Untitled Quiz

Bone Development

• Bone forms through two pathways: endochondral and membranous ossification
• Endochondral Ossification: Cartilage is replaced by bone, primary method for long bones (e.g., tibia, femur)
  • Diaphysis: Primary ossification center, forms during fetal development
  • Epiphysis: Secondary ossification center, forms after birth
  • Sclerotomes: Mesenchymal cells that form the vertebral column, contribute to bone development.
• Membranous Ossification: Mesenchyme directly differentiates into bone, process for flat bones (e.g., skull bones)

Wolff's Law

• Mechanical stress influences bone growth and remodeling
• Mechanical Stress: Bone adapts to forces placed on it
• Long Bones: Thinner shafts compared to wide heads, growth occurs with compression
• Stunted Growth: Can occur in children with developmental disorders (e.g., Cerebral Palsy, Spina Bifida) due to reduced stress
• Calcium Levels: Increased stress leads to increased calcium deposition
• Osteopenia: After age 30, calcium levels naturally decline leading to bone density decrease
• Osteoporosis: More likely in inactive or sedentary individuals, or wheelchair-bound individuals
• Immobilization: Can cause joint contracture (stiffening of joints)
• Fetal Development: Fetal movement is crucial for joint development

Bone Pathology

• Conditions affecting bone health and development
• Rickets/Osteomalacia: Poor bone mineralization, weak bones
• Osgood-Schlatter Disease: Overgrowth of bone at tendon attachment site, often due to repetitive stress
• Spondylolysis: Fracture through the pars interarticularis (portion of vertebral arch)
• Spondylolisthesis: "Step-off" deformity where one vertebra slips forward
• Arthrogryposis Multiplex Congenita: Rare, autosomal recessive condition, fused joints

Fracture Healing

• Fracture healing process
• Primary Bone Healing: Fracture is stable and minimally displaced
  • Stages: Hematoma formation, soft callus formation, hard callus formation, remodeling
• Secondary Bone Healing: Fracture is unstable or displaced
  • Procedures: Closed reduction, open reduction and internal fixation (ORIF)
  • Complications: Malunion (improper alignment), delayed union (slower than expected healing), nonunion (failure to heal)

Skeletal Muscle Fiber Types

• Different muscle fiber types with varying characteristics and functions
• Type I (Slow Twitch): Low power output, fatigue resistant, high mitochondrial content, oxidative phosphorylation
  • Examples: Postural muscles, soleus (calf muscle), finger flexors
• Type IIA (Fast Twitch): Intermediate between Type I and IIB
• Type IIB (Fast Twitch): High power output, glycolytic metabolism, easily fatigued
  • Examples: Gastrocnemius (calf muscle), finger extensors

Motor Units

• Functional unit of muscle contraction, consisting of a motor neuron and all the muscle fibers it innervates
• Motor Unit: One alpha motor neuron and all the muscle fibers it innervates
• Muscle Fiber Type: All muscle fibers within a motor unit are the same type (e.g., slow twitch, fast twitch)
• Size: Smaller motor units for fine movements (e.g., eye muscles), larger motor units for gross movements (e.g., lumbricals)
• Recruitment: Motor units recruited based on size, smallest first, largest last

Poliomyelitis

• Viral infection damaging alpha motor neurons, leading to muscle weakness and paralysis
• Alpha Motor Neuron Death: Virus destroys alpha motor neurons
• Initial Function: Individuals may initially function normally, but as they age, the surviving motor neurons may not be able to maintain metabolic activity to innervate the extra muscle fibers.
• Post-Polio Syndrome: Muscle weakness, fatigue, and pain years after polio
• Axon Degeneration: Axons to extra muscle fibers die, causing muscle weakness

Muscle Force Generation

• Factors influencing muscle force
• Cross-Sectional Area: Larger area, greater force
• Myoarchitecture: Arrangement of muscle fibers
• Pennation Patterns: Angle of muscle fibers relative to the tendon
• Sex: Men generally have more muscle mass than women
• Age: Muscle mass declines with age (sarcopenia)

Muscle Contraction Types

• Different types of muscle contractions and their roles in movement
• Agonist: Primary muscle for a movement
• Antagonist: Muscle opposing the agonist
• Co-Contraction: Simultaneous contraction of both agonist and antagonist to stabilize a joint
• Synergist: Muscles assisting the agonist in performing a movement
• Substitution: Use of a muscle to carry out a movement a different primary muscle would usually perform

Factors Affecting Muscle Function

• Factors influencing muscle function
• Single Joint Muscles: Primarily responsible for movements at a single joint
• Multi-Joint Muscles: Control complex movements involving multiple joints
• Length-Tension Curve: Muscle generates greatest tension at optimal length
• Passive Insufficiency: Multi-joint muscle stretched from both ends, limiting range of motion
• Active Insufficiency: Multi-joint muscle contracted from both ends, limiting range of motion

