The Skeleton
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Bones of the Skeleton
o The skeletal system consists of ______ separate bones
o Two main groups, by location
 _____________________________________
 _____________________________________
o Supports and protects the organ systems in the brain and spinal cavities, and the ventral
body cavities
The Axial Skeleton
o Consists of 80 bones
o Three major regions
 ________________________
 ________________________
 ________________________
The Skull
o Two sets of bones
 _______________________
 Enclose the brain in the cranial cavity
 ______________________
 Framework of face
 Cavities for special sense organs for sight, taste, and smell
 Openings for air and food passage
 Sties of attachment for teeth and muscles of facial expression
Cranial Bones
o Frontal bone
o Parietal bones (2)
o Occipital bone
o Temporal bones (2)
o Sphenoid bone
o Ethmoid bone
Frontal Bones
o ____________________________________
o Most of anterior cranial fossa
o Superior wall of orbits
o Contains air-filled frontal sinus
Parietal Bones and Major Associated Sutures
o ____________________________________
o Four sutures mark the articulations of parietal bones with frontal, occipital, and
temporal bones:
 Coronal suture—_____________________________________________
 Sagittal suture—_____________________________________________
 Lambdoid suture—_______________________________________________
 Squamous (squamosal) sutures—________________________________
________________________________________
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Occipital Bone
o Most of skull’s posterior wall and posterior cranial fossa
o Articulates with ____________________________ at the occipital condyles
o ____________________________________________________________________
o Contacts the parietal bones at the lambdoid suture
o Contains the ___________________________ – connects the cranial cavity and the
brain with the spinal cavity
Temporal Bones
o Below the parietal bones and contributing to the sides and base of the cranium
(___________________________________________)
o Contains the external acoustic meatus which leads to the tympanum (eardrum)
o Other associations with the mouth:
 _________________________ – point of attachment with mandible
 _________________________ – anchors muscles associated with the tongue
and pharynx
o __________________________ – cite for muscle attachment for rotation of the head
Sphenoid Bone
o Forms floor of the cranium
o _________________________________________________
o Complex, bat-shaped bone
o Sella turcica – ______________________________________________________
Ethmoid Bone
o Anterior to the sphenoid bone
o Superior part of __________________________________________________________
________________________________________________________________________
o Largely associated with the nose and nasal passages
Facial Bones
o Mandible
o Maxillary bones (maxillae) (2)
o Zygomatic bones (2)
o Nasal bones (2)
o Hyoid bone
o Lacrimal bones (2)
o Palatine bones (2)
o Vomer
o Inferior nasal conchae (2)
o Nasal complex
Mandible
o ____________________________________
o Largest, strongest bone of face
o Temporomandibular joint: only freely movable joint in skull
 ______________________________
________________________________
o ______________________________________________________________________
______________________________________________________________________
o Articulate with all other facial bones except for the mandible
o Contain large maxillary sinuses which lighten the portion of the maxillae above the teeth
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Nasal Bones and Lacrimal Bones
o ____________________________
 Form bridge of nose between the orbits for the eyes
o Lacrimal bones
 ________________________________________
 Lacrimal fossa houses lacrimal sac
Zygomatic Bones
o Articulates with the frontal bone and the maxilla to complete the lateral wall of the orbit
o _________________________
Palatine Bones, Vomer and Inferior Nasal Conchae
o Palatine bones
 _________________________________________
 Contributes to the floor of the nasal cavity
 Small part of the floor of the orbits
o Vomer
 Plow shaped
 _________________________________________
o ________________________________________
 Form part of lateral walls of nasal cavity
Nasal Cavity (Complex)
o Roof, lateral walls, and floor formed by parts of four bones (______________________)
 Frontal
 Sphenoid
 Ethmoid
 Palatine bones
 Maxillary bones
 Inferior nasal conchae
o Nasal septum of bone and hyaline cartilage
 Ethmoid
 Vomer
 Anterior septal cartilage
Paranasal Sinuses
o _______________________________________________
o _______________________________________________
o Enhance resonance of voice
