Download Microscopic Structure

Chapter 7 Skeletal System
Skeletal System:
Bone Functions: Describe the role the skeletal system plays in each of the following functions.
Support: Bones support the weight of the body and structures such as the head and face
Protection: Bones protect delicate organs such as the brain and spinal cord, heart and lungs
muscle attachment – movement: bones act as levers to which muscles are attached
blood production: blood cells are produced within red bone marrow
store minerals: Minerals such as calcium and phosphorus, etc. are stored in bone matrix
What are some of the various tissues that are contained within bone? Bones also contain nerves and blood
vessels
Long Bone Structure:
Expanded ends of bones that form joints with adjacent bones are called _epiphyses___.
__articular cartilage________(hyaline cartilage) cover the ends at the joints.
The shaft of the bone is called the _diaphysis_. What type of bone makes up the outside of this part? Compact
The epiphyseal plate (disc) is the site of bone __growth (in length)____.
A tough layer of vascular connective tissue, called the __periosteum____, covers the bone and is
continuous with ligaments and tendons.
The diaphysis contains a hollow _medullary___ cavity that is lined with __endosteum__ and filled with
___yellow marrow___.
What is the function of red marrow? Blood cell production
Where is it found? In spongy bone
What is yellow marrow? Marrow that functions to store fat
Where is it found? The medullary cavities
A bone's shape makes possible its function; bony processes or grooves indicate places of attachment for
__muscles and tendons______________________.
Microscopic Structure
Bone cells called ____osteocytes__ are located within spaces called _lacunae____ that lie in concentric circles
around __Haversian___ canals that contain blood vessels, and nerves.
Osteocytes pass nutrients and wastes back and forth in passageways in the matrix called
_canaliculi__________________.
The intercellular material consists of __collagen____ and inorganic _salts________________.
Describe how the microscopic structure of spongy bone differs from that of compact bone.
Spongy Bone:
Unlike compact bone, the osteocytes and intercellular material in spongy bone are not arranged around
osteonic canals. Rather, they are irregularly arranged and form cross connections called trabeculae
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Where is spongy bone found?
Most bones contain a mixture of compact and spongy bone. Important sites for spongy bone include the skull the
ribs, the vertebrae and the sternum
compact bone:
In compact bone, osteocytes and intercellular material are organized into columns called
__osteons________ that are cemented together.
Osteonic canals contain blood vessels and nerve fibers, and extend in what direction through bone?
Longitudinally
Osteonic canals are interconnected by _transverse__ __perforating__canals.
Where is compact bone found? Most bones of the body contain a mixture of compact and spongy bone, The
diaphysis of a long bone is compact bone, and compact bone covers the epiphyses
Bone Development:
Bones form by replacing connective tissue in the fetus.
Intramembranous bone formation:
The flat bones of the skull form as intramembranous bones that develop from layers of
___connective________tissue.
Cells called ___osteoblasts___ deposit bony tissue around themselves.
Once these cells deposit bone they are enclosed within little compartments called _lacunae____. These
cells are then called __osteocytes___.
Cells of the membranous connective tissue that lie outside the developing bone give rise to the outer
covering, the __periosteum____.
What is a fontanel? A soft spot in an infant’s skull where the membrane has not yet completely
ossified
.
.
Endochondral bone formation:
Most of the bones of the skeleton fall into this category.
They first develop as ___hyaline___ _cartilage_ models and are then replaced with bone.
Cartilage tissue is invaded by blood vessels and _osteoblasts___that first form spongy bone at the primary
ossification center in the diaphysis.
Osteoblasts beneath the periosteum lay down compact bone outside the spongy bone.
__Secondary___ ossification centers appear later in the epiphyses.
A band of hyaline cartilage, the __epiphyseal__ plate, forms between the two ossification centers.
Layers of cartilage cells undergoing mitosis make up the epiphyseal plate.
___osteoclasts____ break down the calcified matrix and are replaced with bone-building
___osteoblasts____ that deposit bone in place of calcified cartilage.
Epiphyseal plates are responsible for __lengthening____ bones while increases in __thickness__________
are due to intramembranous ossification underneath the periosteum.
