Gross Anatomy - Basic Anatomical Concepts

Fibrous Joints (unions or junctions between 2+ bones)

United by FIBROUS TISSUE so the amount of movement of the joints depends on the length of the fibers Types- 1. Sutures- (Synarthrosis) interlock along a wavy line or overlap 2. Syndesmosis- untied with a sheet of fibrous tissue (ligament of fibrous membrane)- partially moveable 3. Dentoalveolar syndesmosis (socket/gomphosis)- between a peg-like process and socket articulation (alveolar process of jaw- bone that holds tooth sockets), mobility indicates a pathological state (if something is stuck in teeth, etc.)

Sympathetic (Thoracolumbar) Division of SNS

- Cell bodies located in the spinal cord at vertebral levels T1-L2/3 - Cell bodies for postsynaptic neurons are located either in the paravertebral ganglia (link to form sympathetic trunks/chains on each side of the vertebral column and extend its length) or on the prevertebral (preaortic) ganglia- in plexuses that surround origins of main branches of abdominal aorta -Presynaptic motor fibers exit via ventral horn and roots and enter the VPR from T1-L2 only or L3 only , from the VPR (Ventral primary rami) into the sympathetic trunk via white rami communicants (myelinated), which exits only in this region

OVERVIEW OF PNS

-Cranosacral outflow, presynaptic cell bodies located in brain stem (CN III, VII,IX,X) and spinal cord segments S2-S4 -Isolated response -Long preganglionic neurons and short postganglionic neurons -Ganglia are on or within wall of target organs -Limited distribution- head and neck organs, thorax viscera, abdomen and pelvis

OVERVIEW OF SNS

-Thoracolumbar outflow, whole body response -Presynaptic cell bodies located in IML of spinal cord from T1-L2 or L3 - Shore preganglionic neurons by long postganglionic neurons -Ganglia are close to CNS (sympathetic trunk of prevertebral ganglia) -Wide distribution- whole body including extremities and skin

Skeletal Muscle Classification

-based on muscle fiber arrangement and shape Flat- parallel fibers, often with an aponeurosis (Flat white sheen along muscles; fascia) (External oblique) Fusiform- spindle shaped with a round thick belly and tapered ends (biceps) Pennate- feather-like -Unipennate- fibers on one side of tendon, bipennate- fibers on both sides of tendon, multipennate- radiating fibers that converge on a central tendon Quadrate- 4 equal sides (Rectus abdominis) Circular (sphincteral)- surround body opening or orifice, constrict when it is contracted (external anal sphincter) Multi-headed (multi-bellied)- have more than one head of attachment of more than one contractile belly (gastrocnemius, biceps brachii and triceps brachii)

Visceral Sensation

-visceral afferent fibers hitch a ride with ANS but are NOT a part of ANS bc they are integrated in the CNS -provides info on body's internal environment - triggers visceral or somatic reflexes (or both) (Ex: to regulate blood pressure or internal chemistry), is usually subconscious but becomes conscious with pain (by sudden distinction, strong spasms/contractions, chemical irritants, mechanical stimulation, or pathological conditions, ischemia) -Visceral reflex sensation (unconscious) travel in visceral afferent fibers next to the PNS fibers BUT the visceral pain sensations travel with visceral afferent fibers next to the SNS fibers

Anatomical Planes

1. Coronal/Frontal- like a crown, divides body into anterior (front) and posterior (back) 2. Median plane- a longitudinal cut that divides body into right and half sides 3. Sagittarius- also right down the middle but not necessarily into equal halves 4.Transverse- horizontal cut into superior (upper) and inferior (lower) parts

Skin/Integumentary System Layers (Epidermis, Dermis)

1. Epidermis- tough outer layer, keratinized epithelium, avascular, few nerve terminals 2. Dermis- dense layer with skin tone and toughness of skin, collagen/elastic fibers, forms a cutaneous plexus of anastomosing (fused together in a vein like network) arteries, contains nerve terminals for pain, pressure, and temperature, hair follicles, and sebaceous glands (glands that secret sebum/oil)

