Skeletal System 3
Honors Anatomy
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The Appendicular Skeleton
The Pectoral Girdle
(Shoulder)
• 2 pectoral girdles
• attach bones of upper limbs to axial
skeleton
• each: 1 clavicle
•
1 scapula
Clavicle
• S-shaped, (medial ½ convex
anteriorly, lateral ½ concave
anteriorly) slender bone
• lies horizontally across anterior
thorax superior to 1st rib
Clavicle
• medial end = sternal end is rounded
& articulates with the manubrium @
sternoclavicular joint
Clavicle
• lateral end = acromial end is flat
• articulates with acromion of the
scapula to form acromialclavicular
joint
Clavicle
• last bone to stop growing
• 1 of most frequently fx’d bones (2
curves) usually from fall on
outstretched arm
• or see compression fx in auto
accidents from shoulder strap
which can cause damage to median
n. (between clavicle & 2nd rib)
Scapula
• aka shoulder blade, angel bone
• large, triangular, flat bone
• in superior part of posterior thorax
between levels of 2nd & 7th ribs
• spine: prominent ridge that runs
diagonally across posterior surface
Scapula
• lateral edge: acromion a flattened
expanded process, easily felt as hi
pt of shoulder (tailors use it as
landmark to measure length of arm)
• glenoid cavity: inferior to
acromion, smooth, shallow
depression that accepts head of
humerus in shoulder joint
Upper Limb
• 6 parts:
1. Humerus
2. Ulna
3. Radius
4. Carpals
5. Metacarpals
6. Phalanges
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Joints:
Shoulder
Elbow
Wrist
Hand
Humerus
• longest & largest bone of upper limb
• articulates proximally with scapula
& distally with ulna & radius
• head: rounded proximal end
»articulates with glenoid cavity
of scapula to form
glenohumeral joint
Humerus
• distal end:
• capitulum: rounded knob on lateral
aspect that articulates with head of
radius
• trochlea: medial to capitulum,
spool-shaped, articulates with ulna
Ulna
• medial aspect of forearm
• longer than radius
• proximal end: olecranon
(prominence in elbow)
• distal end: head, styloid process
(posterior)
Radius
• lateral aspect of
forearm
• proximal end:
head of radius:
articulates with
capitulum
• distal end: styloid
process (palpable
proximal to
thumb)
Ulna & Radius
• connect @ 3
places
1. interosseous
membrane
2. proximal end
3. distal end
Carpals
• proximal to the
hand, distal to
radius & ulna
• 8 small bones
joined by
ligaments
• articulations
w/each other
called intercarpal
joints
Metacarpals
Phalanges
• 14 bones of the digits (each hand)
• #’d I to V beginning with thumb
• thumb is the pollex has only 2
phalanges, other digits have 3
• joints between phalanges called
interphalangeal joints
Pelvic Girdle
• 2 hip bones (os coxa) which unite
anteriorly at pubic symphysis and
posteriorly with the sacrum @
sacroiliac joint
Pelvic Girdle
• Functions:
• provides sturdy
support for
vertebral column
• connects lower
limb to axial
skeleton
Newborn Pelvis
• 3 bones on each
side:
1. Ilium
–
superior
2. Pubis
–
anterior &
inferior
3. Ischium
• posterior &
inferior
Ilium
• largest of the 3 hip bones
• distinguishing features:
1. Iliac Crest
• along superior surface
1. Sacroiliac Joint (SI Joint)
• between sacrum and ilium
Ischium
• ramus of ischium fuses with pubis
• distinguishing features:
1. Ischial Tuberosity
• what you feel when someone sits
on your lap
Pubis
• Acetabulum
– formed by ilium, ischium, & pubis
– is the “socket” half of the hip joint
• Pubic Symphysis
– joint between the 2 hip bones
True Pelvis/ False Pelvis
• Pelvic Brim: line that distinguishes
between true & false palvis
Male Pelvis
• generally male bone heavier &
stronger & have larger surface
marker (because larger muscles
attach)
• Pelvis:
– deeper false pelvis, smaller, narrower
– pelvic brim heart-shaped
– acetabulum larger, faces posterior
– obturator foramen round
Female Pelvis
• generally bones lighter & thinner
• Pelvis:
– false pelvis shallow, widers
– pelvic brim larger, more oval
– acetabulum smaller & faces anterior
– obturator foramen oval
Lower Limb
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30 bones in each:
1 femur
1 patella
1 tibia
1 fibula
7 tarsals
5 metatarsals
14 phalanges
Femur
• longest, heaviest, & strongest bone
in the body
• proximally articulates with the
acetabulum to form hip joint
– Head of the Femur: “ball” part of joint
• small, central depression: fovea capitis
– Greater Trochanter
• prominence felt & seen @ side of hip
Patella (kneecap)
• small, triangular, sesamoid bone
• develops in tendon of quadriceps
femoris muscle
• Parts:
• Base: broad, superior end
• Apex: pointed, inferior end
Tibia
“shin bone”
larger, medial, weight-bearing bone of
lower leg
proximally articulates with femur &
fibula
distally articulates with fibula &
tarsals
Tibia
• medial malleolus
forms prominence
that is palpable &
visible on medial
ankle
Fibula
• parallel & lateral
to the tibia &
considerably
smaller
• head of fibula on
proximal end
• lateral malleolus
at distal end
Tarsals
• 7 bones:
• 1 calcaneous: heel bone, largest of
the tarsals
Metatarsals
• 5 bones between tarsals &
phalanges
• #’d I to V from medial  lateral
Arches of the Foot
• 2 arches in foot:
1. allows the foot to support weight
of body by distributing weight over
the soft & hard tissues
2. provide leverage while walking
fully developed by age 12 - 13
Arches of the Foot
• 2 longitudinal
arches (medial
& lateral
• 1 transverse
arch
Development
of
the
Skeletal
• all skeletal tissue arises from
System
mesoderm
• 1st bone: skull in 4th wk
• U/S ~ 24 – 25 wks:
1. Clubfoot:
Medical
Terminology
– inherited deformity in which baby is
born with foot twisted inferiorly &
medially
– 1/1000 births
– tx: casts or wraps, surgery may be
indicated
Medical Terminology
2. Genu valgum:
•
knees
abnormally close
together with
increased space
between ankles
• aka “knock-knee”