A medullary cavity forms in the region of the diaphysis due to the activity of the cells called
_osteoclasts___.
epiphyseal plate:
What happens at adulthood? The primary and secondary ossification areas meet and there is no further
increase in the length of the bone
Skeletal Divisions:
The __axial_____ skeleton consists of the skull, hyoid bone, vertebral column (vertebrae and
intervertebral disks), and thorax (ribs and sternum).
The __appendicular ______ skeleton consists of the pectoral girdle (scapulae and clavicles), upper limbs
(humerus, radius, ulna, carpals, metacarpals, and phalanges), pelvic girdle (coxal bones articulating with the
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sacrum), and lower limbs (femur, tibia, fibula, patella, tarsals, metatarsals, phalanges).
The bones and markings of the skeleton:
The skull is made up of 22 bones, including 8 cranial bones, 13 facial bones, and the mandible.
Name and locate the 8 cranial bones. Be familiar with their markings and processes such as the foramina,
sinuses, condyles, sutures, processes and fossae. What is the opening for the ear called?
Name and locate the 13 facial bones.
Which makes up the checks? Zygomatic bones
Which two form the nasal septum? Vomer and ethmoid
Which form the hard palate? Palatine bones and the maxillae
What forms the zygomatic arch? Zygomatic bone and the temporal bone
Which two contain the teeth? Maxillae and mandible
What are nasal conchae? Fragile, scroll-like bones attached to lateral wall of nasal cavity
Vertebral Column
The vertebral column, from skull to pelvis, forms the vertical axis of the skeleton.
It is composed of vertebrae separated by intervertebral disks.
What is the drum shaped part of the vertebrae called that supports the weight of the head and trunk?
The body of the vertebra
What is the name of the two lateral processes? Pedicles What is their function? Form the sides of the
vertebral foramen that encloses the spinal cord
What is the name of the dorsal process? lamina
Name the 1st two vertebrae? Atlas and the axis
How can you tell the cervical vertebrae from the rest of them? Cervical vertebra are smaller and have a
forked spinous process. They also have transverse foramina for blood vessels leading to the head
What distinguishes the thoracic vertebrae from the rest? They have lateral facets on the side of the body
that articulate with the ribs.
How many lumbar vertebrae are there? five
What is unique about the sacral vertebrae?They fuse together to form a triangular-shaped bone
What is the anatomical name for the tail bone? coccyx
Pectoral Girdle
The pectoral girdle makes an incomplete ring that supports the upper limbs
The clavicle can be recognized because it forms a/an ______S_- shape.
The scapula is divided by a ___Spine______________.
What is the function of the acromion process? Articulates with clavicle Of the coracoid process?
Attachment for muscles
What is the name of the fossa that articulates with the humerus? Glenoid cavity
Upper Limb
Bones of the upper limb form the framework for the arm, forearm, and hand
Humerus
Where is the head of the humerus? Proximal end What is its function? Articulates with scapula
The humerus articulates with the radius at the _capitulum__, and with the ulna at the _trochlea_________.
Name the two fossae of the humerus. Coronoid and olecranon
Be able to name the processes of the humerus.
Radius
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The ___radius_____ is located on the thumb side of the forearm.
What is the purpose of the flattened head of the radius? Pivot joint with humurus
The radius has the radial _tuberosity__and __styloid__________ process.
Ulna
The ulna is the longer of the two bones making up the forearm and has a __trochlear___notch that
articulates with the humerus.
Other features of the ulna include what four processes? Olecranon, coronoid, styloid, head
What is the name of the notch? Radial notch
Hand
The wrist consists of 8 carpal_ bones. The hand has 5 _metacarpals_ and the bones of fingers
are called _hand phalanges. How many bones does each finger have? 3
The thumb? 2
.
Pelvic Girdle
The pelvic girdle consists of the two coxal bones and the sacrum; it supports the trunk of the body on the
lower limbs.
The largest and most superior portion of the coxal bone is the _ilium_____. It joins the sacrum at the
aptly named __sacroiliac____ joint.
Name the features of this bone.