6 types of synovial joints

1. Plane- allows for gliding/sliding movements on articular surface 2. Hinge- allows for flexion/extension only in the Saginaw plane around a single transverse axis, ligament reinforced (elbow joint) 3. Saddle- allows for abduction/addiction and flexion/extension around two axes at right angles (biaxial/circular rotation possible)- saggital and frontal (carpometacarpal joint of thumb) 4. Condyloid/Ellipsoid- allows for ABD/ADD (biaxial) and flexion/extension movement in the saggital plane, circumduction is also possible, but more limited than saddle joints (metacarpophalangeal/radiocarpal joints) 5.Ball and Socket- multiaxial movement, flexion/extension, ABB/ADD, MR/LR(right or left), circumduction (hip or shoulder joints) 6. Pivot- allows for rotation around a central axis (uniaxial), C1 rotates around the dens of C2 (head rotation of the median atlantoaxial joint)

4 Functions of muscles

1. Prime mover (agonist)- contracts concentrically (shortens) to produce movement, usually a single main muscle 2. Fixator- steadies proximal parts of a limb, isometric contraction 3. Synergistic- compliments actions of prime mover, concentric contraction, several usually involved 4. Antagonist- opposes actions of another muscle, eccentric contraction (relaxes progressively to produce a smooth movement) both primary to oppose prime mover and secondary to oppose synergists

Types of muscle contractions (3)

1. Reflexive contraction- automatic, can control within limits, myotatic reflex (movement of a muscle after a stretch to tendon has been induced by tapping with a hammer) 2. Tonic- slight, always present contraction, creates muscle tone (Tonus), doesn't produce movement but give muscle firmness to stabilize joints and maintain posture, absent when in deep sleep, paralysis or under anesthesia 3. Phasic- a. Isometric (muscle length remains the same but muscle tension is increased to resist gravity or another antagonistic force (holding weight), b. Isotonic- muscles changes length to produce a movement- concentric- muscle shortening (lifting a weight, pushing a door, throwing a punch), eccentric- lengthening of a contracting muscle, controlled and gradual relaxation while continually exerting a diminishing force (walking, running, setting objects down)

Fascias

1. Superficial Facia (Subcutaneous Tissue, Hypodermis)- fatty layer located between dermis and deep fascia, loose connective tissue and most of the body's store fat, sweat glands, superficial blood vessels, lymphatic vessels, and cutaneous nerves cut through the superficial facia to send their terminal branches to the skin 2. Deep Fascia- dense organized connective tissue layer, no fat, invests deeper to surround muscles and neurovascular bundles, if passes over bone there is ALWAYS periosteum (membrane that covers all bones except joints) beneath it, limits outward expansion of contracting muscles and helps push blood out of the veins as muscles are compressed 2a. Subserous fascia- between musculoskeletal walls and serous membranes lining body cavities - also known as endothoracic, endoabdominal, or endopelvic fascia

Skeletal System

206 bones plus the Wormian (skull) and the Sesamoid (in tendons) Axial Skeleton- head, neck, trunk (skull, hyoid bone and cervical vertebrae, ribs, sternum, vertebrae and sacrum Appendicular Skeleton- pectoral girdle, upper extremity, pelvic girdle, and lower extremities

Types of Nerves

Afferent (sensory)- convey neural impulses from sensory organs (Eyes) and sensory receptors (skin) to the CNS Efferent (motor)- convey neural impulses from CNS to effector organs (muscles and glands), cranial or spinal - Cranial nerves-exit cranial cavity via cranium foramina, identified by descriptive name or by Roman numeral (can be somatic afferent, somatic efferent, visceral afferent, visceral efferent) -Spinal nerves- arise in bilateral pairs from a specific segment of spinal cord, exit vertebral column via intervertebral foramina, but may exit above or below vertebra of same number (spinal nerve C1 exits above C1 vertebra not through intervertebral foramen) —31 pairs of spinal nerves arising from 31 segments, identified by a letter and number —-C=cervical, 8 —T=thoracic, 12 —L=lumbar, 5 —S=sacral, 5 —Cx=coccygeal, 1

Joint Vasculature

Articular aa. (Arteries) and articular vv (veins) arise from vessels around joint, often anastomose (communicate) to form network (Periarticular anastomoses and venae comitantes) - ensures blood supply to and from joint

Nervous System

CNS- central nervous system, brain and spinal cord, higher mental functioning PNS- peripheral nervous system, conducts impulses away or to the CNS, Somatic Nervous System (SNS) and the Autonomic Nervous System (ANS)

