The Skeletal System

1
The Skeletal System
2
Bone Function

• Support
• Protection
• Leverage- for motion
• Mineral Homeostasis
• Blood cell production
• Hemopoiesis in red bone marrow
• Triglyceride Storage

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Types of Bones

• Long bones- longer than wide
• e.g. thigh, leg, arm, forearm, fingers toes
• Short bones- almost cube shaped
• Most wrist ankle bones
• Flat bones- thin extensive surface
• E.g. Cranial bones sternum, ribs scapulae
• Irregular bones- dont fit above
• E.G vertebrae and some facial bones

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Divisions of Skeletal System

• Two divisions axial appendicular
• Axial- around body axis
• E.g. head, hyoid, ribs, sternum, vertebrae
• Appendicular- bones of upper lower limbs plus
  girdles that connect them

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Figure 6.6
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Skull Hyoid bone

• Cranial bones
• Frontal, 2 parietal, 2 temporal, occipital,
  sphenoid, and ethmoid
• Facial bones
• 2 nasal, 2 maxillae, 2 zygomatic, mandible,
• 2 lacrimal, 2 paltine, 2 inferior nasal conchae,
  the vomer

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Figure 6.7a
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Figure 6.7b
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Figure 6.7c
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Figure 6.8
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Figure 6.9
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Figure 6.10a
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Figure 6.10b
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Unique Features of Skull

• Sutures- immoveable joint between skull bones
• Coronal, sagittal, lambdoidal, squamous
• Paranasal sinuses-cavities
• Located in bones near nasal cavity
• Fontanels- soft spot in fetal skull
• Allow deformation at birth
• Calcify to form sutures

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Figure 6.11
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Vertebrae

• Encloses spinal cord
• Supports head
• Point of attachment for muscles of back, ribs and
  pelvic girdle
• 7 cervical
• 12 thoracic
• 1 sacrum 1 coccyx

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Normal Curves in Column

• 4 normal curves
• Relative to front cervical lumbar curves are
  convex
• Thoracic sacral curves are concave
• They increase strength, help in balance and
  absorb shocks

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Figure 6.12a
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Figure 6.12b
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Structure of Vertebra

• Body- disc-shaped front part
• Vertebral arch- extends back from body
• creates with the body a hole called vertebral
  foramen
• 7 processes-
• Transverse process extending laterally on each
  side
• Spinous process extending dorsally
• Two each of Superior and inferior articular
  processes- attach to neighboring vertebrae

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Figure 6.13
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Cervical Area

• region is number from top to bottom
• Cervical (C1-C7)
• Spinous process often bifid and have transverse
  foramina on transverse process
• C1- specialized to support head- called the
  atlas- articulates with head
• Lacks body and spinous process
• C2 axis-
• has body spinous process
• Also dens- that creates a pivot for head rotation

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Figure 6.14
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Other Vertebrae

• Thoracic (T1-T12 )
• Larger than cervical
• Have facets for articulating with ribs
• Lumbar (L1-L5)
• Largest strongest. Processes short thick
• Sacrum (S1-S5 fused to one unit)
• Foundation for pelvic girdle
• Contain sacral foramina for nerves and blood
  vessels
• Coccyx- 4 fused coccygeal vertebrae

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Figure 6.12a
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Figure 6.15
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Figure 6.16
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Thorax

• Thoracic cage Sternum, costal cartilages ribs
  and bodies of T1-T12
• Sternum- form by 3 bones that fuse by age 25yrs
• manubrium, body, xiphoid process
• Ribs- 12 pairs
• 1-7 articulate with sternum directly costal
  cartilage true ribs

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Figure 6.17
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Pectoral Girdle

• Attach bones of upper limbs to axial skeleton
• Right left Clavicle Scapula

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Figure 6.18
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Upper Limb

• Humerus arm bone
• Articulates with scapula at shoulder
• Articulates with radius ulna at elbow
• Ulna medial bone
• Radius- lateral bone (thumb side)

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Figure 6.19
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Figure 6.20a
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Figure 6.20b
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Wrist Hand

• Carpus (wrist) -8 bones
• Metacarpals 5 bones of hand
• Number 1-5 starting with thumb
• Phalanges- 14 bones of fingers
• Numbered like metacarpals
• each finger but the thumb has proximal, medial
  distal
• Thumb only proximal distal

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Figure 6.21
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Pelvic Girdle

• Pelvic girdle includes two hip bones
• Joined in front at pubic symphysis
• At back- attached to sacrum sacroiliac joint
• Pelvic (hip) bone also called coxal bones

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Figure 6.22a
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Figure 6.22b
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Parts of Coxal Bones

• 3 bones fuse by age 23 to form coxal
• Ilium- largest most superior
• Ischium- lower posterior part
• Pubis lower anterior part

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Figure 6.23
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Lower Limb

• Femur- thigh bone
• Articulates with hip proximally and
• the tibia and fibula distally
• Patella kneecap in front of knee joint
• Tibia- large medial, weight bearing bone of leg
• Fibula- lateral to tibia and smaller

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Figure 6.24
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Figure 6.25
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Ankle Foot

• Tarsus (ankle) has 7 bones
• Large talus (ankle bone) and
• Calcaneus (heel bone)
• Metatarsals (foot bones)
• Numbered from medial to lateral
• Phalanges (toe bones)
• Big toe has proximal and distal phalanges while
  others have proximal, medial and distal
  phalanges. Numbered like metatarsals

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Figure 6.26
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Figure 6.27