Download Intrinsic Muscles of the Back

Muscles of back
D.Rania Gabr
D.Sama.
D.Elsherbiny
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: Combined movements
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
Action
LEVATOR SCAPULAE; RHOMBOID MINOR & MAJOR
 Origin:
1. Levator scapulae: cervical
transverse processes
2. Rhomboid minor & major:
thoracic spines
 Insertion: back of medial
border of scapula.
 Nerve supply: dorsal
scapular nerve.
 Actions:
1. Levator scapulae: elevates
scapula.
2. Rhomboid minor & major:
retract scapula.
LATISSIMUS DORSI
• Origin:
 Spinous processes of T7 - L5
vertebrae.
 Iliac crest of sacrum.
 Thoracolumbar fascia.
 Inferior angle of the scapula.
 Lower three or four ribs.
 Insertion:
floor of 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 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
3.
Deep intrinsic back muscles:
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:
2.Boundaries: latissimus dorsi,
trapezius, and medial border of
scapula.
2. Importance: 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. Importance: Site of an abdominal
hernia
MUSCULAR TRIANGLES OF
BACK
Muscles of the back
Extrinsic: Movements of upper limb and respiration.
1st layer:
Trapezius - Latissimus Dorsi
2nd layer: Levator Scapulae- Rhomboids (minor & major)
3rd layer: Serratus posterior (superior & inferior)
Intrinsic: Act on vertebral column and neck.
1st layer: Splenius
2nd layer: Erector Spinae: Iliocostalis
Longissimus
Spinalis
3rd layer: Transversospinal:Multifidus
Rotatores
Semispinalis