Muscles of back

• Introduction• Cutaneous nerve supply• Development of muscles• Muscles of back Introduction Classification• Nerve supply of muscles of back• Action of muscles of back

Cutaneous Nerves

• Dorsal primary rami of spinal nerves.

• Each dorsal primary ramus divides into medial and lateral branches.

Muscles of back

Development:• Epaxial muscles: Extensors

of the neck and vertebral column

• Hypaxial muscles: Thoracic myotome form lateral and ventral flexor muscles of the vertabral column,lumbar myotome form quadratus lumborum.

Arrangement of Back Muscles

• Three groups:Superficial:

Extrinsic.Intermediate:

Extrinsic.Deep:

Intrinsic.

Ligamentum nuchae

•Consist of dorsal raphae and medial fascial septum

•Attachment

•extension

Thoracolumbar Fascia

• Deep fascia on the back of trunk.

• It binds long exetonsors of vertabral column to posterolateral surfaces of vertabral bodies.

• Two parts :Lumbar Thoracic

Thoracolumbar Fascia Laminae

• Posterior lamina to lumbar spinous processes.

• Middle lamina to lumbar transverse processes.

• Anterior lamina (deepest) to lumbar transverse processes.

Superficial Extrinsic Muscles

• Connect limb to axial skeleton.• Innervated by ventral rami or CN XI.• Include:

Trapezius.Latissimus dorsi.Levator scapulae.Rhomboideus major.

Rhomboideus minor.

Trapezius:• Diamond shaped• Origin:• Insertion:• Innervation:• Action:

Lattissimus dorsi:• Origin:• Insertion: • Innervation:• Action:

Levator scapulae:• Origin :• Insertion:• Innervation :• Action:

Rhomboid major:• Origin:• Insertion:Rhomboid minor:• Origin:• Insertion:

• Innervation:• Action:

Intermediate Extrinsic Muscles

• Serratus posterior group:

Serratus posterior superior.

Serratus posterior inferior

• Innervated by ventral rami of spinal nerves.

Intrinsic Back Muscles

• True intrinsic muscles of the back are innervated by dorsal (posterior) rami.

• Three groups:SuperficialIntermediateDeep.

INTRINSIC (DEEP) BACK MUSCLES

• Superficial :Splenius , Erector spinae• Deeper layer : Spinotransverse

group, Suboccipitals

• Deepest layer: Interspinous, Intertranseverse

.

Superficial muscles

• Consists of the Splenius group:• Long muscles.

• Originate from ligamentum nuchae and spinous processes.• Cover neck and upper part of thorax.• Two parts: Splenius capitis Splenius cervicis

Splenius capitis:• Attachments:• Relations: • Innervation:• Action:Splenius cervicis:• Attachments:• Relations:• Innervation:• Action:

Superficial IntrinsicErector spinae: Three muscles each

with three regional parts.1.Spinalis:Spinalis thoracis Spinalis cervicis Spinalis capitis2.Longissimus:Longi capitis Longi cervicis Longi thoracis3.Iliocostalis:Iliocost cervicis Iliocost thoracis Iliocost capitis

Spinalis: Components: Thoracis: Attachments: Cervicis: Attachments:

poorely developed Capitis:

Attachments:

Intermediate Intrinsic

• Longissimus:Central component of erector spinae

Longissimus capitis: Attachments Longissimus cervicis:

Attachments: Longissimus thoracis:Largest

component Has lumbar and

thoracic part. Attachments:

.

• Iliocostalis:most lateral component of erector spinae

Components: Iliocostalis cervicis: Attachments Iliocostalis thoracis: Attachment Iliocostalis lumborum: Attachments Has lumbar and

thoracic part

Erector spinae aponeurosis:• Formation:• Attachments:• Relations: • Innervation: • Action:

Deep Intrinsic Muscles• Spinotransverse group:

Present between spinous process and transverse elements of vertebrae.

Components: Rotators: Rotators thoracis Rotators cervicis Rotators capitis Multifidus Semispinalis: Semi cervicis Semi thoracis Semi capitis Suboccipital muscle

Rotatores• Deepest and shortest muscle• 11 pairs of small

quadrilateral muscle• Attachments:• Components: Rotator brevis: Attachments Rotator longus: Attachments

Multifidus

• Thick muscle mass.• Present at

cervical,thoracic,upper lumbar levels lies lateral to spinous process and also expands to cover posterior surface of sacrum.

• Multifidus arises from lateral surface and tip of trnsverse process and insert into transverse elements of vertebrae.

Semispinalis

• Longest fibres of spinotransverse group

• Components: Cervicis:

Attachments Thoracis: Attachments Capitis: Attachments• Relations:• Innervation:• Action:

Suboccipital muscle:

• 4 small muscles that connect occipital bone,atlas and axis.

• Suboccipital triangle• Components: Rectus capitis posterior major: Attachments Rectus capitis posterior minor: Attachments Obliquus capitis inferior: Obliquus capitis superior:• Innervation:• Actions:

Intrinsic Segmental Muscles

• Interspinales: Attachments. • Intertransversarii Attachments.

Applied:

• Low bachache: Lumbar strain Lumbar radiculopathy• Lumbar triangle:

– Superior(Grynfeltt)– Inferior(Petit) • Renal angle