Exam 3 Worksheet Answers Flashcards
(208 cards)
Compare the structure of fibrous, cartilage, and synovial joints, and give an example of each. How does the structure affect the mobility of the joint?
fibrous joints are held together by connective tissue proper (predominantly fibroblasts, collagen, and little ground substance); suture joints of the skull are an example. Cartilaginous joints are held together by cartilage, typically hyaline cartilage or fibrocartilage. The pubic symphysis, holding the two hip bones together anteriorly, is an example of a (fibro)cartilaginous joint. In both fibrous and cartilaginous joints, the connecting material directly attaches to the ends of the bones, preventing them from actually contacting each other directly.
Synovial joints are unique in that the bones are held together by a joint capsule made of dense connective tissue that leaves a space between the two bones; synovial fluid fills the space in the capsule, and lubricates the surfaces where the bones contact one another. This arrangement allows more freedom of movement between the bones while protecting the bony surfaces from wear. All movable joints are synovial joints.
What is the role of tendons and ligaments at joints?
Ligaments are strong bands of dense regular connective tissue holding two bones together at a synovial joint; they keep the bones from shifting.
Tendons are also made of dense regular connective tissue, and attach muscle to bone.
What role does fibrocartilage play as an added feature of some synovial joints?
Fibrocartilage is used as a stabilizing feature at a select few synovial joints (most synovial joints do not have fibrocartilage).
One use of fibrocartilage at ball and socket joints (hip, shoulder). Another is the meniscus cartilages of the knee.
name the plane in which the movement occurs: Flexion-Extension
sagittal
name the plane in which the movement occurs: Abduction-Adduction
coronal (frontal)
name the plane in which the movement occurs: Rotation
transverse
name the plane in which the movement occurs: Dorsiflexion-Plantarflexion
sagittal
A sac of synovial fluid that provides padding between a bone and another tissue is called a
bursa
At the knee joint, synovial fluid is produced by
Cells in the membrane lining the joint capsule
Standing on the toes, as a ballet dancer might do, is as example of which movement?
plantarflexion
Visualize a cross-section through the forearm. What layers would be apparent? What tissues comprise the layers? What holds the layers together?
The outermost layer visible is the skin, which itself has outer and inner layers. The outermost portion of the skin is a stratified squamous epithelium called epidermis; the inner layer of skin is a connective tissue proper layer called the dermis. Deep to the skin is a variable amount of fat, or adipose, tissue. Deep to that are skeletal muscles arranged around the radius and ulna. Dense connective tissue called deep fascia surrounds the muscles and connects on lateral and medial sides to the bones, separating the muscles into anterior and posterior compartments of the forearm. Anterior muscles flex the wrist and fingers; posterior muscles extend the wrist and fingers.
Connective tissue holds bones together, holds muscles to bones, groups muscles into compartments, and attaches skin to muscle – in other words, connective tissue proper connects all the other tissues together.
Compare Dense Regular Connective Tissue with Adipose Tissue. Which one would provide a better environment for nerves and muscles to travel through?
Dense regular connective tissue is a type of connective tissue proper that contains fibroblasts, large bundles of collagen fibers oriented parallel to one another, and very little gel-like ground substance.
Adipose tissue is also a type of connective tissue proper, but contains large numbers of adipose (fat) cells, small numbers of fibroblasts, little collagen and ample gel-like ground substance. Because collagen is resistant to deformation, dense regular connective tissue is very strong and relatively inflexible. Adipose tissue is much more malleable, and expands easily to accommodate nerves and blood vessels growing through the area. In addition, adipose tissue can act as padding around the nerves and vessels, protecting them from injury.
How do muscle cells attach to bone?
Muscle cells do not attach directly to bones. Muscle cells are surrounded by collagen; single cells are surrounded by endomysium, muscle fascicles by perimysium, and the entire muscle by epimysium. These are all names for the collagen-rich connective tissue encasing muscle. As muscle cells contract, they pull on the connective tissues around them. Endo-, peri- and epimysium layers merge to form the tendons at each end of the muscle; ultimately, as muscles contract they pull on the tendons.
Tendons attach to the connective tissue wrapping around a bone, called the periosteum. Collagen fibers of the tendons merge with collagen fibers of the periosteum, allowing a firm attachment to the bone. Thus, when a muscle attaches to a bone, it is the connective tissue around the muscle attaching to the connective tissue around the bone.
