Elbow Joint & Muscles of Proximal Forelimb Flashcards
what does peripheral nervous system supply
supplies the body
cranial nerves –> emerge from brain
spinal nerves –> emerge from spinal cord
what is the afferent pathway
body to brain
sensory fibres (pain, temperature, pressure)
proprioception –> location of limb in space
what is the efferent pathway
brain to body
voluntary movement
how does the nerve supply develop in the embryo
somites in embryo –> blocks of tissue, develop alongside spinal cord, group combines to form each forelimb, drag nerves with them, nerve supply therefore reflects origin
what are spinal nerves and where do they pass
leave spinal cord and pass through intervertebral foramen
paired left and right
what are the branches of spinal nerves that supply the forelimbs
dorsal branches supply dorsal structures
ventral brances from C6, C7, C8, T1, T2 form brachial plexus
what is the brachial plexus
multiple exhanges of fibres –> emerging nerves supply forelimb
how are the fibres of skeletal muscle arranged
parallel bundles
encased in fibrous tissue
what are the origins and insertions of skeletal muscle usually
O: usually proximal
I: usually distal
what are the attachments of skeletal muscle
directly to bone –> rough surface area, bony bumps/tubercles
via aponeurosis (muscle tissue stops but continue on as fibrous tissue) –> sheets, areas of restricted access
via tendons
what are tendons
rope of CT
condensation of fibrous tissue into cords
continuation of muscle as fibrous tissue –> less bulky across joints, small area of attachment
what are the functions of muscle
muscle fibres contract –> muscle belly shorten
points of attachment pulled closer together –> effect depends on origin and insertion
what does action of muscle depend on (2)
- specific joint(s) crossed
- aspect of joint(s) crossed
(a muscle has no effect on a joint if it doesn’t cross it)
what are extrinsic muscles
origin on axial skeleton –> insertion in appendicular skeleton
what movement do extrinsic muscles produce
movement of limb relative to trunk
- protraction (limb moves cranially)
- retraction (limb moves caudally)
- adduction (medually)
- abduction (laterally)
what are intrinsic muscles
original & insertion within appendicular skeleton
movement limited to within lumb (flexion/extension, rotation)
what is flexion and extension
flexion - reduced flexor angle (non-weight bearing position)
extension - increased flexor angle (weight bearing position)
break down what brachiocephalic means
cephalic = head
brachium = arm
what is the origin and insertion of the brachiocephalic muscle
O: cervical vertebrae & skull
I: humerus
where is the brachiocephalic muscle located
cranial to limb
what is the function of the brachiocephalic muscle
forelimb protractor
shoulder extensor (increases angle caudle to the joint and will extend the shoulder)
what is the clavicle
bony remnant in muscle cranial to shoulder
present in cats, absent in dogs
allows differentation on radiographs
what muscle is this
brachiocephalic muscle
what muscle is this
brachiocephalic muscle
what is the latissimus dorsi muscle
latus = broad
dorsi = back
“broadest muscle of the back”
what is the origin and insertion of the latissimus dorsi muscle
O: thoracic vertebrae
I: humerus
where is the latissimus dorsi located
caudal to the limb
what is the function of the latissimus dorsi muscle
forelimb retractor
also propulsion
shoulder flexor (reduces angle)
what muscle is the latissimus dorsi muscle the equal and opposite of
bachiocephalic muscle
what muscle is this
latissimus doris
what muscle is this
latissimus dorsi
what is the origin and insertion of the serratus ventralis muscle
O: thoracic wall (ribs), cervicle vertebrae
I: proximal scapula (medial aspect), (proximal to pivitol point)
where is the serratus ventralis muscle located
between forelimb and trunk
what is the function of serratus ventralis muscle
support weight of trunk between forelimbs
cranial portion –> retractor
caudal portion –> protractor
what muscle is this
serratus ventralis muscle
what is the origin and insertion of the trapezius muscle
O: cervical and thoracic vertebrae
I: proximal scapular spine
how many parts does the trapezius muscle have
2 parts - cranial and caudal
where is the trapezius muscle located
proximal to limb
proximal to pivotal point
what is the function of the trapezius muscle
abduction of the limb (also protraction)
more limited abduction in domestic species –> helps with protraction with serratus ventralis
what muscle is this
trapezius muscle
what muscle is this
trapezius muscle
what muscle is this
trapezius muscle
what is the origin and insertion of the pectoral muscle
O: sternum
I: humerus
what are the two pectoral muscles
deep & superficial groups