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Chapter 7
Skeletal System
Gross Anatomy
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Skeletal System Functions and
Components
•
•
•
•
•
•
•
Provides framework
Provides levers upon which muscles act to move the body
Protection of organs
Mineral storage
Hemopoiesis
Energy storage
Components
– Bones
– Cartilage
– Ligaments
– Tendons
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Anatomic Bone Features
• Projections
• Terms
– Body: main part
– Head: enlarged end
– Neck: constriction
between head and body
– Margin or border: edge
– Angle: bend
– Ramus: branch off body
– Condyle: smooth rounded
articular surface
– Facet: small flattened
articular surface
– Process: prominent
projection
– Tubercle: small rounded
bump
– Tuberosity: knob
– Trochanter: tuberosities
on proximal femur
– Epicondyle: near or
above condyle
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Anatomic Bone Features
• Ridges
– Line or linea: low ridge
– Crest or crista:
prominent ridge
– Spine: very high ridge
• Openings
–
–
–
–
Foramen: hole
Canal or meatus: tunnel
Fissure: cleft
Sinus or labyrinth:
cavity
• Depressions
– Fossa: general term
for a depression
– Notch: depression in
bone margin
– Fovea: little pit
– Groove or sulcus:
deeper, narrow
depression
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Divisions of the Skeleton
• Axial skeleton
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–
–
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Skull
Hyoid bone
Vertebral column
Thoracic (rib) cage
• Appendicular skeleton
– Limbs
– Girdles
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The Complete Skeleton
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The Skull or Cranium
• Functions
– Protects brain
– Supports organs of
special senses
– Provides foundation
for structures that take
air, food, and water
into body
• Superior view of skull
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–
–
–
Parietal bones
Frontal bone
Sagittal suture
Coronal suture
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Posterior View of Skull
• Parietal and occipital
bones are major structures
• Lambdoid suture:
between parietals and
occipital
• Sutural bones may be
present: variable
• External occipital
protuberance
– Ligamentum nuchae:
Helps keep head erect
• Nuchal lines: Neck
muscle attachment points
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Lateral
View of
Skull
• Parietal bones and squamous part of
temporal bone form most of side of
skull
• Squamous suture: joins the parietal and
temporal bone
• Features of the temporal bone
– External auditory meatus
– Mastoid Process
– Temporal lines
– Zygomatic process of the
zygomatic arch
• Greater wing of the sphenoid bone
anterior to the temporal bone
• Zygomatic bones with its temporal
process of the zygomatic arch
• Maxilla
• Mandible. Articulates with the temporal
bone. Body, ramus, condyle, genu, and
coronoid process
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Frontal View of Skull
• Major structures are
frontal bone, zygomatic
bones, maxillae, and
mandible
• Maxilla and Mandible
bear teeth
• Orbits. Cone-shaped
fossae with their apices
oriented posteriorly
– Nasolacrimal canal
– Optic foramen
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The Orbit
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Bones of Nasal Cavity
• Nasal cavity. Pear-shaped,
open anteriorly
• Nasal septum divided nasal
cavity into right and left
halves
– Bony part is vomer and
perpendicular plate of the
ethmoid
– Hyaline cartilage anterior part
• Nasal conchae: form lateral
walls
– Inferior: separate bones
– Middle and superior:
projections of the ethmoid
– Increase surface of nasal cavity
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Paranasal Sinuses
• Associated with the bones
of the nasal cavity
• Functions
– Decrease skull weight
– Resonating chambers
• Named for bones in which
they are found
–
–
–
–
Frontal
Maxillary
Ethmoidal
Sphenoidal
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• Cranial cavity: occupied by the brain
• Calvaria (skull cap): upper dome-like
portion of skull
• Floor divided into anterior, middle, and
posterior fossae
• Crista galli: prominent ridge in center of
anterior fossa. Point of attachment for the
dura mater (one of the meninges)
• Olfactory fossae lateral to crista galli.
