Skeletal Tissue and the Axial Skeleton Flashcards
1
Q
Skeleton Overview
A
- Composed of 206 bones
Provides
o Support, protection, movement, mineral storage, blood cell production
2
Q
Histology
A
- Skeleton formed primarily from connective tissues
o All CT contains cells and extra cellular matrix
o Matrix contains
Fibres
Ground Substance (between cells and fibres)
o Cartilage and bone tissue (different types of supportive CT)
3
Q
Supportive Cartilage
A
Three Types include
o Hyaline Cartilage
o Fibrocartilage
o Elastic Cartilage
Function
- Provides basic template for the foetal skeleton before bone formation
- Binds and protects structures of the adult skeleton
- Has properties of rubber, can bear weight, flexible
4
Q
Cartilage (Cells and Matrix)
A
Cells = chondrocytes
o Cyte = mature cell
o Found in spaces called lacunae
Matrix
o Contains ground substance (composes of proteoglycans, creates flexible, resilient structures
o Many collagenous fibres (for tensile strength)
5
Q
Hyaline Cartilage
A
- Most abundant cartilage in the skeleton
- Located at epiphyses of long bones, anterior end of ribs and airways
- Matrix appears glass-like
- Collagenous fibers are not visible
6
Q
Fibrocartilage
A
- Strongest of cartilages, many collagenous fibres
- Located in pad-like structures (knee menisci), intervertebral disks and pubic symphysis
7
Q
Bone
A
- A hard CT
- Consists of cells and mineralised matrix
- Strength and rigidity allows bones to support organs
Cells include o Osteoblast (build bone) o Osteocyte (mature cell that maintains bone) o Osteoclast (breaks down bone)
8
Q
Matrix of Bone Tissue
A
- 1/3 of bone matrix is collagenous fibres (provide strength and flexibility)
- 2/3 of bone matrix is inorganic matter
o 85% calcium phosphate salt
o 10% calcium carbonate - Inorganic salts resist compression, allow bones to support without sagging
9
Q
Compact and Cancellous Bone
A
Compact
o Makes up the dense outer layer of bone
o Main structural unit = osteon
Spongy
o Consists of interconnecting plates of bone (trabeculae)
o Contain spaces filled with bone marrow
10
Q
Compact Bone
A
- Contain collagenous fibres in criss-crossing arrangements for structural reinforcements
- Canaliculi link osteocytes to blood supply
11
Q
Spongy Bone Anatomy
A
Porous lattice of bony struts called trabeculae
o Lacks true osteons
o Strong but light
o Cavities contain red marrow (source of new blood cells)
Found in abundance in short, flat and irregular bones
12
Q
Periosteum
A
o Double-layered protective membrane lining external surface of bones
o Outer layer of fibrous CT
o Anchored to bone by Sharpey’s Fibres
o Inner osteogenic (bone forming) layer (contains osteoblasts and osteoclasts)
13
Q
Endosteum
A
o Delicate membrane covering internal surfaces of bone
o Contains osteoblasts and osteoclasts
14
Q
Diaphysis
A
- Tubular shaft that forms the axis of long bones
- Composed of compact bone
- Surrounds the medullary cavity (contains yellow marrow)
15
Q
Epiphysis
A
- Expanded ends of long bones
- Exterior = compact bone, Interior = Spongy Bone
- Joint surface lined with articular (hyaline) cartilage
- In immature bones, epiphyseal plate separates the diaphysis from epiphyses
16
Q
Short, Flat and Irregular Bone Membranes
A
- Thin plates of periosteum lined compact bone on the outside with endosteum lined spongy bone on the inside
- Contains red bone marrow (between trabeculae)
17
Q
Bone Formation
A
- Before 8 weeks = embryonic skeleton is composed of membranes and hyaline cartilage
- Bone begins to ossify (initial regions = primary ossification centres)
18
Q
Intramembranous Ossification
A
