The Skeletal System

• Skeletal system includes bones, joints, cartilage, and ligaments
• 206 bones are present in the adult human body
• Joints provide fusion
• Cartilage reduces friction
• Ligaments connect bones to bones

Physiologic Functions

• Supports the body
• Protects soft body parts
• Facilitates blood cell production
• Stores fats and minerals
• Allows movement using muscles and joints

Bone Classification

• Long bones are longer than they are wide
• Short bones are cube-shaped
• Flat bones offer more surface area
• Irregular bones have varied shapes
• Round bones are circular

Bone Structure

• The periosteum is a connective tissue covering of bone of blood vessels
  • Continuous with tendons, connecting muscles to bones, and ligaments, connecting bones to bones
  • Includes osteoprogenitor cells, osteoblasts, osteocytes, and osteoclasts

Bone Cells

• Osteoprogenitor cells are unspecialized cells in the periosteum, endosteum, and central canals
• Osteoblasts are bone-forming cells derived from osteoprogenitor cells
• Osteocytes are mature bone cells originating from osteoblasts
• Osteoclasts handle bone resorption, releasing calcium and phosphorus into the blood

Bone Development & Growth

• Ossification refers to the formation of bone
• Intramembranous ossification forms spongy bone between fibrous connective tissue sheets and comprises skull bones
• Endochondral ossification forms most human bones, utilizing hyaline cartilage models that are replaced by spongy bone then compact bone
• The Epiphyseal plate, a band of hyaline cartilage in the epiphyses of long bones, that allows bone growth in length and remains until ossification

Bone Growth Regulation

• Bone remodeling is regulated by three hormones including parathyroid hormone, calcitonin and growth hormone
• Proper calcium levels prevent osteoporosis

Bone Composition

• The epiphysis is the expanded end of bones made of spongy bone
• The diaphysis is the portion between epiphyses and the shaft, composed of compact bone
• The medullary cavity is the hollow part of the diaphysis containing yellow marrow
• Articular cartilage is a hyaline cartilage layer found at articulations
• The endosteum lines both the medullary cavity and spongy bone spaces
• Red bone marrow, is found in spongy bone of adults, and is where hematopoiesis (red blood cell production) takes place

Compact Bone details

• Compact bone is made of osteons, made layers of matrix called lamellae of collagen and minerals
• Lacunae contain bone cells (osteocytes)
• Canaliculi refers to small connecting canals allowing osteocytes to connect to each other and blood supply
• The central canal contains blood vessels and nerves
• Perforating canals run from the periosteum to the central canal

Spongy Bone

• Referred to as cancellous bone
• Contains bony bars/plates known as trabeculae
• Trabeculae strengthen under stress

Bone Fractures

• Complete fractures involve bone breakage
• Incomplete fractures don't fully separate the bone in two
• Simple fractures do not pierce the skin
• Compound fractures involve a broken bone piercing the skin
• Impacted fractures are when bone ends are wedged together
• Spiral fractures occur when bone excessively twists

Bone Fracture Repair

• Reduction is the realignment of bone fragments
• Closed reduction realigns without needing surgery
• Open reduction involves surgical repair
• Bone repair involves hematoma formation, fibrocartilaginous callus formation, and bony callus formation

Axial Skeleton & Divisions

• Axial skeleton forms the central structure
• Appendicular skeleton comprises the limbs/girdles for articulation

The Skull

• Skull bones include sinuses, mucous membrane-lined spaces
• Sinuses reducing skull weight
• Produces voice resonance
• Paranasal sinuses empty straight into the nose
• Mastoid sinuses drain into the middle ear
• Sinusitis is sinus infection, known as mastoiditis

Bone details

• Frontal bone forms the forehead & eye sockets
• Parietal bones (2) form the skull’s roof & sides
• Occipital bone forms the skull back - has foramen magnum for the spinal cord
• Temporal bones (2) contain ear canal, mastoid, styloid, zygomatic processes
• Sphenoid bone is butterfly-shaped and forms the skull base, holding the pituitary gland
• Ethmoid bone forms the nasal cavity and eye orbit part
  • Crista galli and cribriform plate
• Maxillae (2) are known as the upper jaw that hold tooth sockets
• Palatine bones (2) form the hard palate back
• Zygomatic bones (2) form cheekbones/eye sockets
• Lacrimal bones (2) are small, inner eye orbit bones
• Nasal bones (2) form the bridge of the nose
• Vomer bone (1) forms part of the nasal septum
• Inferior nasal conchae (2) are thin bones supporting mucous membranes nose

Mandible & Hyoid

• The mandible (1) is known as the only movable skull bone
• The hyoid is attached to the tongue and anchoring the tongue to the larynx

The Vertebral Column

• Cervical and lumbar curves (convex)
• Thoracic and sacral curves (concave)
• Provides both support and balance
• Lordosis, kyphosis, scoliosis include abnormal curvatures

Intervertebral Disks

• Fibrocartilage pads form between vertebrae and prevent grinding
• Absorbs shock and allows movement, but can slip or rupture (herniated disk

Regional Variations

• Cervical vertebrae (C1-C7) have smaller bodies and split spinous processes
• C7 exhibits longer spinous processes
• Transverse foramen allows passage of vertebral arteries/veins
• Thoracic vertebrae (T1-T12) feature long, downward-sloping spinous processes and costal facets allowing rib attachment
• Lumbar vertebrae (L1-L5) handles large weight, short spinous processes

Vertebrae details

• Transverse processes of vertebrae serve as locations of muscle attachment Spinous processes of vertebrae are like a flag pole
• Atlas (C1) supports the skull, enabling "yes" movement
• Axis (C2) includes the odontoid process that handles the "no" rotation movement
• Sacrum (5 fused vertebrae) articulates with the pelvic girdle to form the posterior pelvic wall
• Coccyx (3-5 fused vertebrae) is for ligament/muscle attachment

