Name: spinal nerves and body signals
Uploaded: 2025-05-22T09:06:12.000Z
Duration: 1 min 23 s
Channel: JoVE

K12 Standards

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

9-12

Human Anatomy and Physiology

Integration And Coordination

Nervous System

Spinal Nerves: Anatomy

Spinal nerves are mixed nerves that originate from the spinal cord.
A typical nerve begins as dorsal roots having sensory fibers and ventral roots containing motor fibers.
These roots merge, forming a spinal nerve that exits the vertebral column through the intervertebral foramen.
The spinal nerve further divides into a smaller posterior ramus and a large anterior ramus.
The posterior ramus serves the muscles and skin of the posterior side of the torso. In contrast, the anterior ramus serves the limbs, skin, and muscles of the anterior and lateral sides.
Tiny meningeal branches reenter the vertebral column to supply the vertebrae, associated ligaments, and spinal cord-associated blood vessels.
There are 31 pairs of spinal nerves, numbered according to the vertebrae they exit. These include eight cervical, twelve thoracic, five lumbar, five sacral, and one coccygeal nerve.
Except for T2 to T12, the axons of the anterior rami of the adjacent spinal nerves form networks or plexuses before innervating the body parts.
The major nerve plexuses include the cervical, brachial, lumbar, sacral, and coccygeal plexuses.

spinal nerves: anatomy

Spinal nerves are pivotal conduits in the nervous system, bridging the central nervous system (CNS) with the peripheral nervous system (PNS). These nerves enable a complex communication network between the brain, spinal cord, and the rest of the body, facilitating sensory input, motor output, and autonomic functions.
There are 31 bilateral pairs of spinal nerves, each emerging from the spinal cord through the intervertebral foramina&#8212;openings between adjacent vertebrae. These nerves are symmetrically organized and are categorized based on the region of the spine from which they emerge &#8212;&#160; 8 cervical (C1-C8), 12 thoracic (T1-T12), 5 lumbar (L1-L5), 5 sacral (S1-S5), and 1 coccygeal (Co1).
<ul>
	<li>&#8226; Cervical nerves (C1-C8): These eight nerve pairs transmit signals to and from the head, neck, and upper extremities. The cervical nerves are:
	<ul>
		<li>C1: Suboccipital nerve</li>
		<li>C2: Greater occipital nerve</li>
		<li>C3: Lesser occipital nerve</li>
		<li>C4: Supraclavicular nerve</li>
		<li>C5: Dorsal scapular nerve</li>
		<li>C6: Superior plexus root</li>
		<li>C7: Middle plexus root</li>
		<li>C8: Inferior plexus root</li>
	</ul>
	</li>
	<li>&#8226; Thoracic nerves (T1-T12): The 12 pairs of thoracic nerves correspond to the 12 thoracic vertebrae and control the sensation and motor function of the chest, upper back, and abdominal muscles. The T1 to T11 nerves are the intercostal nerves, while T12 is the subcostal nerve.</li>
	<li>&#8226;&#160;Lumbar nerves (L1-L5): Five pairs of lumbar nerves control the lower back, hips, and parts of the legs. The five lumbar nerves are:
	<ul>
		<li>L1: Iliohypogastric nerve</li>
		<li>L2: Ilioinguinal nerve</li>
		<li>L3: Genitofemoral nerve</li>
		<li>L4: Lateral femoral cutaneous nerve</li>
		<li>L5: Lumbar plexus root</li>
	</ul>
	</li>
	<li>&#8226; Sacral nerves (S1-S5): The sacral nerves consist of five pairs, and they are responsible for the function of the lower extremities, pelvic organs, and some muscles in the hips and legs. The sacral nerves are:
	<ul>
		<li>S1: Superior gluteal nerve</li>
		<li>S2: Inferior gluteal nerve</li>
		<li>S3: Sciatic nerve</li>
		<li>S4: Pudendal nerve</li>
		<li>S5: Sacral plexus root</li>
	</ul>
	</li>
	<li>&#8226; Coccygeal nerve (Co1): The single coccygeal nerve pair, called anococcygeal nerve, provides sensory innervation to the skin over the coccyx and surrounding area, as well as to some of the muscles in the pelvic floor. Its motor functions are minimal and not as well defined as those of the other spinal nerves.</li>
</ul>
Structure of Spinal Nerve
Each spinal nerve is formed by the union of two distinct roots &#8212; the dorsal (posterior) root and the ventral (anterior) root.
<ul>
	<li>&#8226; Dorsal Root: The dorsal root carries sensory information from the peripheral receptors to the spinal cord. It contains sensory neurons whose cell bodies are located in the dorsal root ganglion, a bulge in the root just before it merges with the ventral root.</li>
	<li>&#8226; Ventral Root: In contrast, the ventral root conveys motor information from the spinal cord to the muscles and glands. This root consists of axons from motor neurons whose cell bodies are housed within the gray matter of the spinal cord.</li>
</ul>
These two roots combine to form a mixed spinal nerve carrying both sensory and motor fibers. Shortly after emerging from the spinal column, each spinal nerve splits into two primary branches &#8212; the dorsal ramus and the ventral ramus.
<ul>
	<li>&#8226; Dorsal Ramus: This branch innervates the muscles and skin of the posterior trunk, providing sensory and motor functions to these areas.</li>
	<li>&#8226; Ventral Ramus: The larger of the two branches, the ventral ramus, supplies the anterolateral parts of the trunk and the limbs. It carries fibers that form the nerve plexuses &#8212; networks of interconnecting nerves that give rise to peripheral nerves innervating the limbs.</li>
</ul>
Additionally, each spinal nerve has a small meningeal branch that reenters the vertebral column to innervate the vertebrae, ligaments, blood vessels, and meninges of the spinal cord. Spinal nerves also feature communicating rami that connect with the sympathetic trunk of the autonomic nervous system (ANS). These rami consist of:
<ul>
	<li>&#8226; Gray Rami Communicantes: These carry postganglionic sympathetic fibers back to the spinal nerves for distribution to the target organs and tissues.</li>
	<li>&#8226; White Rami Communicantes: These are present only in the thoracic and upper lumbar regions. They carry preganglionic sympathetic fibers from the spinal nerve to the sympathetic trunk.</li>
</ul>