- Produces mostly flat bones of the skull
- Develops from a fibrous membrane
19
Q
Endochrondral Ossification
A
- Produces most bones in skeleton below the skull
- Hyaline cartilage is template material
- Epiphyseal plate facilitates lengthwise growth of long bones until puberty
20
Q
Bone Remodelling
A
- Dynamic living tissue that is constantly broken down and reformed
- Turnover allows the bone structure to meet changing physical stresses
Bone Resorption
o Osteoclasts degrade organic matrix
o Solubilise mineral matrix
Bone Deposition
o Osteoblasts secrete organic matrix
o Mineralisation follows
21
Q
Articulations
A
- Condyle (rounded knob that articulates with another bone)
- Head (prominent expanded end of bone)
- Facet (smooth flat, slightly convex or concave surface)
22
Q
Projections
A
- Epicondyle (projection superior to condyle)
- Trochanter (large processes on femur)
- Tubercle (small, rounded process)
- Tuberosity (rough elevated surface)
- Crest (narrow ridge)
23
Q
Depressions
A
- Meatus (canal-like passage)
- Fossa (shallow depression)
- Foramen (round or oval opening)
- Fissure (slit-like opening)
24
Q
Axial Skeleton
A
Skull, Vertebral Column, Bony Thorax
25
Appendicular Skeleton
Pectoral Girdle, Pelvic Girdle, Limbs
26
The Skull
8 Cranial Bones surround cranial cavity
o Protects brain
o Attachments for head and neck muscles
14 Facial Bones supporting teeth and forming nasal cavity and orbit
o Provide openings for food liquid and air
o Attachments for facial and jaw muscles
6 Auditory Ossicles in the middle ear
27
Cranial Fossa
- Anterior fossa (supports frontal lobe)
- Middle fossa (supports temporal lobe)
- Posterior fossa (supports cerebellum)
28
The Nasal Cavity
Cavity posterior to external nose
o Constructed of bone and cartilage
o Divided into right and left parts by nasal septum
o Helps warm, moisten and purify air
29
Sutures of the Skull
- Immovable fibrous joints, forms boundaries between the cranial bones
- Sutures fuse in adulthood
Sagittal Suture
o Links left and right parietal bones
Coronal/Frontal Suture
o Links frontal bone to parietal bones
Lambdoidal Suture
o Links occipital bone to parietal bones
30
Paranasal Sinuses
Contained air spaces called the paranasal sinuses
o Lighten skull/humidify air
o Lined by pseudostratified ciliated columnar (respiratory) epithelium
Open into nasal cavity via ducts
31
The Orbits
- Bony cavities which encase the eyeball
| - Formed by parts of 7 bones
32
Frontal Bone
- Single bone forms forehead/cranial roof
- Forms roof of orbits
- Contains frontal sinuses
- Forms most of anterior cranial fossa
33
Parietal Bones
- Form rood and lateral walls of cranium
- Contain temporal lines (thickened region of bones, arching across parietal and frontal bones)
- Points of attachment for temporalis muscle
34
Temporal Bone
- Form lateral wall and part of floor of cranial cavity
Features include
o Mastoid Process
Conical process (attachment point for sternocleidomastoid muscle)
o Styloid Process
Slender process, anterior and medial to mastoid process (attachment for muscles/ligaments)
o External Acoustic Meatus
Canal adjacent to middle ear (tympanic membrane)
35
Middle Ear Anatomy
- Each temporal bone contains 3 auditory ossicles (malleus, incus, stapes)
o Facilitate the perception of sound
36
Occipital Bone
Rear and base of skull
o Foramen magnum – surrounds spinal cord
o Occipital Condyles – skull rests on atlas
o Jugular Foramen – allows passage for cranial nerves and blood vessels (e.g., internal jugular vein)
37
Sphenoid Bone
- Butterfly shaped, spans width of middle cranial fossa
- Articulates with all other cranial bones
