Bones of the Axial Skeleton Download

Bones of the Axial Skeleton The components of the axial skeleton and their specific function
• Noting prominent articulations and landmarks
The axial Skeleton forms the vertical axis of the body.
It consists of 80 bones that include, 29 skull and associated bones, 25
thoracic cage bones and 26 vertebral bones.
The axial skeleton adjusts the position of the head, neck and trunk,
performs respiratory motions and stabilizers & position the appendicular
Bony Landmarks:
• Bony Openings = Foramen: rounded opening or passageway
through bone for blood vessels or nerves.
• Depressions: Fossa= Shallow depression. Sulcus = small groove.
• Non Articulating Surface
o Epicondyle = a projection adjacent to a condyle.
o Ramus = Flat angular section of bone.
o Trochanter = massive bony process found on the femur.
o Tubercle = small round bony process
o Tuberosity = Large, rounded process.
The composition of the cranium and the face
• General function, articulations, regions/landmarks
Cranial Bones
• Parietal x2
• Temporal x2
• Occipital x1
• Frontal x1
• Sphenoid x1
• Ethmoid x1
General Function: Form
part of the superior and
lateral surfaces of the
Articulations: Articulate
with one another, the
occipital, temporal, frontal
and sphenoid bones.
Superior and inferior temporal lines = attachment site for the temporalis
Temporal Bone
General Functions: Forms part of the lateral wall of the cranium and
Zygomatic arches. Articulates with the mandible, surrounds and protects
inner ear, attachment site for muscles that close the jaw and move the
Articulations: Articulates with the Zygomatic, sphenoid, parietal and
occipital bones of the cranium and mandible of the face.
Regions/Landmarks: Zygomatic process and arch, mandibular fossa,
mastoid process, styloid process, external auditory meatus.
Frontal Bone
General Functions: Forms the anterior portion of the cranium and roof
of the eye sockets.
Articulations: Parietal, sphenoid, Ethmoid, nasal, lacrimal, maxillary and
Zygomatic bones.
Regions/Landmarks: Superior temporal line, supraorbital margin,
lacrimal fossa, frontal sinuses.
Occipital Bone
General Functions: forms the posterior and inferior surfaces of the
Articulations: Parietal, temporal and sphenoid bones and the first
cervical vertebra (the atlas).
Regions/Landmarks: External occipital protuberance, external occipital
crest, occipital condyles, foramen magnum.
Sphenoid Bone
General Function: forms part of the floor of the cranium, unites the
cranial and facial bones and strengthens the sides of the skull
Articulations: All other Cranial Bones
Region/Landmarks: Lesser & Greater Wings
Ethmoid Bone
General Function: Forms the anteriomedial floor of the cranium, roof of
the nasal cavity and part of the nasal septum.
Articulation: Frontal bones and sphenoid.
Regions/Landmarks: Cribiform plate, paired lateral masses and
perpendicular plate
Facial Bones
• Nasal x2
• Maxillae x2
• Zygomatic x2
• Lacrimal x2
• Palatine x2
• Nasal Concha x2
• Vomer x1
• Mandible x1
The regions and curvatures of the vertebral column
The Vertebral column is made up of Cervical (7), Thoracic (12), Lumbar
(5), Sacral (5 fused) and Coccyx (4 fused) vertebrae. The curves of the
thoracic and sacral section are primary curves and are present at birth.
The curves of the cervical, lumbar and coccyx are secondary curves and
developed after birth. The curves of the spinal column help to increase
strength, maintain balance in an upright position, absorb shock and
protect vertebrae from fracture.
The Thoracic Cage
Consists of the sternum (manubrium, body and xiphoid process) and the
ribs (true, false and floating).
Hyoid Bone
General Function: supports the larynx, attachment site for muscles of
the larynx, pharynx and supports the tongue.
Articulations: Suspended form the temporal bones by ligaments and
Regions/Landmarks: Body, greater horns and lesser horns.