HBIO Midterm 2
The anterior cruciate ligament
attaches to the anterior part of the tibia, in the intercondylar area. From there, it passes posteriorly to attach to the femur on the medial side of the lateral condyle. The anterior cruciate helps prevent anterior sliding of the tibia.
The joint capsule of the knee is reinforced by several capsular and extracapsular ligaments, all of which
become taut when the knee is extended to prevent hyperextension of the leg at the knee.
The sarcomere is the
basic unit of contraction in skeletal muscle. The boundaries at the two ends of each sarcomere are called Z discs. Attached to each Z disc and extending toward the center of the sarcomere are many fine myofilaments called thin filaments. The thin filaments are composed primarily of the contractile protein actin.
articular cartilage (hyaline)
composed of hyaline cartilage. These spongy cushions absorb compressive forces placed on the joint and thereby keep the bone ends from being crushed.
Neurons are highly specialized cells that
conduct electrical signals from one part of the body to another. These signals are transmitted along neurilemma, in the form of nerve impulses, or action potentials.
What structures do they epi, peri, and endomyscium come together to form at the end of skeletal muscles?
connective tissue attachment to bone matrix, i.e., tendon (bundle) or aponeurosis (sheet)
indirect attachment
connective tissue wrappings extend beyond muscle as ropelike tendon or sheetlike aponeurosis
fibrous joints
consists of inflexible layers of dense connective tissue, holds the bones tightly together
endomysium
contains capillaries, nerve fibers surrounds individual muscle fibers
The lateral compartment of the leg
contains the fibularis muscles that plantar flex and evert the foot and are innervated by the superficial fibular nerve.
Muscle fibers increase in diameter by building more
contractile proteins and myofilaments. It is by this process that weight lifters develop large muscles.
Although the average number of muscle fibers in a motor unit is 150, the number may run as high as several hundred or as low as four. Muscles that require very fine control (such as the muscles moving the fingers and eyes) have _______ muscle fibers whereas bulky, weight-bearing muscles, whose movements are less precise (such as the hip muscles), have ________ muscle fibers per motor unit.
few;many
adjoining bones united by collagenic fibers
fibrous
Bursitis
inflammation of a bursa, usually results from a physical blow or friction, although it may also be caused by arthritis or bacterial infection.
Surface anatomy
the study of the external surface of the body, gives insight into the internal organs.
The terminal boutons contain vesicles that release neurotransmitter (acetylcholine) when a nerve impulse reaches the terminals. ACTch diffuses across
the synaptic cleft and binds to receptor molecules on the sarcolemma, where it induces an impulse that initiates fiber contraction
Important synovial joints
the temporomandibular, sternoclavicular, shoulder, elbow, wrist, hip, knee, and ankle joints.
In a fully relaxed sarcomere
the thin filaments partially overlap the thick filaments.
Axon diameter
varies among the different neurons of the body. larger diameters conduct impulses faster than those with smaller diameters
Epimysium
An outer layer of dense, irregular connective tissue surrounds the whole skeletal muscle.
The brain is commonly described as containing four parts, which reflect its embryonic development:
(1) brain stem (medulla oblongata, pons, and midbrain), (2) cerebellum (3) diencephalon, and (4) cerebrum, composed of the two cerebral hemispheres.
The central process is clearly an axon because it The peripheral process, by contrast, is ambiguous
(1) carries a nerve impulse and (2) carries that impulse away from the cell body—the two criteria that define an axon It generates and carries nerve impulses toward the cell body, a fundamental feature of dendrites. however, its fine structure is identical to that of true axons.
The various types of skeletal muscle fibers are categorized according to two characteristics:
(1) how they manufacture energy (ATP) and (2) how quickly they contract.
In development-based scheme, muscles are organized into four groups: (LAMP)
(1) muscle of the visceral organs (2) pharyngeal arch muscles (3) axial muscles (4) limb muscles.
nervous tissue is made up of just two main types of cells:
(1) neurons, the excitable nerve cells that transmit electrical signals, and (2) neuroglia, nonexcitable supporting cells that surround and wrap the neurons.
In regard to the movement of the tibia relative to the femur, specifically what do the anterior and posterior cruciate ligaments prevent?
(ACL) - prevents anterior sliding of the tibia relative to femur (PCL)- prevents posterior displacement of tibia relative to femur
Disorders of Appendicular Skeleton: hip displaysia
(congenital dislocation of the hip) (dysplasia = misformed) is a relatively common birth defect. In this condition, which affects females more than males, either the acetabulum fails to form completely or the ligaments of the hip joint are loose. In either case the head of the femur tends to slip out of its socket. Treatment generally involves using a splint or a harness of straps to hold the femur in its proper position, so that the acetabulum can grow properly and the ligaments can tighten on their own.
The somatic body region consists of the structures of the outer tube . The visceral body region mostly contains the viscera within the inner tube
(skin, skeletal musculature, bones) (digestive tube, lungs, heart, bladder, and so on).
The muscles of the medial compartment
(the adductor group) adduct the thigh and are innervated primarily by the obturator nerve.
dendrites
- contained by most cells - they branch from cell body - contains organelles of cell and chromatophilic substance in its base - receptive sites, conduct signals toward body
Multipolar neurons
- more than two processes - numerous dendrites and a single axon - Well over 99% of neurons in the body belong to this class
axons
- only one per neuron - arises from axon hillock - thin processes of uniform diameter - impulse generators and conductors that transmit nerve impulses away from their cell body - and the Golgi apparatus are absent from the axon and the axon hillock alike.
axodendritic synapse structure is representative of both types of synapses.
- presynaptic neuron has synaptic vesicles. These are membrane-bound sacs filled with neurotransmitters - terminal bouton has mitochondira to supply energy for secretion of neurotransmitters requires a great deal of energy. At the synapse, the plasma membranes of the two neurons are separated by a synaptic cleft.
Unipolar neurons (pseudounipolar neurons)
- short, single, divides like into two - start out as bipolar neurons whose two processes fuse together near the cell body during development. - found in sensory ganglia in the PNS - sensory neurons. - The short, single process near the neuron cell body divides into two longer branches that run along the CNS (CP and PP)
Fast oxidative muscle fibers are intermediate Like fast glycolytic fibers like slow oxidative fibers Because fast oxidative fibers depend largely on aerobic metabolism, they are
- they contract quickly - they are oxygen dependent and have a high myoglobin content, a large number of mitochondria, and a rich supply of capillaries. - fatigue resistant but less so than slow oxidative fibers. - The speed of contraction of fast oxidative fibers is between that of the other two fiber types. The diameter of the fiber is also intermediate; thus, these fibers are more powerful than slow oxidative fibers but not as powerful as fast glycolytic fibers.
Bipolar neurons
- two processes that extend from opposite sides of the cell body - very rare neurons that occur in some of the special sensory organs (inner ear, olfactory epithelium of the nose, retina of the eye) - sensory
cell body of neuron (soma)
- vary widely in size (from 5 to 140 μm in diameter), - all consist of a single nucleus surrounded by cytoplasm. - the nucleus is spherical and clear and contains a dark nucleolus near its center
Common features of synovial joints
-joint cavity -articular cartilage -synovial fluid -capsule - ligaments reinforcing vessels
Nonaxial (plane)
. Adjoining bones do not move around a specific axis.
four functional properties of muscle tissue
1. Contractility 2. Excitability 3. Extensibility 4. Elasticity
1. What are the different functions that skeletal muscles perform? PMSGMS
1. Produce skeletal movement 2. Maintain posture and body position 3. Support soft tissues 4. Guard entrances and exits 5. Maintain body temperature 6. "Store nutrient reserves" (referring to the contractile proteins, which will be catabolized during starvation after adipose tissue reserves are exhausted)
Vertebrae in the upper back
12 thoracic, each articulating to a rib
Bones of the skull and the associated bone
28 total bones. 14 are facial, 8 are cranial. The remaining 7 are associated which include 6 auditory and the 1 hyoid. and 1 associated bone (hyoid)
. There are six types of neuroglia
4 in the CNS 2 in the PNS
vertebrae of the lower back
5 lumbar vertebrae
The saccrum is made of ____ fused bones a d the coccyx is made of_____ fused bones
5;4
a ligament can stretch only about
6% beyond its normal length before it snaps apart.
vertebrae of the neck
7 cervical vertebrae
Whole skeletal muscles have a range of optimal operational length that runs from about
80% of their normal resting length to about 120% of that length. The sites of muscle attachments tend to keep muscles within that optimal range; that is, the joints normally do not let any bone move so widely that its attached muscles could shorten or stretch beyond their optimal range.