The _ischium____forms the L-shaped portion that supports weight during sitting.
Name its features. Ishial tuberosity and ischial spine
The ___pubis______ comprises the anterior portion of the coxal bones and articulates at the
__symphysis_ pubis____ with fibrocartilage in between.
What is the name of the large foramen? Obtuator foramen
Be familiar with the differences in the male and female pelves.
Lower Limb
The bones of the lower limb provide the framework for the thigh, lower leg, and foot.
The __femur___, or thighbone, extends from the hip to the knee and is the longest bone in the body.
Its head articulates with the _acetabul__; it articulates with the tibia at the _medial__and _lateral
condyles.
Other features of the femur include the fovea __capitis_, neck, and greater and lesser _trochanters_.
The knee cap is known as the _patella___.
The __tibia__ (shinbone) supports the weight of the body and articulates with the femur and with
the __tarsal______ bones of the foot.
Its anterior ___tibial tuberosity_ is the point of attachment for the patellar ligament.
Other features include the _medial malleolus_ (inner ankle).
The _fibula_is a slender bone lying lateral on the lower leg, it does not bear body weight.
The ___lateral malleolous_______ forms the outside ankle.
Foot
The ankle is composed of seven ___tarsal____ bones/.
The __talus_____ articulates with the tibia and fibula.
The ___calcaneous____supports the body weight and attaches to a large tendon.
The instep of the foot consists of five __meatarsals____ bones and provides an arch.
Each toe is made up of three __foot phalanges__, with the exception of the great toe, which lacks a
____middle phalanx____.
Joints and Articulations:
Joints (articulations) are the functional junctions between bones.
Joints can be classified according to the degree of movement possible and can be immovable, slightly movable, or
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freely movable.
Joints can also classified according to the type of tissue that binds them together.
___fibrous_________ are held close together by dense connective tissue and are immovable
(sutures of skull) or only slightly movable (joint between the distal tibia and fibula).
Hyaline cartilage or disks of fibrocartilage unite the bones in ___cartilagenous__________ joints.
Give two examples of this kind of joint. Symphysis pubis; first rib with sternum
Most joints of the skeleton are _synovial__ joints, which are more complex than fibrous or
cartilaginous joints.
What is the articular end of this kind of joint covered with? Hyaline cartilage
These joints have a joint ____capsule___ formed from the __connective tissue___ and the
__synovial membrane_. This space is filled with __synovial__ fluid. (hint, same name as the joint type)
Some of these joints contain shock-absorbing pads of fibrocartilage called __menisci___ and
may have fluid-filled sacs called ___bursae_. What is an inflammation of these sacs called? bursitis
There are many types of these joints named for their movement and the shape of the joint.
A __ball-and-socket__ joint consists of a bone with a globular or egg-shaped head articulating with the
cup-shaped cavity of another bone; a very wide range of motion is possible.
Give two examples of this type of joint. Hip and shoulder joints
A __condyloid___joint consists of an ovoid condyle fitting into an elliptical cavity, also
permitting a variety of motions.
Give an example of this type. Metacarpal bone articulating with finger bone
__Gliding____joints occur where articulating surfaces are nearly flat or slightly curved, allowing a
back-and-forth motion.
Give two examples. Joints of wrists and ankle
In a __hinge___joint a convex surface fits into a concave surface movement is in one plane only.
Give several examples of this type of joint. Elbow; joints between hand phalanges
In a __pivot__ joint , a cylindrical surface rotates within a ring of bone and fibrous tissue.
List two examples of this type. Joint between proximal ends of radius and ulna
A __saddle___ joint forms where articulating surfaces have both concave and convex areas,
permitting a wide range of movements.
Name one example of this type. Base of the thumb
Types of Joint Movements
When a muscle contracts, its fibers pull its movable end called the __insertion____ toward its
stationary end called the _origin__ causing movement at a joint.
These terms describe movements that occur at joints: flexion, extension, dorsiflexion, plantar flexion,
hyperextension, abduction, adduction, rotation, circumduction, pronation, supination, eversion, inversion,
retraction, protraction, elevation, and depression. Be prepared to recognize or demonstrate these
movements.
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