1. Location
2. Stimuls type detected
3. Structural complexity

Location

(Classification of sensory receptor)

Exteroceptors- respond to stimuli outside of the body (touch, temperature, pressure, sight, smell, taste, and hearing).

Interoceptors or visceroceptors- respond to stimuli within the body (digestion, respiration, cardiovascular, urinary, and reproductive).

Proprioceptors- respond to internal stimuli like interoceptors but are found in the musculoskeletal system (skeletal muscles, tendons, joints, ligaments, and connective tissue covering the bones and muscles).

There are five

• Mechanoreceptors
• thermoreceptors
• photoreceptor
• chemoreceptor
• nocioceptor

generate nerve impulses when they, or adjacent tissues, are deformed by mechanical forces such as touch, pressure, vibrations, and stretch.

structural complexity

(classification of sensory receptor)

simple receptors- modified dendritic endings of sensory nerves (skin, mucous membranes, muscles, and connective tissues, and monitor most types of general sensory information.

Complex receptors (sense organs)- localized collections of cells working together to accomplish a specific receptive process. Complex receptors are associated with the special senses (vision, hearing, equilibrium, smell, and taste).

Somatic system- consists of the cranial and spinal nerve fibers that connect the skin and skeletal muscles and is involved in conscious activities.

Autonomic system- includes those fibers that connect the CNS to the visceral organs (heart, stomach, intestines), and various glands and is concerned with unconscious activities.

Nerve

endoneurium

perineurium

epineurium

are collections of neuron cell bodies associated with nerves in the PNS.

afferent nerve (dorsal root ganglia)

effenrent nerve(ventral root ganglia)

Sensory (afferent) nerves- carry impulses toward the CNS.

Motor (efferent) nerves- carry impulses away from the CNS.

 Mixed nerves- containing both sensory and motor fibers and transmitting impulses both to and from the CNS. Most nerves are mixed and often carry both somatic and autonomic (visceral) nervous system fibers.

Twelve pairs of cranial nerves arise from various locations on the underside of the brain. -- begins within the cerebrum.They pass from their sites of origin through various foramina of the skull and lead to parts of the head, neck, and trunk.

Olfactory nerve

(sensory) - associated with the sense of smell.

(sensory) associated with the sense of vision and transmit visual impulses from the retina to the thalamus.

arise in the midbrain and pass into the orbits of the eyes and connects to the voluntary muscles that raise the eyelid and muscles that move the eye, and supplies involuntary muscles within the eyes that adjust the amount of light entering the eyes and focus the lens of the eyes.

( motor) the smallest of the cranial nerves. They arise from the midbrain and carry motor impulses to certain voluntary muscles that move the eyes but are not supplied by the oculomotor nerve.

(mixed) – the largest of the cranial nerves. They are the major sensory nerves of the face. They contain three sensory divisions- ophthalmic (eye), maxillary, and mandibular.

(motor) small and they enter the orbits of the eyes and supply motor impulses to a pair of muscles that move the eye.

(mixed) – Their sensory branches are two-thirds of the tongue, and some of their motor fibers transmit impulses to the muscles of facial expression.

(sensory) – Each has two distinct parts- a vestibular branch (equilibrium) and a cochlear branch (hearing).

(mixed) – associated with the tongue and pharynx. The sensory fibers carry impulses from the linings of the pharynx, tonsils, and posterior third of the tongue to the brain.

(mixed) – longest nerve and it extends downward through the neck into the chest and abdomen.

Some somatic motor fibers carry impulses to muscles of the larynx that are associated with speech and swallowing. Autonomic motor fibers supply the heart and a variety of smooth muscles and glands in the thorax and abdomen.

(motor) – originate in the brain (medulla oblongata) and the spinal cord and have both cranial and spinal branches. Each cranial branch joins a vagus nerve and carries impulses to muscles of the soft palate, pharynx, and larynx. The spinal branch descends into the neck and supplies motor fibers to the trapezius and sternocleidomastoid muscles.

(motor) – They pass into the tongue and carry impulses to muscles that move the tongue in speaking, chewing, and swallowing

Thirty-one pairs of spinal nerves originate from the spinal cord and supply all parts of the body except the head and some areas of the neck. They are mixed nerves and they provide two-way communication between the spinal cord and parts of the arms, legs, neck, and trunk.

The spinal nerves are not named individually, but grouped according to the level from which they arise

8 pairs cervical nerve, 12 pairs thoracic nerve, 5 pairs of lumbar nerve, 5 pairs of sacral nerve, 1 pair of cocygeal nerves

cauda equina

(horse's tail)

The spinal cord ends at the level between the first and second lumbar vertebrae, so the lumbar, sacral, and coccygeal nerves descend to their exits beyond the end of the cord. These descending nerves form the______

they lie within the vertebral column

1.dorsal root (sesory root)

2. ventral root (motor root)

dorsal root

(sensory root)

contains an enlargement (dorsal root ganglion) which contains cell bodies of the sensory neurons whose dendrites conduct impulses inward from the peripheral body parts

THE FIBER ARE AFFERENT

Ventral root

(motor root)

of each spinal nerve consists of axons from the motor neurons, whose cell bodies are located within the gray matter of the cord. The fibers are efferent and extend to and innervate the skeletal muscles (somatic), and visceral effectors.

Just beyond its foramen, each spinal nerve divides into a large ventral ramus, a smaller dorsal ramus

Dorsal rami serve the muscles and skin of the posterior body trunk.

Ventral rami T1 and T12, form plexuses that serve the limbs. T2-T11 ventral rami give rise to intercostal nerves that serve the thorax wall and abdominal surface.

Except in the thoracic region, the ventral rami combine to form complex networks, called ______, instead of continuing directly to the peripheral body parts.