Lecture 2: Introduction to the Skeletal System and Skull

Question 1

Functions of the skeletal system

Answer 1

Supports and protects organs, attachment site for skeletal muscles, store minerals (Ca, P), produce blood cells (only in bone marrow)

Question 2

Classification of bones

Answer 2

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

Question 3

Skeletal groups

Answer 3

206 bones
Axial: axis of the body (skull, vertebral column, ribs, sternum)
Appendicular: limbs and girdles (shoulder and pelvic girdle, upper and lower limb)

Question 4

Skull

Answer 4

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

Question 5

Paired vs Unpaired bones in viserocranium

Answer 5

Paired: lacrimal, nasal, maxilla, zygomatic, inferior nasal concha, palatine
Unpaired: mandible, vomer

Question 6

Paired vs unpaired bones in the neurocranium

Answer 6

Paired: Parietal, temporal
Unpaired: Frontal, occipital, sphenoid, ethmoid

Question 7

Bones in the Anterior view of the skull

Answer 7

Frontal bone
Nasal bone (nose)
Zygomatic bones (cheek)
Maxillae (upper jaw)
Mandible (lower jaw)

Question 8

Cavities in the Anterior view of the skull

Answer 8

Orbital cavity (2)
Nasal cavity (2)
Oral cavity

Question 9

Orbital Cavity

Answer 9

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

Question 10

Nasal Cavity

Answer 10

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

Question 11

Bones in the Lateral view of the skull

Answer 11

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)

Question 12

Bones in the Posterior View of the skull

Answer 12

Occipital bone (external occipital protuberance - border of head and neck)
Parietal bone
Temporal bone

Question 13

Sutures in the skull

Answer 13

Lambdoid suture - between parietal bones and occipital bones
Sagittal suture - between L/R parietal bones
Coronal suture - between parietal bones and frontal bone

Question 14

Bones in the Superior view of the skull

Answer 14

Frontal bone
Parietal bones
Occipital bone
Bones form a dome shaped roof = calvaria

Question 15

Suture Junctions in the skull

Answer 15

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

Question 16

Bones in the Inferior view of the skull

Answer 16

Hard palette (maxilla and palatine)
Vomer which separates choana
Sphenoid bone + Pterygoid process
Temporal bone (mastoid and styloid process)
Occipital bone (occipital condyles)

Question 17

Cranial fossa

Answer 17

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

Question 18

Olfactory foramina in ethmoid bone

Answer 18

Cribriform plate divided by crista galli
Olfactory nerve (CNI) passes

Question 19

Optic canal

Answer 19

Optic nerve (CNII)

Question 20

Superior orbital fissure

Answer 20

Oculomotor nerve (CNIII)
Trochlear nerve (CNIV)
Ophthalamic division of trigeminal nerve (CNV)
Abducens nerve (CNVI)

Question 21

Foramen rotundum

Answer 21

Maxillary division of trigeminal nerve (CNV)

Question 22

Foramen ovale

Answer 22

Mandibular division of trigeminal nerve (CNV)

Question 23

Foramen spinosum

Answer 23

Middle meningeal artery

Question 24

Foramen lacerum

Answer 24

Filled with cartilage

Question 25

Carotid canal

Answer 25

Internal carotid artery

Question 26

Internal auditory/acoustic meatus

Answer 26

Facial nerve (CNVII)
Vestibulocochlear nerve (CNVIII)

Question 27

Jugular foramen

Answer 27

Glossopharyngeal nerve (CNIX)
Vagus nerve (CNX)
Accessory nerve (CNXI)
Internal jugular vein

Question 28

Hypoglossal canal

Answer 28

Hypoglossal nerve (CNXII)

Question 29

Foramen magnum

Answer 29

Medulla oblongata, vertebral arteries