Flashcards in Axial Skeleton - The Vertebrae, Ribs, Sternum, Hyoid Bone, and Auditory Ossicles Deck (42):
What is the vertebral column?
The spine -- composed of a chain of 33 vertebrae with fibrocartilage intervertebral discs between them --which envelops and protects the spinal cord and provides vertical support for the body
What is the body of a typical vertebra?
A mass of spongy bone and red bone marrow covered with a thin shell of compact bone; the weight-bearing portion of the vertebra
What are intervertebral discs?
Fibrocartilage between bodies of adjacent vertebra
What is the vertebral foramen?
Large hole in a vertebra formed by body and vertebral arch; spinal cord passes through these holes in stacked vertebrae
What is the vertebral arch?
The lateral and posterior border of vertebral foramen comprised of two parts: pedicles (2) and laminae (2)
What are pedicles?
Two 'pillar-like' structures that originate from the body of the vertebra and form the lateral borders of the vertebral foramen
What are laminae?
Plural form of lamina, two 'plate-like' structures extending from pedicles that fuse posteriorly to form the posterior border of the vertebral foramen
What is a spinous process?
Posterior projection from junction of right and left laminae directed downward; can be easily palpated in the neck and back
What is the transverse process?
Lateral extension from point where pedicles and laminae meet that provide points of attachment for ligaments, ribs, and spinal muscles
What is the superior and inferior articular processes?
Articular facets projecting upwards and downwards from a vertebra, respectively, that prevent excessive twisting of the vertebral column which might injure the spinal cord
What are the intervertebral foramina?
Lateral openings between the pedicles of two adjacent vertebrae through which the spinal nerves pass from the spinal cord
How many regions (or divisions) is the vertebral column divided into?
Five: cervical, thoracic, lumbar, sacral, and coccygeal (from superior to inferior, in order)
How many cervical vertebrae are there?
Seven, located in the back of the neck, from C1 (Atlas) to C7 (vertebral promenens)
Describe C1 (Atlas)
Articulates with occipital condyles to support the head; doesn't resemble typical vertebra (lacks body and spinous process -- delicate ring of bone surrounding a very large vertebral foramen); allows for the nodding, "yes" motion of the head
Describe C2 (Axis)
Articulates with C1 and C3 and allows pivotal head rotation from side-to-side (lateral movement); features prominent anterior knob called the dens which projects into the vertebral foramen of C1 (Atlas)
Describe C7 (vertebral prominens)
The seventh and final cervical vertebra that has a very long, prominent spinous process that is easily palpated through the skin between the shoulder blades at the base of the neck; has no bifid (split) spinous process like C2-C6 and marks the transition from cervical to thoracic vertebrae
How many thoracic vertebrae are there?
Twelve: T1 thru T12
What are the characteristics of the thoracic vertebrae?
The bodies of these vertebrae have costal facets that articulate with the ribs; their spinous processes are pointed and angled sharply downward
NOTE: T1 thru T10 have transverse costal facets on ends of their transverse processes; T11 and T12 do not
What is the thoracic cage?
Twelve thoracic vertebrae, twelve pairs of ribs, and the sternum forms the thoracic cage that encloses and protects the heart and lungs
How many lumbar vertebrae are there?
Five: L1 thru L5
What are the characteristics of the lumbar vertebrae?
They are the largest vertebrae as they bear the most weight; have larger, thicker, oval bodies and blunt, square, thick spinous processes to provide area for attachment to inferior back muscles
How many sacral vertebrae are there?
Five: S1 thru S5; fused
What are the characteristics of the sacrum?
The sacrum is a curved, somewhat triangular bone that forms the posterior wall of the pelvic cavity; the five separate vertebrae begin to fuse around age 16 and complete their fusion by the mid-20's
What are sacral foramina?
Four pairs of openings lateral to the sacral canal that allows the passage of nerves and arteries to the pelvic organs
What are transverse lines?
Four lines of vertebral fusion along the anterior surface of the sacrum
What is are the lateral auricular surfaces of the sacrum?
"Ear-shaped" sockets lateral to the sacral canal that articulate with the iliac portions of the hip bones to form the sacroiliac (SI) joint
How many coccygeal vertebrae are there?
Four: Co1 thru Co4; fused
What are the characteristics of the coccyx?
Known as the "tail bone," it is the vestige of a tail that provides an area of attachment for muscles of the pelvic floor; can be fractured during difficult child birth or a hard fall
What is the sternum?
The flat breastbone of the thoracic cage which forms the anterior, midline portion and lies just anterior to the heart; divided into three portions: the manubrium, gladiolus (body -- middle and longest part), and xiphoid process
What is the manubrium?
The widest and most superior portion of the sternum, it has two clavicular notches that articulate with the right and left clavicle; a suprasternal (jugular) notch; and, a raised suture line called a sternal angle that separates the manubrium from the body of the sternum
What is the suprasternal (jugular) notch?
A depression on the middle of the superior aspect of the manubrium; easily palpated and is a CPR landmark
What is the xiphoid process?
The inferior, sharp portion of the sternum which is cartilaginous and does not become bone until the age of 40; also a CPR landmark
What is the hyoid bone?
A slender 'U' shaped bone between the chin and larynx, unique because it does not articulate with any other bone; it is suspended from the styloid process of the temporal bone by muscles and ligaments and forms the superior bony framework for the larynx
What are characteristics of the hyoid bone?
Has a medial body and two paired horn-like processes, the greater and lesser cornu; is fractured in most strangulation deaths
What are the auditory ossicles?
The smallest bones in the body (6 total -- 3 in each ear) housed in the middle ear cavity within the temporal bone of the skull, they at responsible for both amplifying sound waves and transmitting them to the inner ear
Name the three auditory ossicles.
From lateral to medial, they are the malleus (hammer), incus (anvil), and stapes (stirrup)
What are ribs?
Elongated, curved, flattened bones that originate posteriorly on or between the 12 thoracic vertebrae, most of which attach on the anterior end to the sternum by way of strips of hyaline cartilage called costal cartilages
What is the rib head?
The vertebral end of the rib that attaches posteriorly to a thoracic vertebra
What is the neck of a rib?
Narrower portion of the rib between the head and the tubercle
What is a tubercle?
Point of attachment of most ribs (pairs 1-10) to the transverse processes of the thoracic vertebrae
What are true ribs?
Pairs of ribs (1 thru 7) each with its own costal cartilage attaching directly to the sternum