o Found in frontal, sphenoid, ethmoid, and maxillary bones
Hyoid Bone
o ______________________________________________
o U-shaped bone suspended below the skull
o _______________________________________________
o Site of attachment for muscles of swallowing and speech
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Vertebral Column
o Transmits weight of trunk to lower limbs
o _____________________________________________________
o Flexible curved structure containing 26 irregular bones (vertebrae)
 __________________________ (7)—vertebrae of the neck (C1-C7)
 __________________________ (12)—vertebrae of the thoracic cage (T1-T12)
 __________________________ (5)—vertebra of the lower back (L1-L5)
 __________________—bone inferior to the lumbar vertebrae
 __________________________—terminus of vertebral column
Vertebral Column: Curvatures
o ________________________________________________
o Has 4 curves:
 Two primary convex curvatures
 ___________________________________
 Two secondary concave curvatures
 _________________________________________________________
_________________________________________________________
o Abnormal spine curvatures
 ________________ (abnormal lateral curve)
 ________________ (hunchback)
 ________________ (swayback)
Intervertebral Discs
o Cushion-like cartilage pad between vertebrae composed of two parts:
 _______________________________
 Inner gelatinous nucleus that gives the disc its elasticity and
compressibility
 _______________________________
 Outer collar composed of collagen and fibrocartilage
o _______________________________________________________________________
General Structure of Vertebrae
o Body or centrum
 ______________________________________________
o Vertebral arch
 Composed of pedicles and laminae that, along with centrum, enclose vertebral
foramen
o Vertebral foramina
 _______________________________________________
o Intervertebral foramina
 Lateral openings between adjacent vertebrae for spinal nerves
o Seven processes per vertebra:
 _____________________________—projects posteriorly
 _____________________________ (2)—project laterally
 ______________________________ (2)—protrude superiorly inferiorly
 ____________________________ (2)—protrude inferiorly
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Cervical Vertebrae
o C1 to C7: smallest, lightest vertebrae
o C3 to C7 share the following features
 ______________________
 Stumpy spinous processes
 Large, triangular vertebral foramen
 Transverse foramen in each transverse process
 _______________________________________________
o C1 (atlas) and C2 (axis) have unique features
o ___________ (C1)
 ____________________________________________
 Named after Atlas from the Greek myth
o ___________ (C2)
 Dens projects superiorly into the anterior arch of the atlas
 Dens is a pivot for the rotation of the atlas
 ____________________________________________
Thoracic Vertebrae
o T1 to T12
o __________________________________________
o __________________________________________
o Long spinous process
o Location of articular facets allows rotation of this area of spine
Lumbar Vertebrae
o L1 to L5
o Vertebral body that is thicker and more oval than the thoracic
o ________________________________________________
o Allowing attachment of muscles
o Orientation of articular facets locks lumbar vertebrae together so as to prevent rotation
o _________________________________________________
o _________________________________________________
Sacrum and Coccyx
o __________________
 5 fused vertebrae (S1–S5)
 _____________________________
 Articulates with L5 superiorly, and with auricular surfaces of the hip bones
laterally
 ______________________________________________________
 Where muscles attach that are involved in leg movement
 ______________________________________________________
o Coccyx
 _______________________________
 3–5 fused vertebrae
 Usually 4
 Articulates superiorly with sacrum
 _____________________________________________________
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Thoracic Cage
o Composed of
 __________________________
 _________________________
 __________________________
o Functions
 Protects vital organs of thoracic cavity
 __________________________________________________
 Provides attachment sites for many muscles, including intercostal muscles used
during breathing
o ____________________________________
 First 7 ribs are true ribs because they attach directly to the sternum
 ________________________________________________________
 11-12 are called floating ribs because they do not attach at all
Sternum (Breastbone)
o Three fused bones
 ______________________
 Articulates with clavicles and ribs 1 and 2
 Body
 ____________________________________________________
 Xiphoid process
