The Skeletal System: The Axial Skeleton Flashcards
How does the axial skeleton contribute to homeostasis?
By protecting the body’s organs (brain, spinal cord, heart, lungs), support, and releases and stores calcium
What makes up the musculoskeletal system?
Bones, muscles and joints
Orthopedics
Branch of medical science concerned with prevention or correction of disorders of musculoskeletal system
How many bones does an adult, children, and infants have?
Adults have 206 bones, children and infants have more and some of their bones fuse later in life.
What bones and how many are in the axial skeleton?
The Axial skeleton has 80 bones including the cranial cavity and facial bones of the skull, auditory ossicles, hyoid bone, ribs and sternum of the thorax, and vertebral column. There are 8 cranial cavity bones and 14 facial bones that make up the skull, 6 auditory ossicles, 1 hyoid bone, 1 sternum and 24 ribs of the thorax, and 26 bones of the vertebral column.
What are the 5 types of bone based on shape?
Long, short, flat, irregular, and sesamoid
What are long bones? What characteristics do they have? Which bones are considered long bones?
Long bones are greater in length than width. They consist mostly of compact bone tissue in a diaphysis, spongy bone tissue in various number of epiphyses, and are slightly curved. Long bones include the femur, tibia, fibula, humerus, ulna, radius, and phalanges.
What is the significance of long bones being curved?
Curved bones provides strength and resistance to fractures by absorbing strain at several different points and allows the body’s weight to be evenly distributed.
What are short bones? What do they consist of? Which bones are short bones?
Short bones are slightly cube-shaped and almost equal in width and length. They consist of spongy bone tissue and a thin layer of compact bone tissue at the surface. Most carpal and tarsal bones are short bones.
What are flat bones. What are their characteristics and function. Which bones are flat bones?
Flat bones are generally thin. They consist of 2 nearly parallel plates of compact bone tissue around a layer of spongy bone tissue and provide protection and a lot of areas for muscle attachment. Cranial cavity bones, the sternum and ribs are flat bones.
What are the characteristics of irregular bones and which bones are irregular?
Irregular bones have complex shapes and can’t be grouped into any category. They vary in amount of spongy and compact bone. Vertebrae, hip bones, certain facial bones, and the calcaneus are irregular bones.
Where do sesamoid bones develop and what are their functions? Which bones are sesamoid bones?
Sesamoid bones meaning shaped like a sesame seed develop in certain tendons where there’s a lot of tension, friction, and physical strain. They’re typically only a few mm in diameter and protect tendons from wear and tear and improve mechanical advantage at a joint by changing direction of pull of a tendon. These bones vary in number from person to person with the exception of the 2 patellae present in everyone.
What bone is classified by location? Where are these bones found?
Sutural bones are small flat bones located in sutures (joints) between certain cranial cavity bones and number of bones vary by person.
What are surface markings? What are the 2 types and how do they develop?
Surface marking are structural features adopted for specific functions. Most aren’t present at birth but develop from certain forces and are mainly present in adult skeleton.
1. Processes: Raised areas or projections/outgrowths on bone that form joints or serve as attachment points for ligaments and tendons. They result to bone being deposited in response to tension on bone surface from tendons, ligaments, aponeuroses, and fasciae. 2. Depressions and openings: sites that allow passage of blood vessels, nerves, ligaments, and tendons or form joints. They result from compression on a bone surface.
What are the 5 types of depression and openings?
Fissure, foramen, fossa, sulcus, meatus
Fissure
A narrow slit between bones for passage of blood vessels and nerves.
Foramen (pl. foramina)
Opening for passage of blood vessels, nerves or ligaments
Fossa (pl. fossae)
Shallow depression
Sulcus (pl. sulci)
Groove along bone surface for blood vessel, nerve or tendon
Meatus (pl. meati)
Tubelike opening
What are the 3 processes that form joints?
Condyle, facet, head
Condyle (pl. condylus)
Large, rounded projection with smooth articular surface at end of bone
Facet
Smooth, flat, slightly concave or convex articular surface
Head
Usually rounded articular projection supported on neck (constricted portion) of bone
What are the 7 processes that form attachment points for connective tissue?
