The Skeletal System: Appendicular Skeleton

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Chapter 8

• The Skeletal System Appendicular Skeleton

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INTRODUCTION

• The appendicular skeleton includes the bones of
  the arms, legs, hips, and shoulders.
• The primary function of the appendicular skeleton
  is movement.
• It also provides attachment points for muscles,
  supports and protects internal organs, and stores
  and releases calcium.

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Pectoral (Shoulder) Girdle

• The human body has two shoulder girdles that
  attach the arms to the axial skeleton.
• The pectoral (shoulder) girdle is the entire
  shoulder area, including
• - clavicle
• - scapula
• - associated joints and muscle attachments

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Clavicle

• We have 2 clavicles, slender, S shaped bones,
  also called collar bones, which attach the
  shoulder to the breastbone.
• They lie horizontally across the thorax (chest)

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Fractured Clavicle

• The clavicle is one of the most frequently broken
  bones in the body.
• It breaks when you fall and brace yourself with
  your arm.
• It is usually treated with a sling to keep the
  arm from moving outward.

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Scapula

• The scapula (shoulder blade) is a large, flat,
  triangular blade that connects the tendons and
  muscles needed to move the arms.
• We have 2

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UPPER LIMB (EXTREMITY)

• Each upper limb (ARM) consists of 30 bones
• The humerus (1)
• The ulna and radius (2) of the forearm
• The carpals in your wrist (8)
• The metacarpals in your palm (5)
• The phalanges (14) which are your fingers

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Humerus

• The humerus is the longest and largest bone of
  the upper limb.
• It goes from the scapula to the elbow, where it
  meets the radius and the ulna.
• The ulnar nerve, which causes the funny bone
  reaction, can easily be felt at the base of the
  humerus, in the elbow joint, between the radius
  and ulna

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Ulna and Radius

• The ulna is located on the medial aspect of the
  forearm (closer to the midline) on the pinky
  finger side of the hand.
• The radius is located on the lateral aspect
  (thumb side) of the forearm. Radius fracture is
  common in older adults.
• They connect the elbow to the wrist.

thumb
pinky
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Carpals

• The eight carpal bones, bound together by
  ligaments, comprise the carpus (wrist).
• The carpal tunnel is a concave space between the
  carpal bones, and can become inflamed by
  repetitive motion.

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The 8 Bones of the Carpus

• Proximal row (closer to arm) scaphoid, lunate,
  triquetrum, pisiform
• Distal row (closer to fingers) trapezium,
  trapezoid, capitate, hamate
• Stop letting those people touch the cadavers
  hand

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Metacarpals

• The metacarpus is the palm of the hand, and it
  consists of 5 bones, called the metacarpals.
• They are numbered I-V, starting with the thumb,
  from lateral to medial.

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Phalanges

• The phalanges are the bones of the digits, or
  fingers.
• There are 14 phalanges in each hand.
• The digits are also numbered I to V, with I being
  the thumb and V being the pinky.
• A single bone of a digit is called a phalanx.
  Each phalanx has a base, a shaft, and a head.
• Another word for thumb is pollex, and it has only
  2 bones. The other digits have 3 each (index,
  middle, ring, little).
• The first row of bones (closest to palm) are the
  proximal row, the middle is the middle row, and
  the ones at the tips of the fingers are the
  distal row.
• Joints in the fingers are called interphalangeal
  joints.

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PELVIC (HIP) GIRDLE

• The pelvic (hip) girdle consists of two hipbones,
  the sacrum, and the coccyx, and provides a strong
  and stable support for the lower extremities, on
  which the weight of the body is carried.

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The Hipbone

• The ilium is the biggest part of the hipbone (and
  is the top part)
• Bone marrow aspiration or bone marrow biopsy are
  frequently performed on the iliac crest in
  adults.
• The ischium is the inferior, posterior portion of
  the hip bone
• The pubis is the anterior and inferior part of
  the hip bone

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True and False Pelvis

• The top half of the pelvis is called the false
  pelvis because it encloses organs of the
  abdomen, not the pelvis (except for the bladder)
• The bottom half of the pelvis is called the true
  pelvis and it has an inlet, outlet, and cavity.
  It is the route through which the baby exits the
  female body.

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Pelvimetry

• Pelvimetry is the measurement of the size of the
  inlet and outlet of the birth canal.
• This is what doctors measure to determine how far
  a woman has dilated, and if she needs a cesarean
  section.

