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 skeleton. 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 cranium. Articulations: Articulate with one another, the occipital, temporal, frontal and sphenoid bones. Regions/Landmarks: Superior and inferior temporal lines = attachment site for the temporalis muscle. 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 head. 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 cranium. 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 muscles Regions/Landmarks: Body, greater horns and lesser horns.