Osseous Tissue: Bones and Skeletal System

Bones (Osseous Tissue)

• Osteology is the study of bones.
• Bones are a rigid form of connective tissue that form the skeleton.
• The supporting framework of the human body consists of over 200 bones.
• Bones are living structures with a blood and nerve supply.
• The periosteum provides blood and nerve supply to bones.
• Living bones have some elasticity due to organic matter
• Living bones have great rigidity due to lamellous structures and tubes of inorganic calcium phosphate

Functions of Bones

• Bones provide protection for vital structures.
• Bones support and form a rigid framework for the body
• Bones provide a mechanical basis for movement
• Bones are involved in the formation of blood cells (bone marrow).
• Bones store salts such as calcium, phosphorus, and magnesium, acting as a mineral reservoir.

Bone Composition

• Bones consist of two main parts: spongy (cancellous) bone and compact bone.

Skeletal Classification

• The skeleton comprises of the axial and appendicular skeleton
• The axial skeleton includes the skull, vertebrae, ribs, and sternum.
• The appendicular skeleton comprises the bones of the upper and lower limbs and their associated bones.

Bone Shape Classification

• Long bones have a shaft and two extremities, such as the humerus and bones of the fingers.
• Short bones are more or less cuboidal, found in the foot and wrist.
• Flat bones form the calvaria, sternum, and scapula.
• Irregular bones include the facial bones and vertebrae
• Pneumatic bones, such as the maxilla and frontal bone, contain air cells or sinuses.
• Sesamoid bones are round or oval nodules in tendons, like the patella, which is the largest
• Accessory bones develop from additional ossification centers or a lack of fusion

Axial Skeleton - Skull

• Neurocranium bones protect the brain
• Facial bones protect sensory organs

Axial Skeleton - Vertebral Column

• This is the vertebral column

Irregular Bones

• The irregular bones cannot be grouped under the other categories
• The vertebral column and facial bones are irregular bones

Bone Markings

• Bone surfaces are not smooth.
• Bones feature elevations, depressions, and holes.
• Names are given to surface features on the bones to distinguish and define them

Bone Markings - Elevations

• Linear elevation features a line or crest.
• Round elevation constitutes a tubercle (small eminence) or protuberance (swelling).
• Sharp elevation forms a spine or process.
• Rounded articular area forms a head or condyle.
• Facets are areas with a smooth surface where bones articulate.

Bone Markings - Depressions and Openings

• Depressions include fossae (small depressions) and grooves (sulci) (long narrow depressions).
• Foramen are holes
• Canals are foramen having length
• Orifices are openings
• Meatus is a canal entering a structure

Joints - General Information

• Arthrology is the study of joints.
• Joints are formed by the articulation between the articular surfaces of two or more bones.
• The articular system comprises joints along with their associated bones and ligaments.

Joint Classification Based on Movement

• Joints are classified based on their ability to move
• Fibrous joints do not have the ability to move
• Cartilaginous joints can make a very limited amount of movement
• Synovial joints are freely movable

Fibrous Joints

• There is fibrous connective tissue between the articular surfaces of fibrous joints
• Syndesmosis joints are tightly connected by connective tissue, such as the distal tibiofibular joint
• Sutura joints are found between the skull bones
• Gomphosis joints are found between dentures and the alveoli of the upper and lower jaw.

Cartilaginous Joints

• Cartilaginous tissues sit between the articular surfaces of cartilaginous joints.
• These joints provide a very limited amount of movement.
• Synchondrosis is the cartilaginous tissue between articular surfaces lost over time reducing movement, such as the sphenoid-occipital joint
• Symphysis include a disc of fibrocartilaginous tissue between the articular surfaces, such as the symphysis pubis and joints between vertebrae.