What is meant by the term “compartment” when referring to the muscular system?
A muscle compartment is a group of skeletal muscles surrounded by a continuous layer of dense connective tissue. This deep fascia is separate from the epimysium which surrounds each individual muscle – rather, it encloses an entire group of muscles, as well as nerves and vessels which travel between the individual muscles. Muscles in a compartment typically share the same action or actions, and are all supplied by the nerve and vessels in the compartment. Trouble in the compartment (inflammation, infection) typically affects all the contents of the compartment.
Why is nerve compression a problem?
Nerves are structures in the peripheral nervous system carrying axons to and from target tissues like skin and skeletal muscle. Nerves contain both sensory axons, collecting information from the target and sending it to the CNS, and motor axons, carrying commands from the CNS out to the peripheral targets. Compressing a nerve will compress some or all of the axons in the nerve. Compressing motor axons interferes with the instructions from the CNS to the target. Compressing sensory axons interferes with collecting sensations from the target, and typically also stimulates axons conveying pain from the target, leading to the sensation of pain.
which type of cell produces collagen fibers
osteocytes of compact bone
deep fascia is an example of which type of tissue
dense connective tissue
neuron
A neuron is a single electrical cell of the nervous system; it has a cell body, variable numbers of dendrites, an axon, and axon terminals
nerve
A nerve is a collection of many (dozens to many thousands) of axons, wrapped together with connective tissues (endoneurium around single myelinated axons, perineurium around fascicles, and epineurium surrounding the entire nerve), in the peripheral nervous system. Note that in the peripheral nervous system, the myelin is produced by Schwann cells.
fiber bundle
A fiber bundle is the term used to describe a collection of axons traveling together within the central nervous system. Axons are myelinated by oligodendrocytes in the CNS. There is no connective tissue with in the CNS, so there is no collagen wrapping around individual axons or around groups of axons. Axons simply travel adjacent to neighboring axons in the white matter, but there is no tissue in the CNS that can separate groups of axons from other groups
are nerves and fiber bundles similar in structure?
Nerves and fiber bundles as similar structures, in that they are both names given for large numbers of axons traveling together to a target. In the PNS, the axons are supported by connective tissue to form nerves. In the CNS, where there is no connective tissue, axons travel together in bundles without any obvious separation between groups, and are referred to as fiber bundles.
Describe the folding of the neural plate to form neural tube and neural crest
In the third week of human development, the embryo is a long, flat structure comprised of three cell layers. The nervous system forms from the most posterior (dorsal) of these three layers, the ectoderm. The central portion of this cell sheet undergoes rapid cell division, forming a longitudinal groove down the center of the sheet; this is called the neural groove. As the groove deepens, cells at the surface of the groove meet in the midline, closing the groove into a tube-like structure called the neural tube. This structure sinks under the surface and
forms the central nervous system, which will eventually become the brain and spinal cord. At the edges of the neural groove, called the crest region, another population of cells develops called the neural crest. These cell groups also sink under the surface, on either side of the neural tube; once these cells migrate away they will form all the parts of the peripheral nervous system.
At the surface, once neural crest and neural tube structures have sunk anteriorly, the remaining ectoderm grows back over the entire dorsal surface, to enclose the entire neural tube and neural crest under the skin.
List the major divisions of the adult CNS
The major divisions of the CNS, from rostral to caudal, are the cerebrum, diencephalon, brainstem (with three parts: midbrain, pons and medulla), and spinal cord; the cerebellum develops an outgrowth of the pons but is generally not considered a compartment of the brainstem.
Compare the composition of gray matter vs white matter: what cells or cell parts are located in each?
Gray and white are the two colors one sees when looking at sections through the CNS. White matter is white because myelin is white in color; thus, white matter represents areas where there are large numbers of myelinated axons traveling together. Gray matter is darker in color because of a relative lack of myelin, not because there are zero myelinated axons in the area. Gray matter contains neural tissue that lacks myelin – this includes cell bodies and dendrites, and axon terminals, and the support cells called astrocytes. Gray matter, then, represents areas where neurons are receiving information from other cells and processing that information. White matter represents the highways where cell bodies are transmitting information down their axons toward other areas of gray matter.
