Neuroanatomy Lecture 3 PDF

 nghazi / Facu Be lty of of y M it rs ed Unive icine...

 nghazi / Facu Be lty of of y M it rs ed Unive icine Neuroanatomy Department of Anatomy Dr Mustafa Karwad Ass. Professor of Anatomy Lecture No. 3 Anatomy of the spinal cord Blood supply & internal features & Lesions of the spinal cord Dr. Mustafa Karwad  Objectives ❑ By the end of the lecture students should be able to: 1. Describe the blood supply of the spinal cord. 2. Describe the internal features of the spinal cord. 3. Describe the lesions of the spinal cord.  Blood supply of the spinal cord o A single anterior spinal artery. o Two posterior spinal arteries. o Segmental spinal arteries (radicular arteries). posterior spinal arteries Anterior spinal artery.  Anterior spinal artery It is a single artery. Arising from the union of the 2 anterior spinal branches of the vertebral arteries. Passing in the anterior median fissure. Anterior spinal artery  Anterior spinal artery It supply the anterior 2/3 of spinal cord. Posterior spinal artery  Posterior spinal artery Posterior spinal arteries o Two arteries. o Branch from vertebral artery (sometimes arises from PICA). o Passing in the posterolateral sulcus of the spinal cord. o Supply posterior 1/3 of spinal cord.  Radicular arteries ✓ The anterior & posterior spinal arteries are reinforced by radicular arteries that enter the vertebral canal through the intervertebral foramina. Dr. Mustafa  Radicular arteries o They are the major source of blood supply to the lower 2/3 of the spinal cord. o They enter the vertebral canal through the intervertebral foramina & divide into anterior & posterior radicular arteries. o It joins anterior & posterior spinal arteries.  Radicular arteries They are branches from: A. In the neck: from vertebral & ascending cervical arteries. B. In the thorax: from the intercostal arteries. C. In the abdomen: from the Lumbar arteries. D. In the pelvis: from the lateral sacral arteries.  Venous drainage of the spinal cord 6 longitudinal channels correspond to the arteries: 1) Anterior spinal veins. 2) Posterior spinal veins. 3) Anterolateral spinal veins 2. 4) Posterolateral spinal veins 2. ✓ These veins drains into the internal vertebral plexus of vein.  Internal structure of the spinal cord Grey matter: ✓ Mostly made up of cell bodies of neuron. White matter: ✓ Composed of nerve fibers (ascending & descending tracts). Myelin sheath grey mater White mater  Commissures of the spinal cord The two halves are connected by three commissures: - White commissure. - Anterior grey commissure infront of the central canal. - Posterior grey commissure behind the central canal.  Gray Matter of the Spinal Cord & Spinal Roots Formed of the nerve cell bodies. It is H-shaped or butterfly-like. Gray commissure: contains the central canal. 1. Anterior horns: contain cell bodies of motor neurons. 2. Posterior (dorsal) horns: consist of interneurons (contain sensory nuclei). 3. Lateral horn: Gray matter: divided according to somatic and visceral regions. Gray Matter of the Spinal Cord & Spinal Roots Lateral horn: present only in thoracic & lumbar segment (T1-L2) sympathetic nuclei & sacral segments (S2, 3, 4) Parasympathetic nuclei. The gray matter of the spinal cord Dorsal: supplies flexor muscles nuclei Ventral: supplies extensor Central group: in cervical region only muscles (phrenic N. & spinal accessory N.) L1 to S3 Lateral group Ventral horn (motor) efferent supply the limbs Medial group for trunk muscles Dorsal: supplies flexor muscles Ventral: supplies extensor muscles The gray matter of the spinal cord Sensory: 2nd order neuron nuclei Postromarginal N: pain & Temprature (all levels) Medial group for Clarke’s N: proprioception (C8 –L2) 1 Substantia gelatinosa Dorsal horn (sensory) afferent of Rolandi (SGR): pain, Temp & touch General somatic sensory pathway Nucleus proprius: crude touch, light pressure(all level)  White Matter of the Spinal Cord Descending (dorsal) columns. Lateral columns. Composed of axons of the nerve cells, they form tract or fasciculi. It is formed of three types of fibers: 1) Ascending (ventral) columns. 2) Descending (dorsal) columns. 3) Lateral columns. Ascending (ventral) columns.  Next lecture: (Spinal cord applied anatomy) Brain stem T h e E n d Dr. Mustafa Karwad