Chapter 7 Notes
Skeletal System
An individual bone is composed of a variety of tissues, including bone tissues, cartilage,
epithelial tissues, fibrous connective tissue, blood, and nervous tissue.
A bone contains very active, living tissue.
Bone Structure
Although the various bones of the skeletal system differ greatly in size and shape, they are similar
in their structure, development, and tissues.
Parts of the Lone Bone:
Epiphysis – at each end of the bone where there is an expanded portion which forms a joint
with another bone.
Articular Cartilage – on the outer surface of the epiphysis, made of hyaline cartilage.
Spongy Bone – irregular connected spaces occur between plates and help reduce the weight
of the bone. Typically a layer of compact bone is found on top.
Diaphysis – the shaft of the bone; located between the epiphysis.
Compact Bone – the wall of the diaphysis has this tightly packed tissue. Mainly for solid,
strong, and resistance to bending.
Periosteum – the tough, vascular covering of fibrous tissue, not on the ends where the
articular cartilage is.
**Each bone has a shape closely related to its functions.**
Medullary Cavity – tube with a hollow chamber.
Marrow – fills the medullary cavity; specialized type of soft connective tissue.
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The shape of bone cells are circular.
The shape of compact bone is due to the osteocyte cells forming around a canal of blood
vessels and nerves.
Spongy bone is still made of osteocyte cells but arranged differently.
BONE DEVELOPMENT AND GROWTH
2 Major Types of Bones:
1. Some appear between sheet-like layers of connective tissues and are called intramembranous
bones.
Examples: broad, flat bones of the skull
2. Others begin as masses of cartilage, which later are replaced by bone tissue. These are
called Endochondral Bones.
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Most bones of the skeleton are endochondral bones.
These bones grow very fast for a while and then begin to undergo changes.
Development of an Endochondral Bone:
1. Bone starts from a mass of hyaline cartilage with a shape similar to the bone it will become.
2. First change occurs in the center of the diaphysis where the cartilage breaks down and
disappears.
3. Periosteum starts to form.
4. Blood vessels start to form where the cartilage is disappearing.
5. Spongy bone fills in around the blood vessels. This area is called the Primary Ossification
Center.
6. Secondary Ossification Center appears in the epiphysis to form spongy bone.
7. An Epiphyseal Disk forms between the two ossification centers. The area of this disk is
where the new cells are begin made to make the bone longer.
Extra Things To Know!!
If an Epiphyseal Disk is damages before it becomes ossified, growth of the long bone may cease
prematurely, or if growth continues, it may be uneven. For this reason, injuries to the Epiphyses of
young person’s bones are of special concern. On the other hand, an epiphysis is sometimes altered
surgically in order to equalize the growth of bones that are developing at very different rates.
READ PAGE 132!! Repair of a Bone Fracture
Organization of the Skeleton
Axial Skeleton:
1. skull – cranium and facial bones
2. hyoid
3. vertebral column – vertebrae, sacrum, coccyx
4. thoracic cage – ribs, sternum
Appendicular Skeleton:
1. pectoral girdle – scapula, clavicle
2. upper limbs – humerus, radius, ulna, carpals, metacarpals, phalanges
3. pelvic girdle – coxal bones
4. lower limbs – femur, tibia, fibula, patella, tarsals, metatarsals, phalanges
Skull
22 bones
8 cranial bones
13 facial bones
1 mandible
Cranial Skeleton:
1. Frontal bones (Only 1) – forehead
2. Parietal Bone (2) – top of head
3. Occipital Bone (1) – back of skull
4. Temporal Bone (2) – side of head
- External Auditory Meatus – opening in temporal bone for ears
- Mastoid Process – projection under ear (attachment for muscles for neck)
- Styloid Process – projection under ear (attachment for muscles for tongue and pharynx)
5. Sphenoid Bone (1) – wind-like structure which extends laterally toward each side of the
skull.
6. Ethmoid Bone (1) – in front of sphenoid bone; 2 masses on each side of the nasal cavity
Facial Skeleton:
1. Maxillae (2) – upper jaw, contains sockets of upper teeth
2. Palatine Bone (2) – behind maxillae
3. Zygomatic Bone (2)- cheek bones
4. Lacrimal Bone (2) – thin, scale-like structure located in the medial wall of each eye.
5. Nasal Bone (2) – bridge of nose
6. Vomer 91) midline of nasal cavity
7. Inferior Nasal Conchae (2) – scroll-shaped bones attached to the sides of the nasal cavity
Mandible:
- jaw; moveable portion
- Mandibular Condyle – top of mandible that fits into joint
Vertebral Column
Vertebral Column – skull to pelvis and composed of vertebrae
Intervertebral Disks – fibrocartilage that separates the vertebrae; cushions and softens
movements.
