Chapter 7 - Skeletal: Axial System Flashcards
What is the musculoskeletal system?
The combination of bones, muscles, and joints
How does the axial skeleton contribute to homeostasis?
By protecting many of the body’s organs (brain, spinal cord, heart, lungs)
Important in support and calcium storage and release
What is orthopedics?
Prevention and correction of disorders of the musculoskeletal system
How many bones does an adult have?
206
Children have more b/c some of their bone haven’t fused yet
What are the two principle divisions of the skeletal system?
- Axial skeleton - 80 bones
2. Appendicular skeleton - 126 bones
What bones make up the axial skeleton?
Skull (cranium and face) Hyoid Auditory ossicles Vertebral column Thorax (sternum and ribs)
What bones make up the appendicular skeleton?
Pectoral girdles
Upper limbs
Lower limbs
Pelvic girdle
What are the 5 main types of bones based on shape?
Long Short Flat Irregular Sesamoid
What are the characteristics of long bones?
Greater length than width Consist of a shaft and a variable number of extremities or epiphyses (ends) Slightly curved for strength Compact bone tissue in their diaphyses Spongy bone tissue in their epiphyses
Give some examples of long bones.
Femur (thigh bone) Tibia and fibula (leg bones) Humerus (arm bone) Ulna and radius (forearm bones) Phalanges (finger and toe bones)
What are the characteristics of short bones?
Somewhat cube-shaped
Nearly equal in length and width
Consist of spongy bone tissue except at the surface (thin layer of compact bond)
What are some examples of short bones?
Carpal (wrist bones)
Tarsal (ankle bones)
What are the characteristics of flat bones?
Generally thin and composed of two nearly parallel plates of compact bone tissue enclosing a layer of spongy bone tissue
Provide protection and extensive areas for muscle attachment
Give some examples of flat bones.
Cranial bones
Sternum
Ribs
Scapulae
What are the characteristics of irregular bones?
Complex shapes and cannot be grouped into any other previous category
Give some examples of irregular bones.
Vertebrae (backbones)
Hip bones
Certain facial bones
Calcaneus
What are the characteristics of sesamoid bones?
Develop in certain tendons where there is considerable friction, tension, physical stress
Very small! A few mm in diameter
May vary in number from person to person, may not be completely ossified
What are the functions of sesamoid bones?
Protect tendons from excessive wear
Often change the direction of pull of a tendon
Improves mechanical advantage at a joint
What are the notable exceptions of sesamoid bones? (Not small, and present in everyone)
Two patellae (kneecaps) Large sesamoid bones located in the quadriceps femoris tendon
What is another type of classification of bone based on location, not shape?
Sutural bones
What are sutural bones?
Small bones located in sutures (joints) between certain cranial bones
Their numbers vary from person to person
Where is red bone marrow found? Which bones?
Ribs Sternum Skull Vertebrae Hip bones Femur (the proximal epiphyses) Humerus Some short bones
What are surface markings?
Structural features adapted for specific functions
Develop in response to certain forces
Most prominent in the adult skeleton
What are two major types of surface markings?
- Depressions and openings
2. Processes
Describe the characteristics of “depressions and openings” (surface markings)
Allow the passage of soft tissues (such as blood vessels, nerves, ligaments, and tendons) and
Form joints
What are processes (surface markings)?
Projections or outgrowths that either help form joints or serve as attachment points for connective tissue
What is a fissure? What kind of surface marking is it?
Narrow slit between adjacent parts of bones through which blood vessels or nerves pass
*depression or opening
What is a foramen? What kind of surface marking is it?
Opening through which blood vessels, nerves or ligaments pass
*depression or opening
What is a fossa? What kind of surface marking is it?
Shallow depression
*depression or opening
What is a sulcus? What kind of surface marking is it?
Furrow along bone surface that accommodates blood vessel, nerve or tendon
*depression or opening
What is a meatus? What kind of surface marking is it?
