Agriscience 332
Animal Science
The Skeletal System
8646-C
TEKS: (c)(2)(A)
Topic B-1: Knowing the Skeletal, Muscular, Respiratory, and Circulatory Systems of Animals
Topic Goal:
The student shall be provided the opportunity to know the skeletal, muscular, respiratory, and circulatory systems of animals as a means of explaining animal anatomy and physiology related to nutrition, reproduction, health, and management of domesticated animals.
Topic Objectives:
After completing the topic, the student will be able to:
- describe the anatomy of bones and bone tissues;
- explain the physiology of bones;
- recognize the anatomy of bone joints;
- identify the anatomy of the axial skeleton;
- identify the anatomy of the pectoral limb; and
- identify the anatomy of the pelvic limb.
Class Notes
The ______system is all the ______tissues in an animal’s body. Animal’s that have an ______skeleton, or ______, include humans and domestic animals. The skeletons are ______in most species, but may vary in ______and ______of bones. Functions of the skeleton include:
- Giving the body ______and ______,
- Protecting vital ______,
- Allowing for body ______,
- Storing ______, and
- Serving as a site for formation of ______cells.
ANATOMY OF BONES AND BONE TISSUE
The outer portion of the bone is hard, dense bone and forms the ______. The inner portion of the bone is spongy, porous bone that forms a network called the ______cavity. The medulla cavity has a membrane lining called the ______. Bone ______is a thick, red mass of cells inside the medulla cavity, which makes essential ______cells.
Blood cells created in the bone ______include the following:
- ______- fight infection,
- ______- carry oxygen, and
- ______- help the blood to clot.
As the bone ages, the ______bone marrow gradually changes into ______fatty marrow.
Parts of the Bone
- Epiphysis - refers to either ______or extremity of a long bone.
- Proximal epiphysis - end ______to the main body of the animal.
- Distal epiphysis - end ______from the main body of the animal.
- Diaphysis - the long bone ______between the two joint ends.
- Epiphysial cartilage - layer of ______between the joint ends and the shaft that allows the bone to increase in ______.
- Periosteum - fibrous ______that covers the exterior of the bone, excluding the joint ends.
- Articular cartilage - thin layer of ______that covers each joint end.
Total Bone Mass
Of the total bone mass, 26% is ______matter;
the other chemical compositions are 20% ______,
4% ______, and 50% ______.
The ______layer of a bone is composed of mineral deposits,
which makes the bone ______and ______.
Calcium ______makes up almost 85% of the
mineral matter and the remaining 15% is calcium
______and magnesium phosphate.
A bone is the body’s primary mineral ______,
which is constantly being depleted or replenished.
One-third of the bone’s total ______is comprised of living ______that contain replicating ______, ______vessels, ______vessels, and ______. Because a bone is made up of ______organic matter, composed of fibrous tissue and cells, it is vulnerable to ______. However, a bone can ______itself if injured and reacts to changes caused by ______.
Classification of Bones
Bones are classified based on ______and ______. Classifications of bones include:
- ______bones - bones found in ______that serve as supporting columns and ______for the skeleton, assisting in body support, locomotion, and eating. A long bone is an elongated, round shaft with two ends. Examples of long bones include the ______and ______.
- ______bones - short bones are ______-shaped bones that contain a spongy substance filled with marrow spaces surrounded by a thin layer of compact bone. Short bones function to reduce ______and change the ______of tendons in the joint of a limb. Examples of short bones can be found in the ______and ______.
- ______bones - relatively thin, long, and ______bones that contain two plates of compact bone surrounded by spongy bone. Flat bones function to ______vital organs, such as the brain, heart, lungs, and pelvic viscera, and serve as areas of muscle ______. Examples of flat bones are the ______, ______, and ______.
- ______bones - flat and round bones that are located along the course of ______. Sesamoid bones reduce ______and change the ______of tendons or the ______of muscle pull. The kneecap, or ______, is an example of a sesamoid bone.
- ______bones - bones that contain ______spaces (sinuses), which are in contact with the atmosphere. Frontal and maxillary bones are examples of ______bones that can be found in the face.
- ______bones - bones that protect and support the central ______system and are points of some ______attachments. The bones in the ______column and some unpaired bones of the ______are examples of irregular bones.
The surfaces of bones have ______and ______that differ in size and shape, depending on the function. ______projections and depressions, located in the ______, are covered with articular cartilage.
Non-articular projections and depressions, serve as points
of attachment for ______and ______.
PHYSIOLOGY OF BONES
Bones grow in the region of the ______cartilage, which is located between the epiphysis (end) and diaphysis (shaft). This bone ______is an increase in both diameter and length.
The ______produces new boney tissue that increases the ______of the bone. The periosteum, which is the outside covering of the bone, is also involved with repairing bone ______. As the bone increases in diameter, the bone marrow ______increases. This is accomplished by the removal or re-______of portions of the inner bone.