Two basic functions of titin
: (1) It holds the thick filaments in place in the sarcomere, thereby maintaining the organization of the A band; and (2) it unfolds when the muscle is stretched and then refolds when the stretching force is released, thereby contributing to muscle elasticity. Titin does not resist stretching in the ordinary range of extension, but it becomes stiffer the more it uncoils; therefore, it strongly resists excessive stretching that tries to pull the sarcomere apart.
What is the difference between a synovial bursa and a tendon sheath?
A Tendon sheath is an elongated synovial bursa that wraps around a tendon
The length of the A band, the I band, and the position of the Z discs in the relaxed sarcomere
A band and I band is lengthened, Z discs are far apart.
Joint (articular) cavity
A feature unique to synovial joints, the joint cavity is a potential space that holds a small amount of synovial fluid
Fibromyalgia (fibro + myo + algos) •
A mysterious chronic-pain syndrome attributed to both genetic and environmental factors • Affects mostly women (2x, 2% according to book but more recent studies indicate up to 8% of the entire population) • Symptoms—fatigue, sleep abnormalities, severe musculoskeletal pain, and headache
The ratchet-like cycle is repeated many times during a single contraction.
After a myosin head pivots at its "hinge," it lets go, returns to its original position, binds to the thin filament farther along its length, and pivots again. ATP powers this process. It should be emphasized that the thick and thin filaments themselves do not shorten: The thin filament merely slides over the thick filament.
20. What is a motor unit and what is meant by their recruitment? Which motor units are recruited first and which are recruited last when, for example, performing a bicep curl with a heavy weight? On average how many muscle fibers are innervated by a single motor unit in an extraocular eye muscle? 4 In a leg muscle? 2000 Functionally, what does the former allow for that the latter does not?
All muscle fibers controlled by a single motor neuron • Axon branches to contact each fiber. In a whole muscle or group of muscles, smooth motion and increasing tension are produced by slowly increasing the size or number of motor units stimulated Smaller, weaker units activated first • Larger, more fatigable units are added to produce steady increases in tension as required
Know the basic functions of the appendicular skeleton.
Allows us to move and manipulate objects • Includes all bones besides axial skeleton •
H zone of sarcomere
Area where no thick filaments reach
motor (efferent division) signals are carried away from the _____ by ______ to innvervate the muscles and glands to produce secretion. They are divided by _______
CNS nerve fibers of the PNS body regions they serve:
Interneurons
CNS neurons that internally communicate and intervene between the sensory inputs and motor outputs. make up 99.98% of the neurons of the body
adjoining bones by cartilage
Cartilagenous joints
Congenital myopathies •
Central core (ryanodine receptor mutation - periodic paralysis) nemaline rod (accumulation of disorganized filament proteins) and centronuclear myopathies (nuclei in center, not periphery)
Axons lack... As a result...
Chromatophilic substance, rough endoplasmic reticulum (ER), ribosomes, Golgi apparatus, receive their protein components from the cell body
function of the pectoral girdle
Connects the arms to the body, Positions the shoulders, Provides a base for arm movement • Provides attachment for many muscles that move the upper limb •
4. Although we only have 2 coxal bones (coxae), from which bones are they comprised and at what age do these bones fuse?
Coxal bones (sacrum and coccyx) are composite bones made of ilium, pubis, and ischium that join at the pubic symphysis and to the axial skeleton at the sacrum. They fuse at 20 - 25 years of age
A motor mneuron has cell processes that extend from the cell body:
Dendrites are receptive regions of the neuron an axon is a long, singular cell process that initiates and transmits nerve impulses
Inflammatory myopathies
Dermatomyositis that results in perifascicular atrophy due to loss of capillaries (autoimmune destruction of vessels)
General structures of all synovial joints
Diarthrosis
Muscular dystrophies (> 100 disorders of the sarcolemma) •
Duchenne muscular dystrophy (males, 4-years old, X-linked dystrophin mutation; protein required for attachment of endomysium to muscle fiber; typically fatal by 30 years old [respiratory failure]) •
The neuromuscular junction has several unique features.
Each terminal bouton lies in depression of the sarcolemma The invaginations of the sarcolemma are covered with a basal lamina
3. What anatomical differences allow some syndesmoses to be very moveable while others not?
Fiber length
Cartiliginous joints: Symphyses (amphiarthroses)
Fibrocartilage unites bones resists tension and compression Slightly movable joints that provide strength with flexibility Intervertebral discs • Pubic symphysis • Hyaline cartilage IS also present--as articular cartilage on the ends of bones
Perimysium
Fibrous connective tissue that surrounds muscle fascicles (groups of muscle fibers)
8. In addition to reinforcing ligaments, how does muscle tone help to stabilize a joint. Which joints is this especially important for?
Helps stabilize joints by keeping tension on tendons Is important in reinforcing Shoulder and knee joints and Supporting joints in arches of the foot
Cartilaginous Joints: Synchondroses
Hyaline cartilage unites bones Epiphyseal plates (temporary joint) Sternocostal joint between first rib and manubrium
7. How does a muscle shorten (concentric only) according to the sliding filament model or theory?
Initiated by release of calcium ions from the sarco/endoplasmic reticulum • Powered by ATP Myosin head attach to thin filaments at both ends of a sarcomere and pull thin filaments toward the center of the sarcomere Thin filaments slide past thick filaments •Thin and thick filaments do not shorten •
the brain stem has four general functions:
It acts as a passageway for all the fiber tracts running between the cerebrum and the spinal cord. It is heavily involved with the innervation of the face and head; 10 of the 12 pairs of cranial nerves attach to it. It produces the rigidly programmed, automatic behaviors necessary for survival. It integrates auditory reflexes and visual reflexes.
Why do some texts not recognize the synovial membrane as being a "true" membrane?
It is a highly viscous non-Newtonian fluid whose viscosity decreases with increasing shear rate
What is the unhappy triad and what types of movement can result in the tearing of the two ligaments (ACL + TCL or MCL) and the medial meniscus?
Lateral blows to the knee or twisting fall to knee turning medially
Endomysium
Loose connective tissue consisting of reticular fibers Within a fascicle surrounding each each muscle fiber
Metabolic myopathies
McArdle Disease (a glycogen storage disorder in which glycogen accumulates as difficulty breaking it down) mitochondrial myopathies such as myoclonic epilepsy with ragged red fibers, in which mitochondria accumulate in subsarcolemma space •
condylar joint biaxial movement
Metacarpophalangeal (knuckle) joints, wrist joints
Disorders of Axial Skeleton- cleft palate
Most common defect. the right and left halves of the palate fail to join medially. This defect leaves an opening between the mouth and the nasal cavity that interferes with sucking and the baby's ability to nurse mitigated by folic acid supplementation
Synovial Joints
Most movable type of joint, i.e., all are diarthroses • Each contains a fluid-filled joint cavity • Lined by synovial membrane
Multiaxial (ball and socket)
Movement can occur around all three axes and along all three body planes: frontal, sagittal, and transverse.
Biaxial (saddle and condylar)
Movement can occur around two axes; thus, the joint enables motion along both the frontal and sagittal planes.
Uniaxial (hinge and pivot)
Movement occurs around a single axis.
circular pattern of arrangement
Muscles with this arrangement surround external body openings, which they close by contracting. The general name for such a circular muscle is sphincter orbicularis oris, orbicularis oculi
Diseases of the NMJ •
Myasthenia gravis an autoimmune disease in which antibodies are created against nAChRs thereby blocking ACh binding •
3. What cells fuse to form skeletal muscle fibers during development? Why is it thought that the nuclei of these cells are retained in the adult muscle fiber?
Myoblasts. Nuclei of each myoblast retained to provide enough mRNA for protein synthesis in large fibers
provide structural strength in axons
Neurofilaments, actin microfilaments, and microtubules
8. Action potential travels along motor neuron axon and arrives at synaptic terminal or motor neuron endplate.
Neuromuscular Junction Activation Step 1
17. As soon as Ca2+ is released into the sarcoplasm it is actively taken up by the sarco/endoplasmic reticulum Ca2+ -ATPase (SERCA). Similarly, as soon as ACh is released at the NMJ, acetylcholinesterase degrades it (~1 ms), with choline recycled. Both mechanisms minimize the latency period before another excitation-contraction coupling can occur.
