Muscles and Nerves Flashcards
Appendicular muscles
muscles found attached to just to bones of the limbs or to bones of the limbs and axial skeleton.
Axial muscles
muscles just joined to the axial skeleton
origin of a muscle
the proximal /superior/medial attachment of muscles
insertion of a muscle
the distal/inferior/lateral attachment of muscles
aponeurosis
anterior tendons of the abdominal oblique muscles, these tendons and flat, thin and broad.
abdominal oblique muscles
muscles in the abdomen, there are three layers of them and they are arranged with muscle fibres at 90 degrees to each other
Biceps Brachii attachments
attaches to bones at 4 places has two heads at proximal end of muscle (hence its name BI (two)-ceps(heads)) that attach to the scapula.
the two distal attachments are to the radius and ulna
joints biceps brachii crosses
glenohumeral, elbow, proximal radioulnar joint
joints brachioradialis crosses
just elbow joint
joints triceps brachii crosses
elbow and glenohumeral
action of biceps brachii and triceps brachii at elbow
biceps- flexion
triceps- extension
what is a diaphragm
a muscle that crosses the median sagittal plane and has attach on either side. Largest is “the diaphragm”.
action of the diaphragm
when it contracts it descends causing the thoracic volume to increase and the lungs to inflate, breath in. When it relaxes the thoracic volume decreases again and the lungs deflate, breath out.
supporting skeletal muscles
are found around joints to give support eg. the rotator cuff muscles around the shoulder.
they also work against gravity. eg. the intrinsic muscles of the back
arrangement of fibres in the deltoid
split into anterior, middle and posterior fibres
function of anterior fibres in deltoid
contraction causes flexion of shoulder joint
function of posterior fibres in deltoid
contraction extension of shoulder joint
function of middle fibres in deltoid
contraction causes abduction of the shoulder joint.
co-operative muscle action
- antagonistic pairs
- synergists
- fixator/stabilising muscles
antagonistic pairs
a flexor will work with an extensor so that one contracts the other relaxes to allow a movement at the joint. in flexion the flexor will contract and the extensor will relax and for extension it the other way around.
synergists
a muscle that carries out the same action as the agonist to stabilize muscle movements.
Fixator/stabilising muscles
stabilize the joint which they are attached to, prevents dislocation.
brachialis and brachioradialis as synergists
act as synergists to stabilize the action of biceps brachii, flexion.
muscle testing
muscles are assessed bilaterally in pairs for comparison. This can help diagnose muscle and nerve injuries
muscle atrophy
wasting away of muscle, caused by a disorder of a muscle or its innervation. Can also be caused by muscle immobilisation eg. by long period in plaster cast
ways in which muscles can be compartmentalised
- deep fascial intermuscular septa
- nerve innervation, common nerve supply within a compartment
- common action of muscles
brachial plexus
matrix of nerves from the C5-T1 spinal nerve roots. Innervates the arm and forearm muscles
Lumbosacral plexus
matrix of nerves from the L1-S4 spinal roots. Innervates the thigh and leg muscles.
muscle nomenclature, ways in which muscles can be named
- location eg. serratus anterior and posterior
- action eg. extensor digitorum
- direction of muscle fibres eg. oblique muscles
- number of heads eg. biceps brachii
5 points of attachment eg. sternocleidomastoid muscle - shape eg. deltoid
- size eg. pectoralis major and minor
observations when looking at a micrograph slide of skeletal muscle
- presence of cross striations
- normal nuclear size and shape
- multinucleate
- absence of branching fibres
observations when looking at a micrograph slide of cardiac muscle
- presence of cross striations
- large round nuclei
- mononucleate
- presence of branching fibres
observations when looking at a micrograph slide of smooth muscle
- absence of cross striations
- elongated nuclei
- mononucleate
- absence of branching fibres
intervertebral foramen
hole in vertebrae through which a mixed spinal nerve exits.
sensory dorsal root
structure in which somatic sensory nerves enter the spinal cord
motor ventral root
structure in which somatic motor nerves exit the spinal cord.
dorsal ramus
contains both sensory and motor nerve fibres that innervate the skeletal muscle, skin and bones of the posterior side of the trunk only.
ventral ramus
contains both sensory and motor nerves that innervates anteriolateral muscles, skin and bone.
cutaneous nerve
nerves that supply the skin over muscles but are not specific to one spinal level.
dermatomes
areas of skin that are supplied by a single spinal level
dermatome of T2
sternal angle
dermatome of T4
nipples
dermatome of T10
umbilicus
dermatome of L1
inguinal region
endoneurium
layer of delicate connective tissue that surrounds the myelin sheath of nerve fibres
perineurium
protective sheath that surrounds a fascicle (bundle) of nerve fibres
epineurium
protective sheath that surrounds the bundles of fascicles, surrounds the entire nerve.