Tubelike opening
*depression or opening
What is a condyle? What kind of surface marking is it?
Large, round protuberance with a smooth articular surface at end of bone
* process that form joints
What is a facet? What kind of surface marking is it?
Smooth, flat, slightly concave or convex articular surface
* process that forms joints
What is a head? What kind of surface marking is it?
Usually round articular projection supported on neck (constricted portion) of bone
* process that forms joints
What is a epicondyle? What kind of surface marking is it?
Typically roughened projection above condyle
* process that form attachment points for connective tissue
What is a crest? What kind of surface marking is it?
Prominent ridge or elongated projection
* process that form attachment points for connective tissue
What is a line? What kind of surface marking is it?
Long, narrow ridge or border (less prominent than crest)
* process that form attachment points for connective tissue
What is a spinous process? What kind of surface marking is it?
Sharp, slender projection
* process that form attachment points for connective tissue
What is a trochanter? What kind of surface marking is it?
Very large projection
* process that form attachment points for connective tissue
What is a tubercle? What kind of surface marking is it?
Variably sized rounded projection
* process that form attachment points for connective tissue
What is a tuberosity? What kind of surface marking is it?
Variably sized projection that has a rough, bumpy surface
* process that form attachment points for connective tissue
What is the skull?
Bony framework of the head
How many bones are in the skull?
22 bones (not counting the bones in the middle ears)
What are the two categories of skull bones?
- Cranial bones
2. Facial bones
What is the function of the cranial bones?
Form the cranial cavity
Enclose and protect the brain
Name the 8 cranial bones.
Frontal bone 2 parietal bones 2 temporal bones Occipital bone Sphenoid bone Ethmoid bone
Name the 14 facial bones.
2 nasal bones 2 maxillae 2 zygomatic bones Mandible 2 lacrimal bones 2 palatine bones 2 inferior nasal conchae Vomar
What is the frontal bone?
Forms the forehead (anterior part of the cranium)
Where are the 2 parietal bones?
Sides and roof of the cranial cavity (form a large part of it)
What is in the internal surface of the parietal bones?
Many protrusions and depressions that accommodate the blood vessels supplying the dura mater
How is the zygomatic arch formed?
By the zygomatic process of the temporal bone and the temporal process of the zygomatic bone
Where is the mandibular fossa located?
On the inferior posterior surface of the zygomatic process of each temporal bone
What forms the temporomandibular joint (TMJ)?
The mandibular fossa and the articular tubercle
Also articulates the mandible
What serves as an attachment point of muscle and ligaments of the tongue and neck?
The styloid process
What houses the middle and internal ear?
The petrous portion of the temporal bone
What passes through the carotid foramen?
Carotid artery
What is the passageway for the jugular vein?
Jugular foramen
With which bones does the temporal bone articulate?
The mandible, parietal, sphenoid, zygomatic, occipital
What forms the most of the posterior and inferior portions of the cranium?
Occipital bone
What connects within the foramen magnum?
Medulla oblongata connects with the spinal cord
What forms the atlanto-occipital joint?
The occipital condyles and the depressions of the first cervical vertebrae
What allows you to nod your head “yes”?
The atlanto-occipital joint
What is the most prominent midline projection on the posterior surface of the bone just above the foramen magnum?
The external occipital protuberance
What ligament extends from the external occipital protuberance to the 7th cervical vertebrae?
Ligamentum nuchae
What bone is called the keystone and why?
The sphenoid bone, b/c it articulates with all other cranial bones - holding them together
What contains the pituitary gland?
Hypophyseal fossa
What passes through the optic foramen?
Optic (II) nerve and the ophthalmic artery
What is the nasal septum?
A partition that divides the nasal cavity into right and left sides
What is the lacrimal sac? Where is it located?
A structure that gathers tears and passes them into the nasal cavity
Lacrimal fossa
What are the 5 openings associated with each orbit?
- Optic foramen
- Superior orbital fissure
- Inferior orbital fissure
- Supraorbital foramen
- Lacrimal fossa
What is a suture?
