RVU Anatomy Terms MSK 2010

• A.
• Planes Text Fig. I.2

• 1. Median (midsagittal): divides the body into two equal left and right halves vertical longitudinal plane
• 2. Sagittal (parasagittal): divides the body into l & r Unequal portions, parallel to Median
• 3. Coronal (frontal): divides the body into front and back portions, @ right angles to Median
• 4. Horizontal (transverse): divides the body into upper and lower portions, at right angles to median and frontal. Radiologists define as transaxial,axial

Direction Text Fig. I.4

• 1. Anterior/posterior:ventral/dorsal
• 2. Superior/inferior: cranial/caudal
• 3. Medial/lateral: toward or away from the midline of the body
• 4. Proximal/distal: closer to vs. further away from the trunk or known point
• 5. Internal/external inside or closer to center, vs outside of or farther from the center of an organ or cavity, ind of direction
• 6. Superficial/deep:farther from surface, ex humerus is deep to arm muscle
• 7. Ipsilateral/contralateral: same side vs. opposite side
• 8. Rotation: referred to as being medial or lateral, internal or external, inward or outward

1. Flexion, including dorsiflexion and plantar flexion/extension: decreasing (closing) vs. increasing (opening) the angle across a joint. Dorsi vs. plantar flexion refer to the foot, only. usually movement in anterior direction. knee is exception, cause it is rotated 180 degrees to other joints, flexion post-extension ant

2. Adduction/abduction: toward or away from the body or a point of reference

3. Rotation: medial or lateral, internal or external, inward or outward

4. Circumduction: combination of movement resulting in circular motion

5. Opposition: movement of the thumb against the tips of the fingers

6. Protrusion/retrusion: movement of the jaw forward and back

7. Elevation/depression (superior/inferior); protraction/retraction (abduction/adduction): refers to scapular movements, only.

8. Pronation/supination: applies to the hand and foot, only; corresponds to prone (laying on its ventral surface) and supine (laying on its dorsal surface), respectively.

Composition

a. Cells

• 1) Static - fibroblasts, fat, fixed macrophages, mast cells
• 2) Mobile - other macrophages i.e. PMNs and other wandering cells (cytotoxic killer T cells)

b. Fibers

• 1) Collagen - structural integrity
• 2) Elastin - elasticity
• 3) Reticular - support/rigidity

c. Ground substance

1) Mucopolysaccharides

Function

• a. Adds strength
• b. Provides continuity to structures covered\encircled by fascia
• c. Provides ease of movement by allowing structures to move easily over one another

a. Superficial (tela subcutanea) ‑ connective tissue layer found directly beneath the skin composed of two fairly indistinct layers: a more superficial layer composed mostly of fat, referred to as the "fatty layer"; a deeper, more membranous reinforcing layer referred to as the "membranous layer". In the abdomen, these layers are more distinct and are referred to as Camper's and Scarpa's fascia, respectively.

b. Deep ‑ a "stocking‑like" vestment of fibrous connective tissue, devoid of fat, located deep to the superficial fascia. It surrounds the body musculature, forms sheaths for nerves and vessels and provides for general compartmentation by attaching to bony prominences. Also, provides accessory attachments of muscle to bone.

Retinaculum (L. Band, Halter) ‑ a narrow band of deep fascia associated with a joint which functions to hold tendons close to bones as the joint is moved; prevents “bowstringing” of tendons across joints.

a specialization of deep fascia that forms a partition between muscular groups in such areas as the upper and lower limbs and neck. These partitions assist in delineating muscular compartments that are most often named for the major function of the muscles located within the compartment. Intermuscular septa may also increase the strength of a muscle by providing areas of attachment for muscular fibers.

3) Neurovascular sheath - a tubular sheath of deep fascia that surrounds arteries, veins, lymphatics and nerves that traverse and/or feed a muscular compartment.

Bursa (ae) pl. – connective tissue membranes which surround tendons as sheaths, overlay boney prominences, and surround organs as bursal sacs, i.e., pleura, pericardium, and peritoneum. Their linings secrete serous fluid which reduces the frictional component of structures moving within or over them.

• b. Provides a system of levers for the action of skeletal muscles
• c. Blood producing organ
• d. Storage site for calcium and phosphorus

Composition Text Fig. I.12

a. Cortex - outer mantel of compact bone; responsible for shape

b. Cancellous - inner supportive layer of trabeculated "spongy" bone; responsible for strength

c. Medullary cavity - innermost "hollow" area filled with marrow; may be "yellow" serving as a fat storage department or "red" serving as a blood forming organ

d. Periosteum - connective tissue layer surrounding bone which:

• 1) sends fibers (Sharpey) into the bone for anchoring purposes
• 2) possesses an inner layer of osteoprogenitor cells which participate in bone growth and repair
• 3) is highly innervated

NOTE: It is the presence of composition and function which provide landmarks of relief on bone in response to stress exerted on the periosteum by tendons.

e. Endosteum - lines medullary spaces, is less well developed than periosteum, however, does possess osteoprogenitor cells.