Olfactory bulb within
Interior of
the Cranial
Cavity
– Cribriform plate of the ethmoid forms
floor of olfactory fossae
– Olfactory nerves pass through the
foramina of the cribriform plate
• Sella turcica: part of sphenoid bone that
houses the pituitary gland
• Foramen magnum: opening where brain
attaches to spinal cord
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Inferior View of
•
Skull
•
Foramina
– Foramen magnum: spinal cord exits and
vertebral arteries enter
– Carotid canals: internal carotid arteries
– Foramen lacerum: internal carotid
– Jugular foramen: internal jugular veins
Specialized surfaces
– Occipital condyles: articulation between
skull and vertebral column
– Styloid processes: attachment site for
muscles that move the tongue
– Mandibular fossa: site of articulation with
mandibular condyles
– Medial and later pterygoid plates: parts of
sphenoid bone that surround posterior
opening of nasal cavities
– Vomer: posterior portion of nasal septum
– Hard palate: floor of the nasal cavity. With
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cavities
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Bones of the Skull
• Twenty-two bones plus six auditory ossicles that
function in hearing
• Of the twenty-two, two portions– Neurocranium (braincase)
• Surrounds and protects brain
• Parietals, temporals, frontal, occipital, sphenoid, ethmoid
– Viscerocranium (facial bones)
• Protect major sensory organs- eyes, nose, and tongue
• Provide attachment sites for muscles of mastication, facial
expression, and eye movement
• Maxilla and mandible have alveolar processes and sockets for
tooth attachment
• Maxillae, zygomatics, palatines, lacrimals, nasals, inferior
nasal conchae, mandible, vomer. Note: frontal and ethmoid
contribute to the face and mandible is not part of the skull
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Hyoid Bone
• Unpaired
• No direct bony
attachment to skull
• Attachment point for
some tongue muscles
• Attachment point for
neck muscles that
elevate larynx during
speech and swallowing
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Vertebral Column
• Functions
– Supports weight of
head and trunk
– Protects the spinal cord
– Allows spinal nerves to
exit the spinal cord
– Provides site for
muscle attachment
– Permits movement of
head and trunk
• Twenty-six bones in adult; 34 in
embryo
– 5 fuse to form sacrum
– 4 or 5 coccygeal fuse to form
the coccyx
• Regions
– Cervical (7 vertebrae)
– Thoracic (12 vertebrae)
– Lumbar (5 vertebrae)
– Sacral bone (1)
– Coccygeal bone (1)
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Vertebral Column
• Four major curvatures in adults
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–
–
–
Cervical: anterior
Thoracic: posterior
Lumbar: anterior
Sacral and coccygeal: posterior
• At birth, column is C shaped
– When head is raised, cervical curve
appears
– When sitting and walking begin,
lumbar curve develops
• Abnormal curvatures
– Lordosis. Exaggeration of lumbar
– Kyphosis. Exaggeration of thoracic
– Scoliosis. Lateral, often
accompanied by kyphosis
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Intervertebral Disks
• Located between adjacent
vertebrae
• Functions
– Provide support
– Prevent vertebrae rubbing
against each other
• Consist of
– Annulus fibrosus: external
– Nucleus pulposus: internal and
gelatinous
• Becomes compressed with
age and height decreases
• With age, more susceptible to
herniation
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Herniated or Ruptured Disk
Part of the fibrosus has been removed to expose the pulposus.
Breakage or ballooning of the annulus fibrosus
with a partial or complete release of the nucleus
pulposus. May push against spinal nerves
impairing function and causing pain.
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General Structure of a Vertebra
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Articulations and Spaces Between
Vertebrae
• Articular processes
have articular facets
where vertebrae meet
each other
• Spinal nerves exit the
vertebral column
through intervertebral
foramina
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Cervical
Vertebrae
• Superior seven vertebrae
• Have very small bodies, tend to have
bifid spinous processes, and have
transverse foramina
• Atlas: first cervical vertebra
– Articulates with skull and allows
“yes” movement
– No body and no spinous process
• Axis: second cervical vertebra
– Dens or odontoid process extends
superiorly into the vertebral
foramen of the atlas
– Allows rotation of the atlas on the
axis, the “no” movement
• Vertebral prominence: most
prominent spinous process in area.
Usually 7th cervical
• Superior articular facets face
superiorly; inferior facets face inferiorly
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Thoracic Vertebrae
• Long, thin spinous
processes directed
inferiorly
• Long transverse processes
• Articular facets on
transverse processes for
ribs (first 10 thoracic
vertebrae)
• Facets on body for
articulation with ribs
• Most ribs have heads that
articulate with two
sequential vertebrae
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Lumbar Vertebrae
• Large thick bodies
• Heavy rectangular
transverse and spinous
processes
• Superior articular facets
face medially; inferior
articular facets face
laterally
– Adds strength
– Limits rotation
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Spina Bifida
• Lamina of vertebrae: can
be removed
(laminectomy) when they
inhibit a surgery such as a
disc removal.
• Spina bifida: failure of the
laminae to form or to fuse
together during
development. Can affect
the spinal cord. Most often
occurs in lumbar region.
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Sacrum and Coccyx
• Sacrum
– Alae: superior lateral parts of
fused transverse processes
– Auricular surface: articulates
with pelvic bone
– Median sacral crest: partially
fused spinous processes
– Sacral hiatus: site of anesthesia
injection
– Sacral foramina: intervertebral
foramina
– Sacral promontory anterior
edge of body of first vertebra.
