AN29.1-AN30.5 | Posterior triangle of neck — Glossary

Triangular space in the lateral neck bounded by the posterior border of SCM, anterior border of trapezius, and middle third of the clavicle

Major neck muscle with sternal and clavicular heads inserting into the mastoid process; divides the neck into anterior and posterior triangles

Upper and larger subdivision of the posterior triangle above the inferior belly of omohyoid, containing the accessory nerve and cervical plexus branches

Lower and smaller subdivision of the posterior triangle below the omohyoid, containing the subclavian artery (3rd part) and brachial plexus trunks

Cranial nerve providing motor supply to SCM and trapezius; crosses the posterior triangle obliquely and is at risk during lymph node biopsy

Point on the posterior border of SCM at its midpoint where the four cutaneous branches of the cervical plexus emerge

Network of nerves formed by ventral rami of C5-T1 that supplies the upper limb; roots emerge between scalenus anterior and medius

Upper brachial plexus injury (C5-C6) causing waiter's tip position with loss of abduction, lateral rotation, and elbow flexion

Lower brachial plexus injury (C8-T1) causing claw hand with loss of intrinsic hand muscles; may be associated with Horner's syndrome

Head tilted to one side with chin rotated to the opposite side due to SCM spasm or fibrosis; commonest neonatal cause is congenital muscular torticollis

Outermost layer of deep cervical fascia that encircles the neck and forms the roof of the posterior triangle

Deep cervical fascia covering the prevertebral muscles that forms the floor of the posterior triangle

Vertical midline dural fold between the two cerebral hemispheres, containing the superior and inferior sagittal sinuses

Horizontal dural fold separating the occipital lobes from the cerebellum, containing the transverse sinuses

Dural venous sinus lateral to the sella turcica containing the ICA, CN VI (within), and CN III, IV, V1, V2 (in lateral wall)

Visual field defect with loss of temporal fields bilaterally, caused by compression of the optic chiasm by a pituitary tumour

Compression of neurovascular structures (brachial plexus, subclavian vessels) at the thoracic outlet, often by a cervical rib

Supernumerary rib arising from C7 vertebra that may compress the subclavian artery and lower trunk of brachial plexus

Anterior scalene muscle that is the key landmark dividing the subclavian artery into its three parts

Effort thrombosis of the subclavian or axillary vein due to venous TOS, typically after vigorous arm use

Small horizontal dural fold roofing the sella turcica over the pituitary gland, through which the pituitary stalk passes

Dural venous sinus running along the upper border of the falx cerebri, draining cerebral veins into the confluence of sinuses

Meeting point of the superior sagittal, straight, and transverse sinuses at the internal occipital protuberance (torcular Herophili)