Anatomy Midterm 2

Skeletal Muscle Tissue

Voluntary control

Striped appearance of muscle fibers/cell

aka Striated to striped voluntary muscle

Cardiac Muscle Tissue

Involuntary control

Striated appearance

Forms walls of heart

Smooth Muscle Tissue

Involuntary control

Controls flow and secretion in blood vessels, hollow organs, digestive system

Functions of Skeletal Muscle

Produce Skeletal movement - pull on tendons to move bones

Maintain posture and body position - stabilize joints to aid in posture

Support soft tissue - support weight of visceral organs

Regulate entering and exiting of material - voluntary control over swallowing, defecation and urination

Maintain body temperature - some of the energy used for contraction converted to heat

Parallel Fusiform

Round thick belly with tapered ends

Run entire length of a muscle or may be interrupted by transverse, tendinous tissue at regular intervals

Convergent (fan)

Form a broad area but come together at a common point

Pennate (feather like arrangement)

Unipennate - Fibers arranged on the same side of tendon

Bipennate - fibers arranged on both sides of the tendon

Multipennate - The tendon branches within the muscles

Circular (sphincteric)

Muscle fibers from concentric rings, constricting an opening or orifice when contracting

Agonist

Prime mover

Achieve intended movement

Antagonist

Oppose intended movement

Synergist

Contract together to accomplish movement

Assisting muscles

Stabilizer

Action is to primarily fixate a joint

Sternocleidomastoid action

Unilateral - laterally flexes head to same side, rotates head opposite side

Bilateral - Flexes neck, protracts head, aids in inhalation

Scalene action

Flexes and side bends the neck, elevates ribs 1 and 2 (aids in inhalation)

Deep intrinsic Back Muscles

Stabilizes and provide delicate adjustment of vertebrae; slightly extends and rotates vertebrae

Quadratus Lumborum Action

Unilateral - laterally flexes vertebral column

Bilateral - depresses ribs during forced exhalation; stabilizes diaphragm during inhalation

Internal intercostals action

Depresses ribs

External intercostals actions

Elevates ribs

External oblique action

Depresses ribs, flexes and laterally rotates vertebral column to the opposite side

Internal oblique action

Depresses ribs, flexes and laterally rotates vertebral column to the same side

Rotator cuff muscles

Supraspinatus - Abducts arm

Infraspinatus - laterally rotates arm

Teres Minor - Adducts and laterally rotates arm

Subscapularis - Adducts and medially rotates arm

Anterior Compartment of forearm muscles (flexors)

Biceps brachii

Brachialis

Brachioradialis

Pronation and flexion

Posterior compartment of forearm (extensors)

Triceps brachii

Anconeus

Supination and extension

Superficial or 1st layers of anterior forearm

Pronator teres

Flexor carpi radialis

Palmaris longus

Flexor carpi ulnaris

2nd layer of anterior forearm musculature

Flexor digitorum ulnaris

3rd layer of Anterior Forearm Muscles

Flexor digitorum profundus

Flexor pollicis longus

4th layer (deepest) anterior forearm musculature

Pronator quadratus

1st layer posterior forearm muscles

Brachioradialis

Extensor carpi radialis

Extensor Carpi radialis longus

Extensor carpi radialis brevis

Extensor digitiroum communis

Extensor carpi ulnaris

Anconeus

2nd layer posterior forearm muscles

Supinator

Abductor pollicuis longus

Extensor pollicis brevis

Extensor pollisics longus

Extensor indicis

Thenar and hypothenar eminence

Contain muscles to abduct, flex and preform opposition of digits 1 and 5

Midpalmar or central group

Contain muscles that adduct and abduct digits, assist in flexion of MP joints and extension of IP joints

Due to their attachment into the extensor expansion

Superficial fascia of IT band

Continuous layer over whole of thigh, contains fat, superficial vessels and nerves - support stalking

Deep Fascia (fascia lata)