An immovable joint, holds skull bones together
What are the 4 prominent sutures?
- Coronal suture - unites frontal and parietal bones
- Sagittal suture - unites the two parietal bones (top of the skull)
- Lambdoid suture - parietal bones to occipital bone
- Squamous suture - unite the parietal and temporal bones
What are the functions of the paranasal sinuses?
Produce mucus and serve as resonating chambers for vocalization
What are fontanels?
Soft spots
Areas where unossified mesenchyme develops into dense connective tissue of the skull
Serve as spacers for growth
What are the six main fontanels?
- Anterior fontanel
- Posterior fontanel
- Paired anterolateral fontanels
- Paired posterolateral fontanels
What does the hyoid bone do?
Supports the tongue, providing attachment sites for some tongue muscles and for muscles of the neck and pharynx
How is the vertebral column distributed?
7 cervical vertebrae 12 thoracic vertebrae 5 lumbar vertebrae 1 sacrum 1 coccyx
How many curves are in a normal adult spine? In a fetus?
4 in an adult
1 in a fetus
What is special about the hyoid bone? How is it different?
Does not articulate with any other bone
It is suspended by ligaments and muscles
Which normal curves are convex? Which are concave in an adult spine?
Cervical and lumbar are convex
Thoracic and sacral are concave
What are the primary curves?
Thoracic and sacral curves b/c they retain their original curvature of the embryonic vertebral column
What are the secondary curves?
Cervical and lumbar b/c they begin to form several months after birth
What are the names of three abnormal curves of the spine?
Kyphosis
Lordosis
Scoliosis
What are intervertebral discs?
Found between the bodies of adjacent vertebrae from the second cervical vertebrae to the sacrum
What are the two parts of an intervertebral disc?
- Annulus fibrosus - outer fibrous ring consisting of fibrocartilage
- Nucleus pulposus - inner soft, pulpy, highly elastic substance
What are the functions of the intervertebral discs?
Form strong joints, permit various movements, absorb vertical shock
Why do we get shorter during the day?
During the course of the day, the discs compress and lose water in their cartilage
Sleeping, there is less compression and rehydration occurs
Are intervertebral discs vascular or avascular?
Avascular - they rely on blood vessels from the bodies of the vertebrae
What is the vertebral body?
The thick, disc-shaped anterior portion
Weight bearing portion
What is on the anterior and lateral surfaces of the vertebral body?
Nutrient foramina, openings through which blood vessels deliver nutrients and remove wastes
What is a vertebral arch?
Two short, thick processes (the pedicles) project posteriorly from the vertebral body and then unite with the flat laminae
What does the vertebral foramen contain?
Spinal cord, adipose tissue, areolar connective tissue, blood vessels
How many processes arise from the vertebral arch?
7
Name the 7 processes of the vertebral arch.
Transverse process (x2) - where lamina and pedicle join
Spinous process - projects posteriorly from the junction of the laminae
Superior articular process (x2) - join with inferior articular processes
Inferior articular process (x2) - join with superior articular processes
What are osteophytes?
Bony growths around intervertebral discs
Can lead to a narrowing of the vertebral canal
Happens as you age
What are the three main parts of a typical vertebra?
- Vertebral body
- Vertebral arch
- 7 vertebral processes
What is the thorax?
Refers to the entire chest region
What makes up the thoracic cage?
Formed by the sternum, ribs, and their costal cartilage and the bodies of the thoracic vertebrae
What does costal cartilage do?
Attach the ribs to the sternum
What is the function of the thoracic cage?
Protects the organs in the thoracic and superior abdominal cavities
Provides support for the upper limbs
Plays a role in breathing
Identify the location and surface features of the cervical vertebrae.
C1-C7
Smaller than all other vertebrae (except coccyx)
Vertebrae arches are larger
Have three foramina
What is contained in the vertebral foramina and in the 2 transverse foramina?
