chapter 14

what is the major functions of the spinal cord

pathway for transmitting information between the brain and the rest of the body, coordinating reflexes, and controlling motor and sensory functions.

what is the major functions of spinal nerves

to connect the spinal cord to the muscles and skin, facilitating sensory and motor pathways.

what are spinal refexes

involuntary and automatic responses to specific stimuli that involve pathways through the spinal cord, fast reaction time

what is the posterior median sulcus

a longitudinal groove on the posterior side of the spinal cord that partially divides it into left and right halves.

what is the measurements for an adult spinal cord

The adult spinal cord typically measures about 42 to 45 centimeters in length and around 1 to 1.5 centimeters in diameter.

what is the anterior median fissure

A deep vertical groove on the anterior side of the spinal cord that divides it into right and left halves.

what are the parts of the spinal cord

the cervical, thoracic, lumbar, sacral, and coccygeal

what is the cervical enlargement and its functions

corresponds to the cervical vertebrae and is responsible for innervating the upper limbs, It contains a larger number of nerve fibers for communication between the brain and the upper limbs.

what is the lumbar enlargement and functions

It corresponds to the lumbar vertebrae and innervates the lower limbs, containing a larger number of nerve fibers for communication between the brain and lower limbs.

what is a never

A nerve is a bundle of axon that transmit electrical impulses between the brain, spinal cord, and other parts of the body, facilitating communication throughout the nervous system.

how many pairs of spinal nerves are there

There are 31 pairs of spinal nerves in the human body, which emerge from the spinal cord and are responsible for transmitting signals between the spinal cord and the body.

what is the epineurium

outermost layer of connective tissue surrounding a nerve, providing support and protection to the nerve fibers and blood vessels within.

what is the perineurium

protective sheath of connective tissue surrounding each fascicle within a nerve, helping to maintain the structural integrity and protect nerve fibers.

what is the endoneurium

innermost layer of connective tissue surrounding individual nerve fibers, providing support and protection.

what are rootlets

small bundles of nerve fibers that emerge from the spinal cord and converge to form a spinal nerve.

what is the posterior root

part of a spinal nerve containing sensory nerve fibers that transmit information from the body to the spinal cord.

what is the posterior root ganglion

a cluster of sensory neurons located near the spinal cord that relay sensory information to the central nervous system.

what is the anterior root

motor nerve fibers, responsible for transmitting information from the spinal cord to the muscles.

difference between sensory and motor neurons

Sensory neurons transmit sensory information from the body to the central nervous system, while motor neurons transmit signals from the central nervous system to muscles and glands.

what is a mixed nerve

A nerve that contains both sensory and motor fibers, facilitating communication between the central nervous system and the body.

what type of nerve are spinal nerves

Spinal nerves are mixed nerves

what is the cauda equina

The bundle of spinal nerves and nerve roots located at the lower end of the spinal cord, resembling a horse's tail, that helps innervate the lower body.

what are the vertebral column

The series of bones that encase the spinal cord and provide structural support to the body, consisting of individual vertebrae.

what is the spinal cord protected by

the vertebral column, cerebrospinal fluid and surrounding tissues, including the meninges.

what is the intervertebral column

formed by the intervertebral discs, which are cartilage pads that sit between and cushion the vertebrae in the spinal column, allowing for flexibility and movement.

what are spinal cord meninges

dura mater, arachnoid mater, and pia mater. They help to anchor the spinal cord and provide a barrier against infection.

what is the spinal pia mater and its function

innermost layer of the meninges that closely adheres to the surface of the spinal cord. Its function is to protect the spinal cord and provide nourishment through blood vessels.

what is the spinal arachnoid mater

middle layer of the meninges that lies between the dura mater and pia mater. It serves as a protective layer and contains cerebrospinal fluid, which cushions the spinal cord.

what is the spinal dura mater

outermost layer of the meninges that encases the spinal cord. Its function is to provide a protective covering and structural support for the spinal cord.

what is the spinal epidural space and it function

area between the dura mater and the vertebral wall,has fat and blood vessels. Its function is to provide cushioning and support for the spinal cord, as well as serve as a site for the administration of anesthetics during medical procedures.

what is the spinal subdural space

The space between the arachnoid mater and the dura mater, which contains a thin layer of fluid. It serves as a potential space that may expand during certain medical conditions.

how is gray matter distributed in the spine

\ in an H-shaped or butterfly-like pattern within the spinal cord, located centrally and surrounded by white matter. It consists of neuronal cell bodies, dendrites, and unmyelinated axons.

how is white matter distributed in the spinal cord

in columns surrounding the gray matter of the spinal cord, containing myelinated axons that facilitate communication between different regions of the central nervous system.

what are the gray matter posterior horns

The regions of gray matter located at the back of the spinal cord, containing sensory neurons that receive signals from the body.

what are spinal gray matter lateral horns

on the sides of the spinal cord, mainly found in the thoracic and upper lumbar regions, containing autonomic neurons that regulate involuntary functions, only in T1-L2

what is gray commissure

A narrow bridge of gray matter that connects the two halves of the spinal cord, containing unmyelinated axons and central canal.

