Presentation on

back OF neck &Sub occipital TRIANGLE

by

KANAV BHANOTRoll no. 5

INTRODUCTION

CONTENTS OF BACK OF NECK

SKIN

SUPERFICIAL FASCIA

DEEP FASCIA

MUSCLES

SUB OCCIPITAL TRIANGLE

INTRODUCTION

EXPOSURE

BOUNDARIES

CONTENTS OF SUBOCCIPITAL TRIANGLE

CLINICAL RELATIONS

• The back of the neck is limited above by EXTERNAL

OCCIPITAL PROTUBERANCE & SUPERIOR NUCHAL

LINES and below by SPINE OF C7 VERTEBRA.

• The important structures on the back of the neck include :

» Ligamentum Nuchae

» Extensor Muscles of Neck

» Sub occipital Triangle

» Arterial Anastomosis around Semispinalis Capitis

The soft tissues on the back of neck are divided into four

layers :

SKIN

SUPERFICIAL FASCIA

DEEP FASCIA

MUSCLES : Trapezius Levator Scapulae

Splenius Capitis Splenius Cervivis

Longissimus Capitis Semispinalis

Capitis

Semispinalis Cervicis

• The skin on the back of the neck is supplied by the medial branches of

dorsal rami of C2, C3 & C4 spinal nerves.

• The cutaneous nerves derived from the medial branches of dorsal rami

of C2, C3 & C4 are:

• GENERAL OCCIPITAL NERVE (C2)- Supplies the post. Part of scalp.

It is the thickest cutaneous nerve in the body.

• THIRD OCCIPITAL NERVE (C3)- It is a small cutaneous nerve and

supplies the skin of the nape of the neck.

• CUTANEOUS BRANCHES OF C4 & C5- These branches supply the

adjacent skin.

• The superficial fascia of he back is thick and in spite of its fat content, it is

very tough. It contains cutaneous nerves and vessels.

• The cutaneous nerves are :

i. GREATER OCCIPITAL

ii. THIRD OCCIPITAL

iii. CUTANEOUS BRANCH OF C4 & C5

• The cutaneous vessels are :

i. OCCIPITAL ARTERY

ii. Minute twigs from VERTEBRAL ARTERY

• The deep fascia of the back is called Nuchal

fascia. It is attached in the median plane to the

spines, supraspinous ligaments and Ligamentum

Nuchae.

LIGAMENTUM NUCHAEIt is triangular sheet of fibro elastic tissue that

forms the median fibrous septum between the

muscles of the two sides of the back of the neck to

which it is attached under deep fascia. It presents

superior, anterior and posterior borders.

The muscles of the back of the neck on either side

are arranged into Superficial and Deep Group of

Muscles.

SUPERFICIAL GROUP

First layer consisting of TRAPEZIUS

Second layer consisting of LEVATOR

SCAPULAE.

It is a large, flat and triangular muscle which is

placed superficially on the back of the neck and

thorax.

•ORIGIN : Arises from the med. third of

superior nuchal line, external occipital

protuberance, ligamentum nuchae & spine of

C7.

• INSERTION :

Upper surface of lat. third of clavicle.

Med. Border of Acromion

Tubercle of Spine of Scapula

NERVE SUPPLY :

» Spinal Accessory Nerve

» Ventral Rami of C3 & C4

ACTION :

» Helps in the elevation and shrugging of shoulders.

» Also helps in retracting and steadying the scapula.

•ORIGIN : Arise from post.

Tubercles of the transverse

processes of the first four cervical

vert.

• INSERTION : Into the med.

border of the scapula

•NERVE SUPPLY : Branches

from ant. Rami of C3 & C4

• ACTION : Elevates the Scapula

DEEP GROUP

Muscles of this group form the intrinsic musculature. The

muscles are arranged in 4 layers :

External : Consisting of SPLENIUS CAPITIS & S.

CERVICES

Intermediate : Consisting of LONGISSIMUS CAPITIS &

L. CERVICES

Deep : Consisting of SEMISPINALIS CAPITIS & S.

CERVICIS

Deepest layer : Formed by the SUBOCCIPITAL

MUSCLES.

This is a triangular muscular

space situated deep in the sub

occipital region of the neck one

on each side of the midline and

bounded by the three muscles

of the sub occipital group of

muscles.

In order to expose the triangle, the following layers are reflected:

• The skin is very thick

• The superficial fascia is fibrous and dense

• The fibres of trapezius run downwards and laterally over the triangle

and sternocleidomastoid overlaps the region laterally.

• The splenius capitis runs upwards & laterally for insertion into mastoid

process.

• The semispinalis capitis runs vertically upwards for insertion into

medial part of the area between the sup. And inf. Nuchal lines.

{Reflection of semispinalis capitis exposes the sub occipital triangle}

The sub occipital triangle is bounded by the following three muscles of

the sub occipital group of muscles:

• Rectus capitis posterior major - above and medially

• Obliquus capitis superior - above and laterally

• Obliquus capitis inferior - below and laterally

(Rectus capitus posterior minor is also in this region but does not form part

of the triangle)

• SUPEROMEDIALLY- Rectus Capitis Posterior Major supplemented

with RCP Minor

• SUPEROLATERALLY- Sup. Oblique Muscle

• INFERIORLY- Inf. Oblique Muscle

ROOF• MEDIALLY- Dense fibrous tissue covered by the semispinalis capitis

• LATERALLY- Longissimus Capitis

FLOOR• Post. Arch of atlas

Contents of sub occipital triangle include :

a. SUB OCCIPITAL PLEXUS OF VEINS- It lies in and around the

triangle. It connects many veins and plexuses and thus provides a

number of alternative routes for venous drainage.

b. THIRD PART OF VERTEBRAL ARTERY- It appears in the Sub

occipital triangle through foramen transversarium of atlas vertebra.

c. DORSAL RAMUS OF C1-SUBOCCIPITAL NERVE- It emerges

between the post. Arch of the atlas and the vertebral artery and soon

breaks up into branches which supply the four sub occipital muscles.

• The neck rigidity occurs in meningitis due to spasm of

extensor muscles on the back of the neck.

• The posterior cranial fossa is approached by

neurosurgeons to remove the brain tumour by clearing the

sub occipital muscles and removing the exposed bone.

• The connections between the sub occipital venous plexus

and internal vertebral venous plexus serves as a path of

intra cranial infection in carbuncles of the neck.