Difference between revisions of "Joints - Anatomy & Physiology"
Jump to navigation
Jump to search
| Line 1: | Line 1: | ||
<big><center>[[Musculoskeletal System - Anatomy & Physiology|'''BACK TO MUSCULOSKELETAL ANATOMY AND PHYSIOLOGY''']]</center></big> | <big><center>[[Musculoskeletal System - Anatomy & Physiology|'''BACK TO MUSCULOSKELETAL ANATOMY AND PHYSIOLOGY''']]</center></big> | ||
| + | |||
Joints comprise broadly two categories: | Joints comprise broadly two categories: | ||
*'''Synarthroses''' form joints that are relatively rigid | *'''Synarthroses''' form joints that are relatively rigid | ||
| Line 7: | Line 8: | ||
*Allow a variable degree of movement | *Allow a variable degree of movement | ||
| − | == | + | ==Fibrous Joints== |
*Most occur in the skull: known as '''sutures''' | *Most occur in the skull: known as '''sutures''' | ||
**Key in development: allow extension of individual bones during growth | **Key in development: allow extension of individual bones during growth | ||
| Line 15: | Line 16: | ||
*'''Gomphosis''': attachment of tooth to bone within its socket | *'''Gomphosis''': attachment of tooth to bone within its socket | ||
| − | == | + | ==Cartilaginous Joints== |
*'''Synchondroses''': eg. joints between epiphyses and diaphyses of juvenile long bones, disappear on maturity | *'''Synchondroses''': eg. joints between epiphyses and diaphyses of juvenile long bones, disappear on maturity | ||
**Permanent synchondroses: the joint between the skull and '''hyoid''' | **Permanent synchondroses: the joint between the skull and '''hyoid''' | ||
| Line 27: | Line 28: | ||
****Strenghten the area over the discs | ****Strenghten the area over the discs | ||
| − | == | + | ==Synovial Joints== |
*Articulating joints are separated by a fluid-filled joint cavity, which is bounded by a synovial membrane | *Articulating joints are separated by a fluid-filled joint cavity, which is bounded by a synovial membrane | ||
**Synovial membrane: pink connective tissue sheet, vascular and sensitive | **Synovial membrane: pink connective tissue sheet, vascular and sensitive | ||
| Line 68: | Line 69: | ||
==Links== | ==Links== | ||
*[[Joints|Joint Pathology]] | *[[Joints|Joint Pathology]] | ||
| + | |||
| + | <big><center>[[Musculoskeletal System - Anatomy & Physiology|'''BACK TO MUSCULOSKELETAL ANATOMY AND PHYSIOLOGY''']]</center></big> | ||
Revision as of 12:20, 18 July 2008
Joints comprise broadly two categories:
- Synarthroses form joints that are relatively rigid
- Diarthroses form joints that are freely movable
Joint Function:
- Absorb force of impact, transfer force via cartilage to bone
- Allow a variable degree of movement
Fibrous Joints
- Most occur in the skull: known as sutures
- Key in development: allow extension of individual bones during growth
- Gradually eliminated as ossification progresses
- Syndesmoses: facing areas of two bones joined by connective tissue ligaments, very limited movement allowed
- Eg. Joints of the metacarpus in the horse
- Gomphosis: attachment of tooth to bone within its socket
Cartilaginous Joints
- Synchondroses: eg. joints between epiphyses and diaphyses of juvenile long bones, disappear on maturity
- Permanent synchondroses: the joint between the skull and hyoid
- Symphysis: articulating bones are divided by a succession of tissues, with cartilage covering the bones or the tissue between
- Eg. mandibular, pelvic, vertebral
- Fibrocartilagenous joints
- Form major union between vertebrae, except first two cervical vertebrae
- Nucleus pulposus is position eccentrically within annulus fibrosis
- Vertebrae in thoracic region have conjugal ligaments
- Extend from rib to rib on opposite sides
- Strenghten the area over the discs
Synovial Joints
- Articulating joints are separated by a fluid-filled joint cavity, which is bounded by a synovial membrane
- Synovial membrane: pink connective tissue sheet, vascular and sensitive
- Can be unsupported (membrane may pouch, allowing remote access), resting on an outer fibrous capsule, or separated from capsule by pads of fat
- No continuous covering of cells
- Where cells exist, they produce lubricant (aminoglycans) of synovial fluid
- Synovial fluid: Nourishes and lubricates articular cartilage
- Derived from synovial membrane cells and blood plasma
- Normal amount in canine joint - 0.01 - 1.0 ml; possible in equine/bovine: 20-40mL
- Transparent to light yellow (horses)
- Usually very thick due to high hyaluronic acid, forms strands
- Windrowing of cells on smear
- Normal protein < 25g/l (all species)
- Normal cell count: Large mononuclear cells, <12% neutrophils, <11% lymphocytes
- Small animals - < 3 x 10e9/L
- Horses - < 0.5 x 10e9/L
- Cows - < 1 x 10e9/L
- Synovial membrane: pink connective tissue sheet, vascular and sensitive
- Often the synovial membrane is reinforced by a fibrous capsule and ligaments restricting joint movement and providing stability
- Encloses bone and muscle insertions within joint capsule
- Supplied by blood vessels and nerve endings
- Articular cartilage covers the articular surfaces
- Usually, this is Hyaline, although Fibrocartilage or fibrous tissue can substitute
- Articular cartilage is avascular and insensitive
- Nutrients via diffusion from synovial fluid and nearby vessels (adjoining tissue and marrow cavities)
- Some joints possess intracapsular discs or menisci to provide congruence and enable complicated movements
- Eg. Temperomandibular joint, paired menisci of the stifle joint
- Limited response to injury, Little repair capacity
Joint Movements
- Translation: Flat surfaces slide against each other, producing no change in orientation of their bodies
- Rotation: Moving bone turns on an axis perpendicular to articulation
- Swing: Moving bone turns on an axis parallel to articulation
- Flexion:(aka palmar flexion) Angle between two segments of a limb is reduced
- Extension: Angle between two segments of a limb is increased
- Overextension: (aka dorsal flexion) Eg, Posture of equine fetlock standing at rest
- Adduction: Pendular movement toward the median plane
- Abduction: Pendular movement away from the median plane
- Circumduction: Combination of flexion and extension that allows a limb to create a circular movement