The Skeleton: Joints, Vertebrae and Sternum Flashcards
Name 5 functions of the skeleton
- Rigid support framework
- Protection of soft tissues
- Facilitation of movement
- Resistance to gravity and other forces applied to the body
- Surface area for attachment of muscles
What does the Axial skeleton comprise of? (3)
- Head
- Neck
- Trunk
(includes upper and lower limbs)
What does the Appendicular skeleton comprise of? (3)
- Pectoral (includes clavicles and scapulae)
- Pelvic girdles (include hip bones)
- Limbs
What are bumps on the surface of bones called? What do they do?
Tubercles, tuberosities, trochanters
Serve as a point of attachment of muscles or tendons
What are the grooves in bones for?
Smooth areas where blood vessels, nerves or tendons lie
What are the holes in bones called and what are they for?
Foramina, where blood vessels or nerves enter or leave the bone
What is surface/living anatomy?
The study of the relationship of the external features of the body to the underlying skeleton
What is a joint?
Site in the body where 2 or more bones meet or articulate, whether or not there is movement between them
Grouped according to the tissues that lie between the bones.
What are the 3 groups that joints can be classified into?
- Fibrous
- Cartilaginous
- synovial
What do ligaments do?
What are they made of?
- Connect bones to bones at joints
- Provide strength and restrict excessive movements
- Connective tissue with parallel arrays of collagen fibres (or less frequently of fibrillar protein called elastin)
What is a tendon?
What is is composed of?
- A structure connecting muscle and bone
- Consists of connective tissue comprised of parallel bundles of collagen fibres
Sometimes a tendon is flattened out as an aponeurosis
What is a fibrous joint?
Where are they present?
- A joint where adjacent bones are bound together by fibrous (collagen-containing) connective tissue.
- Present between flat bones (sutures) or between long bones (syndesmmoses)
Joints between bones of the cranium of the skull = sutures (Immovable joint)
Joints between the lower end of tibia and fibula, just above the ankle = syndesmosis (Little movement)
Fibrous joints provide stability but little movement
What are cartilaginous joints divided into?
- Primary cartilaginous (synchondrosis)
- Secondary cartilaginous (symphysis)
What is a primary cartilaginous joint and where are they found?
- Consists of hyaline cartilage
- Found between developing and maturing bone (in adults link ribs to costal cartilages)
Whats a secondary cartilaginous joint and where are they found?
*They permit a limited amount of movement and lie on the midline of the
- Surfaces of articulating bones are lined by hyaline cartilage with a fibrocartilage disc/pad in between.
- Joints between vertebral bodies
* intervertebral discs
* manubriosternal joint (between manbrium and sternum)
* symphysis pubis (between 2 pubic bones)
Whats the main characteristic of a synovial joint?
The presence of a cavity that contains a small volume of synovial fluid
What ensures minimal friction during movements of the synovial joint?
- articular hyaline cartilage covering the surface of the bones
- synovial fluid
Describe/name the structures of the synovial joint
- Surfaces of bone covered with **articular hyaline cartilage **
- joint is **enclosed within fibrous capsule **
- fibrous capsule **inner lined **with synovial membrane
- Synovial membrane secretes synovial fluid into joint cavity
- Capsule may be strengthened on outer surface by ligaments
Synovial joints classified on shapes of articulating bones
What are the 6 types of synovial joints?
- Hinge (uni-axial) common
- Condyloid/Ellipsoid (bi-axial) common
- Ball and socket (multi-axial) common
- Hinge
- Saddle
- Pivot
How does a hinge joint permit movements? Give examples
- In one plane only (uni-axial)
* Only flexion and extension
e.g. Elbow, Interphalangeal joint in fingers
How does an ellipsoid/condyloid joint permit movements? Give examples
- In two planes (bi-axial)
* Flexion/extension
* Abduction/adduction
* Circumduction may also occur
e.g. wrist
How does a ball and socket joint permit movements? Give examples
- Sphere articulates with a spherical cup. Permits movement in 3 planes (multi-axial)
* Flexion/extension
* abduction/adduction
* medial/lateral rotation
*Circumduction also occurs at such joints *
Where is a plane joint found and how does it move?
- found between articular processes of vertebrae
- gliding movements
Where are pivot joints found and how do they move
- Rounded process of bone fits into a bony ligamentous socket
- By rotation
What is a saddle joint and what movement does it permit?
