The Nerves – Types, Structures, and Functions

Last updated: February 8, 2026Reviewed date: February 8, 2026Reading time: 7 min read
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The nerves is an enclosed, cable-like bundle of nerve fibers called axons, in the peripheral nervous system. A nerve transmits electrical impulses and is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the electrochemical nerve impulses called action potentials that are transmitted along each of...

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Article Summary

The nerves is an enclosed, cable-like bundle of nerve fibers called axons, in the peripheral nervous system. A nerve transmits electrical impulses and is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the electrochemical nerve impulses called action potentials that are transmitted along each of the axons to peripheral organs or, in the case of sensory nerves, from the periphery back to the central nervous system. Each axon within...

Key Takeaways

  • This article explains Types of a Nerve in simple medical language.
  • This article explains Alphabetical list in simple medical language.
  • This article explains Structure in simple medical language.
Educational health guideWritten for patient understanding and clinical awareness.
Reviewed content workflowUse writer and reviewer profiles for stronger trust.
Emergency safety firstUrgent warning signs are highlighted below.

Seek urgent medical care if you notice

These warning signs are general safety guidance. Local emergency numbers and clinical judgment should always come first.

  • Severe symptoms, breathing difficulty, fainting, confusion, or rapidly worsening illness.
  • New weakness, severe pain, high fever, or symptoms after a serious injury.
  • Any symptom that feels urgent, unusual, or unsafe for the patient.
1

Emergency now

Use emergency care for severe, sudden, rapidly worsening, or life-threatening symptoms.

2

See a doctor

Book a professional medical evaluation if symptoms persist, worsen, recur often, affect daily activities, or occur in a high-risk patient.

3

Learn safely

Use this article to understand possible causes, tests, treatment options, prevention, and questions to ask your clinician.

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Definition

The nerves is an enclosed, cable-like bundle of nerve fibers called axons, in the peripheral nervous system. A nerve transmits electrical impulses and is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the electrochemical nerve impulses called action potentials that are transmitted along each of the axons to peripheral organs or, in the case of sensory nerves, from the periphery back to the central nervous system. Each axon within the nerve is an extension of an individual neuron, along with other supportive cells such as some Schwann cells that coat the axons in myelin.

Types of a Nerve

The Nerves - Types, Structures, and Functions

  • Structure of the nervous system
  • Development of the nervous system
  • The spinal cord or medulla spinalis
  • The brain or encephalon
    • The hindbrain or rhombencephalon
    • The midbrain or mesencephalon
    • The forebrain or prosencephalon
    • Composition and central connections of the spinal nerves
    • Pathways from the brain to the spinal cord
    • The meninges of the brain and medulla spinalis
    • The cerebrospinal fluid
  • The cranial nerves
    • The olfactory nerves
    • The optic nerve
    • The oculomotor nerve
    • The trochlear nerve
    • The trigeminal nerve
    • The abducens nerve
    • The facial nerve
    • The vestibulocochlear nerve
    • The glossopharyngeal nerve
    • The vagus nerve
    • The accessory nerve
    • The hypoglossal nerve
  • The spinal nerves
    • The posterior divisions
    • The anterior divisions
    • The thoracic nerves
    • The lumbosacral plexus
    • The sacral and coccygeal nerves
  • The sympathetic nerves
    • The cephalic portion of the sympathetic system
    • The cervical portion of the sympathetic system
    • The thoracic portion of the sympathetic system
    • The abdominal portion of the sympathetic system
    • The pelvic portion of the sympathetic system
    • The great plexuses of the sympathetic system

