Download The Skeleton

The Skeleton
Dr. Ali Ebneshahidi
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Axial Skeleton
Skull 22 bones
8 cranial bones
– Frontal 1
– Parietal 2
– Occipital 1
– Temporal 2
– Sphenoid 1
– Ethmoid 1
14 facial bones
– Maxilla 2
– Palatine 2
– Zygomatic 2
– Lacrimal 2
– Nasal 2
– Vomer 1
– Inferior nasal concha 2
– 1 mandible
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• Middle ear bones
Malleus 2
Incus 2
Stapes 2
• Hyoid bone
Hyoid 1
• Vertebral column
Cervical
vertebra 7
Thoracic
vertebra 12
Lumbar
vertebra 5
Sacrum 1
Coccyx 1
• Thoracic cage
Ribs 24
Sternum 1
6 bones
1 bones
26 bones
25 bones
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The Appendicular Skeleton
• Pectoral girdle
Scapula 2
Clavicle 2
• Upper limbs
Humerus
Radius
Ulna
Carpal
Metacarpal
Phalanx
4 bones
60 bones
2
2
2
16
10
28
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• Pelvic girdle
Coxal bone
• Lower limbs
Femur
Tibia
Fibula
Patella
Tarsal
Metatarsal
Phalanx
Total
2 bones
2
60 bones
2
2
2
2
14
10
28
206 bones
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Skull (Cranium)
• Skull
Skull: protect brain (brain
case).
Facial bones:
- Contains cavities for sense
organ (eyes, smell).
- Frame of the face.
- Attachment sites for mulches of
mastication & facial expression.
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The Eight bones of the cranium
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a) Frontal bone (forehead )
Frontal sinuses
Forms superior part of orbits
Forms roof of nasal cavity
b) Parietal bones and major
sutures
Curved , rectangular bone
Forms the bulging sides and
roof of cranium
The 4 largest sutures occur
where parietal bone
articulates with other bones.
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• Coronal suture : where
parietal bones meet the
frontal bone anteriorly.
• Lamboid suture : where
parietal bones meet the
occipital bone posteriorly.
• Squamous suture : where
parietal and temporal bone
meet on the lateral aspect
of the skull .
• Sagittal suture : where
the 2 parietal bones meet
superiorly at the cranial
midline .
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• C) Occipital bone :
• Forms the back (posterior) of skull
• Foramen magnum : a large opening on its lower surface houses nerve
fibers that pass through and enter the vertebral canal to become the
spinal cord .
• Occipital condyles : articulates with the first vertebra (atlas)
• Hypoglossal canals : for passage of hypoglossal nerves.
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• d) Temporal bones :
– Lateral sides of skull.
– Contains the external auditory meatus (external ear).
– Mandibular fossa – receive condyles of mandible (lower
jaw).
– Zygomatic arch (process) – projects interiorly from the
temporal bone.
– Mastoid process – attachment for muscles of neck.
– Styloid process – attachment for muscles of tongue and
pharynx.
– Jugular fareamen – at the junction of occipital and petrous
temporal bone allows passage of the internal jugular vein.
– Carotid canal – transmit internal carotid artery.
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• e) Sphenoid bone (butterfly - shaped)
– Sella turcica – indentition of a part of sphenoid,
in the depression lies the pituitary gland .
– Contains 2 sphenoid sinuses.
– It has greater and lesser wings.
– Optic foramina – allows passage of the optic
nerve.
– Superior orbital fissure – a long slit between the
greater and lesser wing allows passage of the
cranial nerves that control eye movements (III ,
IV, VI) to enter the orbit.
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• F) Ethmoid bone:
– Olfactory foramina – passage for the olfactory nerve.
– Middle and superior nasal concha (nasal plates), also known as
turbinates.
– Ethmoid sinuses.
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Facial Skeleton
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Maxillary bones (upper jaw)
All facial bones except mandible articulate with maxillae.
Forms roof of mouth (anterior 2/3 of hard palate).
Contains upper teeth .
Maxillary sinuses (largest sinuses).
Zygomatic process of maxilla articulate with zygomatic
bone.
• Infraorbital foramen – allows passage of infraorbital nerve.
• Infraorbital fissure – at junction of maxilla with the greater
wing of sphenoid allows passage of zygomatic nerve,
maxillary nerve (a branch of cranial nerve V), and blood
vessels.
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• Palatine bones
– L shaped .
– Forms post 1/3 of hard plate .
• Zygomatic bones (cheek bones)
– Temporal process , which extends posteriorly to join the
zygomatic process of temporal bone. Together these
processes form the zygomatic arch .
• Lacrimal bones
– A groove in its anterior portion forms the lacrimal fossa
(tear channel).
• Nasal bones
– Forms bridge of nose medially
– Attachment of cartilaginous tissues that form the shape of
the nose .
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• Vomer bone: unpaired, forms the nasal septum along with
ethmoid bone.
• Inferior nasal conches (largest): Support mucous membranes
within nasal cavity .
• Mandible (lower jaw)
–Unpaired.
