Spinal Cord Anatomy PDF 11/1/2024

11/1/2024 I. Main Functions of Spinal Cord A. Conduction of information B. Reflexes C. Locomotion II. Cross-sectional Anatomy of Spinal Cord A. Gray matter --centrally located --composed mostly of cell bodies and unmyelinated ________________ a...

11/1/2024 I. Main Functions of Spinal Cord A. Conduction of information B. Reflexes C. Locomotion II. Cross-sectional Anatomy of Spinal Cord A. Gray matter --centrally located --composed mostly of cell bodies and unmyelinated ________________ axons B. White matter --outer portion --consists mostly of myelinated _______________ axons Gray commissure dorsal norn White Lateral horn matter ventral norn Central canal Anterior median fissure 1  11/1/2024 Dorsal horn --toward the back --aka. Posterior horn --the more narrow horn *contains _______________ sensory neurons Ventral horn --aka. Anterior horn --broader, with a thicker band of white matter around it *contains _______ Motor neurons Lateral horn --only in thoracic and upper lumbar (T2-L1)segments Sympathetic --contains ___________ motor neurons III. Superficial Anatomy of spinal cord A. The spinal cord is divided into 31 segments 2  11/1/2024 cervical segments 8 ________ thoracic 12 ________ 5 lumbar 5 sacral 1 coccygeal = 31 total Each segment consists of: 1. Dorsal root --contains ______ axons of sensory neurons Dorsal root ganglion: enlarged area along cell bodies the root that contains the __________ of sensory neurons 2. Ventral root --contains axons of motor neurons 3. distal to the ganglion, the dorsal and ventral roots join to form the spinal nerves *each is named after the associated vertebra Dorsal root Dorsal root ganglion Spinal nerve Ventral root _______ 3  11/1/2024 Both the dorsal and ventral roots travel outward through the… intervertebral foraming III. Superficial Anatomy of spinal cord foramen magnum B. The spinal cord starts at the _______________ where it joins to the most inferior part of the brain the medulla oblongata Cervical enlargement: here the cord is thicker because of the additional neurons shoulder/arm needed to service the _____________ Lumbar enlargement: thicker because of servicing the hip & leg 4  11/1/2024 = end of cord proper = a single thin strand of fibrous tissue that extends from the end of the conus medull. to the __________ coccyx ***forms part of a ligament that helps prevent the spinal cord from bouncing up and down Conus medullaris Cauda equina-- refers to the filum termin. AND the dorsal/ventral roots that extend past the conus Literal translation = ___________ Horses tail Filum terminale IV. Spinal Meninges -- 3 membranes that protect the spinal cord from damage caused by it rubbing against the bony vertebrae --these meninges are continuous with those of the brain 5  11/1/2024 Dura mater -- tough outermost , Arachnoid mater -- middle membrane --has fibrous extensions like a “________web” Spider's *space just outside the dura mater - contains _____________ adipose tissue - frequently site for anesthetic injection, “_________” epidurals Epidural space Subarachnoid space *space just below arachnoid mater - filled with cerebrospinal fluid (CSF) 6  11/1/2024 Spinal Taps -- procedure used to sample CSF *inferior to the conus medull. the subarach space is larger (aka. spinal tap) Dura mater Pia mater --clear, innermost *contains blood vessels servicing the spinal cord Arachnoid mater 7  11/1/2024 Meningitis --inflammation of meninges due to infection --can kill neurons if swelling cuts off blood supply I. Functional Organization of Gray Matter A. Divided into 4 regions (starting most posterior) (1) Somatic sensory -- contains sensory neurons for _______________________ skin muscle bone , , , joints (2) Visceral sensory -- contains sensory neurons for __________________ internal organs (3) Visceral motor -- motor neurons for internal organs and glands (4) Somatic motor -- motor neurons that control skeletal muscle SS VS (visceral sensory) VM SM 8  11/1/2024 B. Each of these regions is itself highly organized Ex. Somatic motor (SM) region at level of cervical enlargement VM / shoulder hand , fingers upper arm forearm The functional organization of the gray matter (and the white) is clinically important… SS Ex. car accident causes severe VS swelling at white dot VM SM Symptoms? II. Functional Organization of the White Matter A. The white matter of the spinal cord contains tracts Tract = a bundle of __________________ Similar axons in CNS 11 (Nerve = _______________ in PNS 9  11/1/2024 a nerve Fascicle -a group of axons 1. --carry ________ sensory info to the brain 2. descending -- carry motor commands from muscies/glands brain to the ______________ 3. Different tracts conduct different types of information Examples: --some conduct pain/temperature info --others joint position -- tickle/itch --conscious control of skeletal muscle postural muscles --subconscious control of ________________ 10  11/1/2024 4. many tracts cross-over to the other side somewhere along their path --cross-over may occur in spinal cord itself or in the brain Ex. Dog bites your left hand --sensory info travels up left arm but enters a tract in the right spinal cord and goes to ___________ right brain Ex. Tickles your left foot --tract in left spinal cord but crosses over ___________ in brain *both sensations go to right brain nerve *pain immediately crosses over to right spinal cord (but tickle stays in left spinal cord; doesn’t cross tract over until in brain) Bites left hand Tickles left foot Damage to the Spinal Cord Dorsal horn “Ascending Dorsal root tracts” Dorsal root ganglion A. If any of these parts are damaged, the person loses __________ sensation in those regions of the body normally served by that part of the cord 11  11/1/2024 Ex. Syphilis --caused by a bacterial infection --severe cases result in deterioration of an ascending tract that carries info on soft touch and joint position What symptoms would this cause? great difficulty walking “Descending tracts” Ventral root Ventral horn B. If any of these parts are damaged, the person loses ______________ motor function Ex. Polio --virus destroys ________ ventual horn What if you damage a spinal nerve? Dorsal root Spinal nerve Ventral root lose sensory "motor 12  11/1/2024 C. Multiple sclerosis (MS) --usually the person first loses myelin in tracts of the spinal cord and/or brain Lose sensory or motor? Loss of myelin in white matter of cerebrum Occipital lobe (sometimes MS patients lose their vision) D. If the spinal cord is cut across, the person will lose… sensory" Motor -- ___________________ function -- in general, in body regions inferior to the site of damage 13  11/1/2024 Quadriplegic C5 T1 Paraplegic L1 Why does this occur? Brain --because cord cannot “talk” with ________ Quadriplegic C5 T1 Paraplegic L1 Predict symptoms if cut is: --inferior to L1 * retain some use leg --at C8 Some * use of arms E. Spina bifida – a developmental defect that may affect the spinal cord (a neural tube defect) Occurs when vertebral arches fail to form completely Vertebral Vertebral arch foramen 14  11/1/2024 Spina bifida (cont.) 1. if only a few vertebrae are malformed, no problems *most common type 2. if numerous vertebrae are affected, infant has sac protruding from lower back a) the cyst may contain meninges and CSF, or in extreme cases, of the Spinal cord ________________________ parts b) the more neural tissue present, the more __________________________ severe the problems Spina bifida Spina bifida s.c. tissue 15  11/1/2024 - doctors may screen pregnant women for spina bifida by checking their blood for high levels of alpha-fetoprotein - not enough _________ folic acid [B vit] in diet greatly increases the risk of spina bifida Foods rich in folic acid 16