Download AXIAL SKELETON

Anatomy & Physiology
AXIAL SKELETON
General Information:
Human made of approx. 206 Bones
Function:
Support – provides hard framework
Protection of underlying organs
Movement – skeletal muscles use bones as levers
Mineral storage – reservoir for important minerals
Blood-cell formation – bone contains red marrow
Organization of Skeletal System
Skeleton is divided into 2 portions: Pretty Picture Next Slide
Axial Skeleton – Form axis of body and support & protect: organs of head, neck & trunk
Skull
Cranial bones: Form the braincase
Facial Bones: Support eyes, nose & jaw
Auditory Ossicles: In middle ear: Transmit sound
Hyoid Bone - Above larynx and below jaw
Vetebral Column – Consists of 26 bones
Rib Cage
12 pairs of ribs
Sternum
Costal Cartilages
Appendicular Skeleton: Skull, Vertebral Column, Rib Cage
- Pectoral Girdle – Paired scapulae & clavicles
- Upper Extremeties – Humerus, ulna, radius, carpal bones, metacarpal bones & phalanges
- Pelvic Girdle – Ossa coxae, symphysis pubis, and sacrum
- Lower Extremities – Femur, tibia, fibula, tarsal bones, metatarsal bones, and phalanges
- Long bones – longer than wide – a shaft plus ends (in upper & lower extremities)
Diaphysis: “shaft” of a bone
Ephysis: ends of a bone
Articular Cartilage: Made of thin hyaline cartilage, caps each epiphysis and facilitates
movement
Periosteum: Dense connective tissue which covers the surface of the bone
Endosteum: Inner layer lining
Medulary Cavity: Inner layer lining (hollow cavity – filled w/marrow hollow cavity)
Compact Bone: dense outer layer of bone
Spongy Bone: Internal network of bone
Blood Vessels: well vascularized well vascularized
Membranes: Periosteum, Sharpey’s fibers, and endosteum
Bone Types
- Short bones – roughly cube-shaped
(wrist/ankles – confined spaces)
- Flat bones – thin and flattened, usually curved (cranium, ribs, bones of shoulder girdle)
- Irregular bones – various shapes, do not fit into other categories (vetebrae & bones of skull)
AXIAL Skeleton: Page 1 of 4
Bone Features
Know the Terminology: Table 7.1, p153
Projections that provide attachment for muscles and ligaments
Projections that help form joints
Depressions and openings for passage of nerves and blood vessels
Know the Terminology: Table 7.1, p153
Overview of Skull Geography
The skull contains approximately 85 named openings
Foramina, canals, and fissures
Provide openings for important structures
Spinal cord
Blood vessels serving the brain
12 pairs of cranial nerves
Skeletal Division
Axial Skeleton: Skull, Vertebral Column, Rib Cage
Crainial bones (8) encloses the brain
Anterior roof of the cranium, the forhead, the roof of the nasal cavity, and the superior
arch of the bony orbits (contain eyeballs)
Frontal Bone (1)
Contains frontal sinus
Suborbital foramina allows passage of small nerves and vessels
Parietal Bone (2): Form upper sides and roof of cranium
Temporal Bone (2)form lower sides of cranium
External acoustic meatus – ear canal
Stylomastoid foramen – passage for part of the facial nerve
Occipital Bone (1): Forms back and much of base of skull
Foramen magnum – large hole in which the spinal cord attaches to brain
Sphenoid Bone (1): Forms anterior base of the cranium
Ethmoid Bone (1): Anterior portion of the floor of the cranium between the orbits, forms
the roof of the nasal cavity
Facial Bones (14) - Not in contact with brain, provide shape of face
Maxillae - forms upper jaw
Infraorbital: Under each orbit and serves as passageway for the infraorbital nerve and
artery to the nose
Incisors, canines, premolars, and molars are contained in sockets ([dental] alveoli within
the alveolar process of the maxilla
Palatine Bone (2):
Form posterior third of the hard palate, portion of the orbits, and part
of the nasal cavity
Zygomatic Bone (2): Form the cheekbones of the face
Lacrimal Bone (2): Form anterior part of the medial wall of each orbit [Nasolacrimal
canal – opening through which tears drain from eye into nasal cavity]
Nasal Bone (2):
Form the bridge of the nose
Inferior nasal conchae: Scroll-like bones that project horizontally and medially from the
lateral walls of the nasal cavity.
Covered w/mucuous membrane to warm, moisten/clean inhaled air
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Vomer (1):
Mandible (1):
Hyoid:
Auditory Ossicles
(Ear)
Forms the lower part of the nasal septum
Lower jawbone.
Attached to the skull by a temporomandibular articulation and is the
only movable bone of the skull
Mental & mandibular foramina – nerves and blood vessels pass
through here.
Largest/strongest bone in face
Lies inferior to the mandible
The only bone with no direct articulation with any other bone
Acts as a movable base for the tongue
Smallest bones in the body
Malleus – attaches to the eardrum
Incus – between the malleus and stapes
Stapes – vibrates against the oval window
Vertebral Column
Made of 33 individual vetebrae (most separated by fibrocartilaginous intervertebral discs that lend
flexibility and absorb the stress of movement
Function
Support head & upper extremities, allowing movement
Attachement of muscles
Protect spinal cord
Generalized anatomy of a vertebra
Body/centrum – Anterior drum-shaped structure
Vetebral foramen – hollow space formed by the vetebral arch & body
Pedicle(s) – support body
Lamina(3) – support body
Vetebral foramen – spinal cord passes through
Spinous process – muscle attachment
Transverse process(es) – Muscle attachment
Superior articulating surfaces – Limit twisting
Inferior articulating surface(s) – limit twisting
Cervical Vetebrae (C1-C7)
Form the neck region and support the head
C1=atlas – permits nodding of the head in yes movement
C2 = axis – provides a pivot for rotation of the head in a no movement
C3-C7 – Distinguished by the presence of a transverse foramen
Thoracic Vetebrae (T1-T12)
Serves as attachments of the ribs to form the posterior anchor of the rib cage.
Larger than cervical vertebrae & lack foramen at base of transverse process
Lumbar Vetebrae (L1-L5)
Have Heavy bodies and thick, blunt spinous processes for attachment of powerful back muscles
Largest vertebrae
Sacral Vetebrae (S1-S5)
These bones become fused after age 26These bones become fused after age 26
Provide strong foundation for pelvic girdleProvide strong foundation for pelvic girdle
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Coccygeal Vetebrae (Co-Co5)
Tailbone: Little or no known function
4-5 fused bones forming a triangular-shaped structureTailbone
Curves of Vertebral Columns
Important for increasing strength & maintaining balance of upper body & for Bipedal Stance
Primary & Secondary curves
Secondary Curves
Rib Cage
Parts of Rib
Head and Tubercle – Articulate with a vertebra
Neck
Angle
Body
Costal grove – protects the costal vessels & nerve
Sternum
Manubrium
Body
Xiphoid Process
Juglar Notch
Definition
“True” (vertebrosternal) ribs (1-7) – anchored to sternum by individual costal cartilages
“False” (vertebrochondral) ribs (8-12) – last two pairs do not attach at all (“floating ribs”)
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