Axial Skeleton

How many bones are there in the adult human skeleton

206 bones

Bones are dynamic organs which change in strength and thickness depending on _____________ or ________________

1. muscle strength2. body weight

Our bones are constantly being remodelled through our adult life


Depending on what stresses are being put on it or not, our bones can become ____________ and stronger or _______________ & weaker

1. thicker2. thinner

What is the anatomy of the skeleton

-rigid framework -consists of: bones, cartilage & ligaments

Function of the skeletal system

-support weight of body, allow for movements-protects internal organs (brain, spinal cord, heart, lungs, pelvic organs)-storage site for calcium, phosphate & fat-red marrow houses the blood-cell producing tissue of the body

Fat is stored in the

yellow marrow of the bone

Red marrow contains

blood cells that undergoes hematopoiesis (production of WBC, RBC & platelets)

99% of the body's _____________ is stored in bone


the skeletal system contains..

1. cartilage2. ligaments3. tendons


-provides flexible strength & support (ex. for thoracic cage, external ear, trachea, larynx)-cushions articulating surfaces of the bone

Cartilage allows the_______________ to connect to the breast bone


True or false. The sternum is made out of cartilage


Whenever two bones connect with each other in a joint of articulation there is a layer of _____________ covering the ends that connect together in order to stop ____________ & ____________

1. Hyaline cartilage2. Wear3. tear


-strong connective tissue bands that hold bones at a moveable joint together & prevent excessive movements of the joint that would result in injury

Ligaments are considered the ________________ that hold the bones together

-duct tape


-attach bone to skeletal muscle to move the skeleton, in outer words.. the "interconnection between muscle & bone"-pre

The skeletal system is divided into

1.Axial skeleton 2. appendicular skeleton

Axial skeleton contains _____________ bones


The axial skeleton consists of the __________ & _________ including the sacrum & coccyxand the ___________formed by the ribs & sternum

1. skull2. vertebral column3. thoracic cage

The skull (29) contains more bones than the ________ & the ____________

1. vertebral column (26)2. thoracic cage(25)

Function of the axial skeleton

-supports head, neck, back, chest & protects the brain, spinal cord, heart & lungs-attachment site for muscles that move the head, neck & back-attachment sites for muscles that act across the shoulder & hip joints to move their corresponding limbs

The axial skeleton forms the

-vertical axis of the body

The appendicular skeleton contains __________ bones

126 bones

The appendicular skeleton is made up of all the bones of the __________ & __________ limbs

1. upper2. lower

the pectoral girdle anchors the _______________ to the thoracic cage making them .......

1. upper limbs-highly mobile-have. wide range of motion to manipulate, lift & carry objects or turn the head & trunk

The pelvic girdle anchors the bones of the ______________ to the vertebral column which is............

1. lower limb-adapted for weight-bearing support & stability-adapted for body locomotion (ex. walking, running)

The cranium (skull) contains _____________ & ___________

1. facial bones2. brain case

Facial bones

-support the face-underlie facial features-form nasal cavity-enclose the eyeballs-support the teeth of the upper & lower jaws

Brain case

cranial vault"-rounded, surrounds & protects the brain -houses the middle & inner ear structures

The adult skull contains 22 individual bones, however 21 are _____________ & fused into a single unit

1. immobile

The only moveable bone in the skull is the _____________

1. mandible (lower jaw)

What are the 6 cranial bones

1. Frontal bone2. parietal bone3. temporal bone4. occipital bone5. ethmoid bone6. sphenoid bone

The frontal bone

-forehead, anterior part of the cranium, upper part of orbits (the holes that your eyes are located in

Features of the frontal bone

-contains frontal sinuses & coronal suture (the coronal suture is where the crown sits)

The parietal bone

-found in the buldging top of the cranium

Features of the parietal bone

-contains the lambdoid (occipital), squamous (temporal & sphenoid) & coronal suture (frontal)

Temporal bone

-on the posterior of the ear-form the lower sides of the cranium (skull/brain vault) as well as a part of the temporal floorex. when you tuck your hair behind your ear, you're touching your temporal bone

Features of the temporal bone

-contains middle & inner ear structures& the mastoid sinuses

Occipital bone

-found in the lower (inferior), posterior section of the skull-contains foramen magnum ( area where your spinal cord comes through)

Features of the occipital bone

-has immoveable joints w/ 3 other cranial bones-sits right on top of the first cervical vertebrate known as the: (C1, Atlas)

First cervical veterbrate

C1, Atlas

Ethmoid bone

anterior (infront of sphenoid bone & poster (behind the nasal bones)

Features of the ethmoid bone

-complex, irregular bone-forms: anterior cranial floor, medial orbit walls (where the eyes are located), upper nasal septum & sidewalls of nasal cavity

Sphenoid bone

-forms central portion of the cranial floor

Features of the sphenoid bone

-contains sphenoid sinuses-attaches (anchors) the frontal, parietal, occipital, ethmoid bones-considered the "corner stone" of the cranial vault-forms lateral wall & orbit floor

Which two bones are sort of hidden in the skull itself?