Alphabetical list

  • Abdominal aortic plexus
  • Abducens nerves
  • Accessory nerve
  • Accessory obturator nerve
  • Alderman’s nerve
  • Anococcygeal nerve
  • Ansa cervicalis
  • Anterior interosseous nerve
  • Anterior superior alveolar nerve
  • Auerbach’s plexus
  • Auriculotemporal nerve
  • Axillary nerve
  • Brachial plexus
  • Buccal branch of the facial nerve
  • Buccal nerve
  • Cardiac plexus
  • Cavernous nerves
  • Cavernous plexus
  • Celiac ganglia
  • Cervical branch of the facial nerve
  • Cervical plexus
  • Chorda tympani
  • Ciliary ganglion
  • Coccygeal nerve
  • Cochlear nerve
  • Common fibular nerve
  • Common palmar digital nerves of median nerve
  • Deep branch of the radial nerve
  • Deep fibular nerve
  • Deep petrosal nerve
  • Deep temporal nerves
  • Diagonal band of Broca
  • Digastric branch of facial nerve
  • Dorsal branch of ulnar nerve
  • Dorsal nerve of clitoris
  • Dorsal nerve of the penis
  • Dorsal scapular nerve
  • Esophageal plexus
  • Ethmoidal nerves
  • External laryngeal nerve
  • External nasal nerve
  • Facial nerve
  • Femoral nerve
  • Frontal nerve
  • Gastric plexuses
  • Geniculate ganglion
  • Genital branch of genitofemoral nerve
  • Genitofemoral nerve
  • Glossopharyngeal nerve
  • Greater auricular nerve
  • Greater occipital nerve
  • Greater petrosal nerve
  • Hepatic plexus
  • Hypoglossal nerve
  • Iliohypogastric nerve
  • Ilioinguinal nerve
  • Inferior alveolar nerve
  • Inferior anal nerves
  • Inferior cardiac nerve
  • Inferior cervical ganglion
  • Inferior gluteal nerve
  • Inferior hypogastric plexus
  • Inferior mesenteric plexus
  • Inferior palpebral nerve
  • Infraorbital nerve
  • Infraorbital plexus
  • Infratrochlear nerve
  • Intercostal nerves
  • Intercostobrachial nerve
  • Intermediate cutaneous nerve
  • Internal carotid plexus
  • Internal laryngeal nerve
  • Interneuron
  • Jugular ganglion
  • Lacrimal nerve
  • Lateral cord
  • Lateral cutaneous nerve of forearm
  • Lateral cutaneous nerve of thigh
  • Lateral pectoral nerve
  • Lateral plantar nerve
  • Lateral pterygoid nerve
  • Lesser occipital nerve
  • Lingual nerve
  • Long ciliary nerves
  • Long root of the ciliary ganglion
  • Long thoracic nerve
  • Lower subscapular nerve
  • Lumbar nerves
  • Lumbar plexus
  • Lumbar splanchnic nerves
  • Lumboinguinal nerve
  • Lumbosacral plexus
  • Lumbosacral trunk
  • Mandibular nerve
  • Marginal mandibular branch of facial nerve
  • Masseteric nerve
  • Maxillary nerve
  • Medial cord
  • Medial cutaneous nerve of arm
  • Medial cutaneous nerve of forearm
  • Medial cutaneous nerve
  • Medial pectoral nerve
  • Medial plantar nerve
  • Medial pterygoid nerve
  • Median nerve
  • Meissner’s plexus
  • Mental nerve
  • Middle cardiac nerve
  • Middle cervical ganglion
  • Middle meningeal nerve
  • Motor nerve
  • Muscular branches of the radial nerve
  • Musculocutaneous nerve
  • Mylohyoid nerve
  • Nasociliary nerve
  • Nasopalatine nerve
  • Nerve of pterygoid canal
  • Nerve to obturator internus
  • Nerve to quadratus femoris
  • Nerve to the Piriformis
  • Nerve to the stapedius
  • Nerve to the subclavius
  • Nervus intermedius
  • Nervus spinosus
  • Nodose ganglion
  • Obturator nerve
  • Oculomotor nerve
  • Olfactory nerve
  • Ophthalmic nerve
  • Optic nerve
  • Otic ganglion
  • Ovarian plexus
  • Palatine nerves
  • Palmar branch of the median nerve
  • Palmar branch of ulnar nerve
  • Pancreatic plexus
  • Patellar plexus
  • Pelvic splanchnic nerves
  • Perforating cutaneous nerve
  • Perineal branches of posterior femoral cutaneous nerve
  • Perineal nerve
  • Petrous ganglion
  • Pharyngeal branch of vagus nerve
  • Pharyngeal branches of glossopharyngeal nerve
  • Pharyngeal nerve
  • Pharyngeal plexus
  • Phrenic nerve
  • Phrenic plexus
  • Posterior auricular nerve
  • Posterior branch of spinal nerve
  • Posterior cord
  • Posterior cutaneous nerve of arm
  • Posterior cutaneous nerve of forearm
  • Posterior cutaneous nerve of thigh
  • Posterior scrotal nerves
  • Posterior superior alveolar nerve
  • Proper palmar digital nerves of median nerve
  • Prostatic plexus (nervous)
  • Pterygopalatine ganglion
  • Pudendal nerve
  • Pudendal plexus
  • Pulmonary branches of vagus nerve
  • Radial nerve
  • Recurrent laryngeal nerve
  • Renal plexus
  • Sacral plexus
  • Sacral splanchnic nerves
  • Saphenous nerve
  • Sciatic nerve
  • Semilunar ganglion
  • Sensory nerve
  • Short ciliary nerves
  • Sphenopalatine nerves
  • Splenic plexus
  • Stylohyoid branch of facial nerve
  • Subcostal nerve
  • Submandibular ganglion
  • Suboccipital nerve
  • Superficial branch of the radial nerve
  • Superficial fibular nerve
  • Superior cardiac nerve
  • Superior cervical ganglion
  • Superior ganglion of glossopharyngeal nerve
  • Superior ganglion of vagus nerve
  • Superior gluteal nerve
  • Superior hypogastric plexus
  • Superior labial nerve
  • Superior laryngeal nerve
  • Superior lateral cutaneous nerve of arm
  • Superior mesenteric plexus
  • Superior rectal plexus
  • Supraclavicular nerves
  • Supraorbital nerve
  • Suprarenal plexus
  • Suprascapular nerve
  • Supratrochlear nerve
  • Sural nerve
  • Sympathetic trunk
  • Temporal branches of the facial nerve
  • Third occipital nerve
  • Thoracic aortic plexus
  • Thoracic splanchnic nerves
  • Thoraco-abdominal nerves
  • Thoracodorsal nerve
  • Tibial nerve
  • Transverse cervical nerve
  • Trigeminal nerve
  • Trochlear nerve
  • Tympanic nerve
  • Ulnar nerve
  • Upper subscapular nerve
  • Uterovaginal plexus
  • Vagus nerve
  • Ventral ramus
  • Vesical nervous plexus
  • Vestibular nerve
  • Vestibulocochlear nerve
  • Zygomatic branches of the facial nerve
  • Zygomatic nerve
  • Zygomaticofacial nerve
  • Zygomaticotemporal nerve

