Divisions of Skeletal System - Human Anatomy - Lecture Notes, Study notes for Anatomy. Alagappa University


Description: Divisions of Skeletal System, Axial Skeleton, Appendicular Skeleton, Types of Bones, Bone Surface Markings, Sphenoidal Sinuses, Alveolar Process with Alveoli, Features of Skull are some points f this lecture. This lecture handout was provided by lecturer in Human Anatomy class. Important terms are bold in this handout. Few terms of the lecture are given above.
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A. Divisions of the Skeletal System
1. The 206 named bones in the adult skeleton are grouped in two major divisions
i. axial skeleton consists of the 80 bones located around the longitudinal
axis of the body:
a. skull bones
b. auditory ossicles
c. hyoid bone
d. vertebral column
e. sternum
f. ribs
ii. appendicular skeleton consists of 126 bones that form:
a. pectoral (shoulder) girdles
b. upper extremities
c. pelvic (hip) girdle
d. lower extremities
B. Types of Bones
1. Almost all bones are classified on the basis of shape into five major types:
i. long bones
ii. short bones
iii. flat bones
iv. irregular bones
v. sesamoid bones, which are (typically) small bones embedded in
2. There is one additional type of bone that is classified by location:
i. sutural (or Wormian) bones, which are located in the joints between
certain cranial bones
C. Bone Surface Markings
1. The surfaces of bones have surface markings, structural features that are
adapted to specific functions; the two major types of surface markings are:
i. depressions and openings
ii. processes
2. Important surface markings include fissure, foramen, fossa,
sulcus, meatus, process, condyle, facet, head, crest, epicondyle, line,
spinous process, trochanter, tubercle, and tuberosity.
D. Skull
1. The skull consists of 22 bones
i. 8 cranial bones that form the cranial cavity to enclose and protect the
ii. 14 facial bones that form the face
2. The 8 cranial bones (each having specific surface markings) are:
i. frontal bone
a. frontal squama (vertical plate)
b. supraorbital margin
c. supraorbital foramen
d. frontal sinuses
ii. two parietal bones
iii. two temporal bones, each one having:
a. temporal squama
b. zygomatic process (which contributes to the zygomatic arch)
c. mandibular (glenoid) fossa
d. articular tubercle
e. mastoid portion
f. external auditory (acoustic) meatus
g. mastoid “air cells”
h. mastoid process
i. internal auditory (acoustic) meatus
j. styloid process
k. stylomastoid foramen
l. petrous portion
m. carotid foramen
n. jugular foramen
iv. occipital bone
a. foramen magnum
b. occipital condyles
c. hypoglossal foramen
d. external occipital protuberance
e. superior nuchal lines
f. inferior nuchal lines
v. sphenoid bone
a. body
b. sphenoidal sinuses
c. sella turcica
d. greater wings (each having a foramen ovale)
e. lesser wings
f. optic foramen
g. superior orbital fissure
h. pterygoid processes
vi. ethmoid bone
a. lateral masses
b. ethmoidal sinuses
c. perpendicular plate
d. cribriform plate
e. olfactory foramina
f. crista galli
g. superior nasal conchae (turbinates)
h. middle nasal conchae (turbinates)
3. The 14 facial bones (each having specific surface markings) are:
i. two nasal bones
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