Neuromuscular Junction Activation Step 10
18. With Ca2+ no longer bound to troponin C, tropomyosin slips back to its blocking position over the active sites on actin where myosin binds, thus, ending contraction.
Neuromuscular Junction Activation Step 11
19. ATP is not only required for the SR Ca2+ -ATPase pumps (30%) but primarily (70%) for the release of the myosin head from actin and, thus, breaking the cross-bridge. As ATP is hydrolyzed by the myosin-ATPase in the heads of myosin, the myosin head re-cocks making it ready for another power stroke once binding sites open on actin with the influx of calcium.
Neuromuscular Junction Activation Step 12
9. Voltage-gated calcium channels open and Ca2+ enters into the synaptic terminal.
Neuromuscular Junction Activation Step 2
10. Ca2+ binds to a protein (synaptotagmin) resulting in the release of ACh via exocytosis into the synaptic cleft (gap between motor neuron terminal and motor end plate).
Neuromuscular Junction Activation Step 3
11. ACh diffuses across the synaptic cleft and binds to nicotinic acetylcholine receptor (nAChRs) on the motor end plate, thereby opening the non-selective cation channel.
Neuromuscular Junction Activation Step 4
12. Na+ cations diffuse into the muscle fiber while some K+ diffuses out.
Neuromuscular Junction Activation Step 5
13. If sufficient numbers of nAChRs are occupied such that a threshold potential is reached, an action potential propagates along the plasmalemma and down the T-tubule system driven by voltage-gated sodium channels.
Neuromuscular Junction Activation Step 6
14. The depolarization affects the conformation of dihydropyridine receptors (DHPRs or Cav1.1), which are mechanically linked to ryanodine receptors (RyR1) resulting in the release of sacro/endoplasmic reticulum (SER) Ca2+ and the calcium concentration increases [10-7 M Ca2+ → 10-6 M Ca2+])
Neuromuscular Junction Activation Step 7
15. Ca2+ binds to troponin C (TnC) promotes an interaction with of other troponin isoforms and movement of tropomyosin, which exposes the active sites where myosin heads bind to actin.
Neuromuscular Junction Activation Step 8
16. After cross-bridge formation, the myosin head pivots at the hinge towards the M-line as it undergoes a conformational shift known as the power stroke, pulling the actin toward the center of the sarcomere and thereby shortening the sarcomere.
Neuromuscular Junction Activation Step 9
Why are such injuries so common, in what sports, and to which sex primarily?
Occur when runner stops and changes directions with hyperextended knee. Greater incidence in women •
gouty arthritis, or gout
Occurs uric acid levels rise abnormally in the blood and body fluids, and the acid precipitates as solid crystals of urate in the synovial membranes. An inflammatory response follows as the body tries to attack and digest the crystals, producing gout. The initial attack involves a single joint, usually in the lower limb, often at the base of the big toe. Other attacks usually follow, months to years later.
Neurogenic atrophy •
Peripheral nerve damage (e.g., diabetes mellitus) or demyelinating disorders (e.g., multiple sclerosis - a demyelinating disease [autoimmune attack on myelin producing cells]) • Motor neuron disorders (e.g., amyotrophic lateral sclerosis involving upper and/or lower motor units) •
advantages and disadvantages of pectoral girdle articulations
Pros: flexibility and range of motion (flexion, extension, abduction, adduction, external/lateral rotation, internal/medial rotation and circumduction) Cons: stability
Sensory neurons, or afferent neurons,
Receive information from sensory receptors Relay that information to the CNS
Why Is the pectoral girdle not a true girdle?
Scapulae do not join each other or the axial skeleton
22. What is the difference between males and females in terms of muscle mass? What accounts for these differences? What happened to muscle mass as we age?
Skeletal muscles comprise on average ~38% in males and 31% in females Difference is due to androgens in males Amount of connective tissue increases in muscles • Number of muscle fibers decreases • Sarcopenia—muscle wasting - Decrease in muscular strength can be 10% by decade after age 30 (50% by age 80)
Reinforcing ligaments
Some synovial joints are reinforced and strengthened by bandlike ligaments. Most often, the ligaments are capsular; that is, they are thickened parts of the fibrous layer of the articular capsule. In other cases, the ligaments are extracapsular or intracapsular.
Disorders of Appendicular Skeleton: Club foot
Soles of feet point medially and toes point inferiorly. Either genetic or forms as a result of malposition. Treated by applying a cast.
10. What is a sprain? How far can a ligament be stretched before it typically tears? While we say that people are "double jointed", in actuality what allows for the observed hypermobility? Be familiar with the inflammatory and degenerative conditions discussed in lecture
Sprains—ligaments of a reinforcing joint are stretched or torn Often, genetic condition in connective tissue (e.g., Marfan syndrome - fibrillin-1, a glycoprotein secreted by fibroblasts essential for elasticity) • Beyond "normal" range (ligaments normally only stretch to 6% length
Nerves and vessels
Synovial joints are richly supplied with sensory nerve fibers that innervate the articular capsule. Some of these fibers detect pain, most monitor how much the capsule is being stretched. This monitoring of joint stretching is one of several ways by which the nervous system senses our posture and body movements.
All three sheaths converge to form the
Tendon
Brachiation
The Primate Shoulder (True brachiators: Gibbons and Siamangs)
sympheses joint
The articular cartilages function to reduce friction between the bones during movement. Fibrocartilage resists both tension and compression and can act as a resilient shock absorber
Myofilaments
The contractile proteins, actin and myosin, of muscle cells
The muscles of the posterior compartment of thigh
The hamstring group extend the thigh at the hip and flex the leg at the knee and are innervated by the tibial branch of the sciatic nerve.
What is synovial fluid most like in terms of composition?
The main component is filtered plasma that arises from the capillaries in the synovial membrane. It looks like raw egg white.
Muscle of the visceral organs
The muscle tissue found in the visceral organs is either smooth muscle or cardiac muscle. This muscle develops from the splanchnic mesoderm around the early gut.
synapse
The site at which neurons communicate is called a - transmit information through chemical messenger or by electrical signals through gap junctions.
axonal transport
The transportation of materials from the neuronal cell body to distant regions in the dendrites and axons, and from the axon terminals back to the cell body.
I bands
The two regions on either side of the A band. These regions contain only thin filaments.
double jointed
They don't have more joints than usual. The joint ligaments are simply looser and more stretchable than those of most people.
Fibrous joint: Gomphoses (Dentoalveolar Syndesmosis) An example of this joint is the _______ in a socket joint. The connecting ligament between the tooth, maxillae, and mandible is called the _________.
Tooth periodontal ligament
4. What are myosatellite cells and what are their function(s)? Can they generate new muscle fibers de novo?
Unfused myoblasts in adult (sandwiched between myolemma and basement membrane) - division - fusion to existing fibers for repair and growth (hypertrophy) cannot generate new fibers de novo (no convincing evidence of hyperplasia in humans)
Universal Law of Levers
When the effort arm is longer than the load arm, the lever operates at a mechanical advantage; when the effort arm is shorter than the load arm, the lever operates at a mechanical disadvantage.
Typically, what must be done to help an ACL tear heal?
While the TCL or MCL and meniscus usually heals, if the ACL is completely torn it requires a graft, either from the patellar ligament, the calcaneal tendon, or the semitendinosus tendon.
Each I band is part of two adjacent sarcomeres and has a
Z disc running through its center
Articular disc
a disc of fibrocartilage in synovial joints. occur in the temporomandibular (jaw) joint, sternoclavicular joint, knee joint (meniscus). Such a disc extends internally from the capsule and completely or partly divides the joint cavity in two. Occur in joints whose articulating bone ends have somewhat different shapes. When two articulating surfaces fit poorly, they touch each other only at small points, where the loading forces become highly concentrated; this can damage the articular cartilages and lead to osteoarthritis. An articular disc fills the gaps and improves the fit, thereby distributing the load more evenly and minimizing wear and damage. These discs may also allow two different movements at the same joint—a distinct movement across each face of the disc, as is the case with the jaw joint.