Structure

Each nerve is covered on the outside by a dense sheath of connective tissue, the epineurium. Beneath this is a layer of fat cells, the perineurium, which forms a complete sleeve around a bundle of axons. Perineurial septae extend into the nerve and subdivide it into several bundles of fibers. Surrounding each such fiber is the endoneurium. This forms an unbroken tube from the surface of the spinal cord to the level where the axon synapses with its muscle fibers, or ends in sensory receptors. The endoneurium consists of an inner sleeve of material called the glycocalyx and an outer, delicate, meshwork of collagen fibres.[2] Nerves are bundled and often travel along with blood vessels, since the neurons of a nerve have fairly high energy requirements.

Within the endoneurium, the individual nerve fibers are surrounded by a low-protein liquid called endoneurial fluid. This acts in a similar way to the cerebrospinal fluid in the central nervous system and constitutes a blood-nerve barrier similar to the blood-brain barrier.[3] Molecules are thereby prevented from crossing the blood into the endoneurial fluid. During the development of nerve edema from nerve irritation (or injury), the amount of endoneurial fluid may increase at the site of irritation. This increase in the fluid can be visualized using magnetic resonance neurography, and thus MR neurography can identify nerve irritation and/or injury.

Categories

Nerves are categorized into three groups based on the direction that signals are conducted:

  • Afferent nerves conduct signals from sensory neurons to the central nervous system, for example from the mechanoreceptors in the skin.
  • Efferent nerves conduct signals from the central nervous system along motor neurons to their target muscles and glands.
  • Mixed nerves contain both afferent and efferent axons, and thus conduct both incoming sensory information and outgoing muscle commands in the same bundle. All spinal nerves are mixed nerves, and some of the cranial nerves are also mixed nerves.

Nerves can be categorized into two groups based on where they connect to the central nervous system:

  • Spinal nerves innervate (distribute to/stimulate) much of the body, and connect through the vertebral column to the spinal cord and thus to the central nervous system. They are given letter-number designations according to the vertebra through which they connect to the spinal column.
  • Cranial nerves innervate parts of the head and connect directly to the brain (especially to the brainstem). They are typically assigned Roman numerals from 1 to 12, although cranial nerve zero is sometimes included. In addition, cranial nerves have descriptive names.
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Safety note: This is not a prescription or diagnosis. For severe symptoms, pregnancy danger signs, children with serious illness, chest pain, breathing difficulty, stroke-like weakness, or major injury, seek urgent care.

Which doctor may help?

Start with a registered doctor or the nearest qualified health center.

What to tell the doctor

  • Write when the problem started and how it changed.
  • Bring old prescriptions, investigation reports, and current medicines.
  • Write allergies, pregnancy status, diabetes, kidney/liver disease, and major past illnesses.
  • Bring one family member if the patient is weak, elderly, confused, or a child.

Questions to ask

  • What is the most likely cause of my symptoms?
  • Which danger signs mean I should go to hospital quickly?
  • Which tests are necessary now, and which can wait?
  • How should I take medicines safely and what side effects should I watch for?
  • When should I come for follow-up?

