Chapter 13 Flashcards
Rami
The branches that the spinal nerve divides in to
Posterior (dorsal) Ramus
Serves the deep muscles and skin of the posterior surface of the trunk
Anterior (ventral) Ramos
Serves the muscles and structures of the upper and lower limbs and the skin of the lateral and anterior surfaces of the trunk.
Meningeal Branch
The branch that reenters the vertebral cavity through the intervertebral foramen and supplies the vertebrae , vertebral ligaments, blood vessels of the spinal cord , and meninges.
Plexus
A network of axons ( cervical, brachial, lumbar, and sacral plexus)
Root
“Risk Takers Don’t Cautiously Behave”
Two bundles of axons , connect each spinal Nerve to a segment of the cord by even smaller bundles of axons called rootlets.
Trunks
The roots of several spinal nerves unite to form trunks in the inferior part of the neck.
Divisions
Trunks diverge into divisions (anterior, posterior divisions)
Cords
Divisions unite to form cords called the lateral , medial, and posterior cords.
Axiallary Nerve
Supplies the deltoid and teres minor muscles.
Musculocutaneous Nerve
Supplies the anterior muscles of the arm.
Radial Nerve
Supplies the muscles on the posterior aspect of the arm and forearm.
Median Nerve
Supplies most of the muscles of the anterior forearm and some of the muscles of the hand.
Ulnar Nerve
Supplies the anteromedial muscles of the forearm and most of the muscles of the hand.
Meninges
3 protective connective tissue coverings that encircle the spinal cord and brain. From superficial to deep they are the dura mater, arachnoid mater, and pia mater
Epidural space
A space between the dura mater and the wall of the vertebral canal
Dura mater
“Tough mother”, the most superficial of the tree spinal meninges is a thick strong layer composed of a dense irregular connective tissue
Arachnoid mater
Layer in the middle of the meningeal membranes , a thin avascular covering comprised of cells , loosely arranged collagen and elastic fibers
Subdural space
Between the Dura mater and the arachnoid mater, contains interstitial fluid.
Pia Mater
The Innermost meninx is a thin transparent connective tissue layer that adheres to the surface of the spinal cord and brain. Thin squamous to cuboidal cells , have many blood vessels that supply nutrients to the spinal cord
Denticulate Ligaments
Are thickening of the pia mater. They project laterally and fuse with the arachnoid mater and inner surface of the dura mater between the the anterior and posterior Nerve roots of spinal nerves on either side. They protect the spinal cord against sudden displacement that could result in shock.
Subarachnoid space
Is between the arachnoid mater and pia mater, it contains shock absorbing cerebrospinal fluid
Spinal tap
Lumbar puncture , a long hollow needle is inserted into the subarachnoid space to withdraw CSF for diagnostic purposes. , to introduce antibiotics , contrast media for myelography or anesthetics
Cervical enlargement
Extends from C4 to T1, nerves TO and from upper limbs arise from the cervical enlargement
Lumbar enlargement
The inferior enlargement, extends from T9 to T12. Nerves to and from the lower limbs arise from the lumbar enlargement.
