The Axial Skeleton

Skeletal system includes both: Axial skeleton Skull Vertebral column Thoracic cage Appendicular skeleton Pectoral and pelvic girdles Upper and lower limbs

The Skull

The cranium Cranial vault or calvaria Superior, lateral, and posterior walls of the skull Cranial floor or base Anterior fossa Middle fossa Posterior fossa

The skull Consists of the cranium and the bones of the face Sutures Lambdoid-between occipital and parietal bones Coronal-between parietal and frontal bones Sagittal-between parietal bones Squamous-between parietal and temporal bones

The skull

The skull

The skull

Cranial Bones one occipital bone foramen magnum two temporal bones two parietal bones one frontal bone frontal sinuses glabella two temporal bones auditory ossicles one sphenoid one ethmoid

The Sectional Anatomy of the Skull

The Sectional Anatomy of the Skull

The Occipital and Parietal Bones

Occipital and Parietal Bones Occipital bone Foramen magnum Occipital condyle External occipital protuberance Parietal bone Frontal bone Supraorbital foramen Glabella

Frontal bone

Temporal bone

Temporal bone Squamous suture Zygomatic process Zygomatic arch Mandibular fossa External auditory meatus Styloid process

Temporal bone is divided in regions Mastoid process Mastoiditis Meningitis Stylomastoid foramen Passage for cranial nerve VII Internal acustic meatus Passage for cranial nerves VII and VIII

The Sphenoid

Sphenoid bone Greater wings Sella turcica For the pituitary gland

The Ethmoid

Ethmoid bone Crista galli Attachment of the dura mater Cribiform plate Passage of olfactory nerves

Ethmoid bone Perpendicular plate Forms the superior part of the nasal septum Superior and middle nasal conchae (turbinates) Covered by mucosa Warms and humidifies the air

Facial bones Maxillary bones Mandible Inferior nasal conchae Palatine bones Nasal bones Vomer Inferior nasal conchae Zygomatic bones Lacrimal bones

Maxillae Alveolar margim Palatine process- anterior hard palate Incisive fossa- passage for nerves and blood vessels

Maxillary bone

Vomer, Zygomatic and Lacrimal bones Zygomatic bone articulates with zygomatic process of temporal bone forming the zygomatic arch

Facial bones

Mandible Body- horizontal portion Ramus-vertical portion Mandibular condyle- articulates with temporal bone Coronoid process Angle Alveolar margin- with sockets for the teeth Mandibular foramen – site of Novocain injection

The mandible

The Mandible and Hyoid Bones

Cranial Foramens to identify External view: Supraorbital foramen-for blood vessels and nerves Infraorbital foramen-blood vessels and nerves Mental foramen-blood vessels and nerves Stylomastoid foramen- nerve VII Carotid canal-for carotid artery External auditory meatus-leads to eardrum Incisive fossa-for blood vessels and nerves Incisive = i as in hit

Cranial Foramens to identify Internal view Optic canal -for optic nerve Superior and inferior orbital fissure “ROS” Rotundum- for a branch of V Ovale-for a branch of V Spinosum-for middle meningeal artery

Cranial Foramens to identify Foramen lacerum -internal carotid Jugular foramen -for jugular vein; IX, X,XI cranial nerves Internal acustic meatus -for VII,VIII Hypoglossal canal -for XII Foramen magnum -for spinal cord

The Fetal Skeleton

Fontanels Anterior or frontal Palpable for the first 1 ½ to 2 years of age Posterior of occipital Closes by the end of the first year of age Mastoid Sphenoid

Cranial bones Frontal It is parted Temporal It is incompletely ossified Presence of ossification centers Conical protusions on the cranial bones

The Vertebral Column

Vertebral column 7 cervical vertebrae 12 thoracic vertebrae 5 lumbar vertebrae 5 sacrum fused vetebrae 3-5 fused coccyx vertebrae

Vertebral column Intervertebral discs- pads of fibrocartilage between the vertebrae Nucleus pulposus- central soft region Annulus fibrosus- outer ring. Collagen fibers Herniated disc- protusion of the nucleus pulposus

Spinal curvatures Figure 7.16

Spinal curvatures Four spinal curves- posterior view Primary curvatures – present at birth Thoracic - convex Sacral- convex Secondary curvatures – develops after birth Cervical- concave Lumbar- concave

Abnormal Curvatures of the Spine

Structure of a typical vertebra Body- rounded portion. Anterior part Vertebral Foramen-for the spinal cord Transverse process Spinous process-single and posterior Intervertebral foramina-it is seen when 2 vertebras are put together. Passage of the spinal nerves

Cervical vertebra Transverse foraminas- only present in cervical vertebrae Atlas or C1 No body Join with the head and provides for range of motion (when you nod yes)

Cervical vertebra Axis or C2 Odontoid process or dens-allows rotation of the head (when you nod no)

Thoracic vertebrae Spinous process-long and downward Rib facet – for articulation with 1 rib

Lumbar vertebrae Massive body Short and thick and more horizontal spinous processes No rib facets No transverse foramem Superior and inferior articular processes

Sacrum Medial sacral crest-remnant of the spinous processes Alae- formed by fusion of the transverse processes. It articulates with the hip bones Sacral foramina- passage for blood vessels and nerves Sacral canal- continuation of the verterbral canal

Sacrum and coccyx Sacral hiatus-inferior opening of the sacral canal Sacral promontory- rim on the anterior and superior part of the sacrum Coccyx Attached to the sacrum by ligaments

The bony thorax Sternum Manubrium-articulates with the clavicle Body Xiphoid process-inferior end. Made of hyaline cartilage in children and is ossified in adults Jugular notch Sternal angle-between the body and the manubrium

The ribs Tubercle – is inferior Costal groove –depression along the inferior side Sternal end-articulates with sternum

Types of ribs True Ribs 1-7 Attached to the sternum through their own cartilage

Types of ribs False 8-12 8-10 are vertebrochondral ribs Attaches to the sternum indireclty through the cartilage of the C7 11-12 are floating ribs No attachment to the sternum