Spinal nerves are pivotal conduits in the nervous system, bridging the central nervous system (CNS) with the peripheral nervous system (PNS). These nerves ...

Education

JoVE Core

Anatomy and Physiology

Unit 1

Anatomy of the Central and Peripheral Nervous System

anatomy-of-the-central-and-peripheral-nervous-system

KEY TERMS AND CONCEPTS

spinal nerves and body signals

Spinal nerves carry signals between the spinal cord and the rest of the body. They connect the central nervous system and the peripheral nervous system, which lets the body send sensory input, motor output, and autonomic signals. There are 31 pairs of spinal nerves, and each pair leaves the spinal cord through an intervertebral foramen, the opening between two vertebrae.

These nerves are organized by region of the spine. The 8 cervical nerves are C1 through C8, the 12 thoracic nerves are T1 through T12, the 5 lumbar nerves are L1 through L5, the 5 sacral nerves are S1 through S5, and there is 1 coccygeal nerve, Co1. The cervical nerves send signals to and from the head, neck, and upper limbs. The thoracic nerves serve the chest, upper back, and abdominal muscles. The lumbar nerves help control the lower back, hips, and parts of the legs. The sacral nerves support the lower limbs, pelvic organs, and some muscles in the hips and legs. The coccygeal nerve, also called the anococcygeal nerve, provides sensory input to the skin over the coccyx and nearby area, and to some pelvic floor muscles.

Each spinal nerve forms when two roots join. The dorsal root, or posterior root, carries sensory information from receptors to the spinal cord. It contains sensory neuron cell bodies in the dorsal root ganglion, a swelling in the root just before it joins the other root. The ventral root, or anterior root, carries motor information from the spinal cord to muscles and glands. It contains axons from motor neurons whose cell bodies are in the gray matter of the spinal cord. Together, these roots form a mixed spinal nerve with both sensory and motor fibers.

