Anatomy exam ch 13

Vertebral column

the spinal cord is located within the vertebral canal of this structure.

Meninges

Three distinct, protective, connective tissue coverings that encircle the spinal cord and brain

dura mater

the most superficial of the three spinal meninges is a thick strong layer composed of dense irregular connective tissue

arachnoid mater

middle of the meningeal membranes, is a thin, avascular covering comprised of cells and thin, loosely arranged collagen and elastic fibers

Pia mater

The innermost meningeal membrane is a thin transparent connective tissue layer that adheres to the surface of the spinal cord and brain; consists of thin squamous to cuboidal cells within interlacing bundles of collagen fibers

Subarachnoid space

Space between the arachnoid mater and the pia mater, contains shock-absorbing cerebrospinal fluid

Conus medullaris

Ends at the level L1-L2, where the spinal cord terminates as a tapering conical structure

Denticulate ligaments

Triangular-shaped membranous extensions of the pia mater suspend the spinal cord in the middle of its dural sheath

Cauda equina

Roots of these lower spinal nerves angle inferiorly alongside the filum terminale in the vertebral canal like whisps of hair

Epineurium

the outermost overing of the entire nerve; consists of fibroblasts and thick collagen fibers

Perineurium

Middle layer; wraps around nerve fascicles and is a thicker layer of connective tissue

Endoneurium

wraps individual axons within a nerve and consists of a mesh of collagen fibers, fibroblasts, and macrophages

Posterior ramus

Serves the deep muscles and skin of the posterior surface of the trunk

Rami

A short distance after passing through its intervertebral foramen, a spinal nerve divides into several of these branches

Anterior ramus

Serves the muscles and structures of the upper and lower limbs and the skin of the lateral and anterior surfaces of the trunk

Dermatome

The area of the skin that provides sensory input to the CNS via one pair of spinal nerves of the trigeminal (V) nerve

Phrenic nerve location

C3-C5, diaphragm

Cervical plexus

Formed by the roots of the first four cervical nerves, supplies the skin and muscles of the head, neck, and superior part of the shoulders and chest

Brachial plexus

Extends inferiorly and laterally on either side of the last four cervical and first thoracic vertebrae; provides almost the entire nerve supply of the shoulders and upper limbs

Axillary nerve

supplies the deltoid and teres minor muscles

Musculocutaneous nerve

supplies the anterior muscles of the arm

radial nerve

supplies the muscles on the posterior aspect of the arm and forearm

median nerve

supplies most of the muscles of the anterior forearm and some of the muscles of the hand

ulnar nerve

supplies the anteromedial muscles of the forearm and most of the muscles of the hand

Lumbar plexus

Supplies the anterolateral abdominal wall, external genitals, and part of the lower limbs

Femoral nerve

Largest nerve arising from lumbar plexus; distributed to flexor muscles of hip joint and extensor muscles of knee joint, skin over anterior and medial aspect of thigh and medial side of leg and foot

Obturator nerve

Adductor muscles of hip joint; skin over medial aspect of thick

Sacral plexus

Situated largely anterior to the sacrum; supplies the buttocks, perineum, and lower limbs

Tibial nerve

Gastrocnemius, plantaris, soleus, popliteus, tibialis posterior, flexor digitorum longus, and flexor hallucis longus muscles.

Common fibular nerve

Divides into superficial fibular and deep fibular branch

Sensory receptor

Distal end of a sensory neuron; responds to a specific stimulus by producing a graded potential called a generator potential; if the generator potential reaches the threshold level of depolarization it will trigger one or more nerve impulses in the sensory neuron

Sensory neuron

The nerve impulses propagate from the sensory receptor along the axon of this location to the axon terminals, which are located in the gray matter

Integrating center

One or more regions of gray matter within the CNS acts as this. In the simplest type of reflex, this is a single synapse between a sensory neuron and a motor neuron

Motor neuron

Impulses triggered by the integrating center propagate out of the CNS through this

Effector

The part of the body that responds to the motor nerve impulse

Stretch reflex

causes contraction of a skeletal muscle in response to stretching of the muscle

Tendon reflex

operates as a feedback mechanism to control muscle tension by causing muscle relaxation before muscle force becomes so great that tendons might be torn

Flexor reflex

The incoming and outgoing impulses propagate into and out of the same side of the spinal cord; several motor neurons must simultaneously convey impulses to several limb muscles

Crossed extensor reflex

Sensory neuron activates several interneurons that synapse with motor neurons on the left side of the spinal cord in several spinal cord segments

Monosynaptic reflex arc

A reflex pathway having only one synapse in the CNS

Polysynaptic reflex arc

Involves more than two types of neurons and more than one CNS synapse