Layer surrounds muscles and varies in thickness under the name IT Tract

Separates individual muscles

Dense irregular connective tissue

Deep Lateral Rotators of the thigh

Piriformis

Super gemellus

Inferior gemellus

Obturator externus

Obturator Internus

Quadratus Femoris

Lateral compartment of leg

Fibularis longus

Fibularis Brevis

Superficial posterior compartment Of leg

Gastrocnemius

Soleus

Plantaris

Anterior Compartment of leg

Tibialis anterior

Extensor hallucis longus

Extensor digitorum longus

Peroneus tertius

Deep posterior compartment leg muscles

Popliteus

Flexor hallucis longus

Flexor digitorum longus

Tibialis posterior

Triceps Surae

Tow heads of the gastrocnemius and single head of soleus are grouped together and are known as triceps surae

Neurons

Electrically excitable cells that initiate, transmit and receive nerve impulses

Neuroglia (glial Cells)

non excitable cells that support and protect the neurons

5x more abundant than neurons and accounts for ½ volume of nervous system

Glial cells are smaller than neurons maintain the ability to divide

Neuron classification

structural - process of emanating from cell body

Functional - sensory neurons transmit impulses from peripheral receptors to the brain or spinal chord

Anatomy of Spinal chord

Passes though foramen magnum

End of spinal chord called conus medullaris

Spinal cord subdivided into 5 parts

Cervicale to coccygeal

Parts do not match up exactly with the vertebra of the same name

Collection of axons entering or leaving spinal chord

Roots are a collection of 8 - 12 rootlets

31 pairs of nerves

Cauda equina

Spinal chord Meninges

Protected and encapsulated by these

Pia matter - Innermost meninx that adheres directly to the spinal chord

Delicate layer composed of elastic and collagen fibers and supports some of the blood vessels supplying the spinal chord

Arachnoid matter - spiderlike web fibers

Dura matter - Most external layer of meninges

Epidural space

Between dura matter and periosteum covering the inner walls of the vertebra

Houses areolar connective tissue, blood vessels, and adipose connective tissue

Epineurium spinal nerve

Tough fibrous sheath of dense irregular connective tissue

Isolates neve from general circulation

Perineurium spinal nerve

Not as dense as epineurium

Surrounds bundles of axons, fascicle

Endoneurium

Delicate collagenous and elastic fibers

Spinal Nerve Distribution (somatic nervous system)

After exiting intervertebral foramen it divides into 2 rami

Dorsal ramus - innervate deep muscle and skin of back

Ventral ramus - innervate large portion of the trunk, upper and lower limbs

Nerve Plexuses

Nerves join, branch out, then rejoin

Contributions from ventral rami of spinal nerve

Cervical Plexus

Spinal nerves c1 - c4

Supplies anterior neck muscles: skin of the neck, head and shoulders

Notable branch: phrenic

Phrenic Nerve

Branch of cervicale plexus

Receives contribution from c3 - c5

Provides entire nerve supply to the diaphram

Brachial Plexus

Formed by the anterior rami of spinal nerves c5 - t1

Innervates pectoral girdle and entire upper limb

Dermatomes

Segment of skin supplied by a single spinal nerve

Anesthesia in selected region could innervate a segment of skin

Ambiguous tomograph

Lumbar Plexus

Ventral Rami of spinal nerves

notable - femoral n gives rise to many motor branches to the thigh; saphenous n. longus branch relaying sensory information on the leg

Sacral Plexus

Ventral Rami of spinal nerves L4 - S4

Note - sciatic n. supplies the posterior thigh, leg and foot

Sacral Plexus

Sciatic never, largest and longest nerve in the body

Sciatic n. composed of two divisions wrapped in a common sheath - tibial division and common fibular division

Embryonic Development of the brain

Neural place - Neural groove - Neural tube

Brain Regions

Cerebrum

Diencephalon

Brainstem

Cerebellum

Grey Matter

Neuron cell bodies and their associated dendrites

Form nucelli

Unmyelinated axons

White Matter

Myelinated axon

Form tracts

Support and protection of the brain

Boney cranium

Cranial meninges

Cerebrospinal fluid

Blood brain barrier

Meningeal spaces

Extradural or epidural space

Potential space between bone and dura mater

Exists only under pathological conditions

Subdural space

Subarachnoid Space

Cranial Dural Septa

Extension of meningies

Flax cerebri

Tentorium cerebelli

Diaphragma selae