Lecture 5

Question 1

The skeleton is divided into 2 portions:

Answer 1

the axial skeleton and the appendicular skeleton

o It is a rigid framework of 206 bones , muscles and organs are attached by tendons and
ligaments

o Bones act as levers (with joints acting as pivots) when muscles contract and move body

Question 2

The Axial Skeleton:

Answer 2

composed of bones along the central axis of the body – 80 bones

• Divided into three regions:
o Skull
o Vertebral column
o Thoracic cage

• Functions of the axial skeleton:
o Framework that supports and protects organs in the dorsal and ventral body cavities
o Protects special sense organs for taste, smell, hearing, balance, and vision
o Attachment sites for muscles that:
o Adjust the posture of the head, neck, and trunk
o Move the thoracic cage for respiration
o Stabilize the appendicular skeleton

Question 3

The Skull and Associated Bones

Cranial and Facial Subdivisions of the Skull

Answer 3

The skull consists of
o Face: 14 individual bones
o Cranium: 8 individual bones
o Associated bones: 7 individual bones (auditory ossicles – 3 per ear and hyoid

Question 4

Cranial bones

Answer 4

– form cranium, encase and protect brain (8 bones)

Frontal bone – (1) forehead, roof of orbits
o Parietal bones – (2) either side of the top of head
o Temporal bones - (2) temples on either side of the head, protect sense organs of ear,
extensive area for attachment of muscles that close the jaw and move the head
o Occipital bone – (1) back of head, foramen (opening) magnum connects cranial cavity
with spinal cavity
o Sphenoid bone – (1) butterfly shaped, keystone of skull, unites cranial and facial bones
and base of cranium
o Ethmoid bone – (1) between obits/walls, floor of cranium, part of nasal cavity and nasal
septum, part of nasal conchae involved with movement of air through sinouses

Question 5

Facial bones

Answer 5

Nasal bones - (2) base of nose, cartilage forms the flexible portion
o Lacrimal bones – (2) (lacrima =tear), encloses tear duct and drains tears into nasal
cavity

o Vomer - (1) means plowshare (looks like part of a plow from the front), inferior part of
nasal septum

o Maxilla – (2) the largest of the facial bones, together form the upper jaw, articulate with
all other facial bones except mandible, oral margins form the alveolar processes that
contain the upper teeth

o Mandible – (1) forms the entire lower jaw, teeth are supported by the mandibular body, 2
articulates with the temporal bone (tempomandibular joint) for jaw movements when
talking or eating, high mobility but makes it easy to dislocate the jaw

o Zygomatic bones – (2) cheek bones

o Inferior Nasal Conchae – (2) one on each side of nasal septum, along with the nasal
conchae of the ethmoid bone, they create turbulence in inhaled air (slows air movement
and provides additional time for warming, humidification and dust removal before air
reaches more delicate portions of the respiratory tract)

o Palatine bones – (2) form inferior portions of the hard palate, part of nasal cavity and
eye orbit

Question 6

• Associated Bones

Answer 6

Auditory ossicles – 6 bones in middle ear (ear bones), smallest bones in the body,
transmit sound impulses; 2 malleus, 2 incus, 2 stapes

o Hyoid Bone – only bone that does not articulate with any other bone, above the larynx
(voice box) below mandible (jawbone) supports the tongue, aids in swallowing

Question 7

The Vertebral Column

Answer 7

he adult vertebral column is made up of 26 bones:
o 24 vertebrae
o 7 cervical vertebrae – cervical curve
o 12 thoracic vertebrae – thoracic curve
o 5 lumbar vertebrae – lumbar curve
o 1 sacrum (5 fused vertebrae) – sacral curve
o 1 coccyx (3-5 fused vertebrae)
o These curves, along with muscle attachment to the various vertebral processes, help to
maintain balance

Question 8

Functions of the vertebral column

Answer 8

Encloses and protects the spinal cord
o Supports the skull
o Supports the weight of the head, neck, and trunk
o Transfers weight to the lower limbs
o Helps maintain the upright position of the body
o Curves of the spine act like a spring to absorb muscle shock (without snapping)

Question 9

Vertebral Processes of a Typical Vertebra

Answer 9

Vertebral body
o Vertebral foramen
o Spinous process
o Transverse process (superior articular and inferior articular)
o Transverse foramen

Question 10

Intervertebral Joints

Answer 10

o Function in shock absorbance
o Inferior articular facet articulates with superior articular facet and they come together
in facet joints
o Between bodies of vertebrae are intervertebral discs
o Nucleus pulposis –gel-like pad in center (mostly water)
o Anulus fibrosis – surrounds nucleus pulposis, fibrocartilage with collagen fibers attach
to the vertebrae
o Spinal nerves run through vertebral foramen and intervertebral foramen where the
spinal nerves emerge as they branch off the spinal cord

Question 11

The Thoracic Cage

Answer 11

The thoracic cage has two functions:
• It protects the heart, lungs, thymus, and other structures within the cavity
• It serves as the attachment site for muscles involved in:
o Respiration
o Positioning the vertebral column
o Movements of the pectoral girdle and upper limb

Question 12

The Thoracic Cage consists of

Answer 12

Sternum (3 bones)
§ Manubrium
§ Body
§ Xiphoid process
o Ribs (24 ribs, 12 per side)
§ True ribs: 1−7
§ False ribs: 8−12
§ Vertebral ribs (floating ribs): 11−12 (no anterior cartilage)

Question 13

The Appendicular Skeleton includes:

Answer 13

bones of the upper and lower extremities and the bony girdles 
that anchor the appendages to the axial skeletal system and allow articulation with the trunk (63 bones 
per side, 126 bones total)
• Pectoral girdle
• Shoulder bones
• Upper limbs
• Pelvic girdle
• Hip bones
• Lower limbs

Question 14

Pectoral girdle consists of:

Answer 14

Sternum (1) (breastbone) is the axial component that the clavicle (2)(collarbones) and scapulae
(2) (shoulder blades) appendicular components attach to.
• The main function is to provide attachment for the muscles to move the brachium (arm) and
antebrachium (forearm)

Question 15

Upper limb consists of (per side):

Answer 15

Humerus – proximal within brachia
o Radius and ulna within antebrachia
o Carpal bones (8) bones of the wrist, scaphoid, lunate, triquetrum, pisiform,
trapezium, trapezoid, capitates and hamate
o Metacarpals (5) back of the hand
o Phalanges (14) finger bones of the hand (proximal, middle and distal phalanx for each
finger and proximal and distal phalanx of pollex (thumb))

Question 16

Pelvic Girdle

Answer 16

Supports and protects the lower viscera and developing fetus in females
• The bones of the pelvic girdle and lower limb are much more massive than their homologues of
the upper limb

Question 17

Pelvic girdle consists of:

Answer 17

Sacrum, the axial component that the two coxal bones (hip bones) (appendicular component)
attach to
• Coxal bones form as a result or the fusion of the ilium, ischium and pubis during adolescence
• The coxal bones are united anteriorly by the symphys pubis and posteriorly by the sacrum4
• The pelvic girdle supports the weight of the body through the vertebral column and protects
viscera within the pelvic cavity

Question 18

The Lower limb

Answer 18

is responsible for transferring the body weight to the ground
• Consists of (per side):
o Femur - (thighbone) within thigh
o Patella - kneecap
o Tibia (shinbone) and fibula – within the leg (calf)
o Tarsal bones - (7) ankle bones
o Metatarsal bones – (5) make up arch or the foot
o Phalanges (14) toe bones of the foot (proximal, middle and distal phalanx for each
smaller toe and proximal and distal phalanx of hallux (great or big toe))