1. ethmoid bone2. sphenoid bone

What are the 7 facial bones

1. Lacrimal bone2. nasal bone3. maxilla (upper jaw)4. mandible (lower jaw)5. zygomatic bone6. palatine bone7. vomer bone

Lacrimal bone

tear ducts" (nasolacrimal tear duct)-forms a part of the nasal cavity & the eye (medial orbit wall)-articulates with maxilla, frontal & ethmoid bones

Nasal bones

-forms part of the nose bridge-articulates with ethmoid, nasal septum, frontal bone, maxillae & other nasal bone

Maxilla (upper jaw)

-forms parts of orbital floors, roof of mouth, floor & sidewalls of nose & contains maxillary sinuses

Mandible (lower jaw)

-only moveable joint of skull-largest, strongest facial bone

Zygomatic bone

-forms the cheek bone & shapes the cheek with the zygomatic arch-forms outer margin of orbit

Palatine bone

palate"-forms posterior part of hard palate & lateral wall of the nasal cavity-articulates with the maxillae & sphenoid bone

Vomer bone

-forms the base of the nasal septum (posterior part)-articulates with: sphenoid, ethmoid, palatine & maxillae bones

Paranasal sinuses

-hollow, air filled spaces/ cavities located within certain bones of the skull & are connected with the nasal cavity & is lined with the nasal mucosa

Purpose of paranasal sinuses

-reduce bone mass & lighten the skull (due to their spaces)-add resonance to voice (ex. when you have nasal congestion, the nasal mucosa produces excess mucous & fluids & these fluids fill the spaces changing the tone of your voice)

4 types of paranasal sinuses

1. Frontal sinus2. Maxillary sinus3. sphenoid sinus4. ethmoid air cell

Frontal sinus

-just above the eyebrows within frontal bone

Maxillary sinus

-largest sinus within maxillary bones-most commonly involved in sinus infections

Sphenoid sinuses

-single, midline within sphenoid bone

Ethmoid air cell

-located on the lateral sides of ethmoid bones

Hyoid bone

-independent, unusual u-shaped bone located in the upper neck, near the mandible & does not articulate with any other bone-not part of the skull-attached to small muscles above & belowFunction: involved with movements of the tongue, larynx & pharynx during swallowing & speaking

The hyoid bone is the bone that is ____________________ when someone is being strangled & is usually the first sign of strangulation

1. easily broken

The vertebral column (spinal column or spine) structure:

-flexible column-in between the vertebrate are intervertebral discs-irregular shaped bones that are stacked on top of each other

The function fo the vertebral column

-supports & moves head, neck & body & protects spinal cord

The vertebral column is curved with two primary curvatures ____________ & ______________ curves & secondary curvatures ____________ & ____________ curves

1. thoracic & sacrococcygeal curves2. cervical & lumbar curves

The vertebral column is divided into 3 regions & also includes the ______________ & ______________

1. Sacrum2. Coccyx

What are the 3 regions that the vertebral column is divided into ________________

1. Cervical (C1-C7) Vertebrate: neck2. Thoracic (T1-T12) Vertebrate: chest3. Lumbar (L1-L5) Vertebrate: lower back

The __________ & _________ vertebrate fuse from age 20 onwards; in an adult these get fused into 1 single bone

sacrum & coccyx

The sacrum

bone formed from five vertebrae fused together to form pelvis


four vertebrae fused together to form the tailbone

Fused vetebrae of sacrum & coccyx form

sacrococcygeal curve

Cervical vertebrate are ____________ than ____________ vertebrate & ___________________

1. smaller2. lumbar3. bears less weight

Thoracic vertebrate have sites for ____________; whereas the vertebrate that gives rise to the sacrum & coccyx have ______________________

1. ribs2. fused together into single bones

The function of the curvatures (4) of the vertebral column

-increase strength & flexibility-ability to absorb shock-curvatures increase in depth (become more curved) to accommodate the extra weight

There are two types of curves that exist in the vertebral column:

Primary Curves & Secondary Curves

Primary Curvatures of vertebral column

-originate from fetal curvature-include the thoracic curve & sacrococcygeal curve

Secondary curvatures

-develop after birth & are in opposite direction to original fetal curvature-include the: cervical curve & lumbar curve