Muscle Responses to Changes in Activity

• Muscle adapts to changes in activity level
• Initial Response (Gains of Strength): Increased recruitment, synchronization, and activation of motor units, decreased activation of antagonists
• Losses of Strength (Neural Factors): Decreased activity leading to mobilization or atrophy, delayed response
• Hypertrophy of Muscle Fibers: Increased synthesis of contractile proteins, increased density of capillary beds
• Muscle Atrophy: Decrease in muscle mass
• Muscle Contracture: Shortening and stiffening of muscle, often due to immobilization

Peripheral Nerves

• Nerves transmitting signals to periphery from CNS
• Peripheral Nerve Injuries:
  • Neurapraxia: Temporary loss of nerve conduction (nerve still intact)
  • Axonotmesis: More severe injury (axon damaged, nerve sheath intact), Wallerian degeneration distal to injury site
  • Neurotmesis: Complete severance of the nerve, Wallerian degeneration in distal segment
• Wallerian Degeneration: Degeneration of axon and Schwann cells distal to a nerve injury

Energy Expenditure in Orthopedic Impairments

• Increased energy cost of walking with orthopedic impairments
• Decreased Gait Efficiency: Impairments lead to less efficient walking patterns.
• Increased Oxygen Cost: The body requires more oxygen to maintain a certain walking speed.
• Increased Heart Rate: The heart works harder to compensate for the increased energy demands.
• Amputation Level: Higher level of amputation has greater oxygen cost and slower walking speed
• Effects of Aging on the MSK System:
  • Sarcopenia: Loss of muscle mass
  • Osteoporosis: Decrease in bone density
  • Stiffness: Reduced range of motion
  • Decreased Strength and Endurance: Reduced muscle strength and ability to perform physical activities

Clinical Anatomy Review

• Review of clinically relevant anatomical structures and their relationships
• Glenohumeral Joint:
• Reinforcing Ligaments: Coracohumeral and glenohumeral ligaments
• SITS Muscles: Supraspinatus, infraspinatus, teres minor, subscapularis (rotator cuff muscles)
• Erb Palsy: Brachial plexus injury affecting nerves supplying the shoulder and arm
• Suprascapular Nerve Injury: Weakness in supraspinatus and infraspinatus muscles

Radial, Ulnar, Median Nerves

• Radial Nerve: Extensor muscles of wrists and fingers; injury leads to loss of wrist and finger extension, weakness in supination
• Ulnar Nerve: Flexor muscles of the 4th and 5th fingers, intrinsic muscles of the hand, sensory innervation of the little finger and half of the ring finger; injury leads to weakness of 4th and 5th finger flexion, wrist flexion, loss of interossei and hypothenar eminence muscles
• Median Nerve: Flexor muscles of the wrist and fingers (except the little finger), thenar muscles, sensory innervation of the thumb, index, middle, and half of the ring finger; injury leads to sensory innervation deficits in the “money distribution” area of the hand

Lower Extremity

• Anatomy and function of lower extremities
• Hip Joint: Ball-and-socket, wide range of motion
• Knee Joint: Hinge joint, flexion and extension
• Ankle Joint: Hinge joint, dorsiflexion and plantarflexion

• Foot: Composed of tarsals, metatarsals, and phalanges

Dermatomes

• Areas of skin innervated by a specific spinal nerve root

Imaging of the MSK System

• Different modalities evaluating musculoskeletal system
• Radiography (X-Ray): Visualizes bone structures, ionizing radiation exposure
• Computed Tomography (CT): Detailed images of bone and soft tissues, higher radiation exposure than X-ray
• Magnetic Resonance Imaging (MRI): Detailed soft tissue images, no ionizing radiation exposure
• Ultrasound: Images of soft tissues, non-ionizing radiation exposure, portable
• Uses/Indications: Fractures, dislocations, arthritis, bone tumors, infections, complex fractures, spinal stenosis, ligament/tendon injuries, muscle tears, nerve entrapment

Nuclear Medicine

• Uses radioactive tracers to create images of metabolic activity
• Used to evaluate bone tumors and infections

X-Ray Densities

• Different tissue densities visible on radiographs
• Air: Least dense (black)
- Fat: Slightly denser than air (dark gray)
- Water: Denser than fat (gray)
- Bone: Denser than water (white)
- Metal: Most dense (very white)

Ultrasound Frequencies

• Relationship between ultrasound frequency and image resolution
• Low frequency: Penetrates deeper but lower resolution
• High frequency: Penetrates shallower but higher resolution

Congenital Deformities of the Spine and Scoliosis

• Congenital deformities including scoliosis, lordosis, kyphosis

Scoliosis Treatment

• Treatment options based on severity of curve.
  • Mild (<20 degrees): Conservative (observation, physical therapy, osteopathic manipulative therapy)
  • Moderate (20-45 degrees): Bracing
  • Severe (>45 degrees): Surgery

Random Other Things

• Additional Information on congenital deformities
• Caudal Regression Syndrome: Incomplete development of lower spine and limbs
• Klippel-Feil Syndrome: High-yield association with Sprengel's Deformity (abnormally high scapula)

Spina Bifida Association

• Many have hydrocephalus (fluid buildup in the brain).
• Table of congenital deformities, descriptions, key features, and treatments.