What are synovial bursae?
a flattened fibrous sac that act like a "ball bearing; can be found between bones, muscles, tendons and ligaments
Troponin is
a globular protein with three binding sites: one for actin, one for tropomyosin, and one for calcium. Troponin attaches the tropomyosin strand to the actin molecule.
Ratio of glial to neurons
a little bit less than 10 to 1
Disorders of Axial skeleton: stenosis
a narrowing of the vertebral canal in the lumbar region. The narrowing may result from degenerative or arthritic changes in the vertebral joints and ligaments or be caused by bone spurs projecting into the vertebral canal.
Titin
a springlike molecule in elastic filaments of sarcomeres that resists overstretching. They extend from the Z disc to the thick filament and run within the thick filament to attach to the M line
Tropomyosin forms
a thin strand that spirals around the actin molecule.
This basal lamina contains the enzyme
acetylcholinesterase which breaks down acetylcholine immediately after the neurotransmitter signals a single contraction. This ensures that each nerve impulse to the muscle fiber produces just one twitch of the fiber, preventing any undesirable additional twitches that would result if acetylcholine were to linger in the synaptic cleft.
What are the other types of bursa?
adventitious or accidental bursa, which temporally arise in soft tissue in response to frictional forces, especially over bony prominences, and subcutaneous or superficial bursa below the skin between skin and bone
slow oxidative fibers obtain their energy from
aerobic metabolic reactions; thus, they have a relatively large number of mitochondria and a rich supply of capillaries. These relatively thin fibers are red because of their abundant content of myoglobin an oxygen-binding pigment in their sarcoplasm. There are many of these fibers in the postural muscles of the lower back, muscles that must contract continuously to keep the spine straight and maintain posture. Because they are thin, slow oxidative fibers do not generate much power.
Disorders of axial skeleton: scoliosis
an abnormal lateral curvature of more than 10 degrees that occurs most often in the thoracic region (Figure 7.27a). clinicians treat scoliosis with body braces or surgery before the child stops growing. Severe scoliosis can compress a lung, causing difficulty in breathing
In the limbs, dense fibrous connective tissue divides the extensor (dorsal) and flexor (ventral) muscle masses into
anatomical compartments.
The arrangement of its fascicles influences both the amount of movement produced when a muscle shortens
and the amount of force the muscle produces, its power. Skeletal muscle fibers can shorten by up to one-third of their resting length as they contract.
A bands are ... and I bands are ....
anisotropic, isotropic
Muscles that oppose or reverse a particular movement act as
antagonists. When a prime mover is active, it is possible for its antagonists to be stretched or remain relaxed. Usually, however, the antagonists contract slightly during the movement to keep the movement from overshooting its mark or to slow it near its completion.
Two compartments of the upper limb
anterior and posterior
The arcuate popliteal ligament
arcs superiorly from the head of the fibula over the popliteus muscle to the posterior aspect of the joint capsule
Although muscles with parallel fascicles can have a greater range of motion, they usually
are not powerful. The power of a muscle depends more on the total number of fibers it contains. The stocky bipennate and multipennate muscles contain the most fibers; thus, they shorten very little but tend to be very powerful.
Limb muscles
arise from the ventral region as limb buds, and limb muscles develop from the lateral parts of the nearby myotomes.
posterior cruciate ligament
arises from the posterior intercondylar area of the tibia and passes anteriorly to attach to the femur on the lateral side of the medial condyle. The posterior cruciate, which is even stronger than the anterior cruciate, prevents forward sliding of the femur or backward displacement of the tibia.
RA is an
autoimmune disease—a disorder in which the body's immune system attacks its own tissues. The cause of this reaction is unknown, but RA might follow infection by certain bacteria and viruses that bear surface molecules similar to molecules normally present in the joints. When the body is stimulated to attack the foreign molecules, it inappropriately destroys its own joint tissues as well.
Cartilage tear
avascular, it can not repair itself. Because cartilage fragments (also called loose bodies) can cause joints to lock or bind, the recommended treatment often is surgical removal of the damaged cartilage.
In most people, how many bones make up the axial skeleton and how many make up the appendicular?
axial: 80 bones Appendicular: 126 bones
There are two main types of synapses.
axodendritic synapses and axosomatic synapses.
Syndesmosis example
between tibia and fibula, radius and ulna
anterior compartment of arm
biceps brachii, brachialis, coracobrachialis flex arm at elbow and innervated by musculocutaneous nerve
In each myofibril, several proteins surround the Z discs. These proteins
bind adjacent sarcomeres together.
dislocation (luxation)
bones of a joint are forced out of alignment. The jaw, shoulder, finger, and thumb joints are most commonly dislocated.
The central nervous system (CNS) consists of the
brain and the spinal cord, - occupy the cranium and the vertebral canal, respectively it is the integrating and command center of the nervous system: It receives incoming sensory signals, interprets these signals, and dictates motor responses based on past experiences, reflexes, and current conditions.
The midbrain, pons, and medulla together constitute the Central cavity of neural tube forms
brain stem hollow ventricles of the brain
The fourth ventricle lies in the
brain stem, dorsal to the pons and the superior half of the medulla oblongata. connects caudally to the central canal of the inferior medulla and spinal cord.
The most caudal of the four major parts of the brain is the
brain stem. From caudal to rostral, the three regions of the brain stem are the medulla oblongata, pons, and midbrain Each region is roughly an inch long, and together they make up only 2.5% of total brain mass.
terminal arborization.
branches at axon's end
Neurofibrils
bundles of neurofilaments that run in a network between the chromatophilic substance.
Contraction in skeletal muscle is controlled by
by nerve-generated impulses that travel along the sarcolemma of the muscle fiber.
The release of calcium ions from the sarcoplasmic reticulum and the subsequent contraction of skeletal muscle is initiated
by nervous stimulation. The nerve cells that innervate muscle fibers are called motor neurons.
The sliding filament mechanism is initiated by the release of ______ from the ______. Those ions bind to _______ on the _______. This changes the shape of the _______ which moves the _______ and exposes _______ on the ______ for the _______.
calcium sarcoplasmic reticulum troponin thin filament. troponin, tropomyosin molecule binding sites actin filament myosin heads
The sarcoplasmic reticulum and the terminal cisterns store large quantities of
calcium ions . These ions are released when the muscle is stimulated to contract.
Impulses traveling down the T tubules stimulate the release of _____ from the _____. Calcium diffuses through the _____ to the ______ and triggers_______. After contraction, calcium is pumped back into the ______ for ______.
calcium, terminal cistern, cytosol, actin filaments, muscle contraction, sarcoplasmic reticulum, storage.
saddle joint biaxial movement
carpometacarpal joints of the thumbs
motor nuerons (efferent)
carry messages from CNS to muscles and glands
function of appendicular skeleton function of axial skeleton
carry out movements -supports head, neck, trunk -protects brain, spinal cord, thoracic organs
Articular capsule
cavity enclosed by a two-layered articular capsule, or joint capsule. The outer fibrous layer of dense irregular connective tissue is continuous with the periosteum layer of the joining bones. T he inner layer is a synovial membrane composed of loose connective tissue. In addition to lining the joint capsule, this membrane covers all the internal joint surfaces not covered by cartilage. Its function is to make synovial fluid.
The ______ is the focal point for the outgrowth of the neuron processes during embryonic development. In most neurons, the _______ of the cell body acts as a receptive surface that receives signals from other neurons.
cell body plasma membrane
Each secondary brain vesicle develops rapidly to produce the major structures of the adult brain's The telencephalon develops into the The diencephalon develops three main divisions: The mesencephalon forms the The myelencephalon forms the
cerebral hemispheres cerebrum the thalamus, the hypothalamus, and the epithalamus. midbrain ventral is pons and dorsal is cerebellum medulla oblongata
The ventricles are expansions of the brain's central cavity, filled with Figure 13.3 Ventricles of the brain. The regions of the lateral ventricles,
cerebrospinal fluid and lined by ependymal cells. They are continuous with one another and with the central canal of the spinal cord. the anterior horn, posterior horn, and inferior horn,
Openings in the 4th ventricle wall, lateral apertures and median aperture, connect the 4th ventricle with the subarachnoid space, which allows
cerebrospinal fluid to fill both the ventricles and the subarachnoid space.