After leaving the spinal column, each spinal nerve divides into a dorsal ramus and a ventral ramus. The dorsal ramus supplies the muscles and skin of the back of the trunk. The ventral ramus is larger. It serves the front and side parts of the trunk and the limbs. Its fibers also form nerve plexuses, which are networks of connected nerves that give rise to peripheral nerves in the limbs. Each spinal nerve also sends a small meningeal branch back into the vertebral column. This branch supplies the vertebrae, ligaments, blood vessels, and meninges of the spinal cord.

Spinal nerves also connect with the sympathetic trunk through communicating rami, which are part of the autonomic nervous system. Gray rami communicantes carry postganglionic sympathetic fibers back to the spinal nerves for distribution to target organs and tissues. White rami communicantes are found only in the thoracic and upper lumbar regions. They carry preganglionic sympathetic fibers from the spinal nerve to the sympathetic trunk.

Spinal Nerves and Body Signals

anatomy of the brain: major regions

Brain Regions and Their Main Functions

The human brain is the most complex organ in the body, and it is built from several major regions that work together. These regions include the cerebrum, diencephalon, cerebellum, and brainstem. Each part has a different role in how the brain processes information and controls the body. The cerebrum is the largest part of the brain. It is divided into left and right hemispheres by a deep fissure. Its outer layer is the cerebral cortex, which is gray matter. The cortex has raised folds called...

anatomy of the brain: ventricles

Brain Ventricles and Cerebrospinal Fluid

Brain ventricles are hollow, fluid-filled cavities deep inside the human brain. They hold cerebrospinal fluid, or CSF, which helps protect the central nervous system and supports neural signaling. The two lateral ventricles sit in the cerebral hemispheres, one on each side. Each lateral ventricle has three visible projections from the side: the anterior horn, the inferior horn, and the posterior horn. A thin membrane called the septum pellucidum separates the left and right lateral ventricles.<br...

cerebrum: anatomical overview i

Cerebrum: Lobes and Brain Folds

The cerebrum is the largest part of the human brain. It has an outer cerebral cortex, which is the wrinkled surface with folds called gyri and shallow grooves called sulci. Beneath the cortex is a deeper region inside each hemisphere. The cerebrum is divided into two hemispheres and five lobes. These lobes are the frontal, parietal, temporal, occipital, and insula lobes. The insula is the smallest lobe, and it lies deep within the lateral sulcus. Several sulci help separate the lobes and...

cerebrum: anatomical overview ii

Cerebrum Regions and Fiber Tracts

The cerebrum is organized into three main regions within each cerebral hemisphere. The outermost region is the cerebral cortex. It is a thin gray matter layer, about 2 to 4 millimeters thick, and it contains neuron cell bodies, dendrites, glial cells, and blood vessels. Beneath the cortex is the white matter. This middle region is mostly made of myelinated nerve fibers. These fibers form three large tract types: association fibers, commissures, and projection fibers. Association fibers...

motor and sensory areas of the cortex

How the Cortex Controls Senses and Movement

The cerebral cortex controls voluntary movement and processes sensory information. It is the brain's outermost layer and also helps with complex thinking, emotions, learning, and memory. Its main functional areas are the motor areas, sensory areas, and association areas. The motor areas are in the frontal lobe and control body movement. They include the primary motor cortex and the premotor cortex. The primary motor cortex is in the precentral gyrus and sends signals to skeletal muscles. It is...

association areas of the cortex

Brain Areas for Language and Attention

Association areas in the cerebral cortex help the brain combine information and make sense of it. Unlike regions with one clear sensory or motor job, these areas support memory, learning, and decision-making. They work by linking signals from multiple parts of the brain. The prefrontal association area sits in the frontal lobe. It helps with planning, decision-making, and social behavior. It also connects with primary motor areas, sensory areas, and the limbic system, which handles emotions. <br...

diencephalon: anatomical regions

Diencephalon Functions and Connections

The diencephalon links the cerebrum with the rest of the nervous system. The term means “through brain,” and the region sits deep beneath the cerebrum. The olfactory system is an exception because it connects directly with the cerebrum. The diencephalon mainly includes the thalamus, hypothalamus, and epithalamus. It also contains the subthalamus, which includes the subthalamic nucleus as part of the basal nuclei. The thalamus acts as a major relay and processing center. It contains many...