 ____________________________________________________
 Not ossified until ~ age 40
Appendicular Skeleton
o Bones of the limbs and their girdles
 __________________________________________________________
 __________________________________________________________
Pectoral Girdle (__________________________)
o Clavicles and the scapulae
 ___________________________________________________________
 __________________________________________________________
__________________________________
o Flattened acromial (lateral) end articulates with the scapula
o Cone-shaped sternal (medial) end articulates with the sternum
o ______________________________________________________________
Scapulae (Shoulder Blades)
o ______________________________________________________________
o Flat and triangular, with three borders and three angles
o Seven large fossae, named according to location
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The Upper Limb
o 30 bones form the skeletal framework of each upper limb
 Arm
 ______________________
 Forearm
 ________________________
 Hand
 8 ___________ bones in the wrist
 5 __________ bones in the palm
 14 __________ in the fingers
Humerus
o _______________________________________________________
o Articulates at the head with the scapula
o Articulates inferiorly with radius and ulna
Bones of the Forearm
o Ulna
 Medial bone in forearm
 ______________________________________________________________
o Radius
 Lateral bone in forearm (___________________________)
 Head articulates with humerus and with radial notch of ulna
 Interosseous membrane connects the radius and ulna along their entire length
Hand: Carpus
o Eight bones in two rows
 Proximal row
 ________________________________________________________
 Distal row
 ________________________________________________________
o Only scaphoid and lunate articulate with radius to form wrist joint
Hand: Metacarpus and Phalanges
o _________________________
 Five metacarpal bones (#1 to #5) form the palm
o _________________________
 Each finger (digit), except the thumb, has three phalanges—distal, middle, and
proximal
 Fingers are numbered 1–5, beginning with the thumb (pollex)
 _________________________________________
Pelvic (Hip) Girdle
o Two hip bones (each also called coxal bone or coxae)
 ______________________________________________________
 Transmit weight of upper body to lower limbs
 ______________________________________________________
o Each hip bone consists of three fused bones: ilium, ischium, and pubis
o ______________________________________________________________________
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Hip Bone
o Three regions
 Ilium
 _______________________________________________
 Auricular surface articulates with the sacrum (sacroiliac joint)
 Ischium
 Posteroinferior part of hip bone
 _______________________________________________
 Pubis
 ______________________________________________
 Midline pubic symphysis joint
Comparison of Male and Female Pelves
o Female pelvis
 ________________________________________
 True pelvis (inferior to pelvic brim) defines birth canal
 Cavity of the true pelvis is broad, shallow, and has greater capacity
o Male pelvis
 Tilted less forward
 _________________________________________________________
 Cavity of true pelvis is narrow and deep
The Lower Limb
o _______________________________________________
o Subjected to exceptional forces
o Four segments of the lower limb
 Thigh: _______________
 Kneecap: ___________________
 Leg: ___________________
 Foot: ___________________________________________________________
______________________________________
Femur
o _____________________________________________________________
o Articulates proximally with the acetabulum of the hip and distally with the tibia and
patella
Bones of the Leg
o Tibia
 Medial leg bone
 _______________________________________________________________
o Fibula
 Not weight bearing; no articulation with femur
 _________________________________________
 Connected to tibia by interosseous membrane
 Articulates with tibia
 _________________________________________
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Foot: Tarsals
o Seven tarsal bones form the posterior half of the foot
o ______________________________________________________________
o Other tarsal bones: cuboid, navicular, and the medial, intermediate, and lateral
cuneiforms
Foot: Metatarsals and Phalanges
o _______________________:
 Five metatarsal bones (#1 to #5)
 Enlarged head of metatarsal 1 forms the “ball of the foot”
 ______________________________________
o __________________________
 The 14 bones of the toes
 Each digit (except the hallux) has three phalanges
 ______________________________________