3. Which bone is the most frequently broken bone in our body?
clavicle
pectoral girdle consists of
clavicle and scapula
How does the pectoral girdle articulate with the axial skeleton
clavicles articulate laterally with acomion and medially with manubrium.
epimysium is made of perimysium is made of endomysium is made of
collagen 1 collagen 1 and 3 collagen 3
The cervical and lumbar curves
compensatory or secondary curvatures developed after birth
epimysium
covers the muscle (exterior collagen layer) and separates it from other tissues
Acetabulum is on the lateral surface of the _____ bone and articulates with the head of the ______ on the______ surface
coxal bone femur lunate surface
synovial joints
created where two bones articulate to permit a variety of motions
oblique popliteal ligament
crosses the posterior aspect of the capsule. It is a part of the tendon of the semimembranosus muscle that fuses with the joint capsule and helps stabilize the posterior joint.
In addition, the knee joint is stabilized by two strong intracapsular ligaments called
cruciate ligaments ) because they cross each other like an X. Each runs from the tibia to the femur and is named for its site of attachment to the tibia.
A band
dark area; extends length of the thick filaments
When a muscle is stretched rather than contracted, the amount of overlap between the thin and thick filaments
decreases: The I bands and H zones lengthen as the Z discs move apart. Again, there is no change in the width of the A bands.
T tubules (transverse tubules) are
deep invaginations of the sarcolemma that run between each pair of terminal cisterns. The complex of the T tubule flanked by two terminal cisterns at the A-I junction is called a triad
Armlike processes extend from the cell bodies of all neurons. These processes are of two types,
dendrites and axons which differ from each other both in structure and in functional properties.
False pelvis extends from blades of the_______ inferiorly to the ______
iliac crest arcuate line 44
Space restrictions force the cerebral hemispheres to grow posteriorly like a horseshoe over the rest of the brain, and soon these hemispheres completely envelop the
diencephalon and midbrain.
The third ventricle lies in the
diencephalon, it connects to each lateral ventricle anteriorly through an interventricular foramen. In the midbrain, the thin tubelike central cavity is called the cerebral aqueduct, which connects the third and fourth ventricles.
Neurons do not
divide. As the fetal neurons assume their roles as communication links in the nervous system, they lose their ability to undergo mitosis.
It would be inaccurate to call skeletal muscle fibers the biggest cells in the body because
each one was formed by the fusion of hundreds of embryonic cells. Because the fibers develop this way, they contain many nuclei. These nuclei lie at the periphery of each fiber, just deep to the sarcolemma
Hinge joint; uniaxial movement
elbow joints, interphalangeal joints
What sheath is pulled when muscle fibers contract
endomysium. Then the pull is exerted upon the perimysium, epimysium, and tendon to create a cascade effect.
direct attachment
epimysium fused to periosteum of bone or perichondrium of cartilage
axon collateralsFor there to be ten thousand of these branches per neuron is not unusual.
extend from the axon at more or less right angles.
The muscle mass that lies dorsal to the limb bones becomes the _____ of that limb, whereas the ventral mass becomes the limb's_______.
extensor muscles flexor muscles
The first three somitomeres in the developing embryo become the _____ muscles that originate outside the eye and function to move the eyes, and the occipital myotomes become the muscles that move the_____.
extrinsic eye muscles tongue
intense resistance training can convert fast glycolytic fibers to
fast oxidative fibers. Any fibers converted in this way do revert to their original type when the training stops.
In week 5, the three primary vesicles give rise to During this period the brain also develops two major bends, or flexures—
five secondary brain vesicles a midbrain flexure and a cervical flexure
menisci
flattened, shock-absorbing pads of fibrocartilage between the articulating surfaces of some joints
anterior compartment of forearm
flexion of wrist and digits innervated by medial nerve and ulnar nerve
At birth, the skull bones remain incomplete and are separated by still unossified remnants of the membranes, called
fontanelles
After training ends, the percentage of fast glycolytic fibers increases significantly from the pretraining level. This phenomenon is the physiological basis
for tapering off training prior to a major competitive event, a common practice among athletes.
In the adult upper limbs the extensor muscles lie on the limb's posterior side and extend. The flexor muscles lie on the anterior side of the limb and flex these parts.
forearm, hand, and fingers forearm, hand, and fingers
ependymal cells (CNS)
form a simple epithelium that lines the central cavity of the CNS Ependymal cells bear cilia that help circulate the cerebrospinal fluid.
plane, hinge, pivot, condylar, saddle, ball and socket
freely movable (diarthrosis) movements depend on design of joint
Diarthrosis
freely movable joints; (in 2 parts) found in appendicular skeleton in every synovial joint
A nerve impulse is typically generated
from the axon hillock and is conducted along the axon to the terminal boutons, where it causes the release of chemicals called neurotransmitters into the extracellular space. The neurotransmitters excite or inhibit the neurons or target organ that are in close contact with the axon boutons.
Eccentric contraction occurs in many movements that resist gravity:
going down stairs, running downhill, landing from a jump. Whenever muscles are acting as a brake, they are contracting eccentrically.
Like the spinal cord, the brain has an inner region of ____ surrounded by ______ .
gray matter white matter
The optimal resting length for skeletal muscle fibers is the length that will generate the
greatest pulling force when the muscle is contracted. This optimal length occurs when a fiber is slightly stretched, so that its thin and thick filaments overlap to only a moderate extent. Under these conditions, the myosin heads can move and pull along the whole length of the thin filaments.
perimysium,
has associated blood vessels and nerves • bundles muscle fibers into groups called fascicles
Oligodendrocytes
have fewer branches than astrocytes - produce insulating coverings called myelin sheaths.
synergists
help prime movers by producing the same movement or by reducing undesirable movements For example, the muscles that flex the fingers cross both the wrist and finger joints, but you can make a fist without flexing your wrist because synergists stabilize the wrist.
The speed of contraction, depends on
how quickly a fiber breaks down ATP to gain the energy needed for contraction. Based on these characteristics, muscle fibers are divided into three general classes: slow oxidative fibers (SO), fast glycolytic fibers (FG), and fast oxidative fibers (FO) (Figure 10.10). Most of the muscles in the body contain all three fiber types, but the proportions differ from one muscle to another.
Disorders of Axial skeleton: Kyphosis
hunchback, is an exaggerated thoracic curvature that is most common in aged women because it often results from spinal fractures that follow osteoporosis. It may also result from either tuberculosis of the spine or osteomalacia.
What additional molecules does synovial fluid contain that help in lubricating the joint and from what cell type is it secreted?
hyaluronan secreted by type B synoviocytes in the synovial membrane and lubricin (a proteoglycan) secreted by both B synoviocytes and surface chondrocytes of the articular cartilage
The muscles of the anterior compartment of thigh
iliopsoas and the quadreceps femoris group flex the thigh at the hip and extend the leg at the knee and are innervated by the femoral nerve.
6. Which bones comprise the acetabulum "hip socket"?
ilium, ischium, and pubis
Gomphosis (peridontal ligament)
immobile
Synchondrosis (hyaline cartilage)
immobile
suture (short fibers)
immobile (synarthrosis)
Synarthoses (Synarthrotic)
immovable; common in axial skeleton
How does a synapse function?
impulse travels along the axon of the presynaptic neuron and stimulates the synaptic vesicles to fuse with the presynaptic membrane. The fused area ruptures, causing the vesicles to release neurotransmitter across the synaptic cleft and bind to the postsynaptic membrane. This binding changes the membrane charge on the postsynaptic neuron, influencing the membrane's ability to generate a nerve impulse.
The more nearly parallel the fibers are to the muscle's long axis, the more the muscle can shorten, resulting
in a larger distance of movement
The M line
in the center of the H zone. It contains tiny rods that hold the thick filaments together
Pharyngeal arch (branchiomeric) muscles
includes the skeletal muscles of the pharynx, head, and neck. They develop around the embryonic pharynx, from the fourth to seventh somitomeres. Function: squeeze things through the pharynx The major muscles in this group include the muscles of facial expression chewing muscles suprahyoid muscles and the pharyngeal constrictors (swallowing) sternocleidomastoid (myotome) trapezius (myotome)
the decrease in length of the I band and the loss of the H zone are due to the
increased amount of overlap of the thin and thick filaments. The length of the thin filament has not changed. The A bands stay the same length because the length of the thick filaments also does not change.