Vertebral foramina - spinal cord
Transverse foramina - vertebral arteries and veins, and nerves
What is the atlas?
C1
First cervical vertebra inferior to the skull
Lacks a body and spinous process
What is the axis?
C2
Has a vertebral body
What allows you to move your head to signify “no”?
The dens (a peglike process) makes a pivot on which the atlas and head rotate
What is the usual cause of death in whiplash injuries?
The dens of the axis is driven into the medulla oblongata of the brain
Identify the location and surface features of the thoracic vertebrae.
T1-T12
Larger and stronger than cervical vertebrae
Spinous processes on T1-T10 are long, laterally flattened and directed inferiorly
How is the spinous process on T11 and T12 different?
Shorter, broader, and directed more posteriorly
What are costal facets? Which vertebrae have them?
Articular surfaces for the ribs Thoracic vertebrae (except for T11 and T12)
What is a facet?
Is formed when the head of a rib articulates with the body of one vertebra
What is a demifacet?
Is formed when the head of a rib articulates with two adjacent vertebral bodies
Identify the location and surface features of the lumbar vertebrae.
L1-L5
Largest and strongest of the unfused bones in the vertebral column
Projections are short and thick
Describe the spinous processes of the lumbar vertebrae
Quadrilateral in shape, thick and broad and project nearly straight posteriorly
Well adapted for the attachment of the large back muscles
What is the sacrum?
A triangular bone formed by the Union of five sacral vertebrae
S1-S5
When do the sacral vertebrae begin to fuse?
Between 16-18 years of age, completed by age 30
What does the sacrum serve as?
A strong foundation for the pelvic girdle
Female - shorter, wider and more curved
What is the sacral canal?
A continuation of the vertebral cavity
What is the sacral hiatus?
When the 4th and 5th sacral vertebrae fail to meet, it leaves an inferior entrance to the vertebral canal
What is the coccyx?
Triangular in shape
Formed by the fusion of 4 coccygeal vertebrae
Co1-Co4
Fuse between the ages of 20-30
What is the sternum?
A flat, narrow bone located in the centre of the anterior thoracic wall
Consists of three parts
What are the three parts of the sternum?
- Manubrium - superior part
- Body - middle and largest
- Xiphoid process - inferior, smallest
Typically fuse by age 25
Describe the xiphoid process in detail.
Does not completely ossify till age 40
No ribs are attached to it
Provides attachment for some abdominal muscles
Incorrect positioning during CPR, may fracture the xiphoid process
With which ribs does the body of the sternum articulate?
Directly or indirectly with ribs 2-10
How many ribs do we have?
Twelve pairs of ribs
Describe the length of the ribs.
1-7 increase in length
8-12 decrease in length
Which ribs have a direct anterior attachment to the sternum?
1-7
By a strip of hyaline cartilage called costal cartilage
Called TRUE ribs
Why are some ribs called false ribs?
8-12
B/c their costal cartilage either attach indirectly to the sternum or do not attach to the sternum at all
Called vertebrochondral ribs
Which are the floating ribs? Why?
11-12
B/c their costal cartilage at their anterior ends do not attach to the sternum at all
How does a rib articulate with a thoracic vertebra?
The facet on the head of a rib fits into a facet on the body of a vertebra, and the articular part of the tubercle of a rib articulates with the fact of the transverse process of the vertebra
What is a herniated disc?
Pressure that ruptures the surrounding fibrocartilage
The nucleus pulposus may protrude (herniate) posteriorly or into one of the adjacent vertebral bodies
What is scoliosis?
Most common
Lateral bending of the vertebral column
Usually in the thoracic region
What is kyphosis?
Increase in the thoracic curve
Hunchback
Common in females with osteoporosis
What is lordosis?
Hollow back
Increase in the lumbar curve
From increased weight of pregnancy or extreme obesity
What is spina bifida?
Laminae of L5 and/or S1 fail to develop normally and unite at the midline
