full study

• Planes of the body

  Coronal (frontal) - separates front and back through middle

  
  

  Transverse (horizontal/cross/axial) - separates top and bottom half

  
  

  Sagittal (median) - separates left & right
• Bones in skeleton


  Axial skeleton (head, vertebrae) - 80 bones

  
  

  Appendicular skeleton (limbs) - 126 bones

  
  

  Total - 206 bones
• Functions of skeletal system

  Mechanics: support, protection & movement

  
  

  Metabolic: nutrient store, blood cell formation
• Bone cells


  Osteoblasts: create bone matrix

  Osteocytes: maintain bone matrix

  Osteoclasts: breakdown bone matrix; much larger
• Bone tissue formation


  Bone tissue is only formed by osteogenesis - a layer of osteoblasts turning into osteoid to mineralised bone
• Bone formation


  Intramembranous - bone tissue is created directly over the mesenchymal tissue & not on cartilage (e.g. flat bones of skull, mandible, clavicle)

  
  

  Endochondral - uses hyaline cartilage as the model for long bone formation (all other bones of skeleton)

  Cartilage between primary & secondary layers - growth plate where the body grows from & after you are finished growing, the growth plates ossify to bone
• Classification of bones


  Long - Shaft with ends; femur, phalanges etc.

  Short - Square shaped; carpals, tarsals, sesamoid bones etc.

  Flat - As name suggests; sternum, scapula, ribs etc.

  Irregular - As name suggests; vertebrae, os coxae, pneumatic bones etc
• Nutrient foramen


  Large in midshaft of long bones to supply large blood vessels to the shaft; they penetrate through the outer layer of the cell to supply nutrients & remove waste
• Membranes of bone


  Periosteum - membrane wrapping around the outside of the bone carrying the blood vessels & the nerves; continuous into the internal part of the bone

  
  

  Endosteum - inside of the bone; new cells from the precursor cells in this membrane
• Parts of bones


  Red bone marrow - blood cell forming

  
  

  Yellow bone marrow - fat packing/storage

  
  

  Compact bone (lamellar) - thick at the ends

  
  

  Trabecular bone (spongy) - good for shock absorption
• Functional classifications of bones

  Synarthrosis - no movement (e.g. growth plate, cartilaginous joints)

  
  

  Amphiarthrosis - small movements (e.g. wedges of cartilage at pubic bone near os coxae)

  
  

  Diarthrosis - free movement; only synovial; most common
• Synovial fluid in joint cavities


  Synovial membrane secretes about half a teaspoon of synovial fluid of ball-and-socket joints to decrease the amount of friction between two cartilaginous joints
• Diarthrosis types


  Non-axial - gliding; does not spin about axis, two flat surfaces glide on top of each other (e.g. short bones in hand & ankle/foot)

  
  

  Mono/uniaxial - pivot/hinge like axis, rotates about 1 axis (e.g. elbow joint, phalanges, head of radius)

  
  

  Biaxial - ellipsoid, saddle; rotation about 2 axes (e.g. base of thumb goes forwards & backwards and side to side)

  
  

  Tri/multiaxial - ball-and-socket; rotation about 3 axes (e.g. shoulder/hip joint, movement of the humeral head at the glenoid fossa)
• Structural classifications of bones

  Bony - bone connecting to bone (synostoses)

  
  

  Cartilaginous

  Synchondroses - hyaline cartilage (e.g. cartilage coming off medial of ribs)

  Symphyses - fibrocartilage (wedge of cartilage; e.g. pubic symphysis, intervertebral column)

  
  

  Fibrous

  Sutral - young, fibrous (e.g. neonate's skull to allow for movement & compression of skull)

  Gomphoses - fibrous/socket (e.g. at mandible holding teeth)

  Syndesmoses - with ligamentous tissue (e.g. joint holding ankle together)

  
  