- Opposing surfaces are saddle-shaped
- Bi-axial movement permitting:
* abduction/adduction
* flexion/extension
Movements occur in planes at right angles so circumduction is possible
What affects the stability of joints?
- Shape, size and form of articular surfaces
- Ligaments
- Tone of muscles around joint
- What are the joints in the skull?
- What skeleton does the skull comprise (axial/appendicular)?
- What is the largest hole in the skull?
- Immovable fibrous joints (sutures)
- Facial and cranial skeleton
- A number of holes (foramina), the largest being foramen magnum (Spinal cord)
What are the structures in the skull that articulate with the 1st cervical vertebra (atlas) ?
The interior surfaces which lie on either side of the foramen magnum, the occipital condyles
How is the vertebral column dividied and how many vertebrae are there?
- Cervical (7)
- Thoracic (12)
- Lumbar (5)
- Sacral (5)
- Coccygeal
What abnormal curvatures of the vertebral column can develop?
- Kyphosis (abnrmal antero-posterior)
- Scoliosis (lateral-curvatures)
Label the axial skeleton (anterior view)
Label the axial skeleton (lateral view)
What are the structures of vertebrae?
- Body anteriorly
- Vertebral arch posteriorly (pedicles form the sides, flattened laminae complete the posterial side)
These enclose the space called the vertebral foramen (spinal canal)
How are vertebral bodies articulated with adjacent ones?
Secondary cartilaginous joint - the intervertebral disc
What does the spinous process which projects posteriorly from the lamina of vertebra do?
- Provides muscle and ligament attachment
- From the junction of the pedicle and lamina on each side, a transverse process projects laterally
What 2 vertebrae are different from the rest?
How are they similar to the others?
How are they different in structure and what does it allow?
- Atlas (C1)
Axis (C2) - They both have foramina in their transverse processes which accommodate vertebral artery and vein on either side
- The atlas (C1) has a ring shape structure.
The axis (C2) has an upwards facing long bony process called the dens which forms a joint with C1 to allow turning movements of the head
How does the atlas connect with the occipital condyle of the skull?
The condylar part of occipital bone forms lateral walls of the foramen magnum (hole for spinal cord)
The 2 occipital condyles serves as an articular surface with the atlas (atlanto-occipital joint)
Occipital joint formed between occipital condyles and C1 allow free flexion/extension and some lateral flexion. No rotation
How is the sacrum formed?
What failure in this form is useful for anasthetic purposes?
- Formed by the fusion of 5 sacral vertebrae
- The failure of the vertebrae to fuse, specifically the laminae leaves the lower end of the spinal canal open, useful access for anaesthetists to administer anaesthetic.
What joint does the sacrum form with the hip?
Sacrum presents roughened surfaces for articulation with each hip bone at the sacroiliac joint
What 3 movements can the vertebral column do?
- Flexion/extension (back and forth)
- Lateral flexion (movement from midline to left of right)
- Rotation about a vertical axis
exceptions for the first two cervical vertebrae
What ligament does the upper cervical vertebrae lie deep to?
Ligamentum nuchae
Surface anatomy
At what C can you visibly see the spinous processes of vertebrae?
Most superior = C7 (vertebra prominens)
Inferior = T1
What does the skeleton of the thoracic cage formed of?
- thoracic vertebrae
- ribs (costae)
- costal cartilages
- Sternum
What is the thoracic inlet? What is it bound by?
- communication between the neck and thoracic cavity
- bound by ribs, manubrium of sternum and T1 (first thoracic vertebra)
What does the sternum consist of?
- Manubrium (upper part) (Bone)
- Body (middle longest) (Bone)
- Xiphoid process (cartilage)
Why is the secondary catilaginous joing between manubrium and body of sternum important clinically? What is it called?
Manubriosternal joint
Important landmark forming the sternal angle used to identify specific ribs, e.g. assessing position of heart and vessels
What number costal cartilages does the sternum articulate with?
1st: manubrium
2nd: sternal angle
3rd-6th: body
7th-9th: united cartilage the costal margin which diverges from the xiphoid
Whats the difference between circumduction and rotation?
- Circumduction is a circular movement where one body part stays stationary (e.g. shoulder)
- Rotation is a circular movement around an axis (e.g. wrist)
