Shared Flashcard Set

Details

XXIX. Spinal Cord & Spinal Nerves
Unit 3: Week 13
19
Anatomy
Undergraduate 2
11/25/2013

Additional Anatomy Flashcards

 


 

Cards

Term
Spinal Cord Anatomy
Definition

-Length: 45cm (17-18in); Ends at level L1-2 in adults.

-Enlargements: in cervical (C4-T1) and lumbar (T11-L1) regions for innervation of upper and lower limbs.

-Conus Medullaris: pointed cone-shaped end of spinal cord L1-2.

-Cauda Equina: Collection of dorsal & ventral nerve roots at inferior ends of spinal cord filling in the vertebral canal.

Term
Meningeal Coverings
Definition

Brain/spinal cord covered by 3 layers of CT (meninges):
Epidural space lies between vertebrae & dura mater; contains fat.

1. Dura Mater: Outermost layer; very thick and tough.

2. Arachnoid Mater: Middle layer; delicate membrane with numerous fine branching fibers (spiderweb-like appearance); space between arachnoid and pia =

Subarachnoid space: contains cerebral spinal fluid.

3. Pia Mater: inner most layer; very thin; adherent to spinal cord except for:

Denticulate Ligaments-20-22 pairs along length of cord which hold cord in place within vertebral column and Filum Terminale- a thin, thread-like extension of pia that holds spinal cord to sacrum. 

Term
Paired Spinal Nerves
Definition

31 pairs; leave vertebral column through appropriate intervertebral foramina; formed by 2 adjacent vertebrae

-Cervical: 8 pairs (C1-C8); cords leave above corresponding vertebrae; ex: C1 in between skull & C1.

-Thoracic: 12 pairs (T1-T12); cords leave below coresponding vertebrae; ex: T1 in between T1 & T2.

-Lumbar: 5 pairs (L1-L5); also exit inferior to corresponding vertebrae.

-Sacral: 5 pairs (S1-S5); exit through correct sacral foramina.

-Coccygeal: 1 pair (CO)

Term
Mixed Spinal Nerves
Definition

Contain both afferent & efferent fibers;

-Ventral Roots: arrise from anterior side of spinal nerve; contains outgoing or efferent (motor) information; sends info to innervate skeletal muscles.

-Dorsal Roots: arrise from posterior side of spinal nerve; contains incoming or afferent (sensory) information; causes impulses from periphery located receptors to spinal cord.

Roots almost immediately unite after passing through dura mater to form a mixed spinal nerve which will then divide again to form a ventral ramus (to anterior/lateral trunk & extremities) and dorsal ramus (to deep back).

Meningeal Branch: innervates meninges and smaller branches of ANS called Rami Communicantes.


Term
Body Innervation
Definition

Posterior Body Trunk: muscles and skin by dorsal rami

Anterolateral Thorax & Abdomen Wall: muscles and skin by ventral rami

Term
Cross Sectional Spinal Cord Anatomy
Definition

Gray Matter: contains dorsal (sensory neurons) and ventral horns (motor neurons).

White Matter: contains motor fibers/tracts descending from brain and sensory fibers/tracts ascending to brain.



Term
Dermatomes
Definition

-An area of skin innervated by the cutaneous (sensory) branch of a single spinal nerve;

-All except C1 participate in dermatomes;

-Adjacent dermatomes on body wall are fairly uniform in width and arranged horizontally; those in extremites are longitudinally arranged.

-Trunk dermatomes regions overlap

-Limbs less obvious overlap

Upper Limbs: ventral rami C5-T1

Lower Limbs: ventral rami L1-S2

Term
Brachial Plexus
Definition

-Braid or network of several spinal nerves which come together to supply the upper extremities

Ventral Rami (5): C5-T1; can have postfix or prefix brachial plexus-contribution from C4 or T2 (one level higher/lower)

Trunks (3): formed from rami; Upper Trunk- C5-6; Middle Trunk- C7; & Lower Trunk- C8-T1.

Divisions (2): formed from trunks; Anterior Division- Flexor compartments; Posterior Division: Extensor compts.

Cords (3): formed from divisions; Lateral Cord- anterior division of upper & middle trunks; Medial Cord- anterior division of lower trunk; Posterior Cord- posterior divisions of all 3 trunks

Branches (5): formed from cords; Axillary Nerve- smaller branch of posterior cord; Radial Nerve- larger branch of posterior cord; Musculocutaneous Nerve- 1 branch of lateral cord; Ulnar Nerve- 1 branch of medial cord; Median Nerve- 1/2 branch of both lateral and medial cord

Term
Lumbosacral Plexus
Definition

-A network of nerves which supply the lower extremities; 

Lumbar Plexus: L1-4 (contributions from T12); forms 2 major branches- Femoral Nerve (iliacus/anterior thigh) & Obturator Nerve (medial thigh)

Sacral Plexus: L4-S4; major branch= Sciatic Nerve which splits into Tibial Nerve (hamstrings/posterior leg) & Common Fibular Nerve (lateral/anterior leg)

-Other branches: Superior Gluteal Nerve (gluteus medius & minimus/tensor fascia lata), Inferior Gluteal Nerve (gluteus maximus), & Pudendal Nerve (skin of perineum)

Term
Femoral Nerve Injury
Definition
(Quadriceps) Loss of strong leg extension
Term
Obturator Nerve Injury
Definition
Loss of thigh adduction
Term
Tibial Nerve Injury
Definition
Loss of strong plantar flexion (posterior leg); weak inversion of foot; some decreased extension of thigh
Term
Superficial Fibular Nerve Injury
Definition
Loss of eversion
Term
Deep Fibular Nerve Injury
Definition
Loss of dorsiflexion; weak inversion of foot
Term
Herniated Disc (Slipped Disc)
Definition

Protrusion of nucleus pulposus into the annulus fibrosus of an intervertebral disc;

Pushes on nerve root exiting from cord;

Common in lumbar region of back (L4-5 or L5-S1);

Sciatic nerve affected- causes pain in lower back, weakened hamstrings, and weakness of posterior leg muscles (sciatica)

Term
Musculocutaneous Nerve Injury
Definition
Weakened flexion and supination
Term
Radial Nerve Injury
Definition
Inability to extend wrist (wrist drop); possible inability to extend forearm
Term
Median Nerve Injury
Definition
Inability to flex 2nd & 3rd fingers; thenar function weakened
Term
Ulnar Nerve Injury
Definition
Loss of hand muscles (except thenar group)
Supporting users have an ad free experience!