- Sella turcica – houses pituitary gland
- Greater and lesser wings
- Contains air sinus, numerous foramina
38
Ethmoid Bone
- Located medial to orbits
- Forms lateral walls and roof of nasal cavity
- Contains air sinuses
- Perpendicular plate forms part nasal septum
- Contain superior and middle conchae
39
Maxillae
- Two medially fused bones (form superior jaw)
- All facial bones except mandible articulate with it
- Holds upper teeth and contain air sinuses
- Palatine process contributes to hard palate (roof of mouth)
40
Mandible
- Only moveable bone in skull
- Holds lower teeth
Features include
o Coronoid Process (attachment point for muscles of mastication)
o Mandibular Condyles (articulates with mandibular fossa of temporal bone)
41
Zygomatic Bones
- Form prominence of cheeks and inferolateral margins of the orbits
- Articulate with zygomatic processes of temporal bones
42
Nasal and Lacrimal Bone
Nasal Bones
o 2 medially fused bones (form bridge of nose)
Lacrimal Bones
o 2 bones contributing to medial wall of orbits
43
Palatine Bones
o Form portions of hard palate, orbits, lateral walls of nasal cavities
44
Vomer
o Plough-shaped bone that forms part of nasal septum
45
Inferior Nasal Conchae
o 2 curved bones (form part of the lateral walls of the nasal cavity)
46
Vertebral Column
- 26 bones (24 individual vertebrae)
- Fused vertebrae from sacrum and coccyx
Functions
o Provide support, maintain upright body position, housing and protecting spinal cord
47
General Vertebrae Structure
Body
- Disk-shaped anterior portion
- Weight bearing structure of vertebra
Vertebral Arch
- Extends posteriorly from body
- Surrounds vertebral foramen (spinal cord)
Processes
- Seven process arise from arch
- Points of attachment for muscles
- Articulate with other vertebrae
48
Cervical Vertebrae
- 7 small superior vertebrae (3 atypical – C1/Atlas, C2/Axis, C7)
- Relatively small and large vertebral foramen
- Transverse process short with transverse foramen for vertebral arteries
- Bifid spinous in C2 to C6
49
Atlas and Axis
Atlas
- No body or spinous process
- Superior articular facets articulate with occipital condyles of skull
Axis
- Has knoblike odontoid process
- Provides pivot for rotation of Atlas
- Articulation between C1 and C2 facilitates rotation of the head
50
Thoracic vs Lumbar Vertebrae
Thoracic
- Heart-shaped body
- Long spinous processes angled inferiorly
- Costal facets for articulation with ribs
Lumbar
- Large kidney shaped bodies
- Relatively short processes
51
Sacrum vs Coccyx
Sacrum
- Formed by 5 fused vertebrae
- Articulates with coxal bones of pelvis
Coccyx
- Formed by 4 fused vertebrae
52
Bony Thorax
Consists of the:
- Thoracic vertebrae (posteriorly)
- Ribs (laterally)
- Sternum (anteriorly)
Functions
- Protection
- Attachment point for muscles for support pectoral girdles, chest, neck, shoulders, back, muscles in respiration
53
Sternum
- Bony plate anterior to heart
- Articulates with clavicle and costal cartilages
- Adult sternum consists of:
o Manubrium Sterni
o Body/Corpus
o Xiphisternum (Xiphoid Process)
54
Ribs
- Includes 12 pairs of ribs, thoracic vertebrae, sternum
- All ribs have posterior articulations with thoracic vertebrae
True Ribs
- Superior 7 ribs of ribs attach to sternum via costal cartilage strips
False Ribs
- Ribs 8-10 (attach indirectly to sternum via a common cartilage strip)
- Ribs 11-12 (lack anterior attachment and are also termed floating ribs)
55
Hyoid Bone
- Lies inferior to mandible
- Only bone to not articulate with another bone
- Provides attachment for neck muscles involved with raising the larynx during speech and swallowing