Cutaneous nerves

Carry sensory information from skin, motor innervation to glands and smooth muscles

Muscle Tissue

Classified according to: Voluntary vs. involuntary Striated vs. smooth Somatic(muscle or skeletal) vs. visceral (internal organs) Types: 1. Skeletal Striated- voluntary somatic, skeletal muscles 2. Cardiac Striated- involuntary, heart muscles, pump blood 3. Smooth muscle- involuntary visceral muscle, forms vessel and hollow organ walls, moves substances using peristalsis (coordinated sequential contractions)

Somatic nerve plexuses

Combining of VPR from adjacent spinal nerves 1. Cervical plexus- C1-C4 2. Brachial plexus- C5-T1 3. Lumbar plexus (L1-L4) 4. Sacral plexus- L4-S4 T2-712 remain segmental and do not form a plexus

Types of Bone

Compact- thin layer of bone surrounding central mass of spongy bone, small and less numerous spaces, near weight-bearing bones Spongy- central compartment of bones except where it is replaced by medullary cavity (yellow fatty and/or red blood cell/platelet forming bone marrow), large numerous spaces that contains trabeculae

Somatic Nervous System

Composed of somatic parts of CNS an PNS Sensory and motor innervation INNERVATES ONLY SKELETAL MUSCLES (not smooth muscles, glands or viscera/hollow organs) Sensations reach conscious level

Skeleton- Cartilage

Connective tissue that forms parts of the skeleton requiring the most flexibility (costal cartilages connect ribs to sternum), is Avascular (Gets its nutrients by diffusion) and Articulate- covers articulating surfaces (bearing surfaces) of bones participating in synovial joints (a joint continuous with the periosteum and makes a cavity filled with synovial fluid over the articulating surface (surface where the joint connects bones -> Smooth low friction movement)

Autonomic Nervous System and its divisions

Consists of visceral efferent motor fibers, uses two neurons to reach destination, simulates smooth involuntary muscles, cardiac muscle, and glandular (Secretory) cells Accompanied by visceral afferent fibers (not part of ANS, but hitch a ride)- atomic reflexes and visceral pain impulses, regulation Divisions: 1. Sympathetic (thoracolumbar) 2. Parasympathetic(craniosacral) Conduction for both involves the presynaptic/preganglionic nueron in the gray matter of CNS, and the axon fibers synapse on the cell body of a postsynaptic/postgangionis neuron outside the CNS in autonomic ganglia where the fibers terminate on an effector organ

Spinal Nerve Rami

Dorsal primary Ramus- motor and sensory fibers, gives off medial and lateral cutaneous branches, medial branches have a dorsal branch which become dorsal cutaneous (skin) nerves, supply synovial joints of vertebral column, deep muscles of back, and overlying skin in a segmental pattern, do not merge to form major plexuses Ventral primary ramus- motor and sensory fibers, supply anterior and lateral regions of trunk(remain separate and Innervate muscles and skin in a segmental pattern), upper and lower limbs, MOST VPR MERGE TO FORM SOMATIC NERVE PLEXUSES (a network- fibers intermingles and a new set of peripheral nerves emerge)- larger than DPR

Collapsed Bursal Sacs and Viscera

Double layer of membranes surrounding important organs, create sacs that surround organs, but do NOT contain them inside, allows for freedom of movement Pericardial sac- surrounds heart Pleural sac- surrounds lung Peritoneal sac- surrounds abdominal viscera (internal organs) 2 layers of the sac are- 1. Parietal layer- outer layer 2. Visceral layer inner layer

Somatic and visceral fibers

General somatic afferent sensory fibers- transmit from body to CNS (skin, muscles, tendons and joints-pain, temp, pressure, proprioception-subconscious) General somatic efferent motor fibers- transmit voluntary impulses to skeletal muscles General Visceral afferent sensory fibers- transmit sensations from organs or blood vessels to CNS (dissension, blood gas and pressure) General Visceral efferent motor fibers- transmit involuntary impulses to smooth muscles and glandular tissues (has pre and post synaptic fibers)

Skeleton- Bone

Hard form of cartilage - support, protection, movement, storage of salts, supply of new blood cells Periosteum- membrane connect tissue that covers all bones except joints/cartilage, provide interface for attachment of tendons and ligaments Perichondrium- covers cartilage instead

