Principles Anatomy Outcomes Flashcards
What is a joint?
A joint is an articulation between adjacent parts of the skeleton (i.e. bones and cartilage).
What does the presence of joints enable our skeleton to do?
Joints provide mobility and enable locomotion.
Name the three subcategories of fibrous joints, explain them, and give an example of each.
SYNDESMOSES: fibrous membranes uniting bones via fibrous sheets, e.g. = interosseous membrane between the tibia and fibula. They are partially movable.
SUTURES: joints between the bones of the skull, e.g. = coronal suture. They are highly stable.
FONTANELLES: wide sutures in the neonatal skull, e.g. = anterior, posterior, & lateral fontanelles. These allowing growing bones to “slide” over each other.
Name the TWO subcategories of cartilaginous joints, explain them, and give an example of each.
PRIMARY CARTILAGINOUS: synchondrosis- i.e. bones connected by hyaline cartilage. These may be temporary, e.g. EPIPHYSEAL GROWTH PLATE, which permits growth in bone length, when growth is complete it undergoes ossification & fusion. E.g. = between the epiphysis and diaphysis of long bones, between the occipital & the sphenoid.
SECONDARY CARTILAGINOUS: symphysis- i.e. 2 closely joined bones, forming either an immovable or completely fused joint. These are strong fibrocartilage. E.g. = invertebrate discs.
Nb: both types of joint can slip, primary-> slipped femoral epiphysis. Secondary-> slipped disc.
Name 3 features of a typical synovial joint.
Any 3 of:
- Two or more bones articulating with each other.
- Articulated surfaces are covered in hyaline ‘articular’ cartilage.
- A capsule wraps around the joint: a superficial, strong, fibrous layer & a deeper synovial membrane layer which secretes synovial fluid.
- Joint cavity: contains synovial fluid (cushioning, nourishing, lubricating).
- Supported by ligaments (fibrous bands from bone-bone-> strength and stability).
- Associated with skeletal muscles and their tendons (fibrous band from muscle-bone, which insert onto bones at either side of the joint).
- Associated with bursae (prevent friction), = extensions of joint cavity/closed sacs separate from the joint cavity.
- May have special features, e.g. articular disc of the TMJ.
What is meant by the term bursa?
A fluid filled sac/cavity at a joint which prevents friction..
What is meant by a slipped femoral epiphysis?
The femoral epiphysis remains in the hip socket, but the metaphysics moves in an anterior direction with external rotation.
Summarise the basic anatomy of an invertebral disc.
Outer ring of annulus fibrosus- a fibrous ring of fibrocartilage.
Inner soft nucleus pulposus - a soft centre, which is 90% water in newborns.
Each disc allows small amounts of movement in all direction, when combined this allows for considerable movement.
Describe what is meant by the term herniation/dislocation/ slipped disc.
It is the complete loss of contact between articular surfaces.
Describe what is meant by the term subluxation.
A reduced area of contact between articular surfaces.
What is meant by a torn ligament?
Ligament injury, but articular surfaces are still in their normal anatomical relations to each other.
Summarise the relative stability of the different joint types.
Fibrous is most stable, then cartilaginous, then synovial (least stable).
Summarise the relative mobility of the different joint types.
Synovial is most mobile, then cartilaginous, then fibrous (least mobile).
What is meant by the normal range of movement of a joint?
The full movement potential of a joint, usually its range of flexion and extension. Note: some patients may have natural or pathological hypermobility.
Define hypermobility of a joint.
The joint has a range of movement greater than that of the normal range of movement.
Name three joints which commonly dislocate.
Any 3 of:
- Temporomandibular
- Acromioclavicular
- Craniovertebral
- Shoulder
- Elbow
- Hip
- Pubic symphysis
- Interphalangeal (DIP & PIP)
- Knee
- Ankle
Describe the anatomy of the TMJ.
Right and left TMJ. The synovial articulations between the mandibular fossa, & the articular tubercle of the temporal bone SUPERIORLY, & the head of the condylar process of the mandible INFERIORLY.
What happens in a TMJ dislocation?
The head of the condylar process of the mandible becomes stuck anterior to the articular tubercle of the temporal bone. It may be unilateral or bilateral. Chin remaining in midline suggests bilateral.
Are joints well or poorly vascularised? What challenges does this present if the joint is dislocated?
Joints are well vascularised, and periarticular arterial anastomoses are common.
If the joint is dislocated, this may result in damage of these arteries, and compromise blood flow distal of the joint.
Which sensations are detected by the sensory receptors of joint nerves?
Pain, touch, temperature and proprioception.
Define endochondral ossification.
It is the process in which an initially small, hyaline cartilage version of a bone, grows, ossifies and subsequently becomes a bone.
Name the parts of a long bone.
Epiphysis, epiphyseal growth plate, metaphysis, and diaphysis.
What is an epiphyseal growth plate? Name an example.
Temporary hyaline cartilage, permits growth in bone length. When growth is complete it undergoes ossification & fusion. E.g. = between the epiphysis and diaphysis of long bones, between the occipital & the sphenoid.
What are the layers of bone? Describe each.
- Outer layer of compact cortical bone: which is dense, strong & heavy.
- Inner medulla of spongy/trabecullar bone: porous, weak & light.
- Central medullary cavity: may contain bone marrow. Red in hematopoeitic bones, and white/fatty marrow in non-blood cell forming bones.