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Chapter 7Muscular system
VTHT 1205
ROOTS
• ARTHR/O- JOINT (arthroscopy)
• CERVIC/O- NECK (cervicoplasty)
• CHONDR/I, CHONDR/O, CHONDR/IO- CARTILAGE (chondromalacia)
• COST/O- RIB (intercostals muscles)
• GNATH/O- JAW (brachygnathous)
• MYEL/O- BONE MARROW OR SPINAL CORD (myelocyte, myelogram)
• THORAC/O- CHEST(thoracocentesis)
ROOTS
• MY/O- MUSCLE (myositis)
• OCCIPIT/O- BACK OF HEAD (occipitoatlanto)
• OSS/EO, OSS/I, OST/E, OST/EO- BONE (osteotome)
• SACR/O- SACRUM (sacroiliac joint)
• SPONDYL/O- VERTEBRA (spondylosis)
• STERN/O- STERUM (sternotomy)
• STETH/O- CHEST (stethoscope)
• TEND/O, TEN/O- TENDON (tendonectomy)
Introduction
• My/o/logy: Study of muscles
• Functions– Movement: contract and extend muscles– Posture: Support and maintenance– Producing body heat– Form: heart, uterus, lungs and intestines
• Always working
Tendon : attaches muscle to bone
• Tendons– Strong FIBROUS white
bands
– Attaches muscle to bone
• Ligaments– Bone to bone
Tendon
• Aponeurosis– Broad flat connective
tissue
– Attaches muscle > bone OR muscle > muscle
– “Flat and ribbon like”
Tendon Sheath
• CT around tendon when there is a long distance to attachment or when tendon pulls over a joint
Fascia : Sheet of fibrous tissue that encloses muscles and separates them into groups
Ligament : attaches bone to bone or bone to cartilage
• Strong bands of fibrous tissue
• Help/hinder movement and support organs
Origin - Insertion
• Origin : the less movable of the two points of attachment
• Insertion : the point of attachment by a musclePortion that moves during contraction
Muscles
• Muscles may attach directly to cartilage, joints, skin, mucous membrane, or fascia of other muscles
Muscle cells
• Motor or neuromotor unit: nerve cell + group of muscle cells
• Causes muscle to move by stimulating a group of muscle fibers
circumduction
• FLEXION – bending at a joint• EXTENSION – straightening at a
joint• ABDUCTION – moving a body
part away from the body• ADDUCTION – moving a body
part toward the body• ROTATION – turning a body part
on its axis• CIRCUMDUCTION – circular
movement
Composition of muscle
• Long slender cells called MYOFIBERS– Larger than other body cells
• Plasma membrane: sarcolemma
• Cytoplasma: sacroplasma
• Fascia: Encloses fibers which are held together by CT
• Within myofibers there are multiple myofibrils
Composition of muscle
• Very vascular
• Move when fibers contract
• Speed: varies with type muscle and size of body part to be moved– Smaller structures move faster e.g. eye
• Movement carried out by group of muscles
• Exercise increase fiber thickness, does not produce NEW fibers
Muscle Classification
SKELETAL
• Voluntary
• Striated
• Usually attached to skeleton
– Striated muscle not attached to skeleton: eyes, tongue, pharynx, skin muscles, heart
• Contract: muscle becomes short and thick
• CNS and PNS
SMOOTH• Visceral• Not striated
– Spindle shaped fibers
• Involuntary– Not controllable at will
• Stomach, intestine, uterus, blood vessel, eye-iris– Some influenced by
hormones
Some organs = skeletal + smoothe.g. esophagus ruminants: regurgitate and chew cud
bladder
uterus
Smooth muscle vs skeletal muscle
CARDIAC
• Striated• Involuntary
– Unlike other involuntary muscle
– Fine transverse striations
• ANS
cardiac
striated
smooth
Muscle attachments
• Muscle > tendon > phalanges: movement and reduction of bulk
• Voluntary m. – bone – Except larynx and thorax: muscle is attached to
thorax
• Attached to skin (cheek), mucous membrane (tongue)
• Attached to fascia of other muscles
A muscle must depend on other muscles to assist in a desired movement. For this reason
muscles are called prime movers, antagonists and synergysts.