Divisions Text Fig. I.11

a. Axial - skull, vertebral column, rib cage

b. Appendicular - limbs and bones of "girdle" which attach them to the axial skeleton.

• b. Short (cuboidal) - carpals and tarsals
• c. Irregular - vertebrae, os coxa (hip), irregular bones of the skull, i.e., sphenoid, ethmoid, etc.
• d. Flat - scapula, sternum, ribs, flat bones of skull, i.e., parietal, occipital, frontal, etc.
• e. Sesamoid - patella

• NOTE: Sesamoid bones develop within tendons where they cross long bones
• of the limbs. They help to reduce erosion of the tendons and help to provide the
• muscle with a greater mechanical advantage by changing the angle of approach
• of a tendon to its insertion.

• a. Shaft - longest portion of a long bone
• b. Head, condyle - expanded smooth articulating portions located at the ends of long bones
• c. Line, ridge, crest, tubercle, tuberosity, spine, and trochanter - areas of relief in order of increasing size; provide sites for muscle attachment
• d. Facet - smooth articulating surface
• e. Pit, fovea, fossa - depressions listed in increasing depth
• f. Groove, sulcus - linear depressions
• g. Foramen - hole
• h. Canal, canaliculus

• 1) Diaphysis:shaft
• 2) Metaphysis: expanded portion of shaft approaching the epiphysis
• 3) Epiphysis(es): distal ends of long bones

1) Growth in length

a) Expanding growth of cartilage located at epiphyseal plate (located between respective metaphyses and epiphyses) grows distalward toward the epiphysis.

b) Cartilage closest to the epiphyses ossifies.

c) During adolescence (hormonally determined) growth stops and the epiphyseal plate ossifies, leaving an identifiable epiphyseal line.

NOTE: Disruption of epiphyseal plates can cause premature closer of the plate resulting in shortening of the affected bone.

2) Growth in width (appositional growth)

a) Appositional growth is the result of synergistic activity of osteoclasts and osteoblasts to alternately remove bone from the wall of the medullary cavity and form new bone on its external surface.

Vertebral levels

1) Vertebral levels are a convenient means of locating important structures within the body, i.e., the arch of the aorta is located opposite vertebral level TV4, bifurcation of the aorta exists opposite vertebral level LV4, etc.

• NOTE: Do not confuse vertebral level with dermatome, i.e., the dermatome at
• the umbilicus is T10, however, the umbilicus is located approximately oppositevertebral body L3.

1. Fibrous (synarthrosis) ‑ joints united by fibrous tissue

a. Suture

• 1) Occur only between bones of the skull
• 2) In the adult, bones united by sutures may be slightly moveable

b. Syndesmosis

1) Union between two bones is accomplished by a fibrous sheet or ligament, i.e., tibiofibular & tympanostapedial joints

2) Joints of this type vary in their degree of movement.

• a. Synchondrosis ‑ joints united by hyaline cartilage
• 1) Epiphyseal plate
• 2) Normally immovable
• b. Symphysis ‑ joints united by fibrocartilage
• 1) Symphysis pubis, joints between intervertebral bodies
• 2) Partially movable

• Synovial (diarthrosis) ‑ most common type of articulation
• a. Joint characteristics
• 1) Articular surfaces covered by hyaline cartilage
• 2) Presence of a joint capsule surrounding a joint cavity
• 3) Joint capsule lined by a synovial membrane that secretes synovial fluid important for joint lubrication and is nutritive to the articular cartilage
• 4) Joint capsule reinforced with capsular ligaments txt-accessory
• 5) May possess a fibrocartilaginous articular disk or interarticular ligaments
• 6) Joints are freely mobile

Blood Supply

1) A rich network of vessels surrounds the joint supplying the epiphysis, joint capsule and synovial membrane, all areas except the articular cartilage.

c. Nerve supply

1) Joints are highly innervated, nerve endings being located in the articular capsule and synovial membrane.

• 2) Fibers are of two types:
• a) Pain-nociceptor
• b) Proprioceptive ‑ provide information concerning the position and movements of the bones involved in a specific joint.

• Note: Hilton's law: In general, nerves which supply muscles moving a specific
• joint also provide innervation to the overlying skin as well as to the interior of that joint.

