Module 18- Spinal Patho Flashcards
The spine
- 33 vertebrae
- Stabilized by ligaments and muscles
- Support and protect neural components; allow for fluid movement and erect stature
Identified by location as…
- Cervical
- Thoracic
- Lumbar
- Sacral, or coccyx
What are the components of the vertebrae?
- Lamina
- Pedicles
- Spinous processes
- Each vertebrae is unique in appearance but they share basic structural characteristics (except for C1 and C2, the atlas and axis)
What does each pedicle contain?
- Each pedicle contains a notch forming the intervertebral foramen
- This space allows exit of the peripheral nerve roots and spinal vein, and entrance of the spinal artery bilaterally
Transverse spinous process
- The junction of the pedicle and lamina bilaterally
- The posterior spinous process is a fusion of the posterior lamina where muscles and ligaments attach
Cervical Spine
- The cervical spine includes the first seven bones
- Supports the weight of the head and permits a high degree of mobility
- The atlas (C1) and axis (C2) allow for rotational movement of the skull
Thoracic Spine
- 12 vertebrae
- The thoracic spine is supported by ribs, muscles, and ligaments
Lumbar Spine
- Five largest bones of the column
- Integral in carrying a large portion of body weight
- Susceptible to injury
Sacral Spine
- five fused bones, forms the posterior pelvis
- Coccyx made up of 3-5 fused bones
Each vertebra is separated and cushioned by what?
Intervertebral discs
What do intervertebral discs do?
- Limit bone wear and act as shock absorbers
- Lose water content and become thinner with age
- Discs can herniate into the spinal cord
- Herniated discs result in pressure on the nerve rot or spinal cord
Body flexion and extension is allowed by what?
- Allowed by muscles, tendons, and ligaments without stressing the spinal cord
What does the central nervous system include?
Brain & spinal cord
Brain & Meninges
- Located in the cranial cavity and is the largest component of the CNS
- Brain contains billions of neurons
Brain Stem
- Medulla, pons, and midbrain
- Brain stem connects to spinal cord
- 10 of 12 cranial nerves exit here
Entire CNS enclosed by 3 membranes, called what?
- Meninges
Outer layer
- Dura mater (tough & fibrous)
Middle layer
- Arachnoid mater (contains blood vessels that have the appearance of spider web)
Inner layer
- Pia mater (rests directly on the brain or spinal cord)
Cerebrospinal Fluid
- CSF bathes the brain and spinal cord
- This cushion of fluid protects the CNS
What does the spinal cord do?
- Transmits nerve impulses between the brain and the rest of the body
- Exits the skull through a large opening called the foramen magnum
- Extend from base of skull to L2
At L2, where does the spinal cord branch?
- Spinal cord branches into the cauda equina, a separate collection of individual nerve roots (also known as the “horse’s tail”)
- 31 pairs of spinal nerve named according to the level of origin
What does the spinal cord look like?
- A cross-section of spinal cord shows inner gray matter and outer white matter
- Gray matter: butterfly-shaped central core
What are the neural cell bodies divided into?
- Posterior (dorsal) horn: sensory input
- Anterior (ventral) horn: motor input
White matter
- Three columns of myelinated ascending and descending fiber pathway
- Messages are relayed to and from brain along these spinal tracts
Ascending tracts
carry info to brain
Descending tract
carry info away from the brain
Anterior spinothalamic tracts (ascending)
Carry sensation of crude touch and pressure sensation to the brain
Lateral spinothalamic tracts (ascending)
Carry pain and tempature
Spinocerebellar tracts (ascending)
Coordinate impulses necessary for muscular movements by carrying impulses from muscles in the legs and trunk to the cerebellum
Corticospinal tracts (descending)
Voluntary motor commands
Reticulospinal tracts (descending)
Muscle tone and sweat glands activity
Rubrospinal tracts (descending)
Posterior Spinal Tracts
Muscle tone
Fasciculus gracilis and cuneatus
Proprioception vibration, light touch, deep pressure, two-point discrimination, and stereognosis
How many cervical nerves?
8
8 cervical nerves
perform functions in the scalp, neck, shoulders, and arms
How many thoracic nerves?
12
12 thoracic nerves
the upper nerves supply the muscles of the chest to assist in coughing and breathing; the lower nerves supply the sympathetic nervous system and the abdominal muscles
How many lumbar nerves?
5
5 lumbar nerves
supply hip flexors and leg muscles, and provide sensation to anterior legs
How many sacral nerves?
5
5 sacral nerves
supply bowel and bladder control, sexual function, and sensation to posterior legs and rectum
How many coccygeal nerve?
1
Cervical plexus (C1-C5) includes what nerve?
Phrenic nerve (C3-C5), which innervates the diaphragm
- Any injury above C4 breathe no more
Brachial plexus (C5-T1)
nerves controlling the upper extremities (axillary, median, musculocutaneous, radial, and ulnar
Lumbar plexus (L1-L4)
nerves of the skin and muscles of the abdominal wall, external genitalia, and lower limbs
Sacral plexus (L4-S4)
includes the pudendal and sciatic nerves supplying the buttocks, perineum, and lower limbs
What is the peripheral nervous system divided into?
- The somatic nervous system (SNS)
- The autonomic nervous system (ANS)
Somatic Nervous System
- Made up of peripheral nerve fibers that send sensory information to the central nervous system and motor nerve fibers that send information to skeletal muscle
- Control voluntary movements of your body and to help you feel through all your senses
What is the autonomic nervous system subdivided into?
- Sympathetic nervous system
- Parasympathetic nervous system
Sympathetic Nervous System
- Controlled by the hypothalamus in the brain
- Governs our fight or flight response
- Information is transmitted through the brainstem and the cervical spinal cord
- Exits at the thoracic and lumbar levels to reach target structures
The thoracolumbar system provides what?
- Sympathetic stimulation to the periphery through alpha and beta receptors
Alpha receptors
Induce smooth muscle contraction in blood vessels and bronchioles
Beta receptors
Respond with relaxation of smooth muscle in blood vessels and bronchioles, has effects on myocardial
Chronotopic
controls HR
Inotropic
Controls force of contraction
Dromotropic
controls conduction speed at AV node
Somatic Nervous System
- Sweating
- Pupil dilation
- Temperature regulation
- Shunting blood from the periphery to the core
- Fight or flight responses
- An SCI at T6 or below may disrupt the flow of sympathetic communication
What can disruption of SNS communication cause?
- Disruption of homeostasis, leaving the body unable to cope with environmental changes
- Autonomic dysreflexia due to sympathetic overdrive (sympathetic stimulation without parasympathetic input)
- Causes life threatening hypertension
The parasympathetic nervous system
- Carries signals from the brain stem and upper spinal cord to the organs (abdomen, heart, lungs) and skin above the waist
- Includes fibers arises from brain stem and upper spinal cord
Vagus Nerve
- Travels outside the medulla to the heart via the carotid arteries, thus vagus tone remain intact following a spinal injury
- Vagus nerve controls HR and when stimulated can slow HR. Vaso vagal response
What do the parasympathetic nerves supply?
- They supply the reproductive organs, pelvis, and legs
- They begin at the sacral level (S2-S4)
