Chapter 13

Lumbar Enlargement

Area of the spinal cord from which nerves to and from the lower limbs arise

Meningeal Branch

Spinal nerve branch that supplies vertebrae, vertebral ligaments, blood vessels of the spinal cord, and meninges

Anterior (ventral) Ramus

Spinal nerves branches that serve the muscles and structures of the upper and lower limbs and the lateral and ventral trunk

Dura Mater

Superficial spinal cord covering of dense, irregular connective tissue

Coccygeal Plexus

Supplies a small area of skin in coccygeal region

Sacral Plexus

Supplies the buttocks, perineum, and lower limbs

Reciprocal Innervation

a neural circuit that coordinates body movements by causing contraction of one muscle and relaxation of antagonistic muscles or relaxation of a muscle and contraction of the antagonists

Crossed Extensor Reflex

A balance-maintaining reflex

Flexor (withdrawal) Reflex

Polysynaptic reflex initiated in response to a painful stimulus

Anterior (ventral) Root

Contains motor neuron axons and conducts impulses from the spinal cord to the peripheral organs and cells

The connective tissue surrounding each individual axon is:

Endoneurium

Contralateral Reflex Arc

Sensory impulses enter on one side of the spinal cord and motor impulses exit of the opposite side

Central Canal

Space within the spinal cord filled with cerebrospinal fluid

Gray matter of the spinal cord contains somatic motor and sensory nuclei, autonomic motor and sensory nuclei, and functions to receive and integrate both incoming and outgoing information.

True

Stretch Reflex

A reflex resulting in the contraction of a skeletal muscle when it is stretched

Stretch Reflex

Acts as a feedback mechanism to control muscle length by causing muscle contraction

Filum terminale

An extension of the pia mater that anchors the spinal cord to the coccyx

Cervical Enlargement

Area of the spinal cord from which nerves to and from the upper limbs arise

Arachnoid Mater

Avascular covering of spinal cord composed of delicate collagen fibers and some elastic fibers

Posterior (dorsal) Root

Contains sensory neuron axons and conducts impulses from the peripheral receptors into the spinal cord

Denticulate Ligaments

Extending the length of the spinal cord, these pia mater thickenings fuse with the arachnoid mater and dura mater and help to protect the spinal cord from shock and sudden displacement

The epidural space is located between the wall of the vertebral canal and the pia mater.

False

Lumbar Plexus

Femoral nerve arises from this plexus

Coccygeal Plexus

Formed by anterior rami of S4-S5 and coccygeal nerves

Cervical Plexus

Formed by the anterior rami of C1-C4 with some contribution of C5

Brachial Plexus

Formed by the anterior rami of C5-C8 and T1

Lumbar Plexus

Formed by the anterior rami of L1-L4

Sacral Plexus

Formed by the anterior rami of L4-L5 and S1-S4

Cervical Plexus

Injury to this plexus can affect breathing

Cutting the posterior root of a spinal nerve would:

Interfere with the flow of sensory impulses

Example of a motor tract?

Lateral Corticospinal

Stretch Reflex

Maintains proper muscle tone

Brachial plexus

Median nerve arises from this plexus

Because they contain both sensory and motor axons, spinal nerves are considered to be _____ nerves.

Mixed

Ipsilateral Reflex Arc

Motor nerve impulses exit the spinal cord on the same side that sensory impulses entered the spinal cord

Intersegmental Reflex Arc

Occurs when sensory nerve impulse travels up and down the spinal cord, thereby activating several motor neurons and more than one effector

Tendon Reflex

Operates as a feedback mechanism to control muscle tension by causing muscle relaxation when muscle force becomes too extreme

Cervical Plexus

Phrenic nerve arises from this plexus

Tendon Reflex

Protects the tendon and muscle from damage due to excessive tension

Brachial Plexus

Provides the entire nerve supply of the shoulders and upper limbs

Lumbar Plexus

Provides the nerve supply of the anterolateral abdominal wall, external genitals, and part of the lower limbs

Cervical Plexus

Provides the nerve supply of the skin and muscles of the head, neck, and superior part of the shoulders and chest

Muscle Spindles

Receptors that monitor changes in muscle length

Tendon (Golgi tendon) Organs

Receptors that monitor changes in muscle tension

Monosynaptic Reflex

Reflex arc that consists of one sensory and one motor neuron

Polysynaptic Reflex

Reflex pathway that contains sensory neurons, interneurons, and motor neurons

Sacral Plexus

Sciatic nerve arises from this plexus

The five components of a reflex arc, in order from the beginning to the end, are:

Sensory receptor, sensory neuron, integrating center, motor neuron, effector

Posterior (dorsal) Ramus

Spinal nerve branches that serve the deep muscles and skin of the posterior surface of the trunk

The following are true:

The anterior (ventral) gray horns contain cell bodies of neurons that cause skeletal muscle contraction, Cell bodies of autonomic motor neurons are located in the lateral gray horns, and Gray matter in the spinal cord consists of cell bodies of neurons, neuroglia, unmyelinated axons, and dendrites of interneurons and motor neurons.

Plexus

The joining together of the anterior rami of adjacent nerves

Cauda Equina

The roots form the nerves that arise from the inferior part of the spinal cord but do not leave the vertebral column at the same level as they exit the cord

Pia Mater

Thin transparent connective tissue composed of interlacing bundles of collagen fibers and some elastic fibers adhering to the spinal cord's surface

The tracts of the posterior column are involved in:

conscious proprioception, touch, pressure, and vibration