Chapter 7: The Skeletal System: The Axial Flashcards
How many bones do adults have?
206
What are the 2 main divisions of the skeleton?
Axial (80 bones) and appendicular (126)
What is the axial skeleton and what are some examples?
Consists of bones that lie around the longitudinal axis of the body. Examples: skull bones, auditory, ossicles (earbones), hyoid bones, ribs, sternum, bones of the vertebral column
What is the appendicular skeleton and what are some examples?
Bones of the upper and lower limbs (extremities and appendages). Plus bones forming the girdles that connect limbs to the axial skeleton.
What are the 5 types of bones based on shape?
Long, flat, short, irregular and sesamoid
What is long bone and what are some examples?
Greater in length than width, have a shaft and variable number of extremities or epiphyses (ends). Slightly curved for strength (a curved bone absorbs stress of the body’s weight at several points so it’s easily distributed). Compact bone tissue in diaphysis and lots of spongy bone tissue in epiphyses. Includes femur (thigh bone), tibia, tibula (leg bones), humerus (arm bone), ulna and radius (forearm bones) and phalanges
What are short bones and what are some examples?
Cube shaped. Legnth=width. Mainly spongy bone except at surface which is thin layer of compact bone tissue
What are flat bones and what are some examples?
Thin and composed of 2 nearly parallel plates of compact bone tissue enclosing a layer of spongy bone tissue. For protection and provides extensive areas for muscle attachment. Examples: Cranial bones, sternum, ribs, and scapulae.
What are irregular bones and what are some examples?
Complex shapes and can’t be grouped into any of the previous categories. Examples: Vertebrae, hipbones, certain facial bones, and the calcaneus.
What are sesamoid bones and what are some examples?
Develop in certain tendons where there’s lots of friction, tension and physical stress (Ie palms and soles). Varies in number from person to person, not totally ossified, only a few mm in diameter (except for the 2 patallae), protects tendons from wear and tear. Change direction of pull of a tendon which improves the mechanical advantage at a joint.
What are sutural bones?
Small bones located in sutures (joints) between certain CRANIAL BONES
Where is red bone marrow found?
Flat bones (ribs, sternum, skull), irregular bones (vertabrae and hip bones), long bones (proximal epiphyses of femur and humerus) and some short bones.
What are surface markings of bones?
Structural features adapted for specific functions
What can cause surface markings?
Tension (new bone may be deposited resulting in raised or roughened areas) and compression (can result in depression of bone)
What are the 2 main types of surface markings?
1) Depressions + openings: Allows passage of soft tissues like blood vessels, nerves, ligaments and tendons or it forms joints. 2) Processes: Projections/outgrowths that either help form joints or serve as attachment points for connective tissues (like ligaments and tendons)
How many bones does the skull contain and what are the 2 categories they are grouped in?
22 bones. They are grouped in either cranial bones or facial bones
What are the cranial bones?
Forms the cranial cavity (encloses and protects the brain). 8 cranial bones: 1 frontal, 2 parietal, 2 temporal, 1 occipital, 1 sphenoid, and 1 ethmoid
What are the facial bones ?
14 bones: 2 nasal, 1 ethmoid, 2 zygomatic, 1 mandible, 2 lacrimal, 2 palatine, 2 inferior nasal conchae, and 1 vomer
What is the frontal bone?
Forms the forehead, roof of the orbits (eye sockets) and most of the anterior part of the cranial floor.
What is the frontal squama?
Scale-like plate of bone that forms the forehead of the skull.
What is the parietal bone?
Forms the greater portion of the sides and roof of the cranial cavity. The internal surfaces of the parietal bones contain. Many protrusions and depressions that accommodate the blood vessels that supply dura matter (the superficial connective tissue covering the brain).
What do the parietal bones form?
The internal surfaces of the parietal bones contain many protruions and depressions that accomodate the blood vessels that supply the dura mater (the superficial connective tissue covering the brain).
What do the temporal bones form?
Inferior lateral aspects of cranium and part of cranial floor. Temporal squama is thin, flat and forms the anterior+superior part of the temple (the region around the ear). Zygomatic processes project from the inferior portion of the temporal squama and articulates with the temporal process of the zygomatic bone to form the zygomatic arch
What is the mandibular fossa?
On the inferior posterior surface of the zygomatic process of each temporal bone. ANterior to the mandibular fossa is the articular tubercle. The mandibular fossa and articular tubercle articulate with the mandible (lower jaw) to form the temporomandibular joint (TMJ).
What are mastoid air cells?
Located in the mastoid portion and communicates with the hollow space of the middle ear
What is mastoiditis?
A painfull inflammation caused by middle ear infection that goes untreated and spreads into the mastoid air cells
What does the mastoid process do?
Point of attachment for several neck muscles
What does the internal auditory meatus do?