Perineum region are the ______ edges of the true pelvis. It forms the pelvic________
inferior outlet
The two regulatory proteins control the
interaction of actin with the thick filaments. In the center of the sarcomere and overlapping the inner ends of the thin filaments is a cylindrical bundle of thick (myosin) filaments.
Intracapsular ligaments
internal to the capsule, for example, the anterior and posterior cruciate ligaments in the knee. Intracapsular ligaments are covered with a synovial membrane that separates them from the joint cavity through which they run.
gray matter contains ________that ________. The white matter in the brain allows for _______ between areas of the CNS. These pathways are called ________
interneurons process info interconnection/communication fiber tracts/tracts
rheumatoid arthritis (RA)
is a chronic inflammatory disorder. Its onset usually occurs between the ages of 30 and 50, but it may arise at any age. The course of RA is variable: It may develop gradually or in spurts that are years apart. It is marked by flare-ups and remissions.
Sarcoplasmic reticulum (SR)
is an elaborate smooth endoplasmic reticulum whose interconnecting tubules surround each myofibril like the sleeve of a loosely crocheted sweater surrounds your arm. Most SR tubules run longitudinally along the myofibril.
Tendonitis and Tenosynovitis
is inflammation of a tendon and a tendon sheath. These two conditions commonly occur together. Causes (overuse injury or infection), symptoms (pain, swelling, tenderness) and treatments (rest, ice, anti-inflammatory drugs) mirror those of bursitis.
Knee injuries occur frequently in contact sports because ,
its articular surfaces offer no stability. The nearly flat tibial surface has no socket to secure the femoral condyles. Thus, the knee joint is especially vulnerable to horizontal blows.
cartilagenous joints
joints filled with cartilage, typically are immovable or slightly movable. Lack a cavity.
neurofilaments
keep the cell from being pulled apart when it is subjected to tensile forces.
Chromatophilic substance
large clusters of rough endoplasmic reticulum and free ribosomes that stain darkly with basic dyes. These cellular organelles continually renew the membranes of the cell and the protein components of the cytosol.
Other SR tubules, called terminal cisterns form
larger, perpendicular cross channels over the junction between each A-I junctions.
sprain
ligaments reinforcing a joint are stretched or torn. Common sites of sprains are the lumbar region of the spine, the ankle, and the knee. Partly torn ligaments eventually repair themselves, but they heal slowly because ligaments are poorly vascularized
fibrous joint: syndesmosis are connected by ____ of _____ tissue. Movement depends on ________. The short joints (________) are ______. Interossesous membrane of the ______ and _____ are _____. These are ______ and _____ respectively.
ligaments; connective tissue• fiber length • Tibiofibular joint; immovable synarthrosis joints • radiu; ulna; long Amphiarthrotic; diarthrotic
Extracapsular ligaments
located just outside the capsule, for instance, the fibular and tibial collateral ligaments of the knee
The extracapsular fibular and tibial collateral ligaments
located on the lateral and medial sides of the joint capsule. The FCL descends from the lateral epicondyle of the femur to the head of the fibula. The TCL runs from the medial epicondyle of the femur to the medial condyle of the tibia. Besides halting leg extension and preventing hyperextension, these collateral ligaments prevent the leg from moving laterally and medially at the knee.
Skeletal muscle fibers
long, cylindrical cells. They are huge cells, relatively speaking. Their diameter is (up to ten times that of an average body cell), and their length is phenomenal: from several centimeters in short muscles to dozens of centimeters in long muscles.
Neurons have extreme
longevity. They can live and function for a lifetime, over 100 years.
A multipennate arrangement
looks like many feathers situated side by side, with all their quills inserting into one large tendon. deltoid muscle
In addition to variation in the size of motor units in different muscles, each individual muscle contains
many motor units. The addition of motor units to accomplish a movement is called recruitment. If a small force is required, a small number of motor units are stimulated. As more force is needed, additional motor units are recruited.
two menisci
medial and lateral menisci
Gout is far more common in men than in women because
men naturally have higher levels of uric acid in their blood (perhaps because estrogens increase the rate of its excretion).
Neurons have an exceptionally high
metabolic rate, requiring continuous and abundant supplies of oxygen and glucose. Neurons cannot survive for more than a few minutes without oxygen
By week 26, the continued growth of the cerebral hemispheres causes their surfaces to crease and fold. This infolding allows
more neurons to fit in the limited space.
The conical medulla oblongata, or simply medulla is the
most caudal part of the brain stem continuous with the spinal cord at the level of the foramen magnum of the skull
osteoarthritis (OA),
most common arthritis. a chronic (long-term) degenerative condition that is often called "wear-and-tear arthritis." It is most common in the aged and is probably related to the normal aging process. OA affects women more often than men, but most of us will develop this condition by the age of 80.
A motor neuron and all the muscle fibers it innervates are called a
motor unit. When a motor neuron fires, all the skeletal muscle fibers in the motor unit contract together.
Myelin sheaths are produced by oligodendrocytes in the CNS and Schwann cells in the PNS. These sheaths are segmented structures that are composed of
myelin and surround the thicker axons of the body. Myelin sheaths form an insulating layer that prevents the leakage of electrical current from the axon, increases the speed of impulse conduction along the axon, and makes impulse propagation more energy-efficient.
The white matter is composed of
myelinated and nonmyelinated axons
Under the light microscope, the light and dark striations in skeletal muscle fibers are clearly visible. These striations result from the internal structure of long, rod-shaped organelles called myofibrils.
myofibrils
Fast glycolytic fibers are pale because they contain little
myoglobin. They are about twice the diameter of slow oxidative fibers, contain more myofilaments, and thus generate much more power. Because these fibers depend on anaerobic pathways to make ATP, they contain few mitochondria or capillaries but have many glycosomes containing glycogen as a fuel source. Fast glycolytic fibers contract rapidly and tire quickly. They are common in the muscles of the upper limbs, which often lift heavy objects for brief periods.
thick filaments
myosin filaments overlapping the inner ends of the thin filaments. They also contain ATPase enzymes that split ATP (energy-storing molecules) to release the energy required for muscle contraction.
Both ends of a thick filament are studded with knobs called
myosin heads
Parts of the mesoderm that are present during the second month of development include the
myotomes and splanchnic mesoderm. The first seven myotome-like structures in the head collectively are called somitomeres
The three sheaths produce
natural elasticity, carry nerves and blood vessels, and produce force
The peripheral nervous system (PNS), the part of the nervous system outside the CNS, consists mainly of the
nerves that extend from the brain and spinal cord. Cranial nerves carry signals to and from the brain, whereas spinal nerves carry signals to and from the spinal cord. These peripheral nerves serve as communication lines that link all regions of the body to the central nervous system. Also included in the PNS are ganglia, areas where the cell bodies of neurons are clustered.
The nervous system consists mostly of
nervous tissue, whose cells are densely packed and tightly intertwined.
All neurons associate closely with non-nervous supporting cells called
neuroglia ( glial cells) - Provide a supportive scaffolding for neurons. - Cover all nonsynaptic parts of the neurons, thereby insulating the neurons and keeping the electrical activities of adjacent neurons from interfering with each other.
Each muscle fiber in a skeletal muscle is served by a nerve ending, which signals the fiber to contract. The point at which the nerve ending and fiber meet is called a
neuromuscular junction or a motor end plate
weeping lubrication
nourishes the cells in the articular cartilages (cartilage is avascular) and lubricates the free surfaces of these cartilages, allowing the adjoining bones to move across each other with a minimum of friction.
myelin sheath gaps (nodes of Ranvier)
occur at regular intervals about 1 mm apart. In myelinated axons, nerve impulses do not travel along the myelin-covered regions of the axonal membrane but instead jump from the membrane of one myelin sheath gap to the next in a way that greatly speeds impulse conduction.
axosomatic synapses
occur between axons and neuron cell bodies
axodendritic synapses
occur between the terminal boutons of one neuron and the dendrites of another neuron; (most common)
2. The connective tissue sheaths that include the epimysium, perimysium and endomysium help to
organize skeletal muscles
perineal muscles support
organs of pelvic cavity
The membranous bones of the skull begin to ossify late in the second month of development. In these flat bones, bone tissue grows outward from
ossification centers within the mesenchyme membranes.
cortex
outermost covering of the brain consisting of densely packed neurons, responsible for higher thought processes and interpretation of sensory input
Some muscle fibers predominantly produce ATP aerobically (using oxygen) and are thus called Others make ATP anaerobically (without oxygen) via glycolysis and are referred to as
oxidative fibers. glycolytic fibers.
