The Skeleton: Joints, Vertebrae and Sternum

Question 1

Name 5 functions of the skeleton

Answer 1

1. Rigid support framework
2. Protection of soft tissues
3. Facilitation of movement
4. Resistance to gravity and other forces applied to the body
5. Surface area for attachment of muscles

Question 2

What does the Axial skeleton comprise of? (3)

Answer 2

1. Head
2. Neck
3. Trunk
   (includes upper and lower limbs)

Question 3

What does the Appendicular skeleton comprise of? (3)

Answer 3

1. Pectoral (includes clavicles and scapulae)
2. Pelvic girdles (include hip bones)
3. Limbs

Question 4

What are bumps on the surface of bones called? What do they do?

Answer 4

Tubercles, tuberosities, trochanters

Serve as a point of attachment of muscles or tendons

Question 5

What are the grooves in bones for?

Answer 5

Smooth areas where blood vessels, nerves or tendons lie

Question 6

What are the holes in bones called and what are they for?

Answer 6

Foramina, where blood vessels or nerves enter or leave the bone

Question 7

What is surface/living anatomy?

Answer 7

The study of the relationship of the external features of the body to the underlying skeleton

Question 8

What is a joint?

Answer 8

Site in the body where 2 or more bones meet or articulate, whether or not there is movement between them

Question 9

Grouped according to the tissues that lie between the bones.

What are the 3 groups that joints can be classified into?

Answer 9

1. Fibrous
2. Cartilaginous
3. synovial

Question 10

What do ligaments do?
What are they made of?

Answer 10

1. Connect bones to bones at joints
2. Provide strength and restrict excessive movements
3. Connective tissue with parallel arrays of collagen fibres (or less frequently of fibrillar protein called elastin)

Question 11

What is a tendon?
What is is composed of?

Answer 11

1. A structure connecting muscle and bone
2. Consists of connective tissue comprised of parallel bundles of collagen fibres

Sometimes a tendon is flattened out as an aponeurosis

Question 12

What is a fibrous joint?
Where are they present?

Answer 12

1. A joint where adjacent bones are bound together by fibrous (collagen-containing) connective tissue.
2. 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

Question 13

What are cartilaginous joints divided into?

Answer 13

1. Primary cartilaginous (synchondrosis)
2. Secondary cartilaginous (symphysis)

Question 14

What is a primary cartilaginous joint and where are they found?

Answer 14

1. Consists of hyaline cartilage
2. Found between developing and maturing bone (in adults link ribs to costal cartilages)

Question 15

Whats a secondary cartilaginous joint and where are they found?

*They permit a limited amount of movement and lie on the midline of the

Answer 15

1. Surfaces of articulating bones are lined by hyaline cartilage with a fibrocartilage disc/pad in between.
2. Joints between vertebral bodies
   * intervertebral discs
   * manubriosternal joint (between manbrium and sternum)
   * symphysis pubis (between 2 pubic bones)

Question 16

Whats the main characteristic of a synovial joint?

Answer 16

The presence of a cavity that contains a small volume of synovial fluid

Question 17

What ensures minimal friction during movements of the synovial joint?

Answer 17

1. articular hyaline cartilage covering the surface of the bones
2. synovial fluid

Question 18

Describe/name the structures of the synovial joint

Answer 18

1. Surfaces of bone covered with **articular hyaline cartilage **
2. joint is **enclosed within fibrous capsule **
3. fibrous capsule **inner lined **with synovial membrane
4. Synovial membrane secretes synovial fluid into joint cavity
5. Capsule may be strengthened on outer surface by ligaments

Question 19

Synovial joints classified on shapes of articulating bones

What are the 6 types of synovial joints?

Answer 19

1. Hinge (uni-axial) common
2. Condyloid/Ellipsoid (bi-axial) common
3. Ball and socket (multi-axial) common
4. Hinge
5. Saddle
6. Pivot

Question 20

How does a hinge joint permit movements? Give examples

Answer 20

1. In one plane only (uni-axial)
   * Only flexion and extension

e.g. Elbow, Interphalangeal joint in fingers

Question 21

How does an ellipsoid/condyloid joint permit movements? Give examples

Answer 21

1. In two planes (bi-axial)
   * Flexion/extension
   * Abduction/adduction
   * Circumduction may also occur

e.g. wrist

Question 22

How does a ball and socket joint permit movements? Give examples

Answer 22

1. 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 *

Question 23

Where is a plane joint found and how does it move?