The Rib Cage

• The rib cage includes thoracic vertebrae, ribs, costal cartilages and the sternum to handle, providing breathing flexibility
• Supports the pectoral girdle
• Ribs attach at thoracic vertebrae
• True ribs (1-7) attach to the sternum via costal cartilage and vertebrosternal ribs
• False ribs (8-10) attach via cartilage to rib 7 and vertebrochondral ribs
• Floating ribs (11-12) lack sternum attachment, also known as vertebral ribs

The Sternum

• the sternum is flat, protects heart/lungs, and handles CPR placement
  • Manubrium is on the upper part and articulates w/ ribs 1 & 2
  • The Body is the middle, articulates w/ ribs 2-7
  • The Xiphoid process is inferior and turns to bones as age increase

Humerus

• The humeral head joins with the glenoid cavity of the scapula
• Tubercles provide muscular support for the arms
• The intertubercular groove contains biceps brachii tendon
• Deltoid Tuberosity handles deltoid muscle attachment
• Capitulum handles head radius articulation
• Trochlea handles ulna articulation
• Coronoid fossa handles ulna flexion
• Olecranon fossa handles ulna extension

Radius

• The radius is lateral and connects the thumb
• Ulna is medial and connects other digits
• The radial and ulnar notch connects to the radius and ulna
• The styloid process handles ligament attachment

Pelvis

• Two coxal bones handle anterior pubic symphysis connection
• Bones connect posteriorly to the sacrum and connect to the coccyx inferiorly
• The ilium covers the upper margin, hands-on-hips area
• The ischium is lower and supports weight, including ischial tuberosity
• Pubis covers the front hip and has pubic symphysis cartilage
• The obturator foramen offers large openings for BV and nerves

Tibia and Fibula

• the medial tibial bone sustains the femur weight
• tibia includes medial and lateral condyles articulating w/ the femur
• the lateral fibula only works to balance
• Lateral malleolus forms the bulge area for the ankles

Muscle System

• All muscles contract or shorten to handle all movement
• Muscle types are skeletal, cardiac, smooth
  • Skeletal handles defining striations
  • cardiac handles gap junctions for communication
  • smooth handles single nucleus

Muscle Function

• Supporting posture via various body locations, fluid movement, and stabilizes joints

Skeletal Muscle

• Skeletal muscle contracts, allowing bodies to be upright
• Heat results from skeletal muscle Connective tissue covers are endomysium, perimysium, and epimysium

Muscle Details

• Connective tissue:
  • Endomysium covering surrounds fibers
  • Perimysium surrounds groupings into fascicles
  • Epimysium surrounds all musculature connecting fascia and collagen

Cardiac muscle

• Uninucleated and branched to have intercalated disks handling contractions and gap functions
• Smooth muscle is spindle-shapes, uninucleated, and doesn't fatigue quickly

Muscle Anatomy

• Sarcolemma is the plasma membrane that makes up glycogen and myoglobin
• Sarcoplasmic reticulum stores calcium
• T Tubules form by sarcolmenna penetrating the cell
• Myofibrils are cylindrical for length and contraction

Microscopic Anatomy

• Sarcomeres expand from vertical Z lines and contain protein and myofilaments
• The I band contains thin filaments
• The A band contains thick/thin filaments
• the H zone has only myosin filaments.

Myofilament Types

• Thick Filaments form hundreds of myosin molecules creating cross-bridges
• Think filaments have two strands of atcin coils having tropomyosin to attach the troponin

Muscle Stimulus

• Skeletal muscle contracts when stimulated by a motor neuron or units
• units connect to the nervous system, however Botox hinders this . - at rest, atcin has Active ties covered during sliding filament, but nerve signals allow exposure to atcin, thus filaments form a chain

Muscle performance

• Contractions involve sliding and ATP with the help if troponin moving ATP
• muscle contraction keeps moving until signal stops and muscle returns to normal.

Muscle Support

• phosphate bonds provide immediate release to start contractions
• Glucose and fats provide extra power
• Myoglobin handles the release of O as backup, but fatigue hinders sustained effort in lactate acids

Muscle twitch

• Twitch can make or break for signal/fatigue and power
• muscles use or ignore stimulus, and it can be hard to engage fibers if they are too far stretched or weak
  • tone and stimulus increase the connection.
  • muscles take practice and need to build tone, as weight lifting has hypertrophy

Muscle Characteristics

• Slow, intermediate, fast include fiber types of aerobics in mitochondria, blood supply and myoglobin level

Body movement details

• origin muscle connection to bones that doesn't engage or work hard
• insertion allows all action to occur and move bones
• prime does the main portion for muscles
• antagonist works against the target bone
• size and shape handles direction and fibers and levels of movement

Body group notes

Thorax uses lungs as a main muscle (rib cage) forearms use extensor group lower are hamstrings The shoulder has the rotator cuff

Aging

• Aging slows production in mass and response for the heart to pump
• regular light exercise keeps muscles active for people.

Digestive system

• GI tract handles a flow for muscular functions
• Includes food to liquid via stomach and the intestine absorbs or releases fluid
• Most food is passed or dissolved, fluids use it as a form.

Oral location

• Tongue and taste work as duo (salty/sweet/sour vs bitter (sensitive))
• the esophagus seals everything for easy flow

Structure

• The Mucosa helps in the walls
• Submucosa is also important
• Muscularis move it along
• the small/large does its work
• smooth also performs sphincters to keep it all organized

System Details

• The tongue presses material along the roof, but is only activated after stimulation reaches oropharynx
• nerves connect to brain to respond
• water travels to the kidneys