Primer Movers
Muscles that actively produce a movement
Antagonist
Muscles that are in opposition to the prime movers
Synergist
Muscles that contract simultaneously with the prime
mover to help execute a movement or steady a part
The names of muscles are based on six points of identification* named for their action* named for their origin and insertion* named for their location* named for their shape or use* named for the direction of their fibers* named according to the number of their sections
• ORBICULARIS OCULI (C)– moves the eyelids
• MASSETERS (M) – muscles of mastication that raise the mandible to close the jaw
FACIAL MUSCLES
Serratus muscle group
Assist in respirationSupport trunk of the body
MUSCLES OF NECK, BACK, AND THORAX
• PECTORALS (7) – forms chest, adducts forelimb
• LATISSIMUS DORSI (2) – broadest muscle in the back. Provides support for the forelimb and aids in flexion of the shoulder
EPAXIAL MUSCLES IN BACK
EXTEND THE THORAX AND PRODUCE LATERAL MOVEMENT OF THE TRUNK
-ILIOCOSTALIS
-LONGISSIMUS
-TRANSVERSOSPINALIS
MUSCLES OF THORAXAID IN RESPIRATION, ALLOW THE THORAX TO
ENLARGE AND THE LUNGS TO EXPAND
- INTERCOSTALS (external
and internal):respiratory
muscles that are located
between the ribs
– DIAPHRAGM – wall that
separates the abdominal
and thoracic cavities
During respiration: the external intercostals lift the
ribsthe internal intercostals lower the
ribsthe diaphragm contracts and
flattens out causing the thorax to enlarge and the lungs to expand
MUSCLES OF FORELIMBS
• BICEPS BRACHII – flex the distal forelimb
• TRICEPS BRACHII – extend the distal forelimb
ABDOMINAL MUSCLES
KEEP VISCERA IN PLACE, SUPPORT AND COMPRESS THE ABDOMEN,
CONTRACT (DURING PARTURITION, DEFECATION, URINATION, COUGHING), ROTATE THE
VERTEBRAL COLUMN
tricep
bicep
ABDOMINAL MUSCLES• EXTERNAL OBLIQUE • INTERNAL OBLIQUE• RECTUS ABDOMINUS• TRANSVERSUS ABDOMINUS
• LINEA ALBA – fibrous band of connective tissue that is the center of attachment of the abdominal muscles on the ventral abdominal wall. Landmark for Sx.
Rectus abdominis
External oblique
Internal obliqueTransversus abdominis
Linea alba
Muscles of the hindlimbThese muscles have several
functions in movement. The most important muscle groups include
*gluteal group*quadricep group
*semi group
MUSCLES OF THE HINDLIMB• GLUTEALS – located over the pelvis, extend and abduct
the limb
• QUADRICEPS FEMORIS – extend the hind leg
– Rectus femoris, vastus lateralis, vastus medialis, vastus intermedius
MUSCLES OF THE HINDLIMB
• GROUP THAT IS LOCATED ON THE POSTERIOR ASPECT OF THE LIMB. FORMS THE HAMSTRINGS AND FLEXES THE HIND LEG
- SEMIMEMBRANOSUS– SEMITENDINOSUS– BICEPS FEMORIS
MUSCLES OF THE HINDLIMB
• GASTROCNEMIUS– Flexes the leg and foot
- Forms the Achilles Tendon
Miscellaneous muscles:arrector pili
These are smooth muscles attached to hair on the dorsum. When stimulated these muscles
raise the hair on the back.
Cutaneous trunci: a muscle that attaches to the dermis and controls the insect twich in large animals
Another large animal muscle is the cremaster, this muscle is part of the spermatic cord and attaches to the
scrotum. This muscle contracts and relaxes, raising and lowering the testicles. This movement helps to regulate testicular
temperature