  Synovial

  Plane/gliding

  Pivot - trochoid

  Hinge - ginglymus

  Condyloid - ellipsoid

  Saddle - sellar

  Ball-and-socket - spheroid
• Movements of synovial joints

  Flexion/extension occurs in the sagittal plane

  
  

  Flexion decreases the joint angle, extension increases it

  
  

  Adduction/abduction occurs in the coronal plane

  
  

  Adduction moves a body part towards the midline, abduction moves it away from the midline

  
  

  Rotation occurs around a long axis
• Functions of the skull

  Mechanics: support, protection, movement (muscle attachments)

  
  

  Metabolic: nutrient store (minerals and lipids) & blood cell formation
• Elements of the skull

  Cranium - brain case

  Mandible - includes jaw

  Calvaria - cranium without face

  Splanchnocranium - facial skeleton

  Cranial vault and base - walls on anterior & posterior side make up cranial vault; base is the bottom of the skull which meets the facial skeleton
• Diploë


  Diploë is a layer of spongy bone between two plates of compact bone (e.g. cranium)

  It contains red bone marrow so expands when blood cells are in demand
• Sella turcica (Turkish Saddle)


  Lies behind optic groove

  
  

  Has three parts:

  Tuberculum sellae

  Hypophseal fossa

  Dorsum sellae
• Temporomandibular joint


  Condylar head of ramus of mandible/glenoid fossa of temporal bone

  
  

  Movements of sliding motion & cartilage disk (C-like) provides a socket for the mandible to rest in
• Sutures of the skull

  Coronal - across skull from left to right

  Sagittal - across skull from front to back

  Lambdoidal - between parietal & occipital bones

  Squamosal - above ear

  
  

  Start off as fibrous in youth and become more bony
• Joints of sutures


  Serrate - dovetail joint (zig-zag)

  
  

  Lap - miter joint (angled cut)

  
  

  Plane - butt joint (straight cut)
• Neonate skulls


  Frontal suture - splits forehead in half; after 5yrs, it's metopic

  
  

  Frontal bone & parietal bone come to point

  
  

  Fontanelles (baby soft spots)
• Foramina of the skull

  Foramen magnum (for medulla oblongata, meninges, vertebral arteries)

  
  

  External auditory meatus

  
  

  Foramen spinosum (internal maxillary artery)

  
  

  Foramen ovale (for mandibular branch of Trigeminal nerve, CNV) - trigeminal nerve exists there

  
  

  Foramen lacerum (mostly filled with cartilage) - L shaped laceration

  
  

  Carotid canal (for internal carotid artery

  
  

  Jugular foramen/notch (jugular vein, and 3 cranial nerves: glossopharyngeal, vagus and accessory)
• Para-nasal sinuses/pneumatic bones


  Frontal

  Ethmodial

  Sphenoidal

  Maxillary

  
  

  All communicate with the nasal cavity
• Teeth


  Permanent teeth 2I, IC, 2PM, 3M 2I, IC, 2PM, 3M

  
  

  Deciduous teeth 2I, IC, 2M 2I, IC, 2M
• Sex differences in skull

  Vault - bossing/eminences, slope of forehead

  
  

  Glabella - less prominent in women

  
  

  Mastoid process - smaller in women

  
  

  External occipital protuberance - smaller in women

  
  

  Mental eminence

  
  

  Sharpness of supraorbital margins

  
  

  Robustness - less robust women
• Connective tissue of muscles

  Epimysium goes around the muscle fibre bundles

  
  

  Perimysium runs around the muscle fibres to connect them together

  
  

  Endomysium wraps around the individual muscle fibres
• Muscle shapes


  Quadrilateral - square shaped

  
  

  Strap - long & thin giving lots of movement bc there are lots of sarcomeres in line

  
  

  Fusiform - spindle shaped & pointed at the end

  
  

  Tricipital - can have multiple heads

  
  

  Triangular - aka convergent muscles bc they converge at the end

  
  

  Cruciate - cross

  
  