Conus Medullaris
Inferior to the lumbar enlargement the spinal cord terminates as a tapering , conical structure called the conus medullaris, which ends at the level of the intervertebral disc between the first and second lumbar vertebrae in adults
Filum Terminale
Arises from the conus medullaris , an extension of the pia mater that extends inferiorly , fuses with the arachnoid mater and dura mater , anchors the spinal cord to the coccyx
Spinal nerves
Are the paths of communication between the spinal cord and specific regions of the body
Posterior / dorsal roots
Contain only sensory axons which conduct never impulses from sensory receptors in the skin , muscles , and internal organs in the CNS
Anterior/ Ventral Roots
Contain axons of motor neurons which conduct nerve impulses from the cns to effectors (muscles and glands)
Cauda Equina “horse tail”
A tail Like array of roots of spinal nerves at the inferior end of the spinal cord
Anterior median fissure
A wide groove on the anterior (ventral) side of the spinal cord
Posterior median fissure
Is a narrow furrow on the posterior (dorsal) side of the spinal cord
Gray commissure
Forms the cross bar of the H in the gray matter of the spinal cord
Central canal
A space in the center of the gray commissure that extends the entire length of the spinal cord and is filled with CSF
Anterior (ventral) White commissure
Connects the white matter of the right and left sides of the spinal cord
Horns
The gray matter on each side of the spinal cord is subdivided into regions called horns
Posterior Gray Horns
Contain cell bodies and axons of interneurons as well as axons of incoming sensory neurons
Anterior Gray Horns
Contain somatic motor nuclei
Lateral Gray Horns
Are between the posterior and anterior gray horns, are only present in Thoracic and upper lumbar segments of the spinal cord
Sensory Tracts
Consist of of axons that conduct of axons that conduct nerve impulses toward the brain
Motor tracts
Tracts consisting of axons that carry nerve impulses FROM the brain
Endoneurium
Wrap around individual axons within a nerve, the inner most layer contains collagen fibers, fibroblasts and macrophages
Fascicles
Groups of axons with their endoneurium are held together in bundles called fascicles
Perineurium
Around each fascicle , middle layer
Epineurium
Outermost covering over the entire nerve , fibroblasts and thick collagen fibers
Rami Communicantes
Branches of a spinal nerve that are components of the autonomic nervous system
Intercostal Nerves
A nerve supplying a muscle located between the ribs aka thoracic nerves
Dermatome
The area of the skin that provides sensory input to the CNS through one pair of spinal nerves or trigeminal nerve
Spinothalamic tract
Conveys nerve impulses for sensing pain , warmth, coolness, itching , tickling , etc.
Posterior Column
Consists of two tracts: gracile and cuneate fasciculus. Posterior Column tracts convey nerve impulses for discriminative touch, light pressure, vibration, and conscious proprioception ( the awareness of the positions and movements of muscles, tendons , and joints )
Direct Motor Pathways
Include the lateral corticospinal, anterior corticospinal, and corticobulbar tracts. They convey nerve impulses that originate in the cerebral cortex and are destined to cause voluntary moments of the skeletal muscles.
Indirect Motor Pathways
Include the rubrospinal, tectospinal, vestibulospinal, and medial reticulospinal tracts. These tracts convey nerve impulses from the brain stem to cause automatic movements and help coordinate body movements with visual stimuli
Spinal Reflex
When integration takes place in the spinal cord gray matter . Ex: patellar reflex
Cranial Reflex
When integration occurs in the brain stem . Ex: tracking movements of your eyes while reading a sentence.
Reflex Arc
The pathway followed by nerve impulses that produce a Reflex
Sensory Receptor
The distal end of a sensory neuron or an associated sensory structure serves as a sensory receptor , it responds to a specific stimulus
Sensory Neuron
Neuron that carries sensory information from cranial and spinal nerves into the brain and spinal cord from a lower To higher level in the spinal cord and brain aka afferent neuron
Integrating Center
A single synapse between a sensory neuron and a motor neuron
Motor Neuron
Impulses triggered by the integrating center propagate out of the CNS along a motor neuron to the part of the body that will respond.
Effector
The part of the body that responds to the motor nerve impulse , such as a muscle or gland .
Somatic Reflex
If the effector is skeletal muscle
Autonomic Reflex
If the effector is smooth muscle , cardiac muscle , or a gland .
Stretch Reflex
Causes contraction of a skeletal muscle in response to stretching of the muscle.
Muscle Spindles
An encapsulated proprioceptor in skeletal muscle , consisting of specialized intrafusual muscle fibers and nerve endings ; stimulated by changes in length or tension of muscle fibers
Ipsilateral Reflex
Snensory nerve impulses enter the spinal cord on the same side from which motor nerve impulses leave it . All monosynaptic reflexes are ipsilateral
Muscle tone
The small degree of contraction present while the muscle is at rest
