Skeletal muscle: to move the skeleton
Chapter 3 Myology Cardiac muscle: to form the heart
Smooth muscle: to constitute viscera
Over 600 muscles in the body;
Muscles are grouped by location:
muscles of head; muscles of neck;
muscles of thorax; muscles of Abdomen;
muscles of upper limb; muscles of lower
limb; ( muscles of pelvis and perineum )
Naming the skeletal
muscles by sereral criteria:
1. location (brachialis); 2.
shape (trapezius); 3. relative
size of the muscle; 4. direction
of the muscle fibers
(rectus,oblique); 5. location of
attachments(brachioradialis); 6.
number of origins (biceps); 7.
action (flexor,extensor)
Morphology of skeletal muscle
Belly: the fleshy part of a muscle
Tendon: the bundles consisting of
connective tissue blending with
strong collagen
Different patterns of arrangement of
the fascicles in muscles
1. Parallel arrangement: the long
axes of the fascicles run parallel
Biceps unipennate bipennate multipennate
to the long axes of the muscle
itself
2. Pennate pattern: feather-like
muscle including unipennate,
bipennate and multipennate
arrangemengs
3. Convergent pattern: with a broad
origin the fascicles converge
toward a tendon
4. Circular pattern: arranged in
concentric rings
rectus flate orbicular digastric
Origin, insertion and action of the muscles
Origin: a fixed (less movable) attachment of a muscle
Insertion: a movable attachment of
a muscle
The origin lies proximal to the
insertion in the muscles of limbs
Agonists ( prime movers ): the main
muscles which contract to produce
desired movement
Antagonist: the muscles which act
to oppose the action of agonist
Synergists: the muscles which triceps
cooperate in performing an action
Fixators: the muscles which steady
the proximal parts of a limb while
movements occur in distal parts
Superficial fascia
Fascia and tendinous sheath
Fascia
1) Superficial fascia: lies under skin and covers the
entire body containing a lot of fat / increase mobility
of skin; thermal insulation; a store of energy /
contain cutaneous nerve, blood vessels and skin
muscles 2) Deep fascia: dense and inelastic
membrane of collagenous fibers
Deep fascia
Intermuscular septa
Visceral layer
Parietal layer Tendinous sheath
Consist of synovial sheath and fibrous sheath;
Fibrous sheath exist only in hand and foot
mesotendon Synovial sheath 1. visceral layer 2. parietal
layer / mesotendon: conjunctive structure
between visceral and parietal layer
Fibrous sheath outmost layer consisting of
fibrous tissue
periosteum
Section 3 Muscles of Head and Neck
Muscles of the head
1. Craniofacial muscles: epicranius
( occipitofrontalis ) frontal belly +
epicranial aponeurosis + occipital belly,
orbicularis oculi, orbicularis oris
2. Masticatory muscles: masseter,
temporalis, medial pterygoid, lateral
pterygoid
ORBICULARIS ORIS
Origin Action
Near midline on ant surface Narrows orifice of
of maxilla and mandible mouth, purses lips and
and modiolus at angle of puckers lip edges
mouth
Insertion Nerve
Mucous membrane of Accessory parts are
margin of lips and raphe incisivus labii
with buccinator at modiolus superioris and
inferioris
ORBICULARIS OCULI
Origin Action
Med orbital margin and Closes eyelids , aids
lacrimal sac(orbital, passage and drainage
palpebral and lacrimal of tears
parts)
Insertion
Nerve
Lat palpebral raphe Temporal and
zygomatic brs of facial
N (VII)
MASSETER
Origin Action
Ant two thirds of Elevates mandible
zygomatic arch and (enables forced closure
zygomatic proces of of mouth)
maxilla
Insertion Nerve
Lat surface of angle Ant div of mandibular N
and lower ramus of (Vc)
mandible
TEMPORALIS
Origin Action
Temporal fossa Elevates mandible
between inf temporal and post fibres
line and infratemporal retract
crest
Insertion Nerve
Med and ant aspect Deep temporal brs from
of coronoid process of ant div of mandibular N
(Vc)
mandible
MEDIAL PTERYGOID
Origin Action
Deep head. Med side of lat Elevates, protracts