–Horseshoe – shaped (u-shaped).
–Largest bone of the face.
–It has a body –anchors the lower teeth.
–2 ramus.
–Coronoid process – site of attachment of
temporalis muscle that elevates jaw
during chewing.
–Mandibular condyle – articulates with
mandibular fossa of temporal bone to
form T.M.J.
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• The orbits:
• Bony cavities within which the eyes are encased. The walls of each
orbit are formed by parts of seven bones (the frontal, sphenoid,
zygomatic, maxilla, palatine, lacrimal, and ethmoid bones).
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Infantile skull
• At birth, skull is incompletely developed, with fibrous
membranes connecting the cranial bones. These membranes
are called fontanels (soft spots).
• Allow brain growth by allowing skull to expand.
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The vertebral Column
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The vertebral column (the spine) :
Cervical spine (C1-C7)
Thoracic spine (T1-T12)
Lumbar spine (L1-L5)
Sacrum (5 vertebra fused into one bone)
Coccyx (4 vertebra fused)
Curvatures of spine:
• Cervical & Lumbar are concave posteriorly
• Thoracic & sacral curvature are convex
posteriorly
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Abnormal Curvatures:
• Scoliosis: abnormal
lateral curvature of
spine.
• Kyphosis : (hunch
back) , exaggerated
dorsally (T – spine ).
• Lordosis :
exaggerated Lumbar
curvature.
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Intervertebral Disc
• Intervertebral discs : cushion like pads located between
vertebrae. It is composed of 2 parts.
• Nucleus pulpous – act like a rubber ball which gives disc
elasticity and compressibility.
• Annulus fibrosus – a strong collar of collagen fibers and fibrocartilage, holds the nucleus pulpous in place and resists tension
in spine. Rupture of annulus fibrosus causes protrusion of
nucleus resulting in herniated disc.
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General structure of vertebrae
• Body: weight bearing
portion, located anteriorly.
• Vertebral arch : located
posteriorly. Seven
processes project form
this arch.
• Vertebral foramen: opening
enclosed by the body and
vertebral arch, through
which the spinal cord
passes.
• Pedicle: project posteriorly
from the vertebral body.
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• Lamina: flattened plates that
fuse posteriorly to close the
arch.
• Spinous process: posterior
projection arising from the
junction of 2 lamina
(posterior projection of the
arch).
• Transverse process: extends
laterally from each side of
the arch.
• Intervertebral foramina: the
spinal nerves arising from
the spinal cord pass through
these holes.
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Vertebral Characteristics
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Cervical vertebrae: (C1-C7)
C1= known as atlas.
C2= known as axis.
C7= known as vertebra prominens.
C1 – has no body and no spinous process.
C2 – has a knob like structure called dens or odontoid process
projecting superiorly. Odontoid allows rotation of atlas.
C3- C7 have the following characteristics:
The body is oval shaped
The SP's are short (except for C7 that is long).
Vertebral foramen is triangular & large .
Each T.P contains a transverse foramen through which the
vertebral blood vessels pass to service the brain .
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Thoracic vertebrae: (T1-T12)
The body is heart shaped
Vertebral foramen is circular
Sp is long and points sharply inferiorly
With exception of T11 and T12 ,they articulate
with ribs.
Lumbar vertebrae: (L1-L5)
The body is massive and kidney shaped
(support body weight).
Vertebral foramen is triangular
Sp's are short
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• Sacrum: Triangular shaped structure. Formed by fusion of 5 vertebrae.
Strengthen and stabilize the pelvis.
• Coccyx (Tail bone): Formed by fusion of 4 vertebrae.
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The bony Thorax (Thoracic Cage )
• Includes the ribs, thoracic vertebrae, the sternum, and the
costal cartilages.
• Sternum : (breast bone)- lies in anterior mid – line of the
thorax. It results from the fusion of 3 bones: the
Manubruin, the body and the xiphoid process.
• Ribs :
• 12 pairs
• 1-7 ribs are true ribs because they join the sternum
directly.
• Reaming 5 ribs are false ribs (8 -12) they donot have
sternal attachment, directly.
• Ribs 11-12 are floating ribs – no anterior attachment .
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The Appendicular Skeleton
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The pectoral girdle (shoulder girdle ): 4 parts
2 clavicles (collar bones) & 2 scapulae (shoulder blades)
Clavicle: has a sternal (medial end) & an acrominal (lateral end)
Scapulae:
– has the genocide cavity that articulates with the humerus of the
arm, forming the shoulder joint.
– spine – divides the scapula into unequal portions called the supraspinous and infraspinous fossa.
– the Acromion: the spine ends laterally in an enlarged anterior
projection, articulates with clavicle to form A-C joint.
– coracoids process – site of attachment of biceps muscle and other
upper limb muscles .
– subscapulars fossa (cavity) – concavity of entire anterior scapular
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surface .
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The upper Limb
• Humerus : single bone of
the arm.
• Head – fits into the glenoid
cavity of scapula.
• It has a greater tubercle & a
lesser tubercle which are
sites of attachment of
muscles that move the upper
limb, at shoulder.