Marks separation of abdominal
and pelvic cavities
• Coccyx: tailbone
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Thoracic or Rib Cage
• Functions
– Protects vital organs
– Forms semi-rigid chamber for
respiration
• Parts
– Thoracic vertebrae
– Ribs (12 pair)
• True or Vertebrosternal:
superior seven. Attach
directly to sternum via costal
cartilages
• False: inferior five
– Vertebrochondral (3)
joined by common
cartilage to sternum
– Floating or vertebral
(2) do not attach to
sternum
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Sternum
• Manubrium
– Articulates with first rib and
clavicle
– Jugular notch superiorly
– Sternal angle: point where
manubrium joins body. Second
rib articulates here
• Body: third through seventh
ribs articulate
• Xiphisternum
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Appendicular Skeleton
• Girdles
– Pectoral or shoulder
– Pelvic
• Upper Limbs
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–
–
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Arm
Forearm
Wrist
Hand
• Lower Limbs
– Thigh
– Leg
– Foot
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Pectoral Girdle
• Scapula (2)
– Acromion process
• Forms protective cover
• Attachment for clavicle
• Attachment for muscles
– Scapular spine: divides posterior
surface into supra- and
infraspinous fossae
– Coracoid process: attachment for
muscles
– Glenoid cavity: articulates with
humerus
• Clavicle (2): articulates with
acromion and with manubrium
of sternum
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Humerus (Arm)
• Head
• Neck: anatomic and
surgical
• Tubercles: greater and
lesser
• Intertubercular groove
• Deltoid tuberosity
• Capitulum: rounded,
articulates with radius
• Trochlea: spool-shaped,
articulates with ulna
• Epicondyles
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Forearm: Radius
• Medial: thumb side
• Proximal end
– Head rotates in radial notch
of ulna.
– Radial tuberosity: site of
biceps brachii insertion
• Distal end
– Articulates with carpals and
ulna
– Styloid process
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Forearm: Ulna
•
•
Lateral: little finger side
Proximal end
– Trochlear notch: fits over
trochlea of humerus
– Olecranon process: point
of elbow
– Coronoid process
•
Distal end
– Head articulates with
radius and with carpals
– Styloid process
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• Wrist: eight carpal bones
– In order from lateral to medial
for proximal row and medial to
lateral for distal row: So Long
Top Part, Here Comes The
Thumb
– Scaphoid, Lunate, Triquetrum,
Pisiform, Hamate, Capitate,
Trapezoid, Trapezium
– As a unit are convex posteriorly
and concave anteriorly
– Carpal tunnel: on anterior
surface. Ligament from
tubercle of trapezium to hook
of hamate
Wrist and Hand
• Hand: five metacarpals (palm
of hand); five digits with their
phalanges
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Pelvic Girdle
• Coxae and sacrum form
ring
• Pelvis: pelvic girdle and
coccyx
• Coxae: Right and Left
– Ilium
– Ischium
– Pubis
• Acetabulum: articulates
with head of femur
• Obturator foramen
• Sacrum
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Coxae
• Formed as fusion of embryonic
ilium, ischium, pubis. All three
contribute to acetabulum
• Ilium: iliac crest, anterior and
posterior superior iliac spines,
greater sciatic notch, auricular
surface, sacroiliac joint, iliac
fossa
• Ischium: ischial tuberosity
• Pubis: pubic crest, symphysis
pubis (pubic symphysis)
• Pelvic brim
– False (greater pelvis) pelvis
superior to brim
– True pelvis inferior to brim
• Pelvic inlet
• Pelvic outlet
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Male and Female Pelvis
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Thigh:
Femur and
Patella
• Femur
– Head: articulates with
acetabulum
– Neck
– Trochanters: attachment for
muscles that fasten lower
extremity to hip
• Greater and lesser
– Distal condyles: articulate with
tibia
• Medial and lateral
– Epicondyles: ligament
attachment
• Medial and lateral
• Patella or kneecap: sesamoid
– In tendon of quadriceps femoris
– Changes force relationship
between femur and tibia
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Leg: Tibia and Fibula
• Tibia
– Larger and supports most of
weight
– Tibial tuberosity: attachment
of quadriceps femoris
– Anterior crest: shin
– Condyles: medial and lateral;
articulate with condyles of
femur
– Intercondylar eminence
– Medial malleolus: medial side
of ankle
• Fibula
– Articulates with tibia not
femur
– Lateral malleolus: lateral wall
of ankle
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Foot: Tarsals, Metatarsals,
Phalanges
• Tarsals (7)
– Proximal row: No
Thanks Cow =
Navicular, Talus,
Calcaneus
– Distal row: MILC =
Medial,
Intermediate and
Lateral Cuneiforms
• Metatarsals (5):
foot
• Phalanges: toes
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• Function
– Distribute weight of body
between heel and ball of foot:
weight transferred from the
tibia and fibula to the talus.
From there, the weight is
distributed first to the
calcaneus then through the
arch system along the lateral
side of the foot to the ball
(head of the metatarsals).
Footprint in wet sand: only
heel, lateral margin, ball, and
toes of foot imprinted.
Arches of
the Foot
• Three major arches
– Transverse arch
– Longitudinal arches: Medial
and lateral
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