Muscles of back and Suboccipital region Dr. Laxman Khanal Assistant professor Department of anatomy, BPKIHS To BDS 2 nd year 21-11-2016
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