The cervical curve develops when

-an infant starts to hold their head up when sitting

The lumbar curve develops when

-as a child learns to stand & walk

True or False: The Lumbar curve is generally deeper in males

-False-It's generally deeper in females in order to accommodate child bearing weight

What are the 4 general parts of the vertebrate

1. Body2. Vertebral arch3. Intevetebral foramen4. vertebral foramen & vertebral (spinal) canal

Body of Vertebrate

location: anterior portion of vertebrateAnatomy: bigger & thicker posteriorly & each separated by intevetebral discfunction: supports body weight

Vertebral arch

location: posterior portion of vertebrateanatomy: formed by lateral pedicles & posterior laminafunction: bony protection & passageway for spinal cord

Intervetebral foramen

location: small opening at each side, just posterior to the bodyanatomy: formed by notches in pedicles of adjacent vertebrate function: opening for spinal nerves to exit from vertebral column

Vertebral foramen & vertebral (spinal ) canal

location: large opening between the vertebral arch & bodyanatomy: formed through the alignment of vertebral foraminafunction: contains the spinal cord

The parts of the vertebrate that sticks out (protude) are called


There are 7 processes in most vertebrate


The only process in the vertebrates that is not paired is the

Spinous process

7 Processes of a vertebrate

1. Transverse process (paired)2. Spinous process (vertebral spine)3. superior articular process (paired)4. Inferior articular process (paired)

Transverse process

-sticks out at the sides (laterally)-projects posteriorly at the midline of the back-series of bumps down the middle of the back

Spinous process

-jets out in the back-projects laterally from between pedicle & lamina

Superior articular process (paired)

-parts of the vertebrate that articulates with the next vertebrate above-in other words, extends/faces upward on each side of the vertebrate

Inferior articular process (paired)

-parts of the vertebrate that faces down on each side of the vertebrate -in other words, it faces or projects downward on each side of the vertebrate

Function of the processes

-Important for muscle attachment sites-form slightly moveable joints between adjacent vertebrate (in order to help move the trunk, head & neck): their shape & orientation vary in diff regions depending on type & range of motion available in each region

Which process allows the superior articular process to connect with the inferior articular process of the vertebrate above

-Spinous process (vertebral spine)

Cervical vertebrate (neck) typical/ unique features

contains a: small body, bifid (Y-shaped) spinous process, transverse processes-the transverse process houses the transverse foramen which allows the carotid artery to carry blood to the brain

Cervical Vertebrate contains ________ & _______

1. atlas (C1)2. Axis (c2)

Atlas (C1)

-first cervical vertebrate-supports the skull on top of the vertebral column-has the foramen for the spinal cord to go through-ring shaped, made of anterior & posterior arches-contains longer & more lateral transverse process-doesn't contain a body or spinous process because it supports the skull via the occipital bone

C2 Vertebrate (Axis)

-second vertebrate-allows for rotation when turning head from side to side (ex. saying no)-contains a unique feature called: dens

Dens of the c2 axis

-"odontoid process"-come out of the C2 vertebrate and projects upward to the C1-dens are held in place from transverse ligament that goes from one side to the other to keep the entire vertebral column in place together with the occipital bone

Thoracic vertebrate typical/unique features

-contains larger bodies which allows it to hold a bit more weight compared to the cervical vertebrate-contains long spinous process that face downwards-the superior articular process of the thoracic vertebrate face anteriorly whereas the inferior processes face posteriorly which allows for range of movements-the unique feature of the thoracic vertebrate are: facets

Facets: unique features of thoracic vertebrate

-attach to ribs-2 types: Costal Facets & Articular facet

Costal facets

-located lateral to the body-articulate with the head of the rib

Articular facets

-located on the transverse process-articulate with the tubercle of the rib

Why does the thoracic vertebrate have these features?

-because it connects with the ribs to stabilize the ribcage itself

Lumbar vertebrate characteristics

-large, thick vertebral body-short rounded spinous process-carries the greatest amount of weight and therefore requires maximum stability


-5 fused vertebrate fused at age 20 into a triangular shaped bone-form a part of the pelvis-thick & wide across -contains little holes called: sacral foramina which allow for spinal nerves to exit the sacrum & go to different parts of the lower body -superior articular process of sacrum articulates with the inferior articular process from the L5 vertebra

Coccyx (tailbone)

-4 vertebrate fused-articulates with he inferior tip of sacrum-not weight bearing when standing; sometimes it's weight bearing when sitting down

Intervetebral discs

-located between each vertebrate-made out of a fibrocartiliganous pad which is thin in the cervical region (because it only supports the head) & is thickest in the lumbar region because it supports everything above it