Subluxation
partial or incomplete dislocation of a joint. The bone ends return to their proper position on their own.
appendicular skeleton components
pectoral girdle, upper limbs, pelvic girdle, lower limbs
True pelvis encloses the
pelvic cavity
FO are abundant in the muscles of the lower limbs, which must move the body for long periods during locomotion. Because individual muscles contain a mixture of the three fiber types, each muscle can
perform different tasks at different times. A muscle in the calf of the leg, for example, uses its glycolytic fibers to propel the body in a short sprint, its fast oxidative fibers in long-distance running, and its slow oxidative fibers in maintaining a standing posture.
The leg also has three compartments:
posterior, anterior, and lateral
The thigh portion of the lower limb has three compartments:
posterior, anterior, and medial
When an electrical impulse in the _______ reaches the________, it stimulates the release of _______ from this neuron. These ________ diffuse across the _________, bind to receptor sites on the__________, and stimulate an electrical response in the ____________. In this way, the electrical signal is passed, via a chemical messenger, from one neuron to another.
presynaptic neuron terminal bouton chemical neurotransmitters synaptic cleft postsynaptic neuron (usually on the dendrite or cell body) postsynaptic neuron
The neuron that conducts signals toward a synapse is called the ______ the neuron that transmits signals away from the synapse is called the______ Most neurons in the CNS function as both.
presynaptic neuron; postsynaptic neuron
Synovial fluid
primarily a filtrate of blood, arising from capillaries in the synovial membrane. It also contains special glycoprotein molecules, secreted by the fibroblasts in the synovial membrane, that make synovial fluid a slippery lubricant that eases the movement at the joint. Synovial fluid not only occupies the joint cavity but also occurs within the articular cartilages. The pressure placed on joints during normal movement squeezes synovial fluid into and out of the articular cartilages.
The thoracic & sacrococcygeal curves
primary curves retained from the original fetal curvature.
A muscle that has the major responsibility for producing a specific movement is the
prime mover, or agonist of that motion. For example, the pectoralis major is a prime mover for flexing the arm at the shoulder. Sometimes, two muscles contribute so heavily to the same movement that both are called agonists.
Antagonists can also be
prime movers; that is, an antagonist for one movement can serve as an agonist for the opposite movement. For example, flexion of the arm by the pectoralis major is antagonized by the latissimus dorsi, which is a prime mover for extension of the arm
It immediately starts to expand three primary brain vesicles appear
prosencephalon or forebrain; the mesencephalon or midbrain rhombencephalon or hindbrain.
The mechanism for eccentric contraction is less well understood than the mechanism for concentric contraction. Both types of contraction occur during
push-ups. During the up portion of the exercise, concentric contractions in the pectoralis muscles of the chest raise the torso off the floor. During the down portion of the movement, these same muscles contract eccentrically and by doing so resist gravity and control the downward motion of the torso.
Completely ruptured ligaments
require prompt surgical repair because inflammation in the joint breaks down the neighboring tissues and turns the injured ligament to "mush."
Functionally, the cruciate ligaments act as
restraining straps to prevent undesirable movements at the knee joint. The two cruciates also function together to lock the knee when one stands
collagen 3
reticular fibers
A myofibril is composed of repeating segments called
sarcomeres
Each skeletal muscle fiber contains two sets of tubules that participate in the regulation of muscle contraction:
sarcoplasmic reticulum and T tubules (Figure 10.5).
The two kinds of neuroglia in the PNS are
satellite cells and Schwann cells
Neurons are grouped functionally according to the direction the nerve impulse travels relative to the CNS. Based on this criterion, there are
sensory neurons, motor neurons, and interneurons
In the sensory (afferent division) signals are picked up by ______ of the _____ into the ______
sensory receptors nerve fibers of the PNS CNS
The axon of some neurons is , and others is any long axon is a
short, but in others it can be extremely long. the axons of the motor neurons that control muscles in the foot extend from the sacral region of the spinal cord to the sole of the foot, a distance of a meter or more (3-4 feet). Any long axon is called a nerve fiber.
The gray matter of the CNS contains
short, nonmyelinated neurons and neuron cell bodies.
ball and socket joint multiaxial movement
shoulder joints and hip joints
epimysium composes perimysium composes endomysium composes
skeletal muscle muscle fascicle, muscle fiber
Axial muscles
skeletal muscles of the thorax, abdomen, and pelvis, neck and a few in the head. They lie anterior and posterior to the body axis (vertebral column). Functions: move the trunk and maintain posture. They develop from the myotomes and some somitomeres. The dorsal regions of the myotomes become the deep muscles of the back The ventral regions of the myotomes become the muscles of the anterior and lateral parts of the trunk and neck, which flex the spine These muscles include those of the anterior neck infrahyoid muscles respiratory muscles of the thorax muscles of the anterior abdominal wall muscles of the pelvic floor
When contracting concentrically, a muscle generates force while shortening. Concentric contraction of skeletal muscle is explained by the
sliding filament mechanism
Syndesmosis (longer fibers)
slightly mobile (amphiarthrosis) and immobile
Amphiarthrosis
slightly movable joint common in axial skeleton ex. pubic symphysis
Symphysis (fibrocartilage)
slightly movalble)
sensory and motor signals are divided by body regions they serve
somatic and visceral each has a sensory and motor subdivision
Myofibrils are
specialized contractile organelles. They contain myofilaments. The myofibrils in a fiber are separated from one another by mitochondria and glycosomes, both of which supply energy for muscle contraction.
Satellite cells Schwann cells
surround neuron cell bodies within ganglia surround all axons in the PNS and form myelin sheaths around many of these axons.
Disorders of Axial skeleton: lordosis
swayback, is an accentuated lumbar curvature. common in people carrying a "large load in front," such as obese men and pregnant women. it can result from spinal tuberculosis or osteomalacia.
The epiphyseal plates and first rib's costal cartilage and the manubrium of the sternum are
synchondroses
Muscles in the same compartment have similar actions and often function _____ to produce a particular movement. Muscles in opposite compartments function _______. In most cases, each compartment is innervated ________
synergistically antagonistically by a single named nerve
Muscles that cross the same joint and have similar actions act as _______ muscles that have opposite actions are ________ pairs.
synergists agonist/antagonist
fixators.
synergists hold a bone firmly in place so that a prime mover has a stable base on which to move a body part. An example is the muscles that fix the scapula when the arm moves.
Adjoining bones spearated by a joint cabvity, covered with articular cartilage, and enclosed within an articular capsule lined with synovial membrane
synovial
The prosencephalon divides into the The mesencephalon remains undivided, The rhombencephalon divides into the
telencephalon and the diencephalon . metencephalon and the myelencephalon.
axons end in knobs called
terminal boutons (axon terminals)
The nerve part of the neuromuscularjunction is a cluster of
terminal boutons (chenmical messenger molecules) or axon terminals. The terminal boutons are separated from the sarcolemma of the muscle fiber by the synaptic cleft
Because the T tubules are continuations of the sarcolemma, they conduct each impulse to the deepest regions of the muscle fiber, thus ensuring
that the deep-lying myofibrils contract at the same time as the superficial ones.
Most dangerous are lateral blows which tear
the TCL and the medial meniscus attached to it, as well as the anterior cruciate ligament (ACL), an injury coined the "unhappy triad."
Microglial cells (CNS)
the smallest and least abundant neuroglia of the CNS - phagocytes/ macrophages of the CNS. - do not originate in nervous tissue; they are derived from blood cells called monocytes.
When the muscle is stimulated to contract
the action of the thick filaments forcefully pulls the two Z discs closer together, causing each sarcomere to shorten. As the Z discs move closer together, the I bands shorten, and the H zones disappear completely.
The major fontanelles—allow the skull to be compressed slightly as the infant passes through the narrow birth canal, and they accommodate brain growth in the baby
the anterior, posterior, mastoid, and sphenoidal
Humans have only one, highly integrated nervous system. However, for the sake of convenience you can think of it as having two anatomical parts:
the central nervous system and the peripheral nervous system
The paired lateral ventricles, once called the first and second ventricles, lie in
the cerebral hemispheres, separated by the septum pellucidum
posterior compartment of the forearm
the digital and carpal extensors, the supinator and brachioradialis extend the wrist innervated by branches off the radial nerve
The anterior compartment of the leg contains
the digital extensor muscles and dorsiflexors, all innervated by the deep fibular nerve.
