Anatomy Quiz 2 myology and locomotion Flashcards
What are the three types of muscles
Smooth muscle, Cardiac muscle, skeletal muscle
Smooth Muscle
Not striated; associated with viscera (gut, vessels, glands, etc.)
Example:: arrector pili muscles , the detrusor muscle
Cardiac Muscle
Striated; musculature of the heart
The heart (myocardium) & the bases of the major blood vessels.
Skeletal Muscle
Striated; generally attached to bone; usually under voluntary control
- Voluntary
- Striated
Skeletal muscle will not contract in the absence of a functional nerve supply (denervation atrophy occurs).
One neuron innervates a variable number of muscle fibers.
The neuron plus the muscle fibers it innervates constitute a motor unit. To produce a stronger contraction, the nervous system activates more motor units.
~ 50% of the body “the carcass”
Most attached to bone
Not limited to the skeleton.
Found in the pharynx, esophagus, & skin (i.e.. cutaneous trunci).
Muscle Fiber
- Bound to the adjacent fibers to form bundles called fascicle.
- Multiple fascicle bound to other fascicles to form a muscle
- With this arrangement, the contraction in one area of a muscle works in conjunction with contracting fibers elsewhere in the muscle.
The binding substance within muscles is the associated loose C.T.
Muscle fibers are within a connective tissue framework that is continuous with tendons
Connective tissue components of skeletal muscle
Myofiber( muscle cell)
Endomysium: small amounts of loose c.t. surrounding individual muscle fiber
Fascicle‘bundle’ = groups of M. fibers
Perimysium loose connective tissue defining muscle fascicles .
Muscle is invested by a c.t. sheet
Epimysium= loose or dense connective tissue surrounding an entire muscle
Structure of the Skeletal Muscle
These C.Ts merge at the end of the muscle “belly” to form the tendon (dense regular connective tissue – attach to bone.)
What is the importance of these c.t. arrangements?
To make sure they all contract simultaneously
Joints of the Forelimb
Synsarcosis
Shoulder
Elbow
Carpus
(fetlock)
Digital
Muscle Actions
Agonist
Antagonist
Synergist
Fixator
Agonist
Prime Movers
Principal muscle(s) executing the particular joint movement
- Produces most of the force during a joint action when activated.
- Muscle activity involve change in the angle they bridge.
Exert action on distal joint
- Produces certain effect a (movement),
- Flexing the elbow -biceps brachii or brachialis!!
- (Origin: distal end of scapula; insert: end in radius and ulna)
Antagonist
Actively opposing the prime mover
Maintains some tension on a joint; thus limits the range of the agonist (preventing excessive movement & joint injury)
Checks the action of the agonist
- Triceps vs biceps brachii
Synergist
It assist the prime mover
Neither facilitate nor directly oppose a movement (may modify the action of agonist by eliminating unwanted side effect)
Assistant to agonist
Brachialis and Biceps brachii
Brachialis(synergist) is also a flexor, it helps the biceps brachii which is an agonist (flexor)
- Helps the biceps brachii by stabilizing the flextion
Fixators
It prevents a bone from moving
Stabilize joints rather than to promote movement
-Biceps brachii and the extrinsic muscles
-(all synsarcosis muscles – attach the limb to the axial skeleton (sling) whole weight is suspended through those muscles )
Naming Muscles
Attachments
- cleidobrachialis.
Cleido 🡪 Clavicle
Shape
- Teres minor
Rounded muscle (non-functional)
Size
- Teres major
Large. Along with latissimus dorsi
Function
- Supinator
Small in dogs, not used. Large in cats
Location/position
- Deep digital flexor (DDF) (SDF – Superficial digital flexor)
Number of heads
- Biceps brachii
Number of bellies
- Digastricus (open jaw of dog)
Muscle Attachments
Accessory structures [necessary for muscle function]:
- tendons
- aponeurosis
Tendons
Low metabolic activity (poorly vascularized)
Tough, but can be damaged by excessive pressure or friction, when change direction over bony prominences
D.R.C.T. in compact cylinder (tensile strength) attaching muscle to periosteum of bone
Aponeurosis
Broad, flat tendon sheet-like union
Forms of Protection for Tendons
Bursa
Tendon sheath
Inflammation of synovial bursae and sheath is common, and it is necessary to know their position and extends.
They occur precisely where they are required.