As an animal ______, bone growth stops.
______occurs; that is, the epiphysial
cartilage becomes ______, bony material.
Although bone continues to be reabsorbed
and replaced, there is no ______bone growth.
Osteogenesis is the process of ______formation.
Osteoblasts, which are the ______cells of
connective tissue, accomplish this process by multiplying and secreting an enzyme called ______. Phosphatase causes some of the cells to mature and secrete ______salts for ossification. Osteocytes (mature ______cells) are surrounded by calcified osteoid material. This ______material appears as small cavities, which are connected by tiny canals that transmit tissue fluid, the life support for osteocytes. Some of the new cells stay in the ______, where they reproduce and are stored until needed.
Re-absorption of bone will occur due to the following reasons:
- bone ______or repair of ______,
- ______,
- ______imbalances,
- ______,
- ______, and
- certain bone ______.
______, cells that secrete phosphatase which ______bone tissue, and increasing ______supply are responsible for bone re-absorption.
Bone growth is affected by ______, ______, and other ______. Nutritional deficiencies can make bones ______and ______. Because of their ______, especially in older animals, bones can ______easily. Bone tissue can also ______itself.
When a ______occurs, it becomes filled with blood and connective tissue cells. The ______-forming cells, osteoblasts, replicate rapidly, forming a fibrin clot or ______, which becomes calcified into true bone tissue with a marrow cavity. Osteoclasts then reabsorb ______bone tissue from the callus.
Common Types of Bone Fractures
- ______Fracture - a broken bone that does not puncture the skin.
- ______Fracture - a broken bone that results in the bone protruding through the
skin, making infections possible.
- ______Fracture - one side of the bone is fractured and the other side is bent.
- ______Fracture - a break in the bone that occurs
at the juncture of the epiphysis (end) and the
diaphysis (shaft).
Greenstick and ephiphysial fractures occur in ______
animals only.
- ______Fracture - the bone is broken completely
across.
- ______Fracture - the bone is broken into
fragments due to crushing or splintering.
When a broken bone occurs, both ends of the fracture should be held ______and ______by a splint or bone pin.
Anatomy of Bone Joints
There are three main types of ______or articulations that join bones together:
- ______Joints - joints that are filled with fibrous tissue early in life and ossify as the animal matures, making them immobile. Example - ______.
- Slightly ______Joints - joints that allow limited movement forward, backward, and sideways. These joints have flattened discs of cartilage and are sometimes called ______joints. Examples - joints of the ______column (backbone) and those adjacent to the ______bone.
- Freely ______Joints - also called ______joints, allow friction-free movement.
These joints consist of:
* Articular surfaces - bone ______are shaped to operate smoothly with the bones to which they connect;
* Articular cartilage - ______that covers the articular surface and absorbs concussions;
* Joint capsule - capsule that contains synovial fluid, which ______the joint and allows for the ______-free movement; and
* Ligaments - connective tissue bands that connect ______to ______.
Types of freely moveable joints:
* ______joint - moves in two directions, flexion and extension. Example - ______joint.
* ______joint - moves in slight gliding motions between flat surfaces. Example - ______or small cube-shaped bones in knee joint.
* ______joint - allows rotary motion. Example - in the ______between the axis & atlas vertebrae.
* ______-and-______joint - allows movement in almost all directions and is characterized by a spherical head on one bone fitting into a cup-shaped socket of the other bone. Example - ______joint.
PARTS OF THE SKELETON
There are three general areas of the
vertebrate's skeletal system:
- ______skeleton
- ______limb
- ______limb
Anatomy of the Axial Skeleton
The axial skeleton consists of the bones that are either on the ______of back or are attached to the bones of the midline, including the ______, ______column, ______, and ______.
Skull - protects the ______, houses many of the ______organs, and contains the beginnings of the digestive and respiratory systems. It is composed of the ______part and the ______part. Many cranial and facial bones occur in pairs, one on each side of the head and are connected at joints called ______.
Major bones in the ______:
- ______bones - situated at the back
and lower part of the cranium
- ______bones - form the sides and
roof of the cranium
- ______bones - serve as the origin of
______in horned animals
- ______bone - contains openings for
olfactory nerves that are responsible for the sense of ______
- ______bone - supports the brain and pituitary gland
Facial parts of the skull:
- Orbital section - contains ______sockets that house
and protect the ______
- Nasal section - two small, oblong bones that form
the “______” of the ______
- Oral section - “______” bones that support the ______
and provide muscle attachment for chewing and
swallowing
Vertebral Column - the vertebral column, or ______, is divided into 5 anatomical regions. The number of vertebrae in each region varies among the different species.
- ______vertebrae - the cervical vertebrae are in the ______area and allow for movement of the head.