The posterior compartment of the leg contains
the digital flexor muscles and plantar flexors innervated by the tibial nerve.
synapses determine
the direction of information flow through the nervous system.
third class lever
the effort is applied closer to the fulcrum than the load, as with forceps (Figure 11.3c). The load arm is longer than the effort arm; thus, third-class levers work at a mechanical disadvantage. Most skeletal muscles function as third-class lever systems for speed. This positioning places muscle insertions close to the joint, providing stability to the joint and producing fast, extensive movements, as in running or throwing, with relatively little shortening of the muscle. flexion of the forearm (load) by the biceps brachii muscle (effort). In this lever system, the elbow is the fulcrum.
Untreated gout can cause
the ends of articulating bones to fuse, immobilizing the joint. Fortunately, effective treatment is available. For acute attacks, nonsteroidal anti-inflammatory drugs such as ibuprofen are used. For the long term, urate-lowering drugs and dietary measures (avoidance of alcohol and red meat) are effective.
In a pennate (penrāt) pattern, The arrangement of its fascicles influences both the amount of movement produced when a muscle shortens, referred to as the muscle's range of motion, and the amount of force the muscle produces, its power. Skeletal muscle fibers can shorten by up to one-third of their resting length as they contract. The more nearly parallel the fibers are to
the fascicles (and thus the muscle fibers) are short and attach obliquely to a tendon that runs the whole length of the muscle . This pattern makes the muscle look like a feather
bipennate/unipennate muscle fibers
the fascicles insert into the tendon from both/one side(s). The rectus femoris muscle of the thigh is bipennate The extensor digitorum longus muscle on the anterior leg is unipennate.
first class lever
the fulcrum is located between the load and the point at which the effort is applied. First-class levers can operate either at a mechanical advantage, for power, or at a mechanical disadvantage, for speed and distance, depending on the lengths of the load arm and effort arm. The posterior neck muscles function in a first-class lever system around the atlanto-occipital joint to support the head
16-18, 30 years old
the fusion ages of the sacrum and coccyx
When first identified, titin generated much excitement because it is
the largest protein ever discovered.
The lower limb rotates during embryonic development; thus in the adult lower limbs the extensor muscles occupy the anterior side of the limb and extend The flexor muscles occupy the posterior side of the lower limb and
the leg at the knee, dorsiflex the foot at the ankle, and extend the toes. flex the leg at the knee, plantar flex the foot at the ankle, and flex the toes.
It is the I bands of the sarcomeres that create
the light portions of the light-dark pattern of striations seen along the length of any skeletal muscle fiber.
second class lever
the load and the effort are on the same side of the fulcrum. In a second-class lever, the effort is applied farther away from the fulcrum than the load, as in a wheelbarrow (Figure 11.3b). The effort arm is longer than the load arm, and the lever operates at a mechanical advantage. Standing on your toes is an example of a second-class lever; the metatarsophalangeal joint is the fulcrum, and the calf muscles (effort) plantar flex the foot, elevating the body (load). In this power lever, the relatively small muscular effort moves a much larger load.
Parallel arrangement of fascicles
the long axes of the fascicles run parallel to the long axis of the muscle, and the muscle fibers extend from origin to insertion. Muscles with this arrangement are either fusiform, with an expanded central belly or straplike biceps brachii sartorius muscle
White matter fiber tracts connecting the more rostral regions of the brain with the spinal cord must pass through
the medulla oblongata. Externally, two longitudinal ridges called pyramids (Figure 13.6a) flank the ventral midline of the medulla. These ridges are formed by the pyramidal tracts, large fiber tracts that originate from pyramid-shaped neurons in the cerebrum and descend through the brain stem and spinal cord carrying voluntary motor output to the spinal cord. In the caudal part of the medulla, 70-90% of these pyramidal fibers cross over to the opposite side of the brain at a point called the decussation of the pyramids (de″kus-sa′shun; "a crossing"). The result of this crossover is that each cerebral hemisphere controls the voluntary movements of the opposite side of the body (Figure 13.17).
Why is it is important that the two members of any agonist/antagonist pair be challenged and developed evenly (it creates muscle boundness)
the more developed muscle will put constant tension on the joint, reducing its flexibility and causing awkward movements
Astrocytes (CNS)
the most abundant glial cells of the CNS (1) regulating neurotransmitter levels by increasing the rate of neurotransmitter uptake in regions of high neuronal activity; (2) signaling increased blood flow through capillaries in active regions of the brain; and (3) controlling the ionic environment around neurons. Astrocytes also help synapses form in developing neural tissue, produce molecules necessary for neural growth (brain-derived trophic factor, BDTF), propagate calcium signals that may be involved with memory.
convergent pattern of fascicle arrangement
the origin of the muscle is broad, and the fascicles converge toward the tendon of insertion. Such a muscle can be either triangular or fan-shaped. pectoralis major
The brain arises as
the rostral part of the neural tube in the fourth week of development. The caudal portion of the neural tube becomes the spinal cord.
The fifth lumbar articulates to
the sacrum and coccyx
posterior compartments of the arm are all Functionally, the supinator supinates the forearm, and the brachioradialis, which crosses the anterior side of the elbow, acts as a forearm flexor.
the triceps brachii innervated by branches off the radial nerve. extend the elbow
Skeletal muscles consist of fascicles (bundles of fibers), which are large enough to be seen with
the unaided eye
The dark bands in a sarcomere are created by the full length of the
thick filaments in the sarcomeres, along with the inner ends of the thin filaments, which overlap the thick filaments.
5. What are reinforcing ligaments?
thickened parts of the fibrous layer such as extracapsular ligaments or intrascapular ligaments • In addition to synovial bursa, there are
Contraction results as the myosin heads of the thick filaments attach to the
thin filaments at both ends of the sarcomere and pull the thin filaments toward the center of the sarcomere by pivoting inward.
Fibrous joint: Sutures ("seams") are _____ bound by a ____ amount of fibrous tissue. The occur only in the _____. They are absent from the facial bones by _____ years old. They allow for _______ during childhood, and it _______ during the middle age.
tightly minimal skull 2 years old bone growth so the skull can expand with brain during childhood ossifies in middle ages
female pelvic girdle
tilted forward adapted for childbearing. True pelvis defines birth canal cavity of true pelvis is broader, larger, shallow lighter, thinner, smoother Broader 80, 90 degrees
male pelvic girdle
tilted less forward adapted for weight bearing, cavity of true pelvis is narrow and deep. acute 50 60 degrees heavier thicker, more prominent markings,
Two regulatory proteins also found on the thin filament with actin
tropomyosin and troponin
The cause of OA
unknown, but According to current theory, normal use causes joints to release metalloproteinase enzymes that break down the cartilage matrix. Whenever the strain on a joint is repeated or excessive, too much of the cartilage-destroying enzyme is thought to be released, causing OA. Because this process occurs most where an uneven orientation of forces causes extensive microdamage, badly aligned or overworked joints are likely to develop OA.
pelvic brim (inlet)
upper edge of true pelvis that encloses the pelvic inlet
The cytoplasm of a neuron contains
usual cellular organelles and chromatophilic substance
The muscle fibers of a single motor unit are not clustered together but rather are spread throughout the muscle. As a result, stimulation of a single motor unit causes a .
weak contraction of the entire muscle
Reasons for higher incidence of ACL injuries in women
wider pelvis, narrower intercondylar fossa, effects of female hormones on joint laxity, and slower muscle reaction times.
RA begins
with an inflammation of the synovial membrane. The end condition, called ankylosis often produces bent, deformed fingers. There is no cure for RA
Myofascial pain syndrome
• Pain is caused by tightened bands of muscle fibers, but pain arises from connective tissue • Very common (up to 50% of people); treated with NSAIDs •
• Toxic myopathies
• Statin-induced necrotizing myopathy develops in 1 - 1.5% of patients on statins due to their deleterious effects on mitochondria - weakness and can lead to death • Steroid myopathy in which corticosteroids lead to destruction specifically of type 2 fibers •