Muscles of back and Suboccipital region

Dr. Laxman Khanal

Assistant professor

Department of anatomy, BPKIHS

To BDS 2nd year

21-11-2016

Q. Main artery of suboccipital triangle is a. External carotid artery b. internal carotid arteryc. Vertebral artery d. occipital artery.

Q. Which part of the vertebral artery lies in suboccipital triangle?a. First part b. second part c. third part d. fourth part

Q. Suboccipital nerve is the branch of.a. C1 dorsal ramus b. C1 ventral ramusc. C2 dorsal ramus d. C2 ventral ramus

Q. Which procedure is done through suboccipital triangle?a. Lumbar puncture b. cistern puncturec. Surgical approach to ant cranial fossa d. all of the above

Identify the landmark.

Identify the bone.

Identify the muscle.

Identify it.

EOC

C1

Trapezius

Ligamentumnuchae

Introduction

• The back of the neck is limited above by external occipitalprotuberance and superior nuchal lines, and below by spine of C7vertebra and horizontal lines extending on either side from it to theacromial process of scapula.

• The important structures on the back of the neck include ligamentumnuchae, extensor muscles of the neck, suboccipital triangle andarterial anastomosis around the semispinalis capitis.

• Suboccipital region lies between occiput and spine of axis vertebra.

• Skeletal framework of backconsists of 33 vertebrae.

Atlas

Atlas & Axis

Typical cervical vertebra

1. Ext occipital protuberance2. Ext occipital crest3. Sup nuchal line4. Inferior nuchal line

Ligamentum nuchae• It is a triangular sheet of fibroelastic

tissue that forms the median fibrousseptum between the muscles of thetwo sides of the back of the neck.

Post free border

Ant border

Apex

Spine and post tubercles of C1-C6

Spine of C7

EOP and external occipital crest

• The musculatures of the backare arranged in a series oflayers.

1. Superficial group of muscles2. Deeper group of muscles• Only the deeper muscles are

true back muscles which aresupplied by dorsal rami of spinalnerves.

• Superficial muscles areinnervated by ventral rami ofspinal nerves.

Erector spinae muscle1. Spinalis2. Longissimus3. Iliocostalis

Levator scapulaeRhomboid minorRhomboid major

Splenius capitisSplenius cervicisSplenius=bandage

Semispinalis capitisSemispinalis cervicis

Suboccipital musclesAnastomosis around the semispinalis capitis

Splenius

Erector spinae

Muscles of back of neck

• The muscles of the back of the neck on either side of midline arearranged into superficial and deep groups

Superficial groupFirst layer: TrapeziusSecond layer: levator scapulae

rhomboid majorrhomboid minor

Deep groupFirst layer: splenius capitis

splenius cervicisSecond layer: Erector spinaeThird layer: semispinalis capitis

semispinalis cervicisFourth layer: suboccipital muscles

Neck rigidity• Occurs in meningitis.• Spasm of extensor muscles on

the back of the neck occurs.• Caused by irritation of nerve

roots of cervical spinal nerves

• Trapezius• Levator scapulae and rhomboids• Splenius- layer 1• Erector spinae- layer 2• Semispinalis- layer 3 # SESS• Sub-occipital group of muscles- layer 4

Nerve supplySpinal accessory nerve (motor).Ventral rami of C3 and C4 (sensory)

Action Upper fibers: elevate the shoulderMiddle and lower fibers: retract shoulder

Suboccipital region

Above: Inferior nuchal lineBelow: Spine and lamina of C2Lateral: Mastoid process and transverse process of C1 and C2

Cistern puncture:• Needle is introduced in the

midline just above the spineof the axis vertebra.

• Utmost care should be takenas medulla lies only 1 inchanterior to the posterioratlanto-occipital membranewhich, if damaged, may befatal.

Muscles of suboccipital triangle

1. Rectus capitis posterior major.

2. Rectus capitis posterior minor.

3. Oblique capitis inferior.

4. Oblique capitis superior.

All these muscles are supplied by the dorsal ramus ofC1 spinal nerve (suboccipital nerve).

Unique feature of C1 nerveno cutaneous branches.

C1C2

Rectus capitis posterior major

Rectus capitis posterior minor

Oblique capitis inferior

Oblique capitis superior

Suboccipital traingle

Floorposterior arch of the atlas atlanto-occipital membrane

Boundaries• Superomedial• Superolateral• Inferior

Suboccipital nerve

Vertebral artery

Greater occipital nerve

Suboccipital venous plexus

The connection between suboccipital venous plexus and internal vertebralvenous plexus serves as a path of intracranial infection in carbuncles of theneck.

Suboccipital venous plexus