The intervertebral disc is made out of the toughest cartilage that we have in our body to ______________

help support the weight of the body

What are the intevetebral discs made out of

1. annulus fibrosus (outer layer that is anchored to the outer margins of the adjacent vetebral bodies)2. Nucleus pulpous (softer, gel like layer in the middle to help resist compression & to help support body weight)

Function of the intevetebral dics

-anchors bodies of adjacent vertebrate-provides padding between bones during weight bearing-provides flexibility for movement between vertebrate-connects with ligaments along vertebral column for overall support & stability

The intevetebral disc make up _________ of the height between the top of the pelvis & the base of the skull


As we age, the discs become _______________ due to decrease in water content & can slip which can also cause the ____________ to slip as well, therefore ____________ & range of motion also decreases

1. thinner2. spinal nerves3. flexibility

The slipping of the disc would result in ________________ which can cause excruciating pain if the nerve is trapped and is most common in the _________ or ________ region

1. herniated/ ruptured disc2. L4-L5 region or L5-S1 region

The pain radiating down the leg as a result of the herniated disc is called _____________


Ligaments of the vertebral column

-connect bone to bone-located down the length of the vertebral column along both its posterior & anterior aspects & serves to resist excess forward or backward bending movements of the vertebral column

4 main types of ligaments connecting the different processes in the vertebrate

1 Anterior longitudinal ligament2. Supraspinous ligament3. Nuchal ligament4. Posterior longitudinal ligament & ligamentum flavum

Anterior longitudinal ligament

located on the anterior side of the vertebral column-function: unites vertebral bodies, resists excess bending back of vetebral column, therefore preventing "whip lash" injury in a car accident

Supraspinous ligament

located on the posterior side of the vertebral column-does the same thing as the anterior ligament except at the back-connects spinous process of lumbar & thoracic vertebrate -supports vertebrate column when bending forward

Nuchal ligament

-located on the posterior neck (extension of the supraspinous ligament)-supports the skull and prevents it from falling forward

Posterior longitudinal ligament and ligaments flavum

-located on the inside of the vertebral canal-supports the vertebral column when bending forward

Which two ligaments supports the vertebral column when bending forward

1. supraspinous ligament2. posterior longitudinal ligament

Thoracic Cage (rib cage)

-mage out of the sternum (breastbone)


-elongated bony structure that actors the anterior thoracic cageMade out of: 1. manubrium wider (superior portion), 2. body elongated (central portion), and diploid 3. Xiphoid process (inferior tip)

There are ribs that are attached to the sternum (3)

1. True ribs2. False ribs3. Floating Ribs

True ribs

vetebrosternal ribs"-ribs that attach directly to sternum via costal cartilage (hyaline)-rib pairs 1-7

False ribs

vetebrochondral ribs"-either attached indirectly to the sternum or not at all-attached to ribs 8-12

floating ribs

-attached to ribs 11&12-called floating ribs because they don't attach to the sternum at all-in other words, the costal cartilages terminate within musculature of lateral abdominal wall

Ribs 8-10

-attached to cartilage of the next higher rib

The costal cartilage is made out of the ____________________

Softest hyaline cartilage

The thoracic cage (rib cage) is made out of:

-12 pairs of ribs, their costal cartilages & sternum which protects the heart & lungs


-contributes to wall of thorax-articulate posteriorly with T1-T12 thoracic vertebrate & anteriorly via their costal cartilages to the sternum, either directly or indirectly

What are the parts of the rib

1. head of rib2. neck of rib3. body of rib (shaft)

Head of the rib

-located at the posterior (back end) of a typical rib-head of rib articulates with the corresponding thoracic vertebrate (ex. rib pair #1 articulates with T1 vertebrate; rib pair 2 articulates with T2 vertebrate etc)

Neck of rib

-Located lateral to the head-narrowed portion that contains tubercle (small bump) which articulates with the facet on the transverse process of the same numbered vertebrate

Body of rib (shaft)

-the shaft/ remainder of the rib-contains the angle of the greatest curvature of the rib (the part that wraps all the way around to where ribs pair 1-10 connects up with the sternum)

Embryonic development of the axial skeleton

-forms during early embryonic development using both: intramembranous & endochondral ossification

New borns contain soft spots known as _____________ where there is no bone


The soft spots (fontanelles)

-allow for the skull too mold/squeeze/deforms itself as it goes through the birth canal during the birth process-soft spots allow for rapid growth of the brain & not be squeezed in by a fixed skull

Growth of the brain in the first two years is rapid


Sutures appear with skeletal maturity


Paranasal sinuses increase in ____________ & ____________ overtime

Size & placement

Face is smaller proportion of total cranium at birth (1/8) versus 1/4 in adult


Head at birth is 1/4 total height; whereas at maturity it's 1/8 body height