall,external genitals &anterior/medial thigh

Lumbar Plexus腰神經叢

•Injury to femoral nerve causes inability to extend leg & loss ofsensation in thigh

•Injury to obturator nerve causes paralysis of thigh adductors

Lumbar Plexus

•Ventral rami of L4-L5 & S1-S4•Supplies buttocks, perineum &part of lower limb

•are organized into an anteriordivision and a posterior division.

Sacral Plexus 薦神經叢

坐骨神經分支

•Sciatica pain extends from the buttock down theleg to the foot (may be sign of herniated disc)

•fibular nerve (deep and superficial) injuryproduces foot drop or numbness

•Tibial nerve injury produces calcaneovalgus (lossof function on anterior leg & dorsum of foot)

•Sciatic nerve - L4 to S3supplies post thigh & all below knee•The sciatic nerve is the largestand longest nerve in the sacralplexus and in the body

•The main branches of the sciaticnerve are the Tibial n,Common fibular n, Deep Fibular n,Superficial fibular n.

Branches of Sciatic Nerve

Branches of Sciatic Nerve

•A dermatome is a region ofthe skin supplied by a singlespinal nerve.

•Damaged regions of thespinal cord can bedistinguished by patterns ofnumbness over a dermatomeregion

•Skin on face supplied byCranial Nerve V

•Herpes 疱疹 is a commonviral infection

Dermatomes皮節

參考書目 :

1. McKinley and O'Loughlin : Human Anatomy.(2nd ed.)

2. Memmler's Structure and function of humanbody. 9th ed.

3. Tortora GJ : Principles of Human Anatomy.11th ed. New York: Harper Collins Co.

4. Marieb and Mallatt : Human Anatomy 5th ed.Benjamin /Cummings Co.