activity 3 - axial skeleton

Activity 3:Axial Skeleton

Chapter 7 – McKinley et al., Human Anatomy, 4e.

Objectives:• Observe and dissect a fresh long bone from a cow• Identify the cranial and facial bones and important bone

markings on each• Identify the vertebrae and other features of the vertebral

column, and important bone markings on each• Identify ribs and sternum, and important bone markings on

each

1Compilation: Kathryn Watson & Claudia GonzalesLast Revision: Mohammad Tomaraei

Axial Skeleton (green) vs Appendicular Skeleton (yellow)

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Axial Skeleton vs Appendicular Skeleton (next activity)

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• Axial Skeleton – forms the long axis of body

• Skull

• Vertebral column

• Thoracic cage

• Appendicular Skeleton – appendages and what they attach to

• Upper limbs (arms)

• Pectoral girdle (shoulder)

• Lower limbs (legs)

• Pelvic girdle

Axial Skeleton (green)

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Axial Skeleton

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Sutures

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• Largest 4 skull sutures – where cranial bones articulate with each

other

• Coronal suture

• Sagittal suture

• Squamous suture

• Lambdoid suture

Sutures

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Sutures

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Paranasal Sinuses

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• Air-filled chambers named after the bone in which they are

housed• “Paranasal” because they cluster around and connect to the

nasal cavity

Fontanelles

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• Unossified remnants of membranes• Present at birth• Anterior fontanelle is the largest• Called “soft spots”• Ossify by 1 ½ - 2 years• Continue to ossify into adulthood• The sutures can become fused in

old age

Cranial and Facial Bones

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• Frontal bone• Supraorbital foramen: supraorbital artery and nerve go through

this foramen

• Frontal sinus: moistens air

• Parietal bones• Nasal bones


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• Frontal bone• Supraorbital foramen: supraorbital artery and nerve go through

this foramen

• Frontal sinus: moistens air

• Parietal bones• Nasal bones


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For labeled photographs of the human skeleton go to this website:

http://homepage.smc.edu/wissmann_paul/bones/EBbonestutorial.html





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• Sphenoid bone:• Greater wing• Lesser wing• Sella turcica: houses the pituitary gland

• Optic foramen / canal: contains the optic nerve (CN II)

• Foramen ovale: contains the mandibular branch of the trigeminal

nerve (CN V)

• Foramen rotundum: contains the maxillary branch of the

trigeminal nerve (CN V)

• Foramen spinosum: contains the middle meningeal vessels

• Foramen lacerum


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• Sphenoid bone:• Superior orbital fissure: contains CN III, the ophthalmic branch

of CN V, and CN VI

• Inferior orbital fissure: contains the maxillary branch of CN V

• Sphenoidal sinus: moistens air

• Lateral and medial plates• Pterygoid plates

Sphenoid Bone

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• Ethmoid bone:• Perpendicular plate: superior part of the nasal septum

• Superior and middle nasal concha(e): increase surface area for

warming and filtering air

• Cribriform plate and foramina: passageway for olfactory nerves

• Crista galli: attachment site for dura mater to skull

Ethmoid Bone

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• Inferior nasal conchae bones• Lacrimal bone:

• Lacrimal groove• Zygomatic bone:

• Temporal process of zygomatic bone: forms anterior portion of

the zygomatic arch (cheekbone)

• Maxilla:• Infraorbital foramen: passageway to infraorbital artery and

maxillary branch of CN V• Alveolar processes: contain upper teeth• Palatine processes: form anterior portion of hard plate• Incisive foramen (fossa): passageway to branches of

nasopalatine nerve from CN V


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Maxilla

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• Mandible:• Body• Ramus• Alveolar processes: contain lower teeth

• Angle• Mental foramen: passageway for the mandibular branch of CN V

and blood vessels

• CoroNOID process: insertion point of the temporalis muscle

• Mandibular condyle or condylar process: forms a joint with the

mandibular fossa of the temporal bone

• Mandibular notch

Mandible

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• Temporal bone:• Zygomatic process of temporal bone: forms the posterior

portion of the zygomatic arch (cheekbone)• Squamous region: squamous means flat – flat part of the bone• Styloid process: attachment for hyoid and tongue muscles• Mastoid process: insertion for sternocleidomastoid muscle• External auditory / acoustic meatus: opening of auditory canal• Petrous part: petrous means rock• Internal auditory / acoustic meatus: passageway for CN VII

and CN VIII nerves, and blood vessels to inner ear• Jugular foramen: passageway for internal jugular vein, CN IX,

