Orthopedics Spine & Pelvis Lecture 4
Orthopedic surgeryERICK M SALADO, M.D.Axial SkeletonSpine & PelvisLecture 4
1Spine compositionThe spine has three major components:
The Spinal Column (i.e., bones and discs)
Neural Elements (i.e., the spinal cord and nerve roots)
Supporting Structures (i.e., muscles and ligaments)
Spinal Anatomy REGIONSREGIONS# of VertebraeBody AreaAbbreviationCervical7Neck C1 C7Thoracic12Chest T1 T12 Lumbar5 or 6Low BackL1 L5Sacrum5 (fused)Pelvis S1 S5Coccyx3-4TailboneNone
NORMAL SPINE CURVATURES
The spine has four natural curves That help to distribute mechanical stress as the body moves.
Cervical and Lumbar curves are Lordotic. Thoracic and Sacral curves are Kyphotic. Vertebral column functionsProtectionSpinal Cord and Nerve Roots Many internal organs
Base for AttachmentLigaments Tendons Muscles
Structural SupportHead, shoulders, chest Connects head, upper and lower body Balance and weight distribution Flexibility and Mobility Flexion (forward bending)Extension (backward bending)Side bending (left and right)Rotation (left and right)Combination of above
OtherBones produce red blood cellsMineral storageFat storage Spinal ligaments
Ligaments in the spineThree of the more important ligaments in the spineThe Ligamentum Flavum forms a cover over the dura mater: (a layer of tissue that protects the spinal cord.) This ligament connects under the facet joints to create a small curtain over the posterior openings between the vertebrae. The Anterior Longitudinal Ligament attaches to the front of each vertebra. This ligament runs up and down the spine (vertical or longitudinal). The Posterior Longitudinal Ligament runs up and down behind the spine and inside the spinal canal. THORACIC VERTEBRAE AnatomyThe thoracic vertebrae increase in size from T1 through T12. They are characterized by small pedicles Long spinous processesRelatively large Neural Foramen, (which result in less incidence of nerve compression). Costal facet joints Costo-Tranverse &
Facet jointsEach vertebra has two sets of facet joints, located at the back of the spine (posterior). One pair faces upward (superior articular facet) and one downward (inferior articular facet). There is one joint on each side (right and left). Facet joints are hingelike and link vertebrae together. Facet joints
ZYGAPOPHYSEAL (Facet) jointsFacet joints are synovial joints. Each joint is surrounded by a capsule of connective tissue and produces synovial fluid to nourish and lubricate the joint. The joint surfaces are coated with cartilage allowing joints to move or glide smoothly (articulate) against each other. These joints allow Flexion (bend forward), Extension (bend backward), and Rotation (twisting motion). The spine is made more stable due to the interlocking nature to adjacent vertebrae. facet joints & discs
FACET JOINTS ANGLE
ZYGAPOPHYSeAL JOINT INNERVATION
Each Facet joint receive double innervations from The Medial Branch of The Dorsal Ramus (posterior) of the Spinal NerveL3L4L5
AscendingDescendingMedial Branch of The Dorsal Ramus of the SPINAL Nerve
One from above from the Descending Branch of the higher spinal segment One from below from the Ascending Branch of the lower Spinal segmentReceives double innervations from The Medial Branch Each Facet Joint Intervertebral discsThe intervertebral discs are Fibrocartilagenous cushions serving as the spine's shock absorbing and shock distribution system, protecting the vertebrae, brain, and other structures (i.e. nerves). The intervertebral discs make up one fourth (1/4) of the spinal column's length. There are no discs between the Atlas (C1), Axis (C2), and Coccyx. The discs allow for some vertebral motion, extension, flexion and rotation. Individual disc movement is very limited however considerable motion is possible when several discs combine forces. Discs are not vascular and therefore depend on the end plates to diffuse needed nutrients.Intervertebral discs structureDiscs are composed of an Annulus Fibrosus and a Nucleus Pulposus.The annulus fibrosus is a strong radial tire like structure made up of lamellae; concentric sheets of collagen fibers connected to the vertebral end plates. The sheets are orientated at various angles. The annulus fibrosus encloses the nucleus pulposus.
Intervertebral discs compositionBoth the annulus fibrosus and nucleus pulposus are composed of water, collagen, and proteoglycans (PGs), the amount of fluid (water and PGs) is greatest in the nucleus pulposus. PG molecules are important because they are hydrophilic (attract and retain water). The nucleus pulposus contains a hydrated gellike matter that resists compression. The amount of water in the nucleus varies throughout the day depending on activity. INTERVERTEBRAL DISC fluid & O
actual disc appearanceNeuro-Anatomy CNS & PNSThe CNS extends to the Peripheral Nervous System (PNS), a system of nerves that branch beyond the spinal cord, brain, and brainstem.