• Intertubercular groove –
tendon of biceps brachii
muscle passes through this
groove.
• Deltoid tuberosity –
attachment site of deltoid
muscle.
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• Radial groove – radial nerve
passes.
• Trochlea – located medially at
distal end of humerus.
• Capitulum – located laterally
at distal end of humerus.
• Medial & lateral epicondyles
for attachment of muscles.
Ulnar nerve passes behind the
medial epicondyle.
• Coronoid fossa – ant. surface,
receives the coronoid process
of ulna.
• Olecranon fossa – posterior
surface of humerus (distally) –
receives the olecranon process
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of ulna.
Forearm (Radius & Ulna)
• Radius:
• located on thumb side of the
forearm.
• extends from elbow to wrist
and crosses over the ulna
when the hand is turned so
that the palm faces
backward.
• head – articulates with
capitulum of the humerus.
• radial tuberosity –
attachment point for biceps.
• styled process – attachment
point for the ligaments of
the wrist.
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• Ulna:
• longer than radius
• forms the elbow joint
with humerus.
• olecranon and coronoid
process fit into the
olecranon fossa and
coronoid fossa of the
humerus when the
elbow bends.
• head – located at distal
end of ulna.
• medial styloid process –
site of attachment of
ligaments of wrist.
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• hand:
Wrist
Palm
5 fingers
• Wrist: consists of 8 short bones.
• Proximal row: (lateral to medial )- scaphoid , lunate,
triquetral, pisiform
• Distal row : (lateral to medial) – trapezium, trapezoid , capitate,
hamate.
• Sally Left The Party To Take Cathy Home.
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Metacarpals & Phalanges of the hand
• 5 bones, one in line with each finger,
numbered 1-5 from thumb to little finger.
• Their base articulate with carpals and their
head with phalanges (are considered long
bones even though small).
• Phalanges (Fingers):
• Numbered 1-5
• Have proximal , middle and distal ends (thumb
lacks middle phalanx).
• So each hand has 14 finger bones.
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The Pelvic (Hip) Girdle
• Consists of 2 coaxal bones (hip bones).
• Transmits the weight of body to legs.
• Protects urinary bladder, distal end of large intestine , and
reproductive organs.
• Coaxal bones:
– Ilium
– Ischium
– pubis
• These 3 bones fuse in a region of cup–shaped cavity called
aceutabulum .
• Ilium:
• largest and most superior portion of the coaxial bone , flares
out ward .
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posterioly it joins the sacrum to form the Sacroiliac joint.
posterioly indents to form the greater sciatic notch.
Ischium:
forms the posteroinferior part of the hip bone, L – shaped.
has an ischial tuberosity , that supports our weight when
seated, and is the strongest part of the hip bones.
Pubis:
forms the anterior portion of the coax bone, the 2 pubic
bones come together at midline to form the pubic symphysis
V – shaped
Obturator foramen – largest foramen of body (skeleton), is
formed by both ischium + pubis bones.
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The Lower Limb
• Femur (thigh bone):
• Longest, strongest bone
of the body.
• Head of femur fits into
the acetabulum.
• Greater & lesser
trochanter – site of
attachment of muscles.
Greater trochanter is
superior and laterally
located. Lesser
trochanter is medially
located and is inferior
to greater trochanter.
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• Lateral and medial
condyles, located
distally and articulate
with tibia of the leg.
• Lateral and medial
epicondyles – provide
attachment for muscles
and ligaments.
• Patella (knee cap):
• Flat bone
• Located anteriorly
over the knee
• Important in knee
motion .
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• Tibia (skin bone)
• Largest of the 2 leg bones.
• Located on the medial side
of leg.
• Next strongest bone in body.
• Leteral & medial condyles.
• Tibial tuberosiy –
attachment point for patellar
ligament.
• medial malleolus - distal
medial ankle.
• Fibula:
• Head- located proximally
• Lat. Malleolus, distally
located
• Forms the lat. ankle
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• Foot:
1) Tarsal bones
2) Metatarsals
3) Phalanges.
• Tarsal bones – 7 tarsals
• Talus – can move freely
where it joins tibia and
fibula.
• Calcaneus – forms the
heel of foot. It is the site
of attachment of Achillis
tendon.
• The reaming tarsal are the
Lat. Cuboid, Navicular
and the Medial,
Intermediate and Lat.
Cuneiforms.
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• Metatarsals:
numbered 1- 5
,beginning on
the medial side
• Phalanges
(toes): 14
phalanges
• 3 phalanges in
each toe except
for great toe
(the hallux),
which has two.
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Clinical Terms
• Bunion – Deformity of great toe; lateral displacement
of great toe and medial displacement of metatarsal 1,
caused by thight shoes.
• Club foot – congenital disease in which the soles of
feet face medially and toes point inferiorly.
• Chiropractic - treating disease by manipulating the
spine.
• Podiatrists - a specialist in foot disorders .
• Orthopedists – surgeon who repair damaged bone and
joints .
• Prolapsed disc – A herniated disc.
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