Lecture 2: Introduction to the Skeletal System and Skull Flashcards
Functions of the skeletal system
Supports and protects organs, attachment site for skeletal muscles, store minerals (Ca, P), produce blood cells (only in bone marrow)
Classification of bones
Long bones: long cylindrical body (diaphysis) and 2 ends (epiphysis). Ex. arm, forearm, legs, thigh, clavicle
Short bones: cuboidal appearance. Ex. wrist, ankle
Flat bones: thin and flattened with mild curve. Ex. ribs, some skull bones, scapula, sternum
Irregular bones: lack specific shapes. Ex. vertebrae, facial bones
Sesamoid bones: small round or flat embedded in tendons to reduce friction between tendons and joints, increase muscle efficiency, or change direction. Ex. patellar
Skeletal groups
206 bones
Axial: axis of the body (skull, vertebral column, ribs, sternum)
Appendicular: limbs and girdles (shoulder and pelvic girdle, upper and lower limb)
Skull
22 bones Supports facial structures and protects brain Viscerocranium - framework of the face Neurocranium - bony box to hold brain Skull without mandible is the cranium
Paired vs Unpaired bones in viserocranium
Paired: lacrimal, nasal, maxilla, zygomatic, inferior nasal concha, palatine
Unpaired: mandible, vomer
Paired vs unpaired bones in the neurocranium
Paired: Parietal, temporal
Unpaired: Frontal, occipital, sphenoid, ethmoid
Bones in the Anterior view of the skull
Frontal bone Nasal bone (nose) Zygomatic bones (cheek) Maxillae (upper jaw) Mandible (lower jaw)
Cavities in the Anterior view of the skull
Orbital cavity (2) Nasal cavity (2) Oral cavity
Orbital Cavity
4 sided pyramidal space
Apex points posteriorly
3 major openings: superior orbital fissure (to cranium), inferior orbital fissure (for cranial nerves), optic canal
Medial corner connects to nasal cavity via nasolacrimal duct
Nasal Cavity
Separated from each other by vertical bony septum
Lateral wall has 3 curved bony plates: superior, middle and inferior nasal conchae
Inferior is an individual bone; superior and middle are part of ethmoid bone
Anterior opening = anterior nasal aperture
Posterior opening = choana
Bones in the Lateral view of the skull
Parietal bone
Frontal bone
Occipital bone
Temporal bone (external acoustic meatus, mastoid and styloid process)
Zymgomatic bone (zygomatic arch with temporal bone)
Lacrimal bone (along with nasolacrimal duct)
Maxilla
Mandible (coronoid process, condylar process, ramus)
Bones in the Posterior View of the skull
Occipital bone (external occipital protuberance - border of head and neck)
Parietal bone
Temporal bone
Sutures in the skull
Lambdoid suture - between parietal bones and occipital bones
Sagittal suture - between L/R parietal bones
Coronal suture - between parietal bones and frontal bone
Bones in the Superior view of the skull
Frontal bone
Parietal bones
Occipital bone
Bones form a dome shaped roof = calvaria
Suture Junctions in the skull
Bregma - junction of coronal and sagittal suture (anterior fontanelles in infants)
Lambda - junction of sagittal and lambdoid suture (posterior fontanelles in infants)
Fontanelles = membranes that allow skull to grow proportionately
Bones in the Inferior view of the skull
Hard palette (maxilla and palatine) Vomer which separates choana Sphenoid bone + Pterygoid process Temporal bone (mastoid and styloid process) Occipital bone (occipital condyles)
Cranial fossa
Anterior cranial fossa (frontal bone, ethmoid bone, lesser wings of sphenoid bone)
Middle cranial fossa (greater wings of sphenoid body - has hypophyseal fossa of sella turcica that houses pituitary gland, temporal bone)
Posterior cranial fossa (temporal and occipital bone)
Anterior and middle fossa separated by lesser wing of the sphenoid bone
Middle and posterior fossa separated by superior petrous (contains middle and inner ear) part of temporal bone
Olfactory foramina in ethmoid bone
Cribriform plate divided by crista galli Olfactory nerve (CNI) passes
Optic canal
Optic nerve (CNII)
Superior orbital fissure
Oculomotor nerve (CNIII) Trochlear nerve (CNIV) Ophthalamic division of trigeminal nerve (CNV) Abducens nerve (CNVI)
Foramen rotundum
Maxillary division of trigeminal nerve (CNV)
Foramen ovale
Mandibular division of trigeminal nerve (CNV)
Foramen spinosum
Middle meningeal artery
Foramen lacerum
Filled with cartilage
Carotid canal
Internal carotid artery
Internal auditory/acoustic meatus
Facial nerve (CNVII) Vestibulocochlear nerve (CNVIII)
Jugular foramen
Glossopharyngeal nerve (CNIX) Vagus nerve (CNX) Accessory nerve (CNXI) Internal jugular vein
Hypoglossal canal
Hypoglossal nerve (CNXII)
Foramen magnum
Medulla oblongata, vertebral arteries