Tests to discuss

  • Vital signs: temperature, pulse, blood pressure, oxygen saturation
  • Basic physical examination by a clinician
  • CBC, urine test, blood sugar, or imaging only when clinically needed

Avoid these mistakes

  • Do not use antibiotics, steroid tablets/injections, or strong painkillers without proper medical advice.
  • Do not hide pregnancy, kidney disease, ulcer, allergy, or blood thinner use.
  • Do not delay emergency care when danger signs are present.

Medicine safety and first-aid guide

This section is for patient education only. It does not replace a doctor, pharmacist, or emergency care.

Safe first steps

  • Avoid heavy lifting, sudden bending, and prolonged bed rest.
  • Use comfortable posture and gentle movement as tolerated.
  • Discuss physiotherapy, X-ray, or MRI only when clinically needed.

OTC medicine safety

  • For mild back pain, pain-relief medicine may be discussed with a doctor or pharmacist.
  • Avoid repeated painkiller use if you have kidney disease, stomach ulcer, uncontrolled blood pressure, or are taking blood thinners.

Avoid these mistakes

  • Do not start antibiotics without a proper medical decision.
  • Do not use steroid tablets or injections casually for quick relief.
  • Do not delay emergency care because of home remedies.

Get urgent help if

  • Back pain with leg weakness, numbness around private area, loss of urine/stool control, fever, cancer history, or major injury needs urgent care.
Medicine names, dose, and timing must be decided by a qualified clinician or pharmacist after checking age, pregnancy, allergy, other diseases, and current medicines.

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Write your symptoms, medicines already taken, test results, and questions before visiting a doctor. This note stays on your device unless you print or copy it.

Doctor to discuss: Orthopedic / spine specialist, physical medicine doctor, or qualified clinician
Tests to discuss with doctor
  • Neurological examination for leg power, sensation, reflexes, and straight leg raise
  • X-ray only if injury, deformity, long-lasting pain, or doctor suspects bone problem
  • MRI discussion if severe nerve symptoms, weakness, bladder/bowel problem, or persistent symptoms
Questions to ask
  • What is the most likely cause of my symptoms?
  • Which warning signs mean I should go to emergency care?
  • Which tests are really needed now?
  • Which medicines are safe for my age, pregnancy status, allergy, kidney/liver/stomach condition, and current medicines?
  • Is physiotherapy, posture correction, or activity modification needed?

Emergency warning signs such as chest pain, severe breathing difficulty, sudden weakness, confusion, severe dehydration, major injury, or loss of bladder/bowel control need urgent medical care. Do not wait for online information.

Safe pathway to proper treatment

Care roadmap for: The Nerves – Types, Structures, and Functions

Use this simple roadmap to understand the next safe steps. It is educational and does not replace examination by a doctor.

Go to emergency care if you notice:
  • Severe or rapidly worsening symptoms
  • Breathing difficulty, chest pain, fainting, confusion, severe weakness, major injury, or severe dehydration
Doctor / service to discuss: Qualified healthcare provider; specialist depends on symptoms and examination.
  1. Step 1

    Check danger signs first

    If danger signs are present, seek emergency care and do not wait for online information.

  2. Step 2

    Record the symptom story

    Write when symptoms started, severity, medicines already taken, allergies, pregnancy status, and test results.

  3. Step 3

    Visit a qualified clinician

    A doctor, nurse, or qualified healthcare provider can examine you and decide which tests or treatment are needed.

  4. Step 4

    Do only useful tests

    Do tests after clinical assessment. Avoid unnecessary tests, random antibiotics, or repeated medicines without diagnosis.

  5. Step 5

    Follow up and return early if worse

    If symptoms worsen, new warning signs appear, or treatment is not helping, return for review quickly.

Rural patient practical tips
  • Take a written symptom diary and all previous prescriptions/test reports.
  • Do not hide medicines already taken, even herbal or over-the-counter medicines.
  • Ask which warning signs mean urgent referral to hospital.

This roadmap is for education. A real diagnosis and treatment plan requires history, examination, and clinical judgment.

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Write your symptom story. A health professional or site editor can review it before any answer is prepared. This box is not for emergency care.

Emergency first: Severe chest pain, breathing trouble, unconsciousness, stroke signs, severe injury, heavy bleeding, or rapidly worsening symptoms need urgent local medical care now.

Frequently Asked Questions

Is this article a replacement for a doctor?

No. It is educational content only. Patients should consult a qualified clinician for diagnosis and treatment.

When should I seek urgent care?

Seek urgent care for severe symptoms, rapidly worsening condition, breathing difficulty, severe pain, neurological changes, or any emergency warning sign.

References

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