Types Text Fig. I.17

• 1) Plane or gliding - small articular surfaces slide one upon the other. Examples: facet joints of the vertebral column, intercarpal and intermetacarpal joints
• 2) Hinge - actions of flexion and extension allowed around a single transverse axis.
• Examples: elbow, interphalangeal joints of the fingers and toes.
• 3) Pivot - a process of bone serves as a pin and is surrounded by an osseofibrous ring; allows rotational movement longitudinally oriented about a single axis. Examples: proximal radioulnar joint, atlantoaxial joint
• 4) Condyloid - modified ball and socket employing a shallow ellipsoidal socket and a ball that is not exactly round; allows movement in two planes (biaxial) at right angles to one another.
• Examples: wrist joint (radiocarpal), metacarpophalangeal and metatarsophalangeal joints.
• 5) Saddle (sellar) - biaxial articulation where the surfaces of each articulating bone lie in opposite directions (concave in one direction, convex in another [like a saddle]) and the two bones reciprocally fit precisely with one another.
• Examples: carpometacarpal joint of the thumb.
• 6) Ball and Socket (spheroidal) - a convex head fits a concavity, more or less, precisely, allows greater freedom of motion
• Examples: shoulder and hip joints

• a. Skeletal, striated, voluntary: innervated by somatic nerve fibers
• b. Smooth, non-striated: innervated by the autonomic nervous system
• c. Cardiac, semi-striated: Innervated by the autonomic nervous system

1) Muscles act upon articulated elements of the skeleton to provide movement only through contraction. A muscle exerts no action when it relaxes.

2) Muscles exert force on skeletal elements through their tendinous attachments; muscles crossing two joints have an action at each joint.


3) Origin - in general* the attachment of a muscle to a more stationary osseous structure.

4) Insertion - in general* the attachment of a muscle to a more moveable osseous structure.

Many muscles have the potential to "reverse" their origin and insertion. That is by "fixing" or otherwise stabilizing the previously more moveable segment the former stationary segment becomes moveable (reference reversal).

• The structure of the belly of muscles is varied and can usually be identified as one of the following:
• (Text Fig. 1.8)

• a) Fusiform: parallel fibers longitudinally oriented; weakest example -biceps brachii
• b) Unipennate: parallel fibers that attach to a tendon obliquely.
• c) Bipennate: "feather-like"
• d) Multipennate: many feathers next to one another; strongest

Medial means toward the midline of the body, whereas lateral structures lie further away from the midline. Intermediate structures lie between medial and lateral structures, and median structures lie on the midline of the body.Example: The trachea is a median structure. It lies medial to the more laterally placed point or top of the shoulder. The clavicle is intermediate between these two. One could also say that the clavicle is medial to the point of the shoulder, but lateral to the trachea

A coronal plane, also called a frontal plane, is any plane passing down through the body parallel to the coronal suture of the skull, dividing the body into front and back portions. Coronal planes are therefore perpendicular to sagittal planes and pass through the length of the body

The sagittal plane is named for the sagittal suture, which is a mid-line suture joint of the skull. It is also known as the median or mid-sagittal plane, and it divides the body into right and left halves. Planes passing parallel but not in the mid-line are called para-sagittal planes.

• In certain areas of the body, i.e., abdomen and back, a
• tendinous insertion may form a large sheet-like attachment referred to as an aponeurosis.

• Structures associated with tendons:
• a) Retinaculum and/or fibrous sheaths - connective tissue structures which hold tendons close to bones which they traverse, thereby preventing them from "bow-stringing" and facilitating their action by acting as pulleys.

b) Bursae and synovial sheaths - fluid filled sacs which lie between tendons and underlying bone or encircle tendons; prevents erosion of the tendon and facilitates its movement.

• a) Maximus, Medius, Minimus (Gluteal muscles)
• b) Longus, Brevis, Magnus (Adductor muscles of the thigh)
• c) Vastus (Medialis, Lateralis, Intermedius of quadriceps)

• a) Deltoid (Triangular)
• b) Quadratus (Square)
• c) Teres (Round)
• d) Trapezius (Trapezoidal)
• e) Pyramidalis
• f) Rhomboideus
• g) Lumbricals (Worm-like)
• h) Scalene (Uneven)
• i) Serratus (Saw-like, notched)
• j) Soleus (Sandal-shaped)

• Number of Heads
• a) Biceps (Two)
• b) Triceps (Three)
• c) Quadriceps (Four)

• Fiber Direction
• a) Rectus (Straight)
• b) Transversus
• c) Oblique

• Location
• a) Latissimus Dorsi (Back)
• b) Interosseous (Between bones)
• c) Superficialis
• d) Profundus (Deep)
• e) Intermedius
• f) Brachialis (of the arm)
• g) Femoris (of the thigh)
• h) Popliteus (of the knee)

Most are named according to function and attachment

• Function
• a) Flexor/Extensor
• b) Levator/Depressor
• c) Pronator/Supinator
• d) Abductor/Adductor
• e) Constrictors/Sphincters
• f) Corrugator
• g) Erector
• h) Tensor

• 7) Attachments
• a) Stylohyoid, thyrohyoid, omohyoid, geniohyoid, mylohyoid
• b) Palatoglossus/palatopharyngeus
• c) Cricothyroid, cricoarytenoid
• d) Thyroarytenoid