Dr. SREEKANTH THOTA DEPARTMENT OF ANATOMY Back. The back comprises the posterior aspect of the...

WINDSOR UNIVERSITYSCHOOL OF MEDICINE

Dr. SREEKANTH THOTA

DEPARTMENT OF ANATOMY

Back

Back•The back comprises the posterior aspect of the

trunk, inferior to the neck and superior to the buttocks.

•The back includes the

•1. Vertebral column: the vertebrae, intervertebral (IV) discs, and associated ligaments

•2. Muscles: superficial layer and deep layer•3. Spinal cord and meninges (membranes that

cover the spinal cord).

VertebraeVertebrae: (33)

7 cervical12 thoracic5 lumbar5 sacral4 coccygeal

Abnormal Curvatures:

•Kyphosis•Lordosis•Scoliosis

Excess of Thoracic Curvature

Scoliosis

Excess of Lateral Curvature

Ligaments of the vertebral column• Anterior longitudinal.• Posterior longitudinal• Ligamentum flava• Ligamentum nuchae• Supra spinous • Interspinous• Intertransverse

Anterior and posterior longitudinal ligaments, Ligamenta flava

Supraspinous ligament and ligamentum nuchae

Interspinous ligaments

Laminectomy• The surgical excision of

one or more spinous processes and the adjacent supporting vertebral laminae in a particular region of the vertebral column is called a laminectomy

• Surgical laminectomy is often performed to relieve pressure on the spinal cord or nerve roots caused by a tumor, herniated IV disc, or bony hypertrophy (excess growth).

Back Muscles

•Muscles of the back are organized into superficial, intermediate, and deep groups.

•Muscles in the superficial and intermediate groups are extrinsic muscles because they originate embryologically from locations other than the back. They are innervated by anterior rami of spinal nerves

•Muscles of the deep group are intrinsic muscles because they develop in the back. They are innervated by posterior rami of spinal nerves.

Superficial Group: (attach upper extremity to the vertebral column)•Trapezius•Latissimus dorsi•Levator scapulae•Rhomboid major & minor

Intermediate group of back muscles

•1.Serratus posterior superior

•2.Serratus posterior inferior

Deep Layer: (postural in function)

•Erector spinae – iliocostalis, longissmus, spinalis

•Splenius capitis & splenius cervicis

Deepest Layer : Transverso spinalis group

•Semispinalis

•Multifidus

•Rotators

Spinal Cord & the Meninges

Spinal Cord•The spinal cord begins as a continuation

of the medulla oblongata the caudal part of the brainstem.

•In adults, the spinal cord is 42 to 45 cm long and extends from the foramen magnum in the occipital bone to the level of the L1 or L2 vertebra.

•In newborns extends till lower border of L3

•Beyond this level a thin filament extends, which is Filum Terminale

Spinal Cord

•The spinal cord is enlarged in two regions in relationship to innervation of the limbs.

•The cervical enlargement extends from the C4 through T1 segments of the spinal cord.

•The lumbosacral (lumbar) enlargement extends from T11 through S1 segments of the spinal cord.

Spinal Meninges and Cerebrospinal Fluid

•Spinal Dura Mater: The spinal dura mater is separated from the periosteum-covered bone and the ligaments that form the walls of the vertebral canal by the epidural space.

• This space is occupied by the internal vertebral venous plexus embedded in a fatty matrix (epidural fat).

Arachnoid Mater•Delicate, fibroelastic layer •Separated from the dura by the

subdural space•Separated from the piamater by the

subarachnoid space•Connected to the pia by fibrous

strands called Arachnoid Trabeculae.

Spinal Pia Mater

• The spinal pia mater, the innermost covering membrane of the spinal cord.

• The spinal cord is suspended in the dural sac by the terminal filum and especially by the right and left sawtooth denticulate ligaments which run longitudinally along each side of the spinal cord

Spinal Nerves31 pairs of spinal nerves:•Cervical – 8•Thoracic – 12•Lumbar – 5•Sacral – 5•Coccygeal – 1

•Each spinal nerve has a dorsal & ventral root.

•C1 lacks a dorsal root in 50% of the cases.

•Spinal roots unite at the intervertebral foramen to form a spinal nerve

Blood Supply of the Spinal CordArterial supply

Ant spinal artery Post spinal artery

Br of vertebral Br of vertebral or Post inf cerebellar artery (PICA)

These vessels are reinforced by blood from segmental arteries called Radicular arteries.

Lumbar puncture • Introduction of long needle into lumbar subarachnoid space to either draw CSF

out or put drugs into the CSF.• 3rd and 4th lumbar spines are marked

4th lumbar spine usually lies on a line joining iliac crests

• Lumbar Puncture Layers 

• 1. Skin2. Superficial fascia3. Supraspinous ligament4. Interspinous ligament5. Ligamentum flavum6. Epidural space containing the internal vertebral venous plexus7. Dura mater8. Arachnoid9. Subarachnoid space containing cerebrospinal fluid.

•  And remember Pia is not Pierced

Lumbar Puncture Layers Mnemonic•Some Super Supra Long L E

Ds Are Substitutes.

Epidural block•Anaesthetic injected into epidural space

of sacral canal – either of the following 3 ways… ▫Sacral hiatus (caudal epidural) using

sacral cornua as landmarks▫Posterior sacral foramina (transsacral

epidural)▫Lumbar region

•Surgery below diaphragm, childbirth, caesarian

•Anesthetic solution spreads superiorly to act on spinal nerves S2 to Co1

Epidural block

Sacral hiatus (caudal epidural)