* ______- first cervical vertebrae that forms a hinge joint with the occipital bone of the skull and allows the head to move up and down.
* ______- second cervical vertebrae that forms a pivotal joint with the atlas and allows the head to turn from side to side.
- ______vertebrae - the thoracic vertebrae are in the ______area and are the attachment sites of the ribs.
- ______vertebrae - the lumbar vertebrae are in the ______area and are slightly more mobile than the thoracic vertebrae. The large, flat projections of the lumbar vertebrae, that extend to either side of the midline, are the long bones seen in a T-bone cut.
- ______vertebrae - the sacral vertebrae are in the ______region and are usually fused to form a single wedge-shaped bone, sacrum, to which the pelvic limb is attached.
- ______vertebrae - the coccygeal vertebrae are in the ______area and vary greatly in number depending on the species.
Ribs - thin, flat, curved bones that ______the heart, lungs, stomach, spleen, and kidneys. ______also assist in respiration by lifting up and allowing the lungs to expand during inhalation and by moving down and squeezing air out during exhalation. The ______of rib pairs usually corresponds to the number of thoracic vertebrae, but sometimes ______ribs can occur in front of or behind the thoracic vertebrae.
- ______ribs (sternal ribs) - ribs that are attached to the sternum by cartilage.
- ______ribs - ribs that do not connect directly to the sternum, but may connect to the last sternal rib by cartilage.
- ______ribs - ribs that have no connection to other ribs in the sternum area.
______- several small bones (sternebrae) that fuse together as the animal ages to form the ______of the thoracic cavity. The ______is the site of attachment for the sternal (true) ribs.
Anatomy of the Pectoral Limbs
The ______legs of ______-legged animals
(quadrupeds) are the ______limbs.
The pectoral limbs are connected to the ______
skeleton (body) by muscles and connective tissues.
The joints formed by the scapula and humerus are
ball-and-socket joints, but function as ______joints.
The remaining joints in the pectoral limb also function
as ______joints.
______(______blade) - a triangular-shaped flat bone that attaches to the humerus.
______(arm) - a long bone that extends toward the front of the animal, forming the point of the ______. The articular angle, the angle formed by the scapula and the humerus, is important to the ______of the front legs. In poultry, the ______or coracoid, connects to the scapula.
______- the ______, well-developed bone in the forearm, located on the inside of the foreleg. The radius connects to the humerus forming the ______joint.
______- the ______of the two bones in the forearm. Together, the radius and ulna make up the bones in the ______. In horses, the radius and ulna are fused, allowing no movement between the bones. In cattle, sheep, and swine, the ulna is more developed and limited movement occurs between the radius and ulna.
______(______) - a complex region of small, cube-shaped bones (sliding joints) that function together as a hinge joint.
______(______) bones - bones that form the lower part of the foreleg. The number of metacarpal bones vary with the species.
______(digits) - the bones that form the ______(fingers in humans) on the pectoral limb. The number of ______vary with the species: horses (1), cattle and sheep (2), swine (4), and dogs (5).
______- second and fifth digits in swine (more developed), cattle and sheep (non-functional).
Each digit (toe) is made up of ______phalanges (small bones). The first phalanx is the long ______bone, the second phalanx is the short ______bone, and the third phalanx is the ______bone.
Anatomy of the Pelvic Limbs
The ______legs of quadrupeds (four-legged animals) are the ______limbs. The pelvic limbs are connected to the axial skeleton by the ______girdle.
Pelvic ______ - three bones (ilium, ischium, and pubis) that are fused together to form an irregular bone called the os coxae or ______. The pelvis is connected to the ______at the sacroiliac joint.
- ______bones - front, dorsal bones in the pelvis; in cattle, the front points of the ilium bones are called the ______bones.
- ______bones - rear, dorsal bones in the pelvis; in cattle, the rear points of the ischium bones are called the ______bones.
- ______- ventral bones in the pelvis that form the ______of the pelvic girdle.
______- a long bone that extends from the hip joint to the stifle joint and is the site of several hip and thigh muscle attachments.
______(kneecap in humans) - the largest sesamoid bone in quadrupeds.
______- the larger, thicker of the two long bones in the hind leg, the tibia is located on the inside of the hind leg and extends from the stifle joint to the hock joint.
______- the thinner bone in the hind leg, the fibula extends from the upper end of the tibia to lengths that vary depending on the species.
Tarsus (______) - two rows of tarsal bones in the hind leg that correspond to the ankle in humans and are similar to the carpus in the front leg.
Fibular ______ - bone that forms the ______of the hock and serves as a lever for muscles that extend the hock.
______(rear ______bone) - bones that are similar to the metacarpals of the foreleg, but are slightly longer.
______- bones that make up the ______of the hind leg, which are similar to those in the front leg.
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