The Peripheral Nervous System

These flashcards cover key concepts related to the Peripheral Nervous System, including its structures, functions, and major nerves.

What does the Peripheral Nervous System (PNS) link to?

The world outside our body.

What are the four parts of the Peripheral Nervous System?

Sensory Receptors, Transmission Lines (Nerves), Motor Endings, Reflex Activity.

What is a nerve?

A cordlike organ of the PNS composed of peripheral axons.

What are the two types of nerves based on origin?

Spinal or cranial nerves.

What does the endoneurium enclose?

Axons and their myelin sheaths.

What is the perineurium?

Coarse connective tissue that bundles fibers into fascicles.

What is the primary function of mixed nerves?

To contain both sensory and motor fibers.

What type of information do sensory (afferent) nerves carry?

Impulses toward the CNS.

What type of information do motor (efferent) nerves carry?

Impulses away from the CNS.

What are ganglia?

Clusters of neuronal cell bodies in the PNS.

What do dorsal root ganglia contain?

Cell bodies of sensory neurons.

How many cranial nerves are there?

Twelve pairs.

Which cranial nerves are purely sensory?

Olfactory (I) and Optic (II).

What is the function of the olfactory nerve (I)?

Sense of smell.

What does the oculomotor nerve (III) control?

Eye movement and pupil constriction.

What is the primary function of the trigeminal nerve (V)?

Facial sensation and chewing.

What is the function of the facial nerve (VII)?

Facial expression and taste.

What is the autonomic function of the vagus nerve (X)?

Heart, lung, and digestive functions.

What is the longest nerve in the body?

Sciatic nerve.

How many pairs of spinal nerves exist?

31 pairs.

What is unique about the cervical spinal nerves?

Eight pairs arise from seven cervical vertebrae.

What do dorsal and ventral roots of the spinal cord contain?

Dorsal roots contain sensory fibers; ventral roots contain motor fibers.

What are intercostal nerves?

Ventral rami of T2–T12 that supply muscles of the thorax and abdominal wall.

What is a dermatome?

An area of skin innervated by cutaneous branches of a single spinal nerve.

What can a lesion of the sciatic nerve lead to?

Severe pain and potentially paralysis of the affected leg.

What branches from the brachial plexus innervate the upper limb?

Axillary, Musculocutaneous, Median, Ulnar, and Radial nerves.

What could happen with damage to the median nerve?

Difficulty using pincer grasp and gripping objects.

What does the lumbar plexus innervate?

Thigh, abdominal wall, and psoas muscles.

What is the function of the obturator nerve?

Innervates adductor muscles of the thigh.

What does the sacral plexus innervate?

Buttock, lower limb, pelvic structures, and perineum.

What is a common symptom of irritation to the phrenic nerve?

Hiccups.

What can damage to the hypoglossal nerve cause?

Difficulties in speech and swallowing.

What can a spinal nerve plexus facilitate?

The innervation of limb muscles by multiple spinal nerves.