Unit 10: Skeletal System

Question 1

What are the two types of bone?

Answer 1

Compact and spongy

Question 2

What is the structure/contents of compact bone?

Answer 2

Covers external surfaces of ALL bones. Is composed of osteons, each of which contains:
i. Lamellae = concentric circles of matrix
ii. Lacunae (w/ osteocytes) = btw. lamellae (space w/in matrix where osteocytes live)
iii. Canaliculi = small channels that connect osteocytes to blood supply and to each other
iv. Central Canal = contains blood vessels and nerves - lined w/ endosteum
v. Perforating Canal = perpendicular to central canal - carry blood and nerve supply from periosteum to central canals and medullary cavity

Question 3

What is the structure/contents of spongy bone?

Answer 3

• NO osteons
• have trabeculae (irregularly arranged lamellae)
• canaliculi connect osteocytes in lacunae
• found in:
  
  • flat and irregular bone (skull, ribs, vertebrae)
  • long bones (epiphyses, lining medullary cavity)
• space contain bone marrow (red marrow produces blood cells)

Question 4

What is anatomical position?

Answer 4

Feet, face, and PALMS forward

Question 5

What are the directional terms?

Answer 5

1. Superior = toward head end/upper part of body: above
2. Inferior = toward feet end/lower part of body: below
3. Anterior/ventral = toward or at front of body
4. Posterior/dorsal = toward or at back of body
5. Medial = midline/middle (ex. = heart = medial to arm)
6. Lateral = away from midline (arms = lateral to chest)
7. Superficial = toward/on body surface
8. Deep = away from body surface: more internal

Question 6

What are the two divisions of the skeletal system?

Answer 6

Axial and appendicular skeletons

Question 7

Info on axial skeleton

Answer 7

• = 80 bones that form central core of body; includes:
  a) skull
  b) hyoid bone
  c) vertebral column
  d) thoracic cage (sternum and ribs)

Question 8

Info on appendicular skeleton

Answer 8

• = 126 bones = limbs and bones that attach them to axial skeleton (girdles); includes:
  a) pectoral girdle
  b) pelvic girdle
  c) upper limb (arm, forearm, and hand)
  d) lower limb (thigh, leg, and foot)

Question 9

What are the connections between bones called?

Answer 9

Articulations (ex. = the humerus articulates w/ the scapula)

Question 10

AXIAL - What are the three main bone groupings for the skull?

Answer 10

1. cranium (8 bones) - next to brain
2. facial bones - 14 bones
3. auditory ossicles - 6 bones (3 on each side in the middle ears)

Question 11

Summary of bones in (1) cranium

Answer 11

i. 1 frontal (forehead)
ii. 2 parietal
iii. 2 temporal
iv. 1 sphenoid
v. 1 ethmoid - forms superior and middle nasal chonchae
vi. 1 occipital

Question 12

Summary of (2) facial bones

Answer 12

i. 2 nasal
ii. 2 maxillae
iii. 2 zygomatic
iv. 2 lacrimal
v. 2 palatine (the two palatine and maxillae bones form the hard palate)
vi. 2 inferior nasal chonchae
vii. 1 vomer
viii. 1 mandible

Question 13

Summary of (3) auditory ossicles - for sound transmission

Answer 13

i. 2 incus
ii. 2 malleus
iii. 2 stapes

Question 14

What is the hyoid bone?

Answer 14

• no articulations (joints/connections to other bones)
• attaches muscles of tongue and neck, assists in swallowing

Question 15

What are the 5 regions of vertebrae and what is the total number in each?

Answer 15

26 vertebrae, separated into 5 regions:
a) cervical (7) - breakfast at 7
b) thoracic (12) - lunch at 12
c) lumbar (5) - supper at 5
d) sacrum
e) coccyx

Question 16

What is the general structure of vertebrae?

Answer 16

a) body - thick anterior portion
b) spinous process (1) - median posterior projection
c) transverse process (2) - lateral bony projections for muscle attachment
d) lamina (2) - connects the two processes
e) pedicle (2) - connects body to transverse process
f) vertebral foramen - hole for spinal cord
g) superior and inferior articular facets - articulate w/ vertebrae above and below
h) intervertebral foramina - exit for spinal nerves

Question 17

What are the characteristics of the (a) cervical (C1-C7) vertebrae?

Answer 17

C1-C7: all have a transverse foramen in each transverse process (for passage of vertebral arteries). C1 and C2 do not follow general vertebral structure.
- C1 = atlas
- no body, no spinous process
- articulates w/ occipital bone of skull
- allows flexion and extension of neck (“yes” motion)
- C2 = axis
- dens (= odontoid process)
- pivot joint around which atlas swivels
- allows rotation of head on neck (“no” motion_
- C3-C7 follow general vertebral structure

Question 18

Vertebral characteristics of (b-e) thoracic, lumbar, sacrum, and coccyx.