Joint Innervation (to supply nerves)

Hilton's law- nerves supplying a joint also supply the muscles moving the joint and the skin covering their distal attachments Articular nn (nerves)- most are nerves that supply muscles that cross and move the joint, distally (hands and feet) are branches of cutaneous nerves that supply the overlying skin -transmit sensory impulses that contribute to sense of proprioception (awareness of location and movement of body, responds to twisting and stretching (synovial membrane is rather insensitive) BUT fibrous layer of joint capsule/accessory ligaments have numerous pain fibers and hurt when injured

Fascial Compartments

In the limbs, contains groups of muscles with similar functions and nerve supply Separated by intermuscular septa (thick sheets of deep fascia), may contain or direct spread of infection or tumors Retinacula- thickening of deep fascia near joints, holds tendons in place during extension/flexion Bursae- closed sacs of serous membrane (can secrete lubricating fluid), enable one structure to move without friction over the other, normally collapsed (potential spaces) Types: 1. Subcutaneous- between skin and bony prominences (elbow, knee) 2. Subfascial- lies beneath deep fascia 3. Subtendinous- movement of tendons over bone 4. Synovial tendon sheaths- specialized bursae that wrap around tendons and encloses them as they pass through osseofibrous tunnels

Spinal Nerve Roots

Initially arise from spinal cord as rootlets (ventral and dorsal), converge to form two nerve roots - ventral (anterior) nerve root- motor fibers from cell bodies in anterior horn of spinal cord to effector organs located peripherally -dorsal (posterior) nerve root- sensory fibers from cell bodies in dorsal root ganglion that extend peripherally to sensory endings and centrally to dorsal horn of spinal cord BOTH UNITE AT THE INTERVERTEBRAL FORAMEN FORMING A MIXED SPINAL NERVE -> IMMEDIATELY DIVIDE INTO TWO RAMI

Classification of Bones

Long bones- tubular (humerus, femur) Short bones- cuboidal, ANKLE AND WRIST ONLY Flat bones- protective (skull) Irregular bones- other (Face) Semisolid bones- develop in tendons to protect them from wear and to change their angle as they pass to attachments

Bone Markings and Parts

Markings- appear wherever tendons, ligaments, and fascias are attached, or where arteries lie adjacent to or enter the bones Parts 1. Diaphyis- shaft of bone, grows as develops 2. Epiphyses- ends of bones 3. Epiphysial plates/ Growth plates- cartilaginous plates between diaphysis and epiphyses to keep them from fusing during long bone growth 4. Epiphysial line- seam formed during fusion of diaphysis and epiphysis

Synovial Joints

Most common, free movements between bones, reinforced by accessory ligaments that are separate (extrinsic) or a thickening of the joint capsule (intrinsic) Some may have articular discs (discs that directly cover joints) or meniscus (cartilage that covers joints) United by joint capsule that encloses articular vacuity- the outer fibrous layer is lined by inner serous SYNOVIAL MEMBRANE Joint cavity- potential space that contains small amount of lubricating synovial fluid (Secreted by the synovial membrane)-> the periosteum of other participating bones blends with the fibrous capsule, may communicate with bursae (Especially the synovial membrane) The articular cartilage covers all articulating surfaces of the bone except that which is covered by the synovial membrane

Actions of Muscles

Muscle contraction produces movement at joint it crosses Flexion/Extension- decrease in angle between bones/parts of body vs. increase in angle in the sagittal plane around a transverse axis Abduction (ABB) vs. Adduction (ADD)- movement away from median plane vs. movement toward it, occurs in frontal plane around an anteroposterior axis - ex) thumb flexes and extends in frontal plane, ABD/ADD in sagittal plane Circumduction- flexion, ABD, extension, ADD (360), distal end moves in a circle Medial rotation and Lateral Rotation (LR)- movement around long. Axis of a bone, MR brings anterior surface of a limb closer to median plane, LR take anterior surface away from median plane (foot shuffle in and out or arm cross across chest and arm extend to side) Dorsiflexion/Plantarflexion- movements of foot at ankle joint, dorsiflexion brings toes up to ceiling, plantarflexion points them towards the floor Inversion/Eversion- Movement of foot, eversion moves sole of foot away from median plane, inversion moves sole of foot towards median plane (holding something between feet vs. side push of foot) Protraction/Retraction- movements of scapular, protraction- push head out away from midline, retraction- double chin stance lol towards midline Elevation/depression- up/down Upward/ downward rotation- rotation of scapular, til it's up or down Radial/Ulnar Deviation- ABD and ADD at the wrist