Answer 23

1. found between articular processes of vertebrae
2. gliding movements

Question 24

Where are pivot joints found and how do they move

Answer 24

1. Rounded process of bone fits into a bony ligamentous socket
2. By rotation

Question 25

What is a saddle joint and what movement does it permit?

Answer 25

1. Opposing surfaces are saddle-shaped 2. Bi-axial movement permitting: * abduction/adduction * flexion/extension *Movements occur in planes at right angles so circumduction is possible*

Question 26

What affects the stability of joints?

Answer 26

1. Shape, size and form of articular surfaces 2. Ligaments 3. Tone of muscles around joint

Question 27

1. What are the joints in the skull? 2. What skeleton does the skull comprise (axial/appendicular)? 3. What is the largest hole in the skull?

Answer 27

1. Immovable fibrous joints (**sutures**) 2. Facial and cranial skeleton 3. A number of holes (**foramina**), the largest being **foramen magnum** (Spinal cord)

Question 28

What are the structures in the skull that articulate with the 1st cervical vertebra (atlas) ?

Answer 28

The interior surfaces which lie on either side of the foramen magnum, the **occipital condyles**

Question 29

How is the vertebral column dividied and how many vertebrae are there?

Answer 29

1. Cervical (7) 2. Thoracic (12) 3. Lumbar (5) 4. Sacral (5) 5. Coccygeal

Question 30

What abnormal curvatures of the vertebral column can develop?

Answer 30

1. Kyphosis (abnrmal antero-posterior) 2. Scoliosis (lateral-curvatures)

Question 31

Label the axial skeleton (anterior view)

Answer 31

Question 32

Label the axial skeleton (lateral view)

Answer 32

Question 33

What are the structures of vertebrae?

Answer 33

* 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)***

Question 34

How are vertebral bodies articulated with adjacent ones?

Answer 34

Secondary cartilaginous joint - the intervertebral disc

Question 35

What does the spinous process which projects posteriorly from the lamina of vertebra do?

Answer 35

* Provides muscle and ligament attachment * From the junction of the pedicle and lamina on each side, a transverse process projects laterally

Question 36

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?

Answer 36

1. Atlas (C1) Axis (C2) 2. They both have foramina in their transverse processes which accommodate vertebral artery and vein on either side 3. 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

Question 37

How does the atlas connect with the occipital condyle of the skull?

Answer 37

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

Question 38

How is the sacrum formed? What failure in this form is useful for anasthetic purposes?

Answer 38

1. Formed by the fusion of 5 sacral vertebrae 2. 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.

Question 39

What joint does the sacrum form with the hip?

Answer 39

Sacrum presents roughened surfaces for articulation with each hip bone at the **sacroiliac joint**

Question 40

What 3 movements can the vertebral column do?

Answer 40

1. Flexion/extension (back and forth) 2. Lateral flexion (movement from midline to left of right) 3. Rotation about a vertical axis ## Footnote *exceptions for the first two cervical vertebrae*

Question 41

What ligament does the upper cervical vertebrae lie deep to?

Answer 41

Ligamentum nuchae

Question 42

# Surface anatomy At what C can you visibly see the spinous processes of vertebrae?

Answer 42

Most superior = C7 (vertebra prominens) Inferior = T1

Question 43

What does the skeleton of the thoracic cage formed of?

Answer 43

* thoracic vertebrae * ribs (costae) * costal cartilages * Sternum

Question 44

What is the thoracic inlet? What is it bound by?

Answer 44

1. communication between the neck and thoracic cavity 2. bound by ribs, manubrium of sternum and T1 (first thoracic vertebra)

Question 45

What does the sternum consist of?

Answer 45

* Manubrium (upper part) (Bone) * Body (middle longest) (Bone) * Xiphoid process (cartilage)

Question 46

Why is the secondary catilaginous joing between manubrium and body of sternum important clinically? What is it called?

Answer 46

**Manubriosternal joint** Important landmark forming the sternal angle used to identify specific ribs, e.g. assessing position of heart and vessels

Question 47

What number costal cartilages does the sternum articulate with?

Answer 47

1st: manubrium 2nd: sternal angle 3rd-6th: body 7th-9th: united cartilage the costal margin which diverges from the xiphoid

Question 48

Whats the difference between circumduction and rotation?

Answer 48

1. Circumduction is a circular movement where one body part stays stationary (e.g. shoulder) 2. Rotation is a circular movement around an axis (e.g. wrist)