Download 17- Muscles of Back

Muscles of Back
Dr. Sama ul Haque
Dr Rania Gabr
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 (fused to form coccyx)
Total= 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
They are organized into 3
groups:
Deep group: attached to &
involved in the movement of
vertebral column & head.
Superficial group: attached
to & involved in the
movements of upper limb.
Intermediate group:
attached to ribs & serve
respiratory functions.
 Intrinsic muscles:
 Develop in the back
 Supplied by posterior
rami of spinal nerves
 Extrinsic muscles:
 Not developed in the
back
 Supplied by anterior
rami of spinal nerves.
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.
Supplied by anterior rami of spinal nerves
Superficial
Extrinsic Back
Muscles
Trapezius
Latissimus dorsi
Levator scapulae
Rhomboids major
& minor
TRAPEZIUS
 Origin: Spines of cervical &
thoracic vertebrae
 Insertion: lateral 1/3 of clavicle +
acromion & spine of scapula.
 Action: rotation of scapula during
abduction of humerus above
horizontal.
1. Upper fibers: elevate scapula.
2. Middle fibers: retract scapula
3. Lower fibers: depress scapula.
 Nerve supply: Spinal part of
accessory (11th cranial) nerve.
Insertion
Action
Origin
LEVATOR SCAPULAE; RHOMBOID MINOR & MAJOR
 Origin:
1. Levator scapulae: cervical
transverse processes
2. Rhomboid minor & major:
thoracic spines
 Insertion: medial border of
scapula.
 Nerve supply: dorsal scapular
nerve.
 Actions:
1. Levator scapulae: elevates
scapula.
2. Rhomboid minor & major:
retract scapula.
LATISSIMUS DORSI
• Origin:
• a. Spinous processes of T7 - L5
vertebrae.
• b. Iliac crest of sacrum.
• c. Thoracolumbar fascia.
• d. Inferior angle of the scapula.
• e. Lower three or four ribs.
 Insertion:
bicipital groove of humerus.
 Nerve supply:
thoracodorsal nerve.
 Actions:
 extension, adduction & medial
rotation of humerus (arm,
shoulder joint).
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
 It is separated from the
deep group by
thoracolumbar fascia.
 It includes:
• Serratus posterior
superior (rib elevator).
• Serratus posterior
inferior (rib depressor).
 Nerve supply: anterior rami
of thoracic spinal nerves.
Intrinsic Muscles of the Back
Called muscles of the back proper.
Deep muscles of the back.
All 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
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 (forms
intermediate column)
 Spinalis (forms medial column)
They extend from sacrum
to skull.
They include extensors and
rotators of head & vertebral
column.
Their tone is responsible for
maintenance of normal
curvature of vertebral
column.
Intrinsic Muscles of the Back
N.S: Posterior rami of spinal nerves
Actions: Acting bilaterally, extend head & neck
from a position of flexion.
Acting unilaterally, laterally flex vertebral
column.
Intrinsic Muscles of the Back
3.
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
Deep Intrinsic Muscles of the Back
1-Major deep layer
Transversospinal
group consist of
semispinalis,
multifidus & rotators.
N.S:Posterior rami of
spinal nerves.
Actions: Extension
and stabilization of
vertebral column.
Deep Intrinsic
Back Muscles
Transversospinal
group
(semispinalis,
multifidus &
rotators)
Deep Intrinsic Muscles of the Back
2- Minor deep layer
Interspinales
Intertransversarii
Levatores costarum
N.S: Posterior rami of spinal nerves
Actions: Extension, rotation, lateral flexion and
stabilization of vertebral column.
Movements of Back and Neck
Auscultatory Triangle:
1. Boundaries: latissimus
dorsi, trapezius, and
medial border of scapula.
2. Site where breath sounds
are most easily heard with
a stethoscope.
Lumbar Triangle:
(Triangle of Petit)
1. Boundaries : latissimus
dorsi, posterior border of
external oblique muscle of
the abdomen, and iliac
crest.
2. Site of an abdominal
hernia; or where pus may
emerge from the
abdominal wall.
MUSCULAR TRIANGLES OF BACK
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