Afferent and Efferent Nerves (Sensory&Motor Nerves) By: Jasleen Bains

Afferent Nerves These are also known as sensory nerves. Take impulses from the receptors to the Central Nervous System. These nerves are located in the Peripheral Nervous System. They extend from the spinal cord, a component of the central nervous system, to receptor cells throughout the body. Also paired with motor nerves (efferent nerves). When the afferent nerves send the impulse to the brain, the brain sends an impulse to the motor nerves which help contract the muscle. For example: If there is a hot stove and you accidently touch it, an impulse is sent via Afferent nerves to the brain which is then sent to the hand via Efferent nerves which tell the hand to move back form the heat. These are also known as sensory nerves. Take impulses from the receptors to the Central Nervous System. These nerves are located in the Peripheral Nervous System. They extend from the spinal cord, a component of the central nervous system, to receptor cells throughout the body. Also paired with motor nerves (efferent nerves). When the afferent nerves send the impulse to the brain, the brain sends an impulse to the motor nerves which help contract the muscle. For example: If there is a hot stove and you accidently touch it, an impulse is sent via Afferent nerves to the brain which is then sent to the hand via Efferent nerves which tell the hand to move back form the heat.

General Somatic Afferent (Somatic sensory fibers) Found in the spinal nerves Occasionally found in the cervical area Conduct impulses of pain, thermal sensation, touch and pressure, and changes in the position of the body. Found in the spinal nerves Occasionally found in the cervical area Conduct impulses of pain, thermal sensation, touch and pressure, and changes in the position of the body.

General Visceral Afferent Conduct sensory impulses (usually pain and reflex impulses) from the viscera, glands and blood vessels to the CNS. Conduct the pain through the general somatic afferent fibers. Parts of the body that have these nerves are rectum, abdomen, lungs, face, scalp, nose, mouth, and colon. Conduct sensory impulses (usually pain and reflex impulses) from the viscera, glands and blood vessels to the CNS. Conduct the pain through the general somatic afferent fibers. Parts of the body that have these nerves are rectum, abdomen, lungs, face, scalp, nose, mouth, and colon.

Special Somatic Afferent SSA refers to afferent nerves that carry information from vision, hearing and balance. Located in the ears and brain. SSA refers to afferent nerves that carry information from vision, hearing and balance. Located in the ears and brain.

Special Visceral Afferent SVA refers to afferent nerves that are related to the gastrointestinal tract. They carry special senses of smell and taste. SVA refers to afferent nerves that are related to the gastrointestinal tract. They carry special senses of smell and taste.

Types of Sensory Receptors Within the sensory nerves, nerve cells are bundled in fibers and end in receptors that can be classified according to their function. Nociceptors: injury and produce a pain response Photoreceptors: respond to light Mechanoreceptors: touch and pressure Olfactory Receptors: in the nose, detect odors Taste Receptors: On the tongue, detect the flavors in food Thermoreceptors: Temperature Within the sensory nerves, nerve cells are bundled in fibers and end in receptors that can be classified according to their function. Nociceptors: injury and produce a pain response Photoreceptors: respond to light Mechanoreceptors: touch and pressure Olfactory Receptors: in the nose, detect odors Taste Receptors: On the tongue, detect the flavors in food Thermoreceptors: Temperature

Efferent Nerves (Motor Nerves) Motor nerve is a nerve that carries an impulse from the brain or spinal cord to a muscle or gland. The motor neuron is present in the grey matter of the spinal cord and medulla oblongata. Motor nerve is a nerve that carries an impulse from the brain or spinal cord to a muscle or gland. The motor neuron is present in the grey matter of the spinal cord and medulla oblongata.

Upper & Lower Motor Neurons Upper motor neurons: Located in the cerebral cortex or brain stem Lower Motor Neurons: Located in the Spinal cord or cranial nerves in the brain stem Upper motor neurons: Located in the cerebral cortex or brain stem Lower Motor Neurons: Located in the Spinal cord or cranial nerves in the brain stem

General somatic efferent fibers Located in the gray matter found in the spinal cord Carry motor impulses to skeletal muscles Located in the gray matter found in the spinal cord Carry motor impulses to skeletal muscles

General Visceral Efferent Located in the autonomic nervous system. Send motor impulses to smooth muscle, cardiac muscle and glands. Located in the autonomic nervous system. Send motor impulses to smooth muscle, cardiac muscle and glands.

Special Visceral Efferent Conduct motor impulses to the muscles of the pharyngeal arches (vertebrates).

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