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Female and Male Skeletons

• Male skeleton
• larger and heavier
• larger articular surfaces
• larger muscle attachments
• Female pelvis
• wider shallower
• larger pelvic inlet outlet
• more space in true pelvis

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COMPARISON OF FEMALE AND MALE PELVES

• Male bones are generally larger and heavier than
  those of the female the males joint surfaces
  also tend to be larger.
• Muscle attachment points are more well-defined in
  the bones of a male than of a female due to the
  larger size of the muscles in males.
• A number of anatomical differences exist between
  the pelvic girdles of females and those of males,
  primarily related to the need for a larger pelvic
  outlet in females to facilitate childbirth.

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LOWER LIMB (EXTREMITY)

• Each lower extremity is composed of 30 bones
• The femur (1)
• The patella (kneecap) (1)
• The tibia and fibula (2)
• The 7 tarsals in the ankle
• The 5 metatarsals in the foot
• The 14 phalanges (bones of the digits) in the
  toes.

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Femur

• The femur or thighbone is the largest, heaviest,
  and strongest bone of the body.
• It connects the hip bone to the knee.
• It is common fracture site

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Patella

• The patella or kneecap is a small, triangular,
  sesamoid bone located anterior to the knee joint.
• It functions to increase the leverage of the
  tendon of the quadriceps muscle, to maintain the
  position of the tendon when the knee is bent, and
  to protect the knee joint.

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Patellofemoral Stress Syndrome

• Runners Knee
• The patella can move left and right as well as
  the normal up and down.
• This is caused by stress on the knee from
  frequent running and jogging, and is very painful.

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Tibia

• The tibia or shinbone is the larger, medial,
  weight-bearing bone of the leg (closer to
  calf/midline)
• Of all the long bones of the body, it is the most
  frequently fractured.

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Fibula

• The fibula is behind and parallel to the tibia,
  and is smaller.

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Bone Grafting

• Bone grafting consists of taking a piece of bone
  from one part of the body to replace a missing
  bone somewhere else.
• The most common bone that is taken for grafting
  is the fibula (remember only the tibia bears
  weight)

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Tarsals

• Your ankle is your tarsus.
• It consists of 7 tarsal bones
• Talus, Calcaneus, Navicular, Third Cuneiform,
  Second Cuneiform, First Cuneiform, Cuboid
• Tall centers never take shots from corners

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Metatarsals

• The metatarsus is the intermediate region of the
  foot.
• It is made of 5 metatarsal bones, numbered I to V
  from the big toe out to the pinky.

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Fractures of the Metatarsals

• Fractures of the metatarsals are common among
  female ballet dancers
• If dancers come off their toes too quickly, the
  full body weight is placed on the metatarsals,
  causing fracture

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Phalanges

• The arrangement of phalanges in the toes is the
  same as that described for the fingers and thumb
  - fourteen bones in each foot
• The toes are numbered I to V, the big toe is I.

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Arches of the Foot

• The bones of the foot are arranged in two
  non-rigid arches
• They are held in position by tendons and
  ligaments
• These enable the foot to support the weight of
  the body provide an ideal distribution of body
  weight over the hard and soft tissues, and
  provide leverage while walking.
• The longitudinal arch has two parts, and runs
  from the heel to the ball of the foot.
• The transverse arch horizontally spans your foot
  beneath the metatarsals.

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Clinical Problems

• Flatfoot
• weakened ligaments allow bones of medial arch to
  drop
• Clawfoot
• medial arch is too elevated
• Hip fracture
• 1/2 million/year in US
• osteoporosis
• arthroplasty

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Development of the Skeletal System

• All skeletal tissue comes from the mesoderm layer
  of the embryo
• The skull and vertebrae start to form 4 weeks
  after fertilization
• 5 weeks after fertilization, arm and leg buds
  appear
• By 6 weeks, hands and feet form
• By the 12th week, most primary bone growth is
  complete

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Skeleton Project Due Friday
Make a creative representation of the
skeleton. It can be a poster, a picture, a song,
a video, a puppet, a documentary, a poem, a skit,
a story, a power point, a model, a
sculptureanything you can think of! You must
include (either by labeling or describing) the 30
arm and 30 leg bones, the clavicle, scapula,
pelvis (ilium, ischium, and pubis), and
hips. These are INDIVIDUAL projects, and each
person will present in 1-2 minutes on THIS
FRIDAY. You are responsible for both an oral
presentation and the actual physical project that
you are turning in.