Synovial Joints - Features

• This type of joint has three features
• Joint cavity
• Articular cartilage is hyaline
• Articular capsule, comprised of two layers

Synovial Joints - Membranes

• Fibrous membrane protects and gives joint stability and connects with the periosteum
• Synovial membrane lines inner fibrous membrane but does not cover articular cartilage and secretes protective synovial fluids

Synovial Joints - Ligaments and Discs

• Articular capsules are strengthened by articular ligaments that connect articulating bones
• Articular ligaments are used to limit undesired and excessive joint movement
• Articular ligaments consist of instrinsic and extrinsic ligaments
• Intrinsic ligaments are the thickening of a portion of the articular capsule
• Articular discs help hold bones together, attached to only one bone in some joints
• Some joints feature a labrum which deepens the articular surface for one of the bones

Synovial Joints - Classification

• Their classification is based on shape of articulating surfaces and type of movement

Synovial Joints - Types

• Plane
• Hinge
• Ellipsoid (condyloid)
• Saddle
• Ball and socket
• Pivot

Synovial Joints - Plane Joints

• It permits gliding and sliding movements and its articular surfaces are flat
• In plane joints, movement occurs on one axis and as such are called uniaxial joints
• The acromioclavicular joint is an example of a plane joint

Synovial Joints - Hinge Joints

• Hinge joints are also uniaxial and allow flex. and ext. around the transverse axis
• Bones are joined with strong collateral
  ligaments. e.g. elbow and knee joints

Synovial Joints - Condyloid Joints

• Allows movements in 2 axis
• They are biaxial joints
• The axes are trans-sagit
• It is exemplified by radiocarpal and MTP joints (metacarpophalyngeal)

Synovial Joints - Saddle Joints

• Articulating surfaces resemble saddle shapes
• They are concave and convex
• The carpometacarpal in the thumb is an example

Synovial Joints - Ball and Socket joints

• A movable multiaxial
• The spheroidal surface shape of a bone connects with the socket shaped articular surface of another
• Shoulders are ball and socket joints

Synovial Joints - Pivot Joints

• These are uniaxial
• They have rotation
• Rounded sections rotate in an osteofibrous sleeve or ring

Joints - Innervation

• According to Hilton's law, joint-innervating nerves consist of muscular branches acting around joints and also sensory regions
• Nerves transmit conscious proprioception and pain

Joints - Vessel and Blood Supply

• Joints are supplied vessels for blood circulation
• They come from surrounding vessels

Joint Stability

• The negative pressure exists
• There exists joint capsules and ligaments
• Also muscles and tendons are around the joint
• Also the articular surface shape

Muscles - General Information

• Myologia is the study of muscles.
• Muscles move the bones, therefore, move the body parts.

Muscle Classifications

• There are three types
• Striated, skeletal, these can be voluntarily controlled
• Smooth muscle, non striated, these are involuntary
• Cardiac muscle is involuntary

Muscle Innervation Classifications

• Striated work with somatic nervous system
• Smooth and cardiac work with autonomic nervous system

Skeletal Muscle Properties

• Skeletal muscles are formed of fusiform-type cells
• Skeletal muscle cells may be referred to as muscle fibers

Muscle Tissue: Fascia

• There is deep and superficial ascia

Muscle Structure

• Belly is the fleshy part
• Tendons, aponeurosis in certain muscles

Attachments on Tendons

• The tendons attach to the fascia, cartilage, skin or bones

Bursae and Tendinous Sheats

• Both are soft tissue pads filled fluid
• Bursae and tendinous sheaths are fluid-filled, helping prevent friction between tendons/tissue.

Muscle Terminology

• Muscles are generally given names according to their shapes, location, number of their bellies, function, and size:
• rhomboideus major – palmaris longus – biceps brachii – tibialis posterior – flexor carpi ulnaris – teres major-teres minor

Contraction

• When muscles engage they length lowers by ½ or ⅓
• Isotonic: Lengthens
• Isometric: Length maintained

Motor Unit

A motor neuron has cells in neuron

Motor Unit Innervation

• Single neuron may innervate thousands of muscles
• Also less muscles can be innervated (3-4, eye muscles)

Motor Unit Action

• Motor units exist in 1 muscle
• The units do not all need to engage during a action
• Count of contracting units determines force.

Muscle Movement and Coordination

• Prime mover
• Synergist muscle for supporter
• Antagonist oppose
• Fixator prevent motions

Explore osseous tissue, the rigid connective tissue forming the skeleton. Learn about bone functions: protection, support, movement, blood cell formation, and mineral storage. Discover bone composition and skeletal classification.