What is sensory nuclei

Sensory nuclei are clusters of neurons located within the gray matter of the spinal cord that process sensory information and relay it to higher brain centers.

what are somatic sensory nuclei

Clusters of neurons in the spinal cord's gray matter that process sensory information from skin, muscles, and joints, relaying it to the brain.

what are visceral sensory nuclei

Clusters of neurons in the spinal cord's gray matter that process sensory information from internal organs and relay it to the brain.

what are motor nuclei

Clusters of neurons in the spinal cord responsible for processing motor commands and sending signals to skeletal muscles.

what are somatic motor nuclei

Clusters of neurons in the spinal cord that process motor commands for voluntary muscle movement and send signals to skeletal muscles.

what are autonomic Motor nuclei

Clusters of neurons in the spinal cord that process and relay motor commands to involuntary muscles and glands.

what are posterior funiculus

Regions in the spinal cord that carry sensory information to the brain, specifically touch and proprioception.

what are lateral funiculus

Regions in the spinal cord that contain both ascending sensory tracts and descending motor tracts, involved in the coordination of voluntary and involuntary movements.

what are anterior funiculus

Regions in the spinal cord that primarily contain descending motor tracts involved in the control of voluntary movement.

what is white commissure

A bundle of nerve fibers located in the spinal cord that connects the left and right sides, allowing communication between them.

what are sensory tracts

Bundles of nerve fibers in the spinal cord ascend sensory information from the body to the brain, processing sensations like pain, temperature, and touch.

what are motor tracts

Bundles of nerve fibers in the spinal cord that descend from the brain to the body, controlling voluntary movements and muscle activity.

what are sensory pathways

connected neurons that transmit sensory information from the peripheral nervous system to the central nervous system, facilitating the perception of sensations., ascend to the brain

what are motor pathways

A series of connected neurons desend signals from the central nervous system to the muscles, enabling voluntary movements and coordination.

what is decussate

The process where nerve fibers cross from one side of the body to the opposite side, often observed in motor and sensory pathways.

what is ipsilateral

referring to structures on the same side of the body.

what are dermatomes

Areas of skin innervated by specific spinal nerves, corresponding to the sensory distribution of the spinal cord.

what is referred visceral pain

Pain that is perceived at a location different from the site of the injury, often due to the shared neural pathways between visceral and somatic structures.

what is nerve plexus

A network of interwoven spinal nerves that serve a specific region of the body, contributing to the formation of peripheral nerves.

what are rami

Branches of spinal nerves that split from the spinal cord, supplying sensory and motor innervation to different parts of the body.

what are reflexes

Involuntary responses to stimuli that occur without conscious thought, typically involving a direct pathway through the spinal cord, rapid and preprogrammed

what is reflex arch

A neural pathway that mediates reflex actions, typically involving a sensory neuron, an interneuron, and a motor neuron, allowing for a quick response to a stimulus.

what is muscle spindle

A sensory receptor located in the belly of muscles that detects changes in muscle length and the rate of stretch, playing a crucial role in proprioception and reflexes.

what are proprioceptors

Sensory receptors that provide information about body position, movement, and muscle tension, including muscle spindles and Golgi tendon organs.

what are intrafusal muscle fibers

Specialized muscle fibers found within muscle spindles, responsible for sensing stretch and providing feedback about muscle length to the nervous system.

what are gamma motor neurons

Motor neurons that innervate intrafusal muscle fibers, regulating their sensitivity to stretch and contributing to the function of muscle spindles.

what are alpha motor neurons

Motor neurons that innervate extrafusal muscle fibers, responsible for muscle contraction and voluntary movement.

what are extrafusal muscle fibers

Muscle fibers that make up the bulk of skeletal muscles, responsible for generating force and enabling muscle contraction.

what is stretch reflex

A muscle contraction that occurs in response to stretching of the muscle, primarily mediated by the spinal cord and involved in maintaining posture and balance.

what is muscle spindle prorioceptor

sensory receptors located within the belly of muscles that detect changes in muscle length and the rate of that change, providing critical information for the stretch reflex and coordination of movement.

what is reciprocal inhibition

A neural process that prevents one muscle from contracting while its opposing muscle relaxes during movement, allowing for smooth and coordinated muscle action.

what is tendon reflex and what is another name for them

A reflex that involves the contraction of a muscle in response to excessive tension detected by tendon organs, protecting muscles and tendons from injury; also known as golgi tendon organs

what is reciprocal activation

A neural mechanism that allows one muscle to contract while its opposing muscle is also activated, facilitating movement in a coordinated manner. This process often works alongside reciprocal inhibition.

what is withdrawal reflex

A protective reflex that causes an automatic withdrawal of a body part away from a painful stimulus, helping to prevent injury.

what is cross-extensor reflex

A complex reflex that involves the extension of an opposite limb in response to a withdrawal reflex, helping to maintain balance and support.

What do the thoracic spinal nerves innervate?

chest and abdominal muscles

What do the sacral spinal nerves innervate?

pelvis, butt, thighs, calves, feet, and genitals

Which spinal nerves form the cervical plexus?

C1-C4

Which major nerve arises from the cervical plexus?

The phrenic nerve; innervates the diaphragm and is essential for breathing.

Which spinal nerves form the brachial plexus

C5-T1

What major nerve arises from the brachial plexus to control the forearm and hand?

median nerve

Which spinal nerves form the lumbar plexus?

L1-L4

What major nerve comes from the lumbar plexus and controls the anterior thigh?

femoral nerve

Which spinal nerves form the sacral plexus?

L1-S4

What is the largest nerve in the body arising from the sacral plexus?

sciatic nerve

what is sciatic nerve

the largest nerve in the body, running from the lower back down the leg, responsible for sensation and movement.

what are the steps of the reflex arc

1. Sensory receptor activation 2. Sensory neuron signal transmission 3. Integration center processing 4. Motor neuron signal transmission 5. Effector response

What type of reflex involves interneurons?

Polysynaptic reflex

what is pulling your hand away from the withdrawal reflex

Pulling your hand away from a hot object.

what is the withdrawal reflex

A protective reflex that causes an immediate reaction to remove a body part from a painful stimulus, such as pulling away from a hot object.