Opening where the facial (VII) and vestibulocochlear (VII) nerve pass
What does the styloid process do?
Point of attachment for muscles and ligaments of the tongue and neck
What does the atylomastoid foramen do?
Between the styloid process and mastoid process. The facial (VII) nerve and stylomastoid artery pass through
What does the petrous portion do?
Floor of cranial cavity of temporal bone. Triangular. Base of skull between sphenoid and occipital bones. Houses the middle ear and internal ear. Contains carotid foramen (which the carotid artery passes)
What does the jugular foramen do?
Anterior to occipital bone. Passage of jugular vein
What does the occipital bone do?
Most of base of the cranium
What does the foramen magnum do?
Large hole. Medulla oblongata (inferior part of brain) connects with the spinal cord within this foramen; and the vertebral and spinal arteries also pass through it along with the accessory (XI) nerve
What do the occipital condyles do?
Articulates with depressions on the first cervical vertibra (atlas)to form the atlanto-occipital joint —> allows you to nod
What is the hypoglossal canal?
Superior to each occipital condyle
WHat is the occipital protuberance?
Most prominent middle projection. Above foramen magnum. Large fibrous elastic ligament (the ligamentum nuchae extends from the external occipital protuberance to the 7th cervical vertebra to help support the head).
What does the sphenoid bone do?
Middle part of the base of the skull. KEYSTONE of the cranial floor because it articulates with all other cranial bones. Joins anteriorly with the frontal and ethmoid bones and laterally with the temporal bones and posteriorly with occipital bone. Forms part of the floor, side walls and rear of the orbit. Resembles butterfly. Space inside body of sphenoid is called the SPHENOIDAL SINUS (drains into nasal cavity).
What is the sella turica? What are the 3 parts?
Bony saddle-shaped structure on the superior surface of the body of the sphenoid and has 3 parts: 1) Tuberculum sellae (anterior part… Horn of saddle) 2) Hypophyseal fossa (contains pituitary gland) 3) Dorsum sellae (posterior part)
Greater wing vs lesser wing?
Greater wing forms the anteriorlateral floor of cranium, part of lateral wall of skull, and anterior to the temporal bone. The Lesser wing is smaller and forms part of the floor of the cranium and posterior part of the orbit of the eye
What does the optic foramen/canal do?
Optic (II) nerve and ophthalmic artery pass into orbit
What does the superior orbital fissure do?
Triangular slit. Blood vessels and cranial nerves pass through it
What do the pterygoid processes do?
Project inferiorly from the points where the body and greater wings of the sphenid bone unite. Form the lateral posterior region of the nasal cavity. Some of the muscles that move the MANDIBLE attach
What is the foramen ovale?
At base of the lateral pterygoid, process in the greater wing
What is the foramen lacerum?
It transmits a branch of the ascending pharyngeal artery
What is the rotundum?
The maxillary branch of the trigeminal (V) nerve passes through the foramen rotundum
What does the ethmoid bone form?
1) Anterior part of the cranial floor, 2) Medial wall of orbits, 3) Superior portion of nasal septum (divides nasal cavity), 4) Most of the superior sidewalls of nasal cavity
What is the cribiform plate?
Part of the ethmoid bone. Forms roof of nasal cavity. Contains olfactory foramina (olfactory nerves pass through)
What is the crista galli?
Point of attachment for the falx cerebri (membrane separating 2 sides of brain). Part of ethmoid bone
What is the perpendicular plate?
Part of ethmoid bone. Forms superior portion of nasal septum
What is the lateral masses?
Most of the wall between the nasal cavity and the orbits. Contains 3-18 air spaces called ethmoid cells… together these cells form ETHNOID SINUSES
What is the role of the conchae (superior and middle concha)?
They greatly increase the vascular and mucous membrane SA in the nasal cavity which warms and moistens inhaled air before it goes to lungs. Conchae also causes inhald air to swirl so many inhaled particles become trapped in the mucous that lines the nasal cavity… this helps cleanse inhaled air before it passes into the rest of te resp passages
Function of nasal bones
Forms bridge of the nose. Protects upper entry to the nasal cavity and provides attachment for a couple of thin muscles of facial expression. Mainly cartilage
Function of lacrimal bones
Smallest bones of the face. Contains the lacrimal fossa (houses the lacrimal sac which gathers tears and passes them to the nasal cavity)
Function of palatine bones
Posterior part of the hard plate and is formed by the horizontal plate of the palatine bones
Function of the inferior nasal conchae
Separate bones not part of ethmoid bones. Superior, middle and inferior cochae increase the SA of the nasal cavity. Only the superior nasal conchae of the ethmoid bone are involved in the sense of smell
Function of the vomer
Forms inferior portion of the bony nasal septum, the partition that divides the nasal cavity into right and left sides