Animal Biology

1
Animal Biology

• The Skeleton and Joints
• Linda J. Pepper, Ph.D.

2
Bones of the Skeleton

• The skeleton
• Supports the body
• Protects the soft body parts and organs
• Houses blood-forming tissues,
• Stores minerals and fat
• Permits body movement

3
(No Transcript)
4
Classification of the Bones

• The 206 bones of the body are classified
  according to their shape.
• Long bones are longer than wide (e.g., the femur,
  humerus).
• Short bones are cube-shaped (e.g. the carpals,
  tarsals).
• Flat bones have plate-like surfaces (e.g., the
  skull).
• Round bones are roughly circular (e.g., the
  patella).
• Irregular bones have varied shapes (e.g., the
  vertebrae, facile bones.

5
The Axial Skeleton

• The axial skeleton lies in the midline of the
  body and consists of the skull, hyoid bone,
  vertebral column, ribs and sternum.

6
The Skull

• The skull is formed by the cranium and facial
  bones.

7
The Cranium

• The cranium is made up of eight bones that are
  incompletely fused in infants, leaving soft
  spots, or fontanels. Sinuses are found in the
  cranium. They reduce the weight of the skull and
  give resonance to the voice.

8
The Cranium cont.

• The major bones of the cranium include the
  frontal bone, two parietal bones, an occipital
  bone housing the foramen magnum, two temporal
  bones, a sphenoid bone, and an ethmoid bone. The
  sphenoid bone makes up the floor of the cranium.
  The ethmoid bone helps form the orbits and the
  nasal septum.

9
(No Transcript)
10
(No Transcript)
11
The Facial Bones

• The frontal bone of the skull forms the forehead
  of the face. The lower jaw is made up of the
  mandible. Zygomatic bones make up the
  cheekbones, and maxillae form the upper jaw. Two
  nasal bones form the bridge of the nose.

12
(No Transcript)
13
The Hyoid Bone

• The hyoid bone is located superior to the larynx,
  anchors the tongue, and serves as a point of
  attachment for muscles used in swallowing.

14
The Vertebral Column

• The vertebral column supports the head and trunk,
  protects the spinal cord and nerves, and is a
  site for muscle attachments. Abnormal curvatures
  include scoliosis ( a sideways curve), kyphosis
  (a hunchback form), and lordosis ( a swayback).
  Each vertebra has facets that articulate with
  each other and spinous processes that project
  toward the back.

15
The Vertebral Column cont.

• Cervical vertebrae are in the neck region and
  include the atlas and axis. Thoracic vertebrae
  are in the upper back and have an extra facet for
  rib attachment. Thick lumbar vertebrae are in
  the lower back. Five sacral vertebrae fuse to
  form a sacrum. The coccyx, or tailbone, is at
  the base of the vertebral column. Intervertebral
  disks, formed of fibrocartilage, provide a
  padding between the vertebrae.

16
(No Transcript)
17
(No Transcript)
18
The Rib Cage

• The rib cage is composed of the thoracic
  vertebrae, the ribs and their cartilages, and the
  sternum.

19
The Rib Cage cont.

• The Ribs consists of twelve pairs all connected
  to the thoracic vertebrae. Ten pairs of ribs
  connect to the sternum via hyaline cartilage.
  The lower tow pairs of ribs are floating ribs
  because they are not attached to the sternum.
• The Sternum (breastbone) protects the heart and
  lungs. It is made of the manubrium, the body,
  and the xiphoid process.

20
(No Transcript)
21
The Appendicular Skeleton

• The appendicular skeleton is made up of the
  pectoral and pelvic girdles, and the arm and leg
  bones.

22
The Pectoral Girdle and Arm

• The pectoral girdle consists of the scapula
  (shoulder blade) and the clavicle (collarbone).
  The glenoid foassa articulates with the head of
  the humerus. The humerus is the bone of the
  upper arm. The radius and ulna make up the lower
  arm. The hand is made up of eight carpal bones,
  with five metacapals and the phlanges of the
  fingers and thumbs.

23
(No Transcript)
24
The Pelvic Girdle and Leg

• The pelvic girdle consists of two heavy coxal
  bones, fused at the sacrum. Each coxal bone is
  made up of the ilium, ischium, and pubis, all
  fused at the acetabulum. The thigh contains the
  femur, and the lower leg is made up of the tibia
  and fibula. The ankle contains seven tarsal
  bones, and five metatarsals make up the arcing
  instep of the foot.

25
(No Transcript)
26
Articulations

• Joints can be immovable, such as those of the
  skull slightly moveable synoval joints, held
  together by ligaments. The joint capsule is
  filled with lubricating synoval fluid. Menisci
  (pads of fibrocartilage) help stabilize the knee
  joint. Fluid-filled sacs (bursae) can be found
  in some joints. Most movable are the
  ball-and-socket joints, such as the hip or
  shoulder. Hinge joints (fingers) can move in one
  direction.

27
(No Transcript)
28
(No Transcript)
29
Movements Permitted by Synoval Joints

• Angular movements increase (extension, abduction0
  or decrease (flexion, adduction) the joint angle
  between the bones of a joint. Circular movements
  such as rotation, supination, circumduction,
  inversion, eversion, elevation, and depression
  occur at ball and socket joints.

30
(No Transcript)
31
Arthritic Joints

• Synoval joints are candidates for arthritis, the
  most common form of which is osteoarthritis.
  Knee and hip replacement surgery is now common
  and successful.

32
(No Transcript)
33
Homeostasis

• The skeletal system functions with the other body
  systems to maintain homeostasis in the body.

34
(No Transcript)
35
(No Transcript)
36
The End.