pterygoid plate and fossa and lat displaces
between med and lat plates mandible to opposite
Superficial head : side for chewing
Tuberosity of maxilla and
pyramidal process of
palatine bone
Insertion Nerve
Med aspect of angle of N to medial pterygoid
mandible (main trunk of
mandibular N (Vc))
LATERAL PTERYGOID
Origin Action
Upper head: Depresses and
infratemporal surface of protracts mandible to
sphenoid bone. Lower open mouth. Pulls
head: lat surface of lat forward cartilage of jnt
pterygoid plate during opening of
mouth
Insertion Nerve
Pterygoid fovea below Ns to lat pterygoid (ant
condyloid process of div of mandibular N
mandible and intra- (Vc))
articular cartilage of
temporomandibular jnt
Muscles of the neck
1. Superficial group: platysma,
sternocleidomastoid
2. Superhyoid muscles: digastric, mylohyoid,
3. Infrahyoid muscles: sternohyoid, omohyoid,
sternothyroid, thyrohyoid
4. Deep cervical muscles:
scalenus anterior, scalenus
medius, scalenus posterior
PLATYSMA
Origin Action
Skin over lower neck and Depresses and wrinkles
upper lat chest skin of lower face and
mouth. Aids forced
depression of mandible
Insertion Nerve
Inf border of mandible and Cervical br of facial N
skin over lower face and (VII)
angle of mouth
STERNOCLEIDOMASTOID
Origin Action
Ant and sup Flexes and lat rotates
manubrium and cervical spine. Protracts
head when acting together
sup med third of
. Extends neck when neck
clavicle already partially extended
Insertion Nerve
Lat aspect of Spinal accessory N (lat
mastoid process and roots C1-5)
ant half of sup
nuchal line
DIGASTRIC (ANTERIOR VIEW)
DIGASTRIC
Origin Action
Ant belly: digastric fossa Elevates hyoid bone:
on post surface of Aids swallowing and
symphysis menti. Post depresses mandible
belly : base of med
aspect of mastoid
process
Nerve
Insertion
Firbrous loop to lesser Ant belly: mylohyoid N
cornu of hyoid bone (Vc). Post belly: facial
N (VII)
MYLOHYOID
Origin Action
Mylohyoid line on Elevates hyoid bone,
int aspect of supports and raises floor
mandible of mouth . Aids in
mastication and
swallowing
Insertion
Nerve
Ant three quarters : Mylohyoid N (Vc)
midline raphe. Post
quarter: sup border
of body of hyoid
bone
STYLOHYOID (ANTERIOR VIEW)
Origin Action
Base of styloid Elevates and retracts
process hyoid bone. Aids
swallowing and
elevates larynx
Insertion Nerve
Base of greater Mandibular br of
cornu of hyoid facial N (VII)
bone
GENIOHYOID
Origin Action
Inf mental spine on Elevates and
post surface of protracts hyoid
symphysis menti
bone. Depresses
mandible
Insertion Nerve
Sup border of body C1 fibres carried
of hyoid bone by hypoglossal N
(XII)
STERNOHYOID
Origin Action
Sup lat post Depresses hyoid
aspect of bone and hence
manubrium larynx
Insertion Nerve
Inf border of Ansa cervicalis N
body of hyoid (C1, 2, 3)
bone
OMOHYOID
Origin Action
Suprascapular lig and Depresses hyoid
adjacent scapula bone and hence
larynx
Insertion Nerve
Inf border of body of Ansa cervicalis N
hyoid bone (C1,2,3)
STERNOTHYROID
Origin Action
Med post aspect Depresses
of manubrium larynx
Insertion Nerve
Oblique line of Ansa
lamina of thyroid cervicalis N
cartilage (C1, 2, 3)
THYROHYOID
Origin Action
Oblique line of Elevates larynx or
lamina of thyroid depresses hyoid
cartilage bone
Insertion Nerve
Inf border of body C1 fibres carried
of hyoid bone by hypoglossal N
(XII)
SCALENUS ANTERIOR
Origin Action
Ant tubercles of Accessory to
transverse inspiration. Lat
processes of C3-6 flexion of neck when
1st rib fixed
Insertion Nerve
Scalene tubercle on Ant primary rami of
sup aspect of 1st C5, 6
rib
SCALENUS MEDIUS
Origin Action
Post tubercles of Accessory to
transverse processes inspiration
of C2-7
Insertion Nerve
Sup aspect of neck of Ant primary rami
1st rib of C3-8
SCALENUS POSTERIOR
Origin Action
Post tubercles of Accessory to
transverse inspiration
processes C4-6
Insertion Nerve
Ant primary rami of C6-8
Post/lat surface of
2nd rib