Accessory Structures of Muscles
Retinaculum
Annular Ligaments
Sesamoid Bones
Ligaments
NOT a structure of muscles:
It joins bone to bone
Clinical Significance of Lipomas ( Mammary)
Tissue masses palpable from the skin surface
abnormal aggregates of normal fat (lipid cells) – with capsule around - “S/C, dogs,& cats”)
Spayed females
Well circumscribed – (contained within capsule)
Not life threatening – only cosmetic
Palpable Features
) Acromion; “hammate & suprahammate in cat”;
b) greater tubercle;
Deeper palpation:
a) Spine of scapula;
b) tendon of origin of biceps;
c) deltoid tuberosity
a) Superficial cervical L. node (limb retracted)
b) Axillary L. node (enlarged), (limb protracted)
a) Olecranon “5th rib or 5th intercostal space)
Point of the elbow.
Mammae
Vary from 8 - 12
Thoracic (2 pairs)
Abdominal (2 pairs)
Inguinal (one pair)
Pups nurse the caudal six mammae (best secretion)
Caudal 3 pairs, frequently involved in tumors, and mastitis.
Mammary Neoplasia
Lumpectomy:
Removal of a mass or part of a mamma
Simple mastectomy:
Is excision of an entire gland
Regional mastectomy:
Is excision of the involved an adjacent glands
Venipuncture
For purpose of withdrawing blood or injection
Cephalic vein and
External Jugular veins
Are important sites for Venipuncture.
Extrinsic
(Pectoral Girdle)
At least one attachment (~origin) is external, i.e., to axial skeleton
Functions:
Sling the body between the forelimbs (serratus ventralis & deep pectoral)
Weight bearing (thoracic limb carries more weight about 60-70%, carry head, neck, thorax)
Stabilize the scapula
Deep pectoral: Sternum to humerus (weight)
Serratus ventalis: sternum to scapula (weight)
DORSAK Median raphe: supraspinus ligaments
Rhomboids: Medial raphe to scapula
Trapezius thoracis:
Intrinsic Muscles
Both attachments are internal to limb bones
Functions of Skeletal Muscle
Muscles provide motive power for:
Locomotion [movement]
Movements of Animal body
Movement: most obvious function is to move the body, as in walking, running, writing, chewing, and swallowing.
Stimulation maintains a state of muscle contraction “tonus” for movement of blood & lymph.
Prevent unwanted movements (stabilizing joints)
Posture
Skeletal muscles maintain posture by stabilizing the flexible muscles.
Certain muscles work in opposition to gravity.
The Functions of Muscles
Muscles provide more power for locomotion
Movement of Body contents (Muscles)
Respiration (diaphragm & intercostal)
Circulation
alimentation ( digestion - GI tract defecation, & urination. (movement of body contents)
Childbirth
Indication of emotional states
- Barking, facial expression (cutaneous muscles), raising hair, or waging tail
Control of body openings and passages
“ maintain continence”
- example : ring-like sphincter muscles ( eyelids pupils, mouth)
Generate heat by shivering
- homeostasis
Bursa
A form of protection for tendons
Fluid-filled Cushions at danger sites:
- If only one aspect of tendon is at risk
- Bursa (bursa synovialis) small fluid-filled sacs located between tendons and stress points.
Infraspinatus go to greater tubercle of humerus.
Needs cushion 🡪 subtendious bursa
Tendon Sheath
If a greater aspect of tendon is vulnerable this will be present
Fluid-filled cylinders surrounding tendons over stress points
Retinaculum
condensed deep fascia over carpus or tarsus
Prevent ‘webbing’
Annular Ligaments
Condensed deep fascia over the digits
Sesamoid Bones ( Form of protection for tendons)
Grow (ossification) in tendons for extra strength at stress points.
Ossification of cartilage (even in embryo).
Move tendon away from axis.
Patella (kneecap):
- prevent wear and displaces tendon from axis of joint.
-(Remember: Ligament attaches bone to bone (patella to tibia)
Clinical Significance of Infiltrate Lipoma
Unencapsulated fatty tumor (deep into tissue)
Deeply attached to muscle fascia
Extrinsic Muscles role in movement
During progression, they resolve into antagonist groups that control the swing - Stride gate progression
Protraction – bring forward (cranially)
- All joints are extended
- End of stride
Retraction- bring back (caudally).
- Beginning of stride
- All joints are flexed
Girdle Muscle groups
Endomysium
Epimysium
Perimysium
