Musculoskeletal System Unit Chapter Notes

Skeletal System

Bone Marrow = site of blood cell production

Joint = place where 2 bones meet and are held by ligaments

Ligaments = give flexibility

Skeleton

A skeleton is the framework of the body when the bones are connected

There are 2 divisions:

  1. Axial Skelton

    • Includes bones on the head, neck, spine, chest, and trunk.

    • It forms the central axis of the whole body and protects internal organs like the brain, lungs, and heart.

    • Head/Skull is 2 parts:

      1. Cranium - Incases the brain

        1. Frontal Bones, Parietal Bones, Temporal Bones, Ethmoid Bones, Sphenoid Bones, and Occipital Bones.

      2. Facial Bones - Surround mouth, nose, and eyes

        1. Mandible Bones, Maxilla Bones, Zygomatic Bones, Vomer Bones Palatine Bones, Nasal Bones, and Lacrimal Bones.

    • The Hyoid Bone is 1 u-shaped bone in the neck between the mandible and larynx, point of attachment for swallowing and speech muscles

  2. Appendicular Skeleton

    • The things for appendages or limbs along with muscles attached to them, responsible for movement are:

      1. Pectoral Girdle

        • has clavicle bones(vertebrae in the neck) and the scapula bones(shoulder blade)

        • attaches upper extremity to the axial skeleton

        • articulating with the sternum anteriorly and the vertebral column posteriorly

      2. Upper Extremities

        • has humerus(upper arm bone), ulna(forearm bone on little finger side of the lower arm), radius(forarm bone on thumb side of lower arm), carpals(bones of wrist), metacarpals(bones in palm of hand), and phalanges(finger bones, 3 each finger, 2 each thumb).

      3. Pelvic Girdle (os coxae or innominate bone or hipbone)

        • has ilium(part of the hipbone),

      4. Lower Extremities

Bones

  • Osseous Tissue = another name for bones

  • Ossification = the gradual process of bones being formed before birth

  • Cartilage = flexible tissue that makes a model for the fetal skeleton

  • Osteoblasts = immature bone cells that gradually replace cartilage

  • Osteocytes = cells in adult bones that gradually replace osteoblasts

Bone Structure

Categories of bones based on shape:

  1. Long bones (long, not wide)

    Ex: femur and humerus

    Most bones are long bones

    Diaphysis = central shaft

    Epiphysis = diaphysis that widens on each end

    Articular cartilage = layer of cartilage covering epiphysis to prevent connective tissue rubbing on bone

    Periosteum = connective tissue membrane covering the remaining surface of the bone, contains blood vessels, nerves, and lymphatic vessels

    Cortical bone = hard, dense exterior bone surface

    Compact bone = another name for cortical

    Spongy bone = has spaces in it and looks like a sponge containing red bone marrow

    Cancellous bone = another name for spongy bone

    Red bone marrow = inside the spaces of spongy bone makes up most of the blood cells and is found in some parts of all bones

    Medullary Cavity = open canal in the center of the diaphysis

    Yellow bone marrow = what red bone marrow in the medullary cavity converts to when people age, is made of fat cells

  2. Short bones (long = wide)

    1. Ex: carpals and tarsals

  3. Flat bones (plate-shaped)

    1. Ex: sternum, scapulae, and pelvis

  4. Irregular bones (shapes are irregular)

    1. Ex: vertebrae

Bone Projections and Depressions

Some projections and depressions are rounded and smooth to articulate with another bone in a joint, but others are rough to provide muscles with attachment points.

Process = general term for bony projection

Specific Terms describe shape, location, and process.

  • Ex:

    • Head = large, smooth, ball-shaped end on a long bone, may be separated from body or bone shaft by a narrow area, the neck.

    • Condyle = smooth, rounded portion at the end of a bone

    • Epicondyle = projection above or on a condyle

    • Trochanter = large rough process for the attachment of a muscle

    • Trubercle = small, rough process that provides the attachment for tendons and muscles

    • Tuberosity = large, rough process that provides the attachment of tendons and muscles

Bones have hollow regions or depressions

  • Ex:

    • Sinus = hollow cavity within a bone

    • Foramen = smooth, round opening for nerves and blood vessels

    • Fossa = shallow cavity or depression on the surface of a bone

    • Fissure = slit-type opening

Muscular System