Crest, epicondyle, line, spinous process, trochanter, tubercle, tuberosity
Crest
Prominent ridge or elongated projection
Epicondyle
Typically roughened projection above condyle
Line (linea)
Long, narrow ridge or border (less prominent than crest)
Spinous process
Sharp, slender projection
Trochanter
Very large projection
Tubercle
Variably sized rounded projection
Tuberosity
Variably sized projection that has a rough and bumpy surface
What is the skull? What are the 2 groups of bones that make up the skull and it’s components?
The skull is the bony framework of the head and the 22 bones are grouped into the cranial cavity bones and the facial bones. There are 8 bones that form the cranial cavity including the frontal bone, 2 parietal bones, 2 temporal bones, occipital bone, sphenoid bone, and ethmoid bone. The cranial base is the floor of the cranial cavity. There are 14 facial bones that form the anterior part of the skull and consists of bones that surround the mouth, nose, nasal, nasal cavity, and most of the orbits. These bones include 2 nasal bones, 2 maxillae, 2 zygomatic bones, mandible, 2 lacrimal bones, 2 palatine bones, 2 inferior nasal concha bones, and vomer.
What are the cavities and sinuses of the skull?
The skull contains the nasal cavity and orbits that open to the exterior and middle ear cavities in the temporal bones that house the auditory ossicles involved in hearing and equilibrium. The paranasal sinuses lined with mucous membranes open into the nasal cavity.
Which structures in the skull are movable?
The auditory ossicles and the mandible
What are sutures?
Sutures are joints that attach the skull bones together and are noticeable in the outer surface on the skull.
What surface markings does the skull have and their functions?
The skull has foramina and fissures that allow blood vessels and nerves to pass
What is the function of the cranial cavity and facial bones?
The cranial cavity protects the brain and stabilizes positions of the brain, blood vessels, lymphatic vessels, and nerves by attaching inner surfaces to meninges (membranes). The outer surfaces provide large areas of attachment for muscles that move parts of the head and produce facial expressions. The facial bones form the framework of the face and provide support for entrances to the digestive and respiratory systems. The cranial cavity and facial bones protect and support sense organs for vision, taste, smell, hearing, and equilibrium.
Frontal bone
Forms forehead, roofs of orbits and most of anterior part of cranial base.
Metopic suture
Joins left and right sides of frontal bone after birth and usually disappears between 6-8 years.
Frontal squama
Scalelike plate of bone that forms forehead of skull; slopes inferiorly from coronal suture on top of skull and angles almost vertically above orbits. Frontal sinuses are deep to frontal squama.
Supraorbital margin
Thickened frontal bone at superior border of orbits (brow line); frontal bone extends posteriorly from margin to form roof of orbits (part of cranial base).
Supraorbital foramen and notch and it’s function
Supraorbital foramen is a hole slightly medial to midpoint within supraorbital margin. Supraorbital notch is an incomplete foramen. The foramen allows passage of the supraorbital nerve and blood vessels.
What causes a black eye?
One cause is trauma to the supraorbital margin that fractures the frontal bone and results in blood and other fluids accumulating around the eye and causes swelling and dark discolouration. Surgical procedures can also cause black eyes.
Parietal bones
2 bones that form greater portion of sides and roof of cranial cavity. Internal surfaces contain many protrusions and depressions that accommodate blood vessels supplying dura mater (superficial connective tissue) covering brain
What is a paired bone?
One member of each bone on right and left sides of body
Temporal bones
Paired bones forming inferior lateral aspects of cranial cavity and part of cranial base.
Temporal squama
Thin, flat part of temporal bone forming anterior and superior part of temple (region of cranium around ear)
Zygomatic process
Projects from inferior portion of temporal squama and articulates with temporal process of zygomatic bone.
Zygomatic arch
Formed from zygomatic process of temporal bone and temporal process of zygomatic bone
