Skeletal System Flashcards
What are the functions of the skeletal system?
- supports the body
- facilitates movement
- protects internal organs
- produces blood cells
- stores and releases minerals and fat
Function of cartilage
- provide flexible strength and support for body structures
- Unite adjacent bones/provide cushioning at joints
Function of ligaments
- Strong connective tissue bands that hold bones at a moveable joint together
- Prevent excessive movements of the joint that would result in injury
- Dense regular connective tissue
Describe long bones and give examples
- cylindrical (longer than wide)
- Function: levers (move when they contract)
- Central chamber in the shaft (medullary or marrow cavity)
- Eg: humerus, ulna, radius, femur…
Describe short bones
- cube-like shape
- Function: stability, support and limited motion
- E.g: carpal bones, tarsal bones
Describe sesamoid bones
- Sesame shape (small, round)
- Contained within tendons/joint capsules
- Function: protect tendons by preventing wear and tear when a tendon moves adj to bony surface or joint
- also important in increasing the distance between the tendon and a joint. This improves the leverage of the muscle so that it requires less energy to move the joint providing the muscle a mechanical advantage in movement.
- E.g: patella
Describe flat bones
- quite thin
- curved rather than flat
- Function: serve as points of attachment for muscles and often protect internal organs
- E.g: cranial bones, scapulae, sternum, ribs
Describe irregular bones
- bones that don’t fulfil the above criteria
- E.g: vertebrae, facial bones
Main parts of long bone
- diaphysis: walls are cortical bone tissue
- epiphysis: trabecular bone tissue, red bone marrow in spaces of this tissue
- medullary cavity: hollow region in diaphysis (yellow bone marrow)
- metaphysis: between epiphysis and diaphysis
- epiphyseal growth plate: at junction b/n epiphysis and metaphysis. hyaline cartilage
- changes to epiphyseal line once growing stops
What is the endosteum?
- membranous lining of medullary cavity
- dense irregular connective tissue
- function: bone growth, repair and remodelling
What is the periosteum
- dense irregular connective tissue
- covers external surface of the bone
- has BVs, nerves, lymph vessels that nourish cortical bone tissue
- Attachment site for tendons and ligaments
- covers the entire external surface except where the epiphyses meet other bones to form joints (covered with articular cartilage (hyaline) that reduces friction and is a shock absorber)
Describe primary ossification centre
- first site of bone ossification - in diaphysis (central part for short and irregular)
- typically forms prenatally
- Some bones have > 1 (e.g os coxae/vertebrae)
What are secondary ossification centres
- additional ossification sites at ends of the bone
- appear postnatally (around puberty)
How do bones grow?
- occurs at epiphyseal plate (hyaline cartilage)
- Longitudinal growth: cartilage forms on epiphyseal side, and diaphyseal side cartilage is ossified and it grows in length
- Rate of growth controlled by hormones
Epiphyseal line
Osseuous scar of where epiphyseal plate was
Appositional growth
While bones are increasing in length, they are also increasing in diameter; growth in diameter can continue even after longitudinal growth ceases.
Appositional growth
While bones are increasing in length, they are also increasing in diameter; growth in diameter can continue even after longitudinal growth ceases.
What are the 3 classes of bone markings?
- articulation: where 2 bone surfaces come together
- projection: projects out from bone surface. attachment points for tendons and ligaments
- depression: hole/groove in the bone that allows BVs and nerves to go through
Types of projections
- Process: Prominent projection, often elongated
- Protuberance: Roughened elevation
- Spine: Pointed process
- Tubercle: Small, rounded process
- Tuberosity: Rough surface
- Crest: Ridge
Types of articulations
- Head: Prominent rounded surface (ball-like)
- Facet: Flat surface
- Condyle: Rounded convex surface
Types of depressions
- Fossa: Elongated basin
- Sulcus: groove
- Canal: passage in bone
- Fissure: slit through bone
- Foramen: hole through bone
- Meatus: opening into canal
- Sinus: air-filled space in bone
What is a suture?
- immobile joint b/n adj bones of the skull
- narrow gap is filled with dense, fibrous conenctive tissue
What are the sutures of the skull?
- Coronal suture: joins frontal bone to R and L parietal bones
- Sagittal suture: joins R and L parietal bones
Frontal bone
flat bone forming the forehead
Parietal bone
- paired
- forms superior lateral side of the skull, convex
Temporal bone
- Forms inferior lateral side of skull
- External auditory canal
- Mastoid process
- Carotid canal and its openings
- Auditory ossicles
Occipital bone
- formen magnum
- jugular foramen
Sphenoid bone
Sella turcica and hypophyseal fossa
Ethmoid bone
- single midline bone that forms the roof and lateral walls of superior nasal cavity
- Osseous nasal septum
- Nasal conchae (superior and middle)
Maxillae
- paired bones that form upper jaw
- hard palate
Mandible
- forms lower jaw
- articulates w temporal bone to form temporomandibular joint
Inferior nasal conchae
- Paired
- form a curved bony plate that projects into the nasal cavity space from the inferior lateral wall
Hyoid bone
- Small U shaped bone in superior aspect of neck (U points posteriorly)
- independent (doesn’t contact others)
- function: base for the tongue
Hyoid bone
- Small U shaped bone in superior aspect of neck (U points posteriorly)
- independent (doesn’t contact others)
- function: stabilisation of tongue during speech and swallowing
Describe each region of the vertebral column and the number of bones in each region
- Cervical (C1-C7)
- Thoracic (T1-T12)
- Lumbar (L1-L5)
- Sacrum
- Coccyx
Structure of typical vertebrae
- body: supports body weight
- vertebral arch: 2 pedicles and 2 laminae (and intervertebral foramen)
- vertebral foramen
processes: - spinous process
- transverse process
- superior articular process
- inferior articular process
Primary curvature
- concave anteriorly
- retained from original foetal curvature (thoracic, sacral and coccygeal regions)
Secondary curvature
- convex anteriorly
- Cervical and lumbar regions
- develop postnatally
Intervertebral disc
- nucleus pulposus: central part. High water content to resist compression and support weight bearing
- Annulus fibrosus: outer tough layer of intervertebral disc. develop postnatally
Sternum
- Manubrium
- Body of sternum: contains lateral notches which articulate with costal cartilage
- Sternal angle: Articulation b/n manubrium and body. Lies at level of T4/5 intervertebral disc
- xiphoid process
Ribs
True ribs: 1-7. articulate by their costal cartilage directly w sternum
False ribs: 8-10
Floating ribs: 11-12. Dont connect with sternum at all via costal cartilages
Sacrum
- auricular surface
- pelvic/anterior surface
- ventral sacral foramina
- dorsal/posterior surface
- median sacral crest
Clavicle
- S shaped bone on anterior side of shoulder
- Sternal end: rounded, articulates w sternum
- Acromial end: flattened, articulates w/ acromion of scapula
Sternum
- Spine
- Ac
