First half of chapter 8 Flashcards
Overview of the Skeleton-Axial skeleton
Axial skeleton -Forms central supporting axis of body
Skull, vertebrae, sternum, ribs, sacrum, and hyoid
Overview of the Skeleton-Appendicular skeleton
Pectoral girdle,Upper extremity,Pelvic girdle,Lower extremity
Number of bones
206 in typical adult skeleton. Varies with development of sesamoid bones. Bones that form within tendons (e.g., patella). Varies with presence of sutural (wormian) bones in skull. Extra bones that develop in skull suture lines. 270 bones at birth, but number decreases with fusion
Anatomical Features of Bones-Bone markings
Bone markings—ridges, spines, bumps, depressions, canals, pores, slits, cavities, and articular surfaces
Ways to study bones
Ways to study bones
Articulated skeleton: held together by wire and rods, shows spatial relationships between bones
Disarticulated bones: taken apart so their surface features can be studied in detail
The Skull
Skull—most complex part of skeleton
22 bones joined together by sutures (immovable joints)
Several cavities—cranial cavity (brain case), orbits (eye sockets), nasal cavity, oral (buccal) cavity, middle- and inner-ear cavities, and paranasal sinuses
The Skull-Foramina
Foramina—holes that allow passage for nerves and blood vessels
The Skull-Paranasal sinuses
Paranasal sinuses—frontal, sphenoid, ethmoid, maxillary
Lined by mucous membrane and are air-filled
Act as chambers that add resonance to the voice; lighten the skull
Facial bones
Facial bones (14)—skull bones anterior to the cranial cavity (do not enclose brain).Support teeth.Give shape to face.Form part of orbital and nasal cavities.Provide attachments for muscles of facial expression and mastication. -2 maxillae 2 palatine 1 mandible 2 zygomatic 2 nasal
Vertebral Column: General Features
Functions of spine
Supports skull and trunk and allows for their movement
Protects spinal cord
Absorbs stresses of movements
Provides attachments for limbs, thoracic cage, and postural muscles
33 vertebrae with intervertebral discs
33 vertebrae with intervertebral discs between most of them
Discs account for about one-quarter of spine’s 71 cm length (on average)
Discs compress a bit during the day due to pressure of body weight
Vertebral Column: General Features (continued)-Five vertebral groups
Five vertebral groups 7 cervical in the neck 12 thoracic in the chest 5 lumbar in lower back 5 fused sacral at base of spine 4 fused coccygeal
Vertebral Column: General Features (continued)-Variations in number of vertebrae occur in 1 in 20 people
Variations in number of vertebrae occur in 1 in 20 people
Generally in the number of fused vertebrae in inferior part of spine
Vertebral Column: General Features (continued)
S-shaped vertebral column with four normal curvatures Cervical Thoracic Lumbar Pelvic
Abnormal Spinal Curvatures
Abnormalities result from disease, paralysis of trunk muscles, poor posture, pregnancy, or congenital defects.
Scoliosis—abnormal lateral curvature.
Cervical Vertebrae-Atlas (C1)
Atlas
Supports the head
Has no body; consists of delicate ring around large vertebral foramen
Lateral masses
Lateral masses
Superior articular facets articulate with occipital bone; allows nodding “yes”
Cervical Vertebrae-Axis(C2)
Axis
Allows head rotation gesturing “no”
Dens or odontoid process—prominent knob on its anterosuperior side
The Thoracic Vertebrae
12 thoracic vertebrae (T1–T12)
Correspond to the 12 pairs of ribs attached to them
Occipital bone (skull)
back of the skull
Frontal bone
on the forehead and over the eyes
Parietal bones
Makes up most of the walls of the head (on the top of head)
Temporal bone
right above the ear and jaw (meaning temple)
Sagittal suture
in the middle of the skill like a stitch bring them together and fuse, sliced vertical
Coronal suture
separate the front of the skull from the back, sliced horizontal
Squamous suture
back side separating the parietal and temporal
Lambdoid
separates the occipital bone from parietal
External acoustic meatus
opening of the ear canal
The Lumbar Vertebrae
Five lumbar vertebrae (L1–L5)
Thick, stout body
Superior articular processes
Lumbar region resistant to twisting movements
The Sacrum
Sacrum—bony plate that forms posterior wall of pelvic cavity
Five separate sacral vertebrae (S1–S5) begin fusing around age 16 and complete fusion by age 26
Maxillae
Bone that holds the front of teeth up to the nose, slightly attributes to cheek bones
Mandible
the lower jaw, only part of our skull that moves
The Coccyx
Coccyx—usually consists of four small vertebrae (Co1–Co4); sometimes five
Fuse into single, triangular bone by age 20 to 30
Zygomatic bone
cheek bones
The Thoracic Cage
Thoracic cage consists of thoracic vertebrae, sternum, and ribs
Encloses lungs and heart
Also provides some protection of spleen, liver kidneys
Provides attachment for pectoral girdle and upper limbs
Rhythmically expanded by respiratory muscles to draw air into lungs
Nasal bones
top of nose
The Sternum
Sternum (breastbone)—bony plate anterior to the heart
palatine bones
makes up small area in the back of the throat
The Ribs
12 pairs of ribs - Posterior (proximal) ends attached to vertebral column - Most ribs’ anterior (distal) ends attached to sternum Costal cartilages (made of hyaline cartilage) attach rib to sternum
In-depth about the ribs The Ribs-True ribs
True ribs (ribs 1–7) Each is directly connected to sternum
Hyoid bone
On top of the thyroid gland
In-depth about the ribs- false ribs
False ribs (ribs 8–12) Lack independent connections to sternum
Indepth about the ribs-Floating ribs (ribs 11–12)
Floating ribs (ribs 11–12) Do not have cartilaginous connection to sternum or higher costal cartilages