diencephalon: thalamus and information relay

diencephalon-thalamus-and-information-relay

Thalamus: Relay Centers of the Brain

The thalamus is the brain’s main relay center for sensory and motor signals. It is often called the gateway to the cerebral cortex because most information headed there passes through it. Olfactory signals are the main exception. The thalamus also helps filter incoming signals and can give priority to some inputs based on the body’s current needs. The thalamus is made of several paired nuclei, or small groups of nerve cells with specific jobs. The anterior nucleus carries information from the...

diencephalon: hypothalamus and coordination

diencephalon-hypothalamus-and-coordination

Hypothalamus: Brain Control and Body Balance

The hypothalamus is a small brain region that helps control many body functions. It sits at the base of the brain, above the brainstem and below the thalamus. It is part of the limbic system and connects directly with the pituitary gland through the hypothalamic-pituitary axis. The hypothalamus receives somatic inputs from the body and visceral inputs from internal organs. It uses this information to regulate important physiological activities. The region is divided into four parts:...

cerebellum: anatomical regions

Cerebellum Structure and Pathways

The cerebellum is a brain region that helps control movement, coordination, and proprioception. It lies in the posterior cranial fossa, below the tentorium cerebelli and behind the brainstem. Because of its role in motor control, it is often called the "little brain." The outer surface of the cerebellum is highly folded. It has many folia, or narrow ridges, separated by shallow sulci, or grooves. A thin midline part called the vermis divides the cerebellum into two hemispheres and helps...

brainstem

Brainstem Pathways and Life Functions

The brainstem links the brain to the spinal cord and helps control vital body functions. It sits below the brain and above the spinal cord. The brainstem has three parts: the midbrain, pons, and medulla oblongata. The midbrain lies below the diencephalon and connects the cerebrum with the lower brain regions. Its cerebral peduncles contain the crus cerebri, which hold the corticospinal tract. This tract carries signals from the cerebral cortex to the spinal cord, so it supports voluntary...

brainstem: control centers of medulla

Medulla Nuclei and Autonomic Control

The medulla oblongata is a key part of the brainstem that helps control involuntary body functions. It contains several nuclei, or clusters of nerve cells, including the olivary, cuneate, gracile, and solitary nuclei. These structures support movement, sensation, breathing, and other vital activities. The olivary nucleus, also called the inferior olivary nucleus, sits in the ventrolateral medulla. It helps with motor coordination and motor learning. It receives input from the spinal cord,...

functional brain systems: limbic system

Limbic Brain Regions and Their Functions

The limbic system is a deep brain network linked to emotion, memory, and sensory processing. It is often called the emotional brain because it helps connect higher mental functions of the cerebral cortex with older emotional responses from deeper brain structures. This functional region includes parts of the diencephalon and the cerebrum. The limbic lobe includes three main gyri: the cingulate gyrus, the parahippocampal gyrus, and the subcallosal gyrus. The cingulate gyrus lies on the medial...

functional brain systems: reticular formation

functional-brain-systems-reticular-formation

Reticular Formation and the Brainstem RAS

The reticular formation is a network of gray and white matter in the brainstem. It extends from the medulla to the midbrain. Its nuclei are grouped into three main regions: raphe nuclei, medial nuclei, and lateral nuclei. The raphe nuclei lie along the midline of the brainstem. They are best known for making and releasing serotonin, a neurotransmitter that helps regulate mood, appetite, sleep, and circadian rhythms. The medial nuclei sit near the center of the reticular formation. They help...

spinal cord: gross anatomy

Spinal Cord Pathways and Protection

The spinal cord carries signals between the brain and the body. It sits inside the vertebral column, where the bones help protect it. It also supports reflexes and helps control complex motor movements. The spinal cord begins at the medulla oblongata, which is at the base of the brainstem. It extends downward and ends at the conus medullaris near the first and second lumbar vertebrae. In adults, the spinal cord is about 45 cm, or 18 inches, long. That is much shorter than the vertebral column,...