The PNS includes the Somatic Nervous System (SNS) and the Autonomic Nervous System (ANS).
The Somatic Nervous System includes the nerves serving the musculoskeletal system and the skin. It is Voluntary and reacts to outside stimuli affecting the body.
The Autonomic Nervous System (Sympathetic Nervous System and Parasympathetic Nervous System). Is Involuntary, automatically seeking to maintain normal function homeostasis.
Upper & Lower Motor NeuronsThe nerves bundle that lie within the spinal cord are Upper Motor Neurons (UMNs). They carry the messages back and forth from the brain to the spinal nerves along the spinal tract. The Spinal Nerves that branch out from the spinal cord to the other parts of the body are Lower Motor Neurons (LMNs). These Spinal Nerves exit and enter at each vertebral level and communicate with specific areas of the body.DermatomesRelationship between the spinal nerves & skin sensation.
Each of the spinal nerves root provides sensation to a predictable area of skin although, there is a great deal of overlapping
myotomesMyotome - Relationship between the Spinal Nerves & Muscles.Each muscle in the body is supplied by a particular level or segment of the spinal cord and by its corresponding spinal nerve with some overlapping.C3,4 and 5 - diaphragmC5 the shoulder muscles and muscle to bend elbow .C6 bending the wrist back.C7 straightening the elbow.C8 bends the fingers.T1 spreads the fingers.T1 T12 supplies the chest wall & abdominal muscles.L2 bends the hip.L3 straightens the knee.L4 pulls the foot up.L5 wiggles the toes.S1 pulls the foot down.S3,4 and 5 bladder, bowel, sex organs, anus and other pelvic muscles.Spinal cord Neuro-AnatomyThe Central Nervous System is composed of the Brain and Spinal Cord. The Spinal Cord, originates immediately below the Brain Stem, and extends to the last Thoracic (T12) or first lumbar vertebra (L1)Beyond L1 the spinal cord becomes the Cauda EquinaSpinal Cord Anatomy
Conus Medullaris & cauda Equina Just below the first Lumbar (L1) vertebra the spinal cord ends at the Conus Medullaris, and the Filum Terminale extends down like a fibrous tract to the level of S2From the conus medullaris, the spinal nerves extend in a group resembling a horses tail, known as the Cauda Equina extending to the coccyx. These nerves are suspended Floating in CSF.
CAUDA EQUINA ANATOMY
Cervical spine bone anatomy
Normal Cervical Spine X Rays
ATLANTO-OCCIPITAL & ATLANTO-ODONTOID
Cervical Spinal StenosisCervical spinal stenosis may cause symptoms in the shoulders, arms, and legs; hand clumsiness and gait and balance disturbances can also occur. In some patients the pain starts in the legs and moves upward to the buttocks; in other patients the pain begins higher in the body and moves downward. This is referred to as a sensory march. Cervical radiculitis hnpHerniated disks and nerve canal stenosis in the neck most commonly affect the:
C5 root causing shoulder pain C6 root causing thumb and second digit pain C7 root causing pain into the middle finger
Other cervical dermatomes are only rarely affected by degenerative disease in the neck.
Cervical Spinal myotomesMyotomes: Muscular innervationsC1: Head and neckC2: Head and neck C3: Diaphragm C4: Upper body muscles (e.g. Deltoids, Biceps) C5: Wrist extensorsC6: Wrist extensorsC7: Triceps C8: Hands TorticollisTorticollis (from the Latin torti, meaning twisted and collis, meaning neck)Torticollis / Stiff Neck / Wryneck / Cervical DystoniaTypesCongenital / Inherited Acquired / Acute, Spasmodic Refers to the neck in a twisted or bent position, manifests in involuntary contractions of the neck muscles, leading to abnormal postures and movements of the head. Dx: Clinical Tx:Overlaying CausePT stretching exercisesMuscle Relaxants/NSAIDsBotoxSurgical elongation
Cervical Spine injuryInjury or mild trauma to the cervical spine can cause a serious or life-threatening medical emergency [e.g. spinal cord injury (SCI) or fracture]. Sx: Pain, numbness, weakness, and tingling are symptoms that may develop when one or more spinal nerves are injured, irritated, or stretched. The cervical nerves control many bodily functions and sensory activities. Cervical Spine injuriesCervical spine injury:Most often, a spine injury results from a collision, and there may be assoc head injury.The head and neck must be immobilized immediately, and ease of breathing and LOC must be ascertained.If spine injury is suspected, it is wise to be extremely cautious until a proper Dx is made.This is the best way to prevent conversion of a repairable injur