Answer 18

b) thoracic (T1-T12) - ALL articulate w/ ribs via costal facets
c) lumbar (L1-L5) - support upper body weight; ALL have large bodies and rectangular spinous processes
d) sacrum = 5 fused vertebrae; articulates w/ ilium (appendicular skeleton) and 5th lumbar vertebra (L5)
e) coccyx = 3-5 fused vertebrae, usually 4; = tailbone

Question 19

What is the curvature of the spinal column (based on S-shaped lateral view)

Answer 19

a) cervical and lumbar regions have a concave posterior curve
b) thoracic and sacrum regions have a convex posterior curve

Question 20

What are the three abnormal curvatures of the spinal column?

Answer 20

a) scoliosis = spinal column curves laterally
b) kyphosis = exaggerated thoracic curve
c) lordosis = exaggerated lumbar curve

Question 21

What are the two parts of the thoracic cage? (Which protects the thoracic organs).

Answer 21

a) sternum (breast bone) = fusion of 3 bones:
i. manubrium - superior
ii. body - middle
iii. xiphoid process - inferior
b) ribs = 12 pairs total (articulate posteriorly w/ T1-T12)
- 7 pairs = true ribs (superior) - attach directly to sternum via costal cartilage (hyaline cartilage)
- 5 pairs = false ribs (inferior) - ribs 8-10 attach indirectly to sternum via the costal cartilage for rib 7; ribs 11-12 are not attached to sternum = floating ribs

Question 22

What are the four parts of the appendicular skeleton?

Answer 22

1. pectoral girdle (upper limb girdle)
2. pelvic girdle (lower limb girdle)
3. upper limb (in anatomical position)
4. lower limb (in anatomical position)

Question 23

Info on (1) pectoral girdle

Answer 23

a) clavicle (collarbone)
- articulates w/ sternum (manubrium) and scapula (acromion process)
- connects axial and appendicular skeletons
b) scapula (shoulder blades)
- spine (runs along posterior surface of scapula)
- acromion process - articulates w/ clavicle
- glenoid cavity - articulates w/ head of humerus
- coracoid process - attachment point for muscles of arm and chest

Question 24

Info on (2) pelvic girdle

Answer 24

Composed of 2 os coxae (hip bones) formed by the fusion of 3 bones:
a) ilium (superior) - articulates w/ sacrum
b) ischium (posterior)
c) pubis (anterior) - left and right joined by pubic symphysis

Joints:
a) pubic symphysis - cartilaginous joint btw. the pubic bones
b) sacroiliac joint - sacrum and ilium
c) acetabulum - articulates w/ head of femur

Question 25

Info on (3) upper limb

Answer 25

a) humerus b) radius (lateral) / ulna (medial) c) carpals (8) - wrist d) metacarpals (5) = palm e) phalanges (14) = digits (fingers and thumb)

Question 26

Info on (4) lower limb

Answer 26

a) femur b) patella (knee cap) c) tibia (medial) / fibula (lateral) d) tarsals (7) - talus - articulates w/ tibia - calcaneus - heel bone e) metatarsals (5) = sole f) phalanges (14) = digits (toes)

Question 27

What are the long bone components?

Answer 27

1) diaphysis - shaft (body) 2) epiphyses - proximal and distal extremities 3) epiphyseal plate - hyaline cartilage - used for bone growth (length) 4) epiphyseal line - replaces plate w/ bone when growth complete - plate/line - where the diaphysis and epiphyses meet 5) medullary cavity - red marrow in child, yellow marrow in adult 6) periosteum - external surface - 2 layers of CT = outer (dense irregular), and inner (mainly osteoblasts and osteoclasts) - allows bone to grow in diameter 7) endosteum - lines medullary cavity AND canals (contains osteoblasts and osteoclasts) 8) articular cartilage - hyaline (only at articulation points) - prevents friction btw. bones (no periosteum here)

Question 28

What are articulations/joints?

Answer 28

Point of contact btw. 2 or more bones; 2 classes = structural and functional: - structural classification (anatomical), based on: - presence/absence of joint cavity - type of CT that joins the bones - functional classification (physiological), based on: - degree of movement

Question 29

What are the types of structural joints?

Answer 29

a) Fibrous (no joint cavity, fibrous CT - e.g. sutures in skull [fontanels in a newborn]) b) Cartilaginous (no joint cavity, cartilage attaches bones - e.g. pubic symphysis, costal cartilages of ribs) c) Synovial (like shoulder, elbow, hip, knee), structure: - articulating bones are connected by the joint capsule and ligaments - articular cartilage (hyaline) of bone - space btw. bones is the joint cavity (contains synovial fluid) - articular/joint capsule encloses the joint cavity - outer layer = fibrous capsule (attaches to periosteum) - inner layer = synovial membrane (CT only) - secretes synovial fluid

Question 30

What are the types of synovial structural joints?

Answer 30

Grouped according to shape of articulating bones: i. plane/gliding - flat surfaces (like sacroiliac) ii. hinge - concave/convex surfaces (like elbow, knee) iii. pivot - projection in ring (like dens [on axis] in atlas) iv. ball and socket - great freedom of movement (like humerus in glenoid fossa, and femur in acetabulum hip)

Question 31

What are the types of function joints?

Answer 31

a) Synarthrotic = immovable (like skull sutures) b) Amphiarthrotic = slightly moveable (like pubic symphysis) c) Diarthrotic = freely moveable (like hip, shoulder)