spinal cord: cross-sectional anatomy

Spinal Cord Gray and White Matter

The spinal cord cross section shows how gray matter and white matter are arranged inside the central nervous system. In the middle, gray matter forms a butterfly or H shape. White matter surrounds it. The dorsal median sulcus and the ventral median fissure divide the cord into left and right halves. At the center of the gray matter is the gray commissure. It surrounds the central canal, which contains cerebrospinal fluid, or CSF. The gray commissure connects the left and right sides of the...

spinal cord: information processing

Spinal Cord Sensory and Motor Pathways

The spinal cord carries sensory signals and motor commands between the brain and the peripheral nervous system (PNS). It acts as a major relay center that helps the brain communicate with the body. In this pathway, sensory input travels upward and motor output travels downward. Sensory processing begins at receptors in the skin and other tissues. These sensory receptors detect somatic stimuli such as touch, temperature, and pain. They trigger nerve impulses that move toward the spinal cord...

peripheral nervous system: ganglia and nerves

peripheral-nervous-system-ganglia-and-nerves

Peripheral Nervous System: Signal Pathways

The peripheral nervous system links the central nervous system to the rest of the body. It includes nerves, ganglia, and sensory receptors. Together, these parts carry information between the brain, spinal cord, and the external environment. Nerves are bundles of axons that act as communication routes in the peripheral nervous system. Each nerve has an outer connective tissue layer called the epineurium. This layer protects the nerve and supports the blood vessels that supply it. Inside the...

cranial nerves: overview and anatomy

Cranial Nerves and Their Functions

Cranial nerves are 12 pairs of nerves that connect the brain to the head and neck. They carry signals between the brain and the body. Each pair is numbered with Roman numerals from I to XII, starting at the front of the brain and moving toward the back. Each nerve also has a name that reflects its function or the structure it serves. These nerves are grouped as sensory, motor, or mixed nerves. Sensory nerves detect information from the environment. Motor nerves control muscle movement. Mixed...

cranial nerves: types part i

Cranial Nerves I-VI: Eye and Face Control

Cranial nerves I through VI carry sensory and motor signals between the brain and the head and neck. The first six pairs help with smell, vision, eye movement, facial sensation, chewing, and some autonomic functions. They are key to everyday tasks like noticing odors, seeing, and moving the eyes together. The olfactory nerve, or cranial nerve I, is a purely sensory nerve for smell. It begins in the olfactory epithelium of the nasal cavity and connects to the olfactory bulb in the brain. If...

cranial nerves: types part ii

Cranial Nerves VII-XII Functions

Cranial nerves VII through XII carry motor and sensory signals between the brain and the body. These six pairs help with facial movement, hearing, balance, swallowing, speech, and control of organs in the chest and abdomen. They also support communication, expression, and autonomic control. The facial nerve, cranial nerve VII, is a mixed nerve. It controls facial expressions and carries taste from the anterior two-thirds of the tongue. It also helps control the lacrimal glands and salivary...

Spinal nerves carry signals between the spinal cord and the rest of the body. They connect the central nervous system and the peripheral nervous system, which lets the body send sensory input, motor output, and autonomic signals. There are 31 pairs of spinal nerves, and each pair leaves the spinal cord through an intervertebral foramen, the opening between two vertebrae. These nerves are organized by region of the spine. The 8 cervical nerves are C1 through C8, the 12 thoracic nerves are T1...

spinal nerves: plexus i

Spinal Nerve Plexuses of the Neck and Arm

Spinal nerve plexuses are networks of interlacing nerves that organize nerve signals across the body. They act as communication hubs and are grouped into the cervical plexus in the neck, the brachial plexus in the shoulder area, the lumbar plexus in the lower back, the sacral plexus in the pelvis, and the coccygeal plexus in the coccyx region. The cervical plexus is formed by the anterior rami of the first four cervical spinal nerves, C1 to C4, with some input from C5. It lies in the neck...

