Meninges and Spinal Nerves Overview

Protective layers of connective tissue that cover the spinal cord and brain. They are made of collagen and elastin fibers and consist of three layers: dura mater, arachnoid mater, and pia mater.

The space between the arachnoid mater and pia mater, filled with cerebrospinal fluid (CSF).

Inflammation of the meninges, usually caused by bacterial, viral, or fungal infections.

Signs and symptoms include high fever, severe headache, stiff neck, vomiting, nausea, seizures, photophobia, phonophobia, confusion, and petechiae.

A physical examination finding that indicates meningitis. When a patient's leg is flexed at the knee and hip, there is resistance to extension of the leg at the knee.

Another physical examination finding suggestive of meningitis. Neck flexion causes involuntary flexion of the hip and knees.

A mixed nerve that carries both sensory and motor information. Each spinal nerve has a dorsal (posterior) root containing sensory (afferent) fibers and a ventral (anterior) root containing motor (efferent) fibers.

There are 31 pairs of spinal nerves.

They carry sensory information from the body to the CNS, convey motor signals from the CNS to muscles, and through their rami communicates autonomic fibers to innervate smooth muscles and glands.

Branches that emerge from spinal nerves after they exit the spinal column. Two primary branches are the dorsal (posterior) ramus and the ventral (anterior) ramus.

Cerebrospinal fluid (CSF) is produced in the choroid plexus of the ventricles in the brain.

CSF circulates in the subarachnoid space, a space between the arachnoid and pia mater membranes surrounding the brain and spinal cord.

CSF enters the cerebral venous sinuses, such as the superior sagittal sinus, through arachnoid villi, finger-like projections of the arachnoid membrane.

Plexuses are networks of intersecting nerves that distribute nerve fibers to specific regions of the body, allowing for complex innervation of muscles and organs.

The cervical plexus is formed by spinal nerves C1-C4 and part of C5. It innervates the skin and muscles of the head, neck, superior shoulders, and chest.

The phrenic nerve, a key part of the cervical plexus, innervates the diaphragm for breathing.

The brachial plexus originates from spinal nerves C5 to T1 in the neck and extends into the arm. It controls motor and sensory functions of the shoulder, arm, and hand.

The lumbar plexus is formed by spinal nerves L1-L4 and provides innervation to the anterolateral abdominal wall, external genitals, and part of the lower limbs.

The femoral nerve, a major nerve of the lumbar plexus, innervates anterior thigh muscles, lower abdomen, buttocks, and anteromedial leg and thigh skin. Its damage causes inability to extend the leg and flex the hip, and sensory loss in the anteromedial thigh.

The obturator nerve innervates the adductor muscles of the medial thigh and small hip muscles, and supplies sensation to the medial thigh and hip joint. Damage leads to inability to adduct the thigh and sensory loss on the medial thigh.

They carry pre-ganglionic sympathetic fibers from the spinal nerves to the sympathetic trunk. They are present only in the lower cervical, thoracic, and upper lumbar regions (C7 to L2).

They carry post-ganglionic sympathetic fibers from the sympathetic trunk back to the spinal nerves. They help control the tone of smooth muscles, glands, and cardiac tissue.

The spinal cord originates at the medulla oblongata and terminates at the conus medularis (L2), near the level of the superior border of the second lumbar vertebra.

It's an arrangement of nerves with roots of the lumbar, sacral, and coccygeal nerves. It innervates the lower body, including the legs, pelvic organs, and bladder.

They emerge from the vertebral column through the intervertebral foramina, spaces between adjoining vertebrae.

It emerges between the atlas (C1) and the occipital bone, unlike other spinal nerves which exit through the intervertebral foramina.

It serves as a chain of interconnected ganglia that play a crucial role in the sympathetic nervous system. It relays autonomic signals between the spinal cord and various target organs.

They are clusters of nerve cell bodies located in the sympathetic trunk. They receive pre-ganglionic sympathetic fibers from the spinal cord and send post-ganglionic fibers to target organs.

They are connected by the white rami communicantes (carrying pre-ganglionic fibers) and the gray rami communicantes (carrying post-ganglionic fibers).

It serves as the central communication pathway between the brain and the rest of the body. It receives sensory information from the body, processes it, and sends motor commands to muscles and glands.