Vertebral Column supports head and trunk and protects spinal cord through the vertebral canal.
Cervical Vertebrae (7)
-transverse processes of vertebrae are distinctive because of the transverse foramina – passage
way for arteries
Atlas – 1st vertebrae; supports and balances head
Axis – 2nd vertebrae; allows head to turn side to side
Thoracic Vertebrae (12)
- starts with vertebrae # 8
- increases in size as move down
- adapted for stress from body weight
- ends with vertebrae #20
Lumbar Vertebrae (5)
- small of back
- adapted for more support of weight
Sacrum
-
triangular structure
-
composed of 5 fused vertebrae
-
lowest part of the vertebral column
composed of 4 fused vertebrae
Coccyx
Upper Limb & Hand Notes
Upper Limb
- functions as levers that move limbs and attachment for muscles
- bones in upper limb include: humerus, radius, ulna, carpals, metacarpals, phalanges
Humerus –
- extends from scapula to elbow
- head of humerus fits into glenoid cavity
- 2 processes:
greater tubercle – sits up higher (larger)
lesser tubercle – sits lower
-
both provide sites for muscle attachment
epicondyles:
Lateral Epicondyles – provides attachment for muscles; on outside (lateral) of bone
Medial Epicondyles – provides attachment for muscles; on the inside of bone
Radius – larger
- elbow to wrist and crosses over ulna
- head of radius attaches with humerus
- radial tuberosity – bump of bone on side; bicep muscle attaches here
Ulna – smaller
- head of ulna goes with notch of radius
Hand
-
wrist, palm, fingers
wrist – 8 carpals
lines up in rows
trapezium is bone in wrist associated with thumb
-
palm – 5 metacarpals
1 with each finger
cylinder shaped bones with a fat end that forms knuckles
thumb begin labeled as #1 – Pinky as #5
-
fingers – 5 phalanges
3 bones in each phalanx (finger)
only 2 bones in thumb
follows same numbering as palm
Proximal Phalanx – bone closest to palm of finger
Middle Phalanx – middle bone of finger
Distal Phalanx – end of finger
Pelvic Girdle & Lower Limb Notes
Pelvic Girdle
- consists of 2 coxal bones
- sacrum, coccyx, and pelvic girdle together for the ring-like pelvis
- function is to provide support for the trunk of the body and attachment for the legs
and muscles
Coxal Bones
- develop from 3 parts
1. ilium
2. ischium
3. pubis
All 3 fuse in a cup-shaped region called the acetabulum – which joins with the femur
Ilium
Ischium
-
largest & uppermost portion of the coxal bone
flares outward to form the prominence of the hip
forms the lowest portion of the coxal bone
supports the weight of the body when sitting
Pubis
-
2 parts to the pubis bone
2 bones come together to form the symphysis pubis
the angle formed from these 2 bones is called the pubic arch
obturator foramen – large opening
Difference between females and males:
- Pelvic Area
female bones are lighter, thinner, and have less obvious muscular attachments
obturator foramen and acetabula are smaller and further apart than in a male
pelvic cavity if wider, shorter, roomier, and less funnel shaped
distance between ischial spins and ischial tuberosity are greater in a male
Lower Limb
- includes femur, tibia, fibula, metatarsals, phalanges
Femur
-
longest bone in body
goes from hip to knee
head fits into coxal bone
2 large processes on upper end
greater trochanter
lesser trochanter
-
both provide attachment for muscles of leg and butt
2 processes on lower end
lateral condyles
medial condyles
associated with tibia
Tibia
-
larger of the lower leg bones
medial and lateral condyles attach with femur
medial malleolus serves as the attachment for ligaments
-
long and slender bone on side of tibia
head is associated with tibia but does not bear much body weight
lateral malleolus – associated with ankle and forms the ankle bone on side of leg
-
ankle, instep, 5 toes
Fibula
Foot –
Tarsals – 7
- one of the 7 is called the talus which moves freely
- the rest are fixed
Metatarsals – 5
- numbered 1 – (#1 is the big toe)
Phalanges – 5
- 3 phalanges in each toe except big toe
- proximal phalanx
- middle phalanx – big toe does not have
- distal phalanx
Joints
Joints – functional joints between bones
Immovable Joints
– occur between bones that come into close contact with one another
– separate by a thin layer of fibrous connective tissue or cartilage
Ex. flat bones of the cranium (in sutures)
Slightly Movable Joints
- connected by disks of fibrocartilage of by ligaments
Ex. vertebral column – have limited movement
Freely Movable Joints ( also called synovial joints)
- covered with hyaline cartilage and held together by a tube-like capsule of dense fibrous
tissue
-
joint capsule- outer layer of ligaments and an inner lining of Synovial membrane which
secretes synovial fluid
Ex. Knee Joint