spinal nerves: plexus ii

Lower Body Nerve Plexuses

The lower body nerve plexuses include the lumbar, sacral, and coccygeal plexuses. These nerve networks carry sensory information and help control motor function in the abdomen, pelvis, legs, and coccygeal region. The lumbar plexus sits in the lower back. It is mainly formed by the first four lumbar spinal nerves, L1 through L4. Its branches include the iliohypogastric, ilioinguinal, genitofemoral, lateral femoral cutaneous, femoral, and obturator nerves. These nerves send signals to the...

cranial and spinal meninges

Protective Layers Around the CNS

The cranial and spinal meninges are protective layers around the central nervous system, or CNS. The CNS includes the brain and spinal cord. These membranes help support the CNS, protect it, and help move cerebrospinal fluid, or CSF. The cranial meninges cover the cranium. The outermost layer is the dura mater, a thick membrane made of dense collagen fibers. It has two layers. The periosteal layer attaches to the inner surface of the skull, and the meningeal layer lies beneath it. The cranial...

cerebrospinal fluid

CSF Pathway and Brain Protection

Cerebrospinal fluid, or CSF, is a colorless liquid that surrounds the brain and spinal cord. It supports the central nervous system, or CNS, and helps it work properly. CSF production, flow, and absorption are tightly controlled. Most CSF is made in the choroid plexus, a network of capillaries and ependymal cells in the brain’s ventricular system. An adult usually has about 125 to 150 mL of CSF, but about 500 mL is made each day. That means the full amount is replaced about every 5 to 6 hours.

key terms and concepts

Learn how spinal nerves connect the spinal cord to the body, carry sensory and motor signals, and branch into regions that serve the back, limbs, and organs.

Spinal Nerves and Body Signals | JoVE K12

anatomy and physiology

JoVE Core Anatomy and Physiology showcases the anatomical and physiological details of the human body in comprehensive, clear, and engaging video animations. This collection of lessons focuses on the structures, components, functions, and requirements of the human body. It is complemented by scientist-in-action videos that demonstrate the application of this knowledge in real-world medical and research settings.

Florida Department of Education

High School

Life Science

SC.912.L.14

SC.912.L.14.21

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The cerebrospinal fluid, or CSF, is a colorless liquid surrounding the brain and spinal cord. It comprises water, blood plasma, proteins, glucose, and ...

Nervous System

Content elaboration: The nervous system consists of neurons and supporting cells that combine to form nerves, the spinal cord and the brain. The primary functions of the nervous system are sensation, integration and response. A comparison of the structures and functions of the central and peripheral nervous systems should be explored. The central nervous system is composed of the brain and spinal cord. The peripheral nervous system includes the remaining nervous tissue. A neuron consists of dendrites, a cell body and an axon. Neurons conduct electrical impulses along their membranes and at synapses. Brain cells can detect and sometimes respond to these impulses. Neuroglial cells help to support neural function. The brain consists of three major parts: the cerebrum, cerebellum and brainstem. The cerebrum is divided into lobes and hemispheres. Functions of the cerebrum that may be explored include voluntary muscle control, memory, sensory perception, emotions and speech. The cerebellum is primarily responsible for balance and coordination. The brainstem, a part of the autonomic nervous system, includes structural divisions that perform basic life functions such as breathing and heart rate. The spinal cord is a continuation of the brainstem. The spinal cord is a bundle of nerve tracts that transmits nerve signals between the brain and the body through electrical impulses. Nerves are bundles of neurons that transmit impulses between the peripheral and central nervous systems. The study of nerves can include sciatic, cranial and spinal nerves. Supporting structures of the central nervous system include the meninges and cerebrospinal fluid which protect the central nervous system. Processes of the nervous system are action potential propagation, simple nerve pathways (reflex arc) and neurotransmitter function. Homeostatic imbalances are explored. These include, but are not limited to, the effects of drugs, mental illnesses, spinal injuries, concussions, meningitis and multiple sclerosis (MS). Investigations are used to understand and explain the nervous system in a variety of inquiry and design scenarios that can incorporate evolutionary concepts, scientific reasoning, comparative analysis, communication skills and real-world applications.

Spinal Nerves and Body Signals

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