Peripheral Nervous System- Parts of a nerve

Nerve fiber- axon, neurolemma (Cell membranes of Schwann cells- myelinated or unmyelinated), and surrounding connective tissues Nerve- bundle of nerve fibers, connective tissue coverings that bind nerve fibers and fascicles together, and blood vessels that nourish the nerve fibers and coverings Ganglion- collection of neuron cell bodies- motor (autonomic) and sensory

Sympathetic trunk routes

Once in the sympathetic stunk, the fibers can either ascend or descend to other synapses in paravertebral ganglion above/below or at that level (this is used for head, neck, body wall, limbs and thoracic cavity activity via gray rami communicates) OR can pass through the sympathetic trunk without synapsing, continuing through the abdominopelvic splanchnic nerves (conveys visceral efferent/autonomic fiber to viscera along with the visceral afferent fibers) to reach prevertebral ganglia (used for presynaptics innervating viscera in adominopelvic cavity- vasomotor, pilomotor, sudomotor)

Skeletal Muscle Parts and Naming

Parts- head of bellies (fleshy, redfish, contractile portion), tendons (white non contractile portions, mainly collagen (provide a means of attachment), aponeurosis (flat sheet formed by some tendons that anchor the muscle to the skeleton or deep fascia) NAMED BY BONES TO WHICH THEY ARE ATTACHED (ex: sternocleidomastoid m- attaches inferiorly (below) to the sternum and clavicle and superiorly (above) to the mastoid process Also named based on... size(gluteus maximus), shape (trapezius, rhomboids, deltoid), location (rectus abdominis), action (abductor digiti minimi), and length (extensor carpi radialis longus)

Parasympathetic (Craniosacral) Division of ANS

Presynaptic cell bodies are located in either the gray matter of brain stem (Exit with cranial nerves III,V11,IX,X) for cranial outflow -> innervation to head, thoracic and abdominal viscera OR in the gray matter of sacral segments of spinal cord S2-4, exit via ventral roots and spinal nerves of S2-S4 for sacral outflow (pelvic splanchnic nerves arise here too) -> innervation to lower GI tract and pelvic viscera, more limited, fibers are not components of spinal nerves except for the initial part of S2-S4 so they synapse in or on the wall of target organs

Functions of ANS (SNS vs PNS)

SNS- CATABOLIC/ENERGY-EXPENDING (FIGHT OR FLIGHT)- heart rate increase, bronchi dilate, pupils dilate, digestive tract peristalsis stops, skin vessels constrict, skeletal muscle vessels dilates, sweat glands increase perspiration, ejaculation PNS- ANABOLIC/ENERGY CONSERVING (REST AND DIGEST)- Heart rate decreases, bronchi constrict, digestive tract increased peristalsis/blood flow, and erection - no effect on skin vessels, skeletal muscle vessels or sweat glands

Dermatome

Thoracic region Unilateral area of skin innervated by sensory fibers of a single spinal nerve- delivered directly by a spinal or cranial nerve or indirectly via a multisegmental peripheral nerve from a plexus Adjacent spinal nerves overlap almost completely- numbness comes from an interruption between at least 2 adjacent spinal nerves

Cartilaginous Joints

United by HYALINE CARTILAGE OR FIBROCARTILAGE (almost translucent thin cartilage found on surface of joints) Types 1. Primary cartilaginous joints (synchondroses)- united by hyaline cartilage, allows for slight bending and temporary unions, permits long bone growth until they eventually calcify and fuse 2. Secondary cartilaginous joints (symphyses)- strong slightly moveable united by FIBROCARTILAGE, (intervertebral discs or pubic symphysis), provides strength, shock absorption and flexibility to the vertebral column

Skeletal Muscle Vasculature and Innervation

Vasculature- blood supply is not as constant as nerve supply, usually supplied by multiple arteries Innervation- variation in nerve supply is rare, motor nerves come in, the muscles of similar actions are contained in a common fascial compartments and share Innervation by the same nerve (there are exceptions)