  Unipennate - muscle fibres arise off one end of the bone

  
  

  Bipennate - muscle fibres arise off both sides of the bone

  
  

  Multipennate - muscle fibres arise off multiple sides of the bone

  
  

  Radial - muscle fibres going out from a central tendon (e.g. diaphragm)
• Types of muscle contractions

  Isotonic = change in length

  Concentric = shortening

  Eccentric = lengthening

  Isometric = length stays same/no change
• Masseter


  Origin: Zygomatic arch

  
  

  Insertion: Lateral surface of mandibular ramus

  
  

  Function: Moves mandible at temporomandibular joint = Elevation, protrusion, lateral deviation

  
  

  Innervation: Trigeminal nerve

  
  

  Internal muscle structure: Multipennate
• Temporalis


  Origin: Temporal lines/fascia

  
  

  Insertion: Coronoid process of mandible

  
  

  Function: Moves mandible at temporomandibular joint = Elevation, retraction, lateral deviation (postural muscle)

  
  

  Innervation: Trigeminal nerve

  
  

  Internal muscle structure: Bipennate
• Scalp muscles


  Occipitofrontalis

  Galea aponeurotica

  Frontalis

  Epicranius

  Occipitalis
• Frontalis


  Structure: Broader than occipitalis and longer no bony attachment

  
  

  Origin: galea aponeurotica (infront of coronal suture)

  
  

  Insertion: supraorbital muscles (procerus, curugator supercilii, orbicularis oculi) and skin

  
  

  Function: moves scalp posteriorly raising eyebrows and wrinkling forehead antagonists of orbicularis oculi

  
  

  Expression: surprise
• Occpitalis


  Structure: shorter and narrower than frontalis medial space between muscle bellies

  
  

  Origin: lateral 2/3rds of superior nuchal line Insertion: galea aponeurotica

  
  

  Function: moves scalp posteriorly raising eyebrows and wrinkling forehead antagonists of orbicularis oculi

  
  

  Expression: surprise
• Obicularis Oris


  Structure: not elliptical has four quadrants (2x pars peripheralis and 2x pars marginalis)

  
  

  Origin: skin and muscle fibres surrounding lips

  
  

  Insertion: mucous membrane of lips at mouth corner

  
  

  Function: compresses and protrudes lips
• Buccinator


  Structure: transverse and anterior orientation quadrilateral muscle deepest extrinsic muscle of lips fibers course anteriorly and medial central fibers of muscle decussate

  
  

  Origin: pterygomandibular raphe and lateral surface of the alveolar process of maxilla and mandible in region of molars Insertion: blend with orbicularis oris and submucosa

  
  

  Function: compress cheeks against teeth draw corners of mouth laterally
• Modiolus


  A dense, compact, mobile, fibromuscular mass lateral to corners of mouth

  
  

  Point of interlacing of approx. nine muscles converging at the angle of the mouth

  
  

  Important for: chewing, biting, drinking, sucking, swallowing, speech, modulation of musical tones, shouting, screaming, crying, facial expression
• Mentalis


  Structure: vertical orientation cone shaped lies lateral to frenulum of lower lip courses inferiorly

  
  

  Origin: incisive fossa of mandible

  
  

  Insertion: skin of chin Function: raises lower lip and mentolabial sulcus protrudes and everts lower lip wrinkles chin

  
  

  Expression: pout, doubt, distain

  
  

  Continuous EMG activity during sleep
• Platysma


  Structure: superficial facial/cervical muscle thin, flat, broad sheet anterior fibers interdigitate at symphsis mentii

  
  

  Origin: fascia as far down as superior aspects of pectoralis major and deltoid muscles

  
  

  Insertion: lower margin of mandible as far back as angle, other muscles at mouth corner, and even zygomaticus major and orbicularis oculi

  
  

  Function: increase diameter of neck draw lower lip and mouth corner lateral and inferior active in broad smiles and speech when lips compressed

  
  

  Expression: smiling, disgust