Muscles of Back
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Transcript Muscles of Back
Muscles of Back
Dr. Sama ul Haque
Objectives
Identify the superficial and deep muscles of
the back in terms of their location, nerve
supply and actions.
Understand the muscle support of the trunk.
Explain the mechanism of body weight
transmission.
Vertebral Column
Cervical:
7
Thoracic: 12
Lumbar: 5
Sacral:
5 (fused to form 1 sacrum)
Coccygeal: 4
Total=
(fused to form coccyx)
33 (counted as 26 in the total bones of
the body because of fusion.
Movements at the Vertebral Column
Flexion:
bending forward
Extension: bending backwards
Lateral flexion: bending side-wards
Rotation: Twisting the trunk
Circumduction:
The axis of movement passes through the
center of the vertebral bodies, so that the
bodies do not move. Movements are mostly
permitted by the cervical & lumbar spines.
Thicker the intervertebral disc, greater the
degree of movement
Functions of the Vertebral Column
Protects
the spinal cord & spinal nerves.
Supports
the weight of the body superior to the
level of the pelvis.
Provides
a partly rigid & flexible axis for the body
& an extended base on which the head is placed
and rotates.
Plays
an important role in posture & locomotion
Muscles of the Back
Extrinsic
Intrinsic
muscles
muscles
Extrinsic Muscles of the Back
1. Superficial extrinsic back muscles:
Trapezius
Latissimus dorsi
Levator scapulae
Rhomboids major & minor
They all connect the upper limb to the trunk.
Superficial
Extrinsic Back
Muscles
Trapezius
Latissimus dorsi
Levator scapulae
Rhomboids major
& minor
Extrinsic Muscles of the Back
2. Intermediate extrinsic back muscles:
Serratus posterior superior
Serratus posterior inferior
They are superficial respiratory muscles and
are supplied by intercostal nerves.
Intermediate
Extrinsic Back
Muscles
Serratus posterior
superior
&
Serratus
posterior inferior
Intrinsic Muscles of the Back
Called
Deep
All
muscles of the back proper.
muscles of the back.
are supplied by the posterior primary
rami of spinal nerves.
Act
to maintain posture and control
movement of the vertebral column.
Intrinsic Muscles of the Back
1.
Superficial intrinsic back muscles:
Splenius cervices & splenius capitis
N.S: Posterior rami of spinal nerves.
Actions: Acting alone; laterally flex neck &
rotate head to side of active muscle.
Acting together; extend head & neck.
Superficial
Intrinsic Back
Muscles
Splenius cervices
&
splenius capitis
Superficial Intrinsic Back Muscles
Intrinsic Muscles of the Back
2.Intermediate intrinsic back muscles:
Erector
spinae is the chief extensor of the
vertebral column & is divided into three columns
(also called as the long muscle of the back).
Ilio-costalis
(forms lateral column)
Longissimus
Spinalis
(forms intermediate column)
(forms medial column)
Intrinsic Muscles of the Back
2.Intermediate intrinsic back muscles:
N.S:
Posterior rami of spinal nerves
Actions:
Acting bilaterally, extend head & neck
from a position of flexion.
Acting unilaterally, laterally flex vertebral
column.
Intermediate
Intrinsic Back
Muscles
Erecter Spinae
(Ilio-costalis
Longissimus
Spinalis)
Intrinsic Muscles of the Back
2.Deep intrinsic back muscles:
This
is a group of muscles that lie deep to erector
Spinae.
It
can be divided into two groups:
Major
deep layer
Minor
deep layer
Intrinsic Muscles of the Back
2.Deep intrinsic back muscles:
Major deep layer
Transversospinal
group consist of
semispinalis, multifidus & rotators.
N.S:Posterior
Actions:
rami of spinal nerves.
Extension and stabilization of
vertebral column.
Deep Intrinsic
Back Muscles
Transversospinal
group
(semispinalis,
multifidus &
rotators)
Intrinsic Muscles of the Back
2.Deep intrinsic back muscles:
Minor deep layer
Interspinales
Intertransversarii
Levatores
N.S:
costarum
Posterior rami of spinal nerves
Actions:
Extension, rotation, lateral flexion and
stabilization of vertebral column.
Movements of Back and Neck
Muscles of the back are organized in layers
Extrinsic: Movements of upper limb and respiration.
1st layer:
2nd layer:
3rd layer:
Trapezius
Latissimus Dorsi
Levator Scapulae
Rhomboids (minor & major)
Serratus posterior (superior & inferior)
Intrinsic: Act on vertebral column and neck.
1st layer:
2nd layer:
3rd layer:
Splenius
Erector Spinae:
Iliocostalis
Longissimus
Spinalis
Transversospinal: Multifidus
Rotatores
Semispinalis
Thank You