CN X, and CN XI nerves• Carotid canal: passageway for internal carotid artery• Mandibular fossa: forms a joint with mandibular condyle of

mandible

Temporal Bone

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• Occipital bone:• Foramen magnum: passageway for spinal cord, vertebral

arteries, and CN XI nerve

• Hypoglossal canal: passageway for CN XII (hypoglossal) nerve

• External occipital protuberance and crest: attachment site for

neck / back muscles

• Occipital condyles: articulate with C1 (atlas)


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• Palatine bone:• Horizontal plates: form posterior portion of the hard palate

• Vomer: forms the inferior part of the nasal septum


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Skull = Cranial Bones + Facial Bones

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Cranial bones • Frontal bone

• Parietal bones (paired)

• Sphenoid bone

• Ethmoid bone

• Temporal bones (paired)

• Occipital bone

Facial bones• Nasal (paired)

• Inferior nasal conchae (paired)

• Lacrimal (paired)

• Zygomatics (paired)

• Maxillae (paired)

• Mandible

• Palatines (paired)

• Vomer

Cranial Bones

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parietal

parietal

frontal

temporalparietal

occipital

_________sphenoid_______ ethmoid

occipital

Vertebrae

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• Typical vertebrae (32):• Lamina: connects transverse process to spinous process

• Pedicle: connects body to transverse process

• Transverse process: process directed laterally

• Spinous process: process directed posteriorly

• Superior and inferior articular processes: form joints between

adjacent vertebrae

• Vertebral foramen: contains spinal cord

• Body: largest part of the vertebra

• Intervertebral foramen: formed when 2 vertebrae come

together; contains spinal nerves

• Intervertebral disc (not a bone): fibrocartilage found between

adjacent vertebral bodies

Vertebrae

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Vertebrae

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• Cervical vertebrae (7) – have bifurcated spinous processes

• Transverse foramen: cervical vertebrae have transverse

foramen which contains the vertebral arteries

• Atlas (C1):• Arch: contains articulation point for dens of C2 (axis)

• Body: C1 has no body – it has become the dens of axis

• Axis (C2):• Body: has odontoid process (dens)

• Odontoid process (dens): fused body of C1 (atlas);

articulates with atlas

• Vertebra prominens (C7):• Spinous process: very large and easily felt under the skin

Cervical Vertebrae

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C1, C2, and C7

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Vertebrae

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• Thoracic vertebrae (12):• Transverse process: on thoracic vertebrae, transverse

processes contain costal facets for articulation with angle of a rib• Lumbar vertebrae (5)• Sacrum (5 bones fused):

• Anterior sacral foramina: contain ventral rami of the sacral spinal nerves

• Posterior sacral foramina: contain dorsal rami of the sacral spinal nerves

• Median sacral crest: represents fused spinous processes of sacral vertebrae

• Auricular surfaces: ear-like processes, articulate with the iliac bones

• Superior articular processes: articulate with inferior articular processes of L5

• Coccyx (2-3 bones fused):• Cornu or horns: small horns that point superiorly

Thoracic Vertebrae

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Lumbar Vertebrae

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Sacrum and Coccyx

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Sternum and Ribs

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• Sternum:• Manubrium (top):

• Sternal or jugular notch• Sternal angle: division between manubrium and body

• Clavicular notch: articulates with clavicles

• Costal notch: articulates with ribs

• Body• Costal notches: articulates with ribs

• Xiphoid process (bottom): xiphoid means shaped like a sword

Sternum

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Sternum and Ribs

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• Ribs:• True ribs (1-7):

• Head (capitulum)• Neck• Tubercle• Angle• Costal groove• Shaft (body)

• False ribs (8-12)• Floating ribs (11-12)

Ribs

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activity 3 - axial skeleton

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