Download The Appendicular Skeleton

The Appendicular Skeleton
Resident Orientation Course 2012
By Dr. Totakhil
THE SKELETAL SYSTEM
The Appendicular Skeleton
• 2 pairs of limbs and 2 girdles
– Pectoral (shoulder) girdle attaches upper limbs
– Pelvic (hip) girdle secures lower limbs
• 3-Segmented limbs
Upper = arm
Lower = Leg
Arm
Thigh
Forearm
Leg
Hand
Foot
Pectoral Girdle
(Shoulder Girdle)
• Clavicle – anterior: collar bone
– Sternal end attaches to the manubrium medially
– Acromial end articulates with the scapula laterally
• Scapula – posterior: shoulder blade
Scapula
• Glenoid cavity
articulates with the
humerus
• Acromium articulates
with clavicle
• Coracoid process
projects anteriorly
Scapulae: triangular, paired, does not
connect in back (adds thoracic flexibility)
Upper Extremity
• Arm or Brachium = upper arm
– Between shoulder and elbow (humerus)
• Forearm or Antebrachium
– Radius & ulna
• Hand includes:
– Wrist (carpus)
– Palm (metacarpus)
– Fingers (phalanges)
Arm
• Humerus is the only bone
– Head of humerus fits into glenoid cavity of
scapula
– Distal & medially, trochlea articulates with the
ulna
– Distal & laterally capitulum articulates with the
radius
– Medial & lateral epicondyles
Muscles of the Shoulder Girdle
Anterior Compartment Flexors
Posterior Compartment Flexors
Forearm
• Consists of 2 bones the radius and ulna
• These bones articulate with each other proximally
and distally
• An interosseous membrane is between these 2
bones
Radius
• Long bone situated on the lateral side of the forearm
• Together with the ulna, it provides attachment for the
forearm muscles
• It consists of an articular head above, which articulates
with the humerus and ulna to form the elbow joint
• Consists of an articular surface below, which articulates
with the carpal bones to form the wrist
• Its lower end rotates around the ulna, whose position is
fixed, to supinate and pronate the forearm and hand
Ulna
• Long bone situated on the medial side of the
forearm.
• Together with the radius, they provide attachment
for the forearm muscles
• Consists of a large trochlear surface above, which
articulates with the humerus to form the elbow joint
• Consists of a small head below, which articulates
with the radius to form the radioulnar joint
Radius is thinner proximally, like a spool of thread,
and wide distally; ulna is slightly longer and looks
like a monkey wrench (supposedly!)
Anatomic Position
• In the anatomical position:
– Radius is lateral (thumb side); with pronation the palm
faces posteriorly and the bones cross
• Prone: body lying face down
– You can remember prone if you think about how you
would fall forward onto your face if you passed out
• Supine: body lying face up
Proximal and Distal Joints of the
Forearm
Muscles of the Forearm
Muscles of the Forearm
Hand
• Wrist: consists of 8 carpal bones
– Articulate above with the radius at the radiocarpal joint
– Articulate with each other at the intercarpal joints
– Articulate below with the metatarsals at the
carpometacarpal joints
Hand
• Hand: consists of 5 metacarpals bones
– The 1st metacarpal lies laterally, providing a base
for the thumb
– The 5th metacarpal lies medially, forming a base
for the little finger
– Proximally they articulate with the carpal bones at
the carpometacarpal joints
– Distally they articulate with the proximal
phalanges at the metacarpophalangeal joints
Hand
• Fingers (or digits) consist of miniature long bones
called phalanges:
– Thumb has 2 bones: proximal and distal
– The other fingers have 3 bones: proximal, middle,
distal
Pelvic Girdle
•
•
•
•
Strongly attached to axial skeleton (sacrum)
More stable than pectoral (shoulder) girdle
Less freedom of movement
Made up of the paired hip bones
– “Bony pelvis” is basin-like structure: hip bones
plus the axial sacrum and coccyx
Differences Between Male and Female
Pelvis
Male Pelvis
Female Pelvis
Heavier
Lighter and thinner
Heart shaped pelvic inlet
Round or oval shaped pelvic
inlet
Prominent muscle and
ligament attachments
Less prominent muscle and
ligament attachments
Sub-pubic angle is less than
90 degrees
Sub-pubic angle is greater
than 90 degrees
Longer narrower pelvic cavity
Shorter wider pelvic cavity
Hip bone (Os Coxae): 3 separate bones
in childhood which fuse
Ilium
• Iliac crest
• Anterior superior iliac
spine
• Greater sciatic notch
• Forms part of
“acetabulum”
(hip socket) which receives
ball-shaped head of femur
Ischium
• Body
• Ramus
• Ischial spine
• Ischial tuberosity
• Part of hip socket
Pubis
• Joins medially in pubic symphysis
• Forms “obturator foramen” (large hole) with ischium
• Part of hip socket
Lower Limb
• Thigh: femur
• Leg (Lower Leg)
– Tibia
– Fibula
• Foot
Thigh
• Femur: Longest bone in the body
– It consists of a head above, which articulates with
the hip bone to form the hip joint
– Has two large condyles below, which articulate
with the tibia and patella to form the knee joint
Patella
• The patella, the largest sesamoid bone in the body
• It is embedded in the tendon of quadriceps femoris, and
is located anterior to the knee-joint
• Its outline is somewhat in the shape of an inverted
triangle
• It is separated from the femur by the suprapatellar bursa
Leg
• Tibia
– The larger and medial of the two bones of the leg
– It consists of two expanded extremities joined by
a shaft
• Fibula
– Lateral and more slender of the two bones of the
leg
Foot
• Tarsus: 7 tarsal bones
– Talus: articulates with tibia and fibula anteriorly and
calcaneus posteriorly
– Calcaneus: heel bone
– Other bones: Cuboid, navicular, and 3 cunieforms (medial,
intermediate and lateral)
• 5 metatarsals
• 14 phalanges
– Great toe is called the hallux
Muscles